Co-reporter:Wei Wang, Ye Wang, and Gui-Chang Wang
The Journal of Physical Chemistry C March 30, 2017 Volume 121(Issue 12) pp:6820-6820
Publication Date(Web):February 28, 2017
DOI:10.1021/acs.jpcc.7b00903
Spin-polarized density functional theory computations have been used to investigate the CO dissociation mechanisms and the different catalytic activities of the reaction on Fe(100) surfaces with different Pd coverages. CO can dissociate on Pd/Fe surfaces via three different mechanisms: direct and H-assisted mechanisms via HCO intermediate or COH intermediate. In our calculation, it was found that the activation barriers of direct CO and COH dissociation mechanisms on pure and Pd-doped Fe(100) surfaces were higher than that of the HCO dissociation mechanism. Besides, energy barriers for the identical reaction pathway on Fe-rich Fe(100) surfaces were lower than those on Pd-rich Fe(100) surfaces, namely, CO dissociation mainly occurs via the HCO intermediate pathway and the catalytic activity becomes lower with Pd coverage increasing toward CO dissociation in both direct CO and H-assisted CO dissociation mechanisms. As a result, CO dissociation mainly occurs on Fe-rich Pd/Fe surfaces, leading to the formation of CHx, and Pd-rich Pd/Fe surfaces can stabilize CO, which may afford the high selectivity to oxygenate. The bimetallic catalysts will provide two different active sites that are synergetic for the formation of higher alcohols. Moreover, the difference between Pd-doped and Cu-doped Fe(100) systems was compared and analyzed based on the d-band model, and it was found that the d-bandwidth of Cu/Fe(100) was more narrow compared to that of Pd/Fe(100); this was agreement with the calculation results that the energy barrier for C–O bond scission on Cu/Fe(100) was lower than that on Pd/Fe(100). We predicted that methane content decreases and methanol content increases with Pd coverage increases on Pd/Fe(100), and the selectivity of methanol on Pd/Fe(100) is higher than that on Cu/Fe(100). Importantly, a typical “ volcano curve” between ethanol synthesis and the HCO dissociation barrier was gained, in which the selectivity for the ethanol synthesis is highest on the Fe2Cu2/Fe(100) system among these studied bimetallic model catalysts due to its moderate catalytic activity for HCO dissociation.
Co-reporter:Kang Cheng;Jincan Kang;Qinghong Zhang
Science China Chemistry 2017 Volume 60( Issue 11) pp:1382-1385
Publication Date(Web):11 August 2017
DOI:10.1007/s11426-017-9086-2
Co-reporter:Xinquan Shen;Jincan Kang;Wei Niu;Mengheng Wang;Qinghong Zhang
Catalysis Science & Technology (2011-Present) 2017 vol. 7(Issue 16) pp:3598-3612
Publication Date(Web):2017/08/14
DOI:10.1039/C7CY01041A
ZnO-containing MFI zeolite catalysts with bimodal and trimodal hierarchical pore structures were prepared, characterized and studied for the conversion of methanol to aromatics. Treatments of H-ZSM-5 with NH4F and NaOH generated bigger micropores with a mean size of around 0.8 nm and mesopores with mean sizes of 5–20 nm, respectively. The combination of alkaline and fluoride treatments resulted in a trimodal pore structure. The method for H-ZSM-5 treatments affected the dispersion of ZnO. The fluoride treatment favoured the dispersion of ZnO, whereas the alkaline treatment led to large ZnO particles. We clarified that the hierarchical pore structure, acidity and dispersion of ZnO played crucial roles in the formation of aromatics. Benzene, toluene and xylenes (BTX) mainly constituted the aromatics over our catalysts, and the yield of BTX decreased with increasing reaction time. A larger density of Brønsted acidity favoured the yield of BTX at the initial stage but was unbeneficial to the stability for BTX formation. The increase in pore hierarchy suppressed the coke deposition inside the micropores and increased the coke tolerance, thus enhancing the catalyst stability for BTX formation. The catalyst with a larger pore hierarchy also showed higher selectivities for aromatics and BTX. Aromatics can be formed via lower olefin intermediates by hydrogen-transfer or dehydrogenation pathways. We propose that ZnO, in particular the highly dispersed ZnO clusters, enhances the selectivity for aromatics by catalysing the dehydrogenation pathway, whereas the hierarchical pore structure facilitates the transfer of reaction intermediates and thus accelerates the formation of aromatics.
Co-reporter:Shunji Xie;Zebin Shen;Huamin Zhang;Jun Cheng;Qinghong Zhang
Catalysis Science & Technology (2011-Present) 2017 vol. 7(Issue 4) pp:923-933
Publication Date(Web):2017/02/20
DOI:10.1039/C6CY02510B
Bismuth vanadate (BiVO4) single crystals with controllable facets and cocatalysts were synthesized and studied for photocatalytic coupling of formaldehyde into C2 compounds mainly including ethylene glycol and glycolaldehyde. By using chloride anions as a morphology-controlling agent, we succeeded in synthesizing BiVO4 single crystals with a uniform truncated tetragonal bipyramidal morphology enclosed with {010} and {110} facets. The ratio of exposed {010} and {110} facets could be regulated by changing the concentration of Cl−. BiVO4 with an equal fraction of exposed {010} and {110} facets exhibited the highest capability of electron–hole separation and the highest C2-compound yield. The loading of core–shell structured Pt@MoOx and MnOx particles onto {010} and {110} facets, respectively, further enhanced the formation of C2 compounds. Our studies suggested that the Pt core and the MnOx particles accelerated the separation of photogenerated electron–hole pairs, whereas the MoOx shell catalyzed the coupling of HCHO possibly via a redox mechanism. The yields of C2 compounds and ethylene glycol reached 21% and 11%, respectively, under irradiation with UV-vis light for 12 h. Quantum yields of 11% and 4.8% were achieved for the coupling products under ultraviolet (350 nm) and visible (450 nm) light irradiation, respectively.
Co-reporter:Bang Gu, Shun He, Wei Zhou, Jincan Kang, ... Ye Wang
Journal of Energy Chemistry 2017 Volume 26, Issue 4(Volume 26, Issue 4) pp:
Publication Date(Web):1 July 2017
DOI:10.1016/j.jechem.2017.04.009
Uniform iron nanoparticles dispersed on polyaniline have been used as catalysts for the direct conversion of synthesis gas into lower olefins. As compared to active carbon and N-doped active carbon, polyaniline as a support of Fe catalysts showed higher selectivity of lower olefins (C2–4). The C2–4 selectivity reached ∼50% at a CO conversion of 79% over a 10 wt% Fe/polyaniline catalyst without any promoters. The XRD, H2-TPR, TEM and HRTEM studies revealed that the presence of nitrogen-containing groups in polyaniline structure could promote the dispersion and reduction of iron oxides, forming higher fraction of iron carbides with smaller mean sizes and narrower size distributions. The propylene-TPD result indicates that the use of polyaniline support facilitates the desorption of lower olefins, thus suppressing the consecutive hydrogenation to form undesirable lower paraffins.Polyaniline support with abundant surface electron-rich nitrogen groups can enhance the dispersion and reduction of iron species, thus favoring the CO conversion and lower olefins selectivity in Fischer–Tropsch synthesis.Download high-res image (125KB)Download full-size image
Co-reporter:Kang Cheng, Wei Zhou, Jincan Kang, Shun He, ... Ye Wang
Chem 2017 Volume 3, Issue 2(Volume 3, Issue 2) pp:
Publication Date(Web):10 August 2017
DOI:10.1016/j.chempr.2017.05.007
•One-step conversion of syngas to aromatics with striking selectivity was achieved•Zn-ZrO2/H-ZSM-5 catalyst showed 80% aromatic selectivity and 1,000 hr stability•Zn/Zr ratio, strong acidity, and proximity of catalyst components are key factors•Self-promotion effect of CO contributes to selective formation of aromaticsSyngas chemistry has become a hot research area because of the increasing interest in the utilization of non-petroleum carbon resources, such as natural gas or shale gas, coal, biomass, and CO2 for sustainable production of clean fuels and chemicals. Significant progress has recently been achieved in the selective synthesis of gasoline, diesel, and lower olefins from syngas by modification of the classic Fischer-Tropsch process. However, no success has been achieved in the direct conversion of syngas into aromatics, key building blocks for the production of various polymers, with attractive selectivity. Here, we report a highly selective syngas-methanol-aromatics (SMA) process, that is, a one-step conversion of syngas to aromatics via methanol by a reaction coupling method. We demonstrate that the successful design of bifunctional catalysts not only enables process intensification but also solves the problems of limited selectivity and catalyst deactivation that besets the synthesis of aromatics.Syngas (CO/H2) is a key platform for chemical utilization of non-petroleum carbon resources. Among syngas transformation routes, the direct synthesis of aromatics, which are among the most important bulk chemicals, is less successful because of the limited selectivity and poor catalyst stability. We report a successful design of bifunctional catalysts composed of Zn-doped ZrO2 nanoparticles dispersed on zeolite H-ZSM-5 for one-step conversion of syngas to aromatics with high selectivity and stability. Aromatics with 80% selectivity at CO conversion of 20% were achieved, and there was no catalyst deactivation in 1,000 hr. Methanol and dimethyl ether were formed as major intermediates on Zn-doped ZrO2, which were subsequently converted into aromatics on H-ZSM-5 via olefins. We discovered a self-promotion mechanism of CO in the selective formation of aromatics. As well as being a reactant, CO facilitates the removal of hydrogen species formed on H-ZSM-5 in the dehydrogenative aromatization of olefins.Download high-res image (325KB)Download full-size image
Co-reporter:Bing An, Kang Cheng, Cheng Wang, Ye Wang, and Wenbin Lin
ACS Catalysis 2016 Volume 6(Issue 6) pp:3610
Publication Date(Web):April 19, 2016
DOI:10.1021/acscatal.6b00464
We prepared highly active catalysts for Fischer–Tropsch (FT) synthesis through the pyrolysis of iron-containing metal–organic frameworks (MOFs). The Fe-time yields of the nitrogen-doped catalyst were as high as 720 μmolCO gFe–1 s–1 under the conditions of 300 °C, 2 MPa, and H2/CO = 1, which is a value that surpasses that of most FT catalysts reported in the literature. The pyrolysis of the MOFs yielded nanoparticles with a unique iron oxide@iron carbide core–shell structure dispersed on carbon supports. Such a structure is favorable for FT synthesis and has never been reported previously. Our strategy resolved the problem that the strong metal–support interactions that are usually required to stabilize dispersed particles in calcination compromise the catalytic activity, because of the difficulty of reducing metal oxides. Moreover, we found full coverage of carbonates on the particle surfaces, which likely result from decarboxylation of the MOFs and further stabilize the particles before decomposing to CO2, leaving an active surface rich with dangling bonds for catalytic turnover.Keywords: core−shell; Fischer−Tropsch synthesis; iron oxide@iron carbide nanoparticles; metal−organic frameworks; pyrolysis; weak interaction
Co-reporter:Shunji Xie, Qinghong Zhang, Guodong Liu and Ye Wang
Chemical Communications 2016 vol. 52(Issue 1) pp:35-59
Publication Date(Web):30 Oct 2015
DOI:10.1039/C5CC07613G
The development of efficient artificial photocatalysts and photoelectrocatalysts for the reduction of CO2 with H2O to fuels and chemicals has attracted much attention in recent years. Although the state-of-the-art for the production of fuels or chemicals from CO2 using solar energy is still far from practical consideration, rich knowledge has been accumulated to understand the key factors that determine the catalytic performances. This Feature article highlights recent advances in the photocatalytic and photoelectrocatalytic reduction of CO2 with H2O using heterogeneous semiconductor-based catalysts. The effects of structural aspects of semiconductors, such as crystalline phases, particle sizes, morphologies, exposed facets and heterojunctions, on their catalytic behaviours are discussed. The roles of different types of cocatalysts and the impact of their nanostructures on surface CO2 chemisorption and reduction are also analysed. The present article aims to provide insights into the rational design of efficient heterogeneous catalysts with controlled nanostructures for the photocatalytic and photoelectrocatalytic reduction of CO2 with H2O.
Co-reporter:Weiping Deng, Jiashu Chen, Jincan Kang, Qinghong Zhang and Ye Wang
Chemical Communications 2016 vol. 52(Issue 41) pp:6805-6808
Publication Date(Web):26 Apr 2016
DOI:10.1039/C6CC01490A
Functionalised carbon nanotube (CNT)-supported Au–Pd alloy nanoparticles were highly efficient catalysts for the aerobic oxidation of amines. We achieved the highest turnover frequencies (>1000 h−1) for the oxidative homocoupling of benzylamine and the oxidative dehydrogenation of dibenzylamine. We discovered a cooperative effect between Au–Pd nanoparticles and ketone/quinone groups on CNTs.
Co-reporter:Zebin Shen, Shunji Xie, Wenqing Fan, Qinghong Zhang, Zaiku Xie, Weimin Yang, Yangdong Wang, Jinchi Lin, Xuejiao Wu, Huilin Wan and Ye Wang
Catalysis Science & Technology 2016 vol. 6(Issue 17) pp:6485-6489
Publication Date(Web):29 Jul 2016
DOI:10.1039/C6CY01468B
We report a novel and direct conversion of formaldehyde into C2 compounds, in particular ethylene glycol, via photocatalytic carbon–carbon coupling over BiVO4, a visible-light-responsive and robust semiconductor. The generation of V4+ on BiVO4 surfaces enhanced the photocatalytic formation of C2 compounds.
Co-reporter:Jincan Kang, Xiaojie Wang, Xiaobo Peng, Yudan Yang, Kang Cheng, Qinghong Zhang, and Ye Wang
Industrial & Engineering Chemistry Research 2016 Volume 55(Issue 51) pp:
Publication Date(Web):December 1, 2016
DOI:10.1021/acs.iecr.6b03810
Cobalt nanoparticles were loaded onto mesoporous zeolite Na–Y (Na–meso-Y) by melt infiltration and impregnation methods. As compared to impregnation, melt infiltration resulted in Co nanoparticles with a narrower size distribution. The Co/Na–meso-Y catalyst prepared by the melt infiltration exhibited higher C10–C20 (diesel fuel) selectivity. The hydrogenolysis of heavier hydrocarbons was confirmed to occur under Fischer–Tropsch reaction conditions. Our studies for the hydrogenolysis of n-hexadecane revealed that the catalyst by the melt infiltration was more active and selective for the formation of C10–C15 hydrocarbons. We propose that the narrower Co size distribution favors the selective hydrogenolysis and thus the C10–C20 selectivity in Fischer–Tropsch synthesis. The addition of Mn with a proper content could further improve the diesel fuel selectivity to 65% by suppressing the formations of CH4 and lighter hydrocarbons. The Mn-modified Co/Na–meso-Y catalyst was very stable and no deactivation was observed in 1000 h.
Co-reporter:Weiping Deng, Hongxi Zhang, Xuejiao Wu, Rongsheng Li, Qinghong Zhang and Ye Wang
Green Chemistry 2015 vol. 17(Issue 11) pp:5009-5018
Publication Date(Web):24 Aug 2015
DOI:10.1039/C5GC01473E
The oxidative transformation of lignin into aromatic compounds is an attractive route for chemical utilization of lignocellulosic biomass. Unlike hydrogenolysis, no consumption of expensive hydrogen is required for the oxidative transformation. However, only limited success has been achieved for the oxidative conversion of lignin. Here, we report that cerium oxide-supported palladium nanoparticles (Pd/CeO2) can efficiently catalyze the one-pot oxidative conversion of 2-phenoxy-1-phenylethanol, a lignin model compound containing a β-O-4 bond and a Cα-hydroxyl group, in methanol in the presence of O2, producing phenol, acetophenone and methyl benzoate as the major products. Pd nanoparticles played a pivotal role in the oxidation of a Cα-hydroxyl group into a Cα-ketonic group, which was crucial for the transformation of the model compound. The presence of the Cα-ketonic group activated the β-O-4 bond, which was subsequently cleaved over the Pd/CeO2 catalyst, affording phenol and acetophenone. At the same time, the Cα–Cβ bond also underwent oxidative cleavage catalyzed by CeO2, producing benzoic acid and further methyl benzoate. The Pd/CeO2 catalyst could also catalyze the oxidative conversion of organosolv lignin under mild conditions (458 K), producing vanillin, guaiacol and 4-hydroxybenzaldehyde.
Co-reporter:Shunji Xie, Yu Wang, Qinghong Zhang, Weiping Deng and Ye Wang
Chemical Communications 2015 vol. 51(Issue 16) pp:3430-3433
Publication Date(Web):20 Jan 2015
DOI:10.1039/C4CC10241J
We successfully synthesized SrNb2O6 with nanoplate morphology by a facile hydrothermal method. The SrNb2O6 nanoplate without any promoters or co-catalysts exhibited promising photocatalytic performance for the preferential reduction of CO2 with H2O vapour to CO and CH4 due to its high electron–hole separation and high CO2 chemisorption abilities.
Co-reporter:Guodong Liu, Shunji Xie, Qinghong Zhang, Zhengfang Tian and Ye Wang
Chemical Communications 2015 vol. 51(Issue 71) pp:13654-13657
Publication Date(Web):21 Jul 2015
DOI:10.1039/C5CC05113D
The combination of polyaniline with TiO2 significantly enhanced the photocatalytic reduction of CO2 with H2O owing to the increased CO2 chemisorption and the facilitated separation of photogenerated electron–hole pairs. We discovered that CO2 played a unique role in enhancing the electron–hole separation and the photocatalytic activity for polyaniline-containing catalysts.
Co-reporter:Dr. Kang Cheng;Lei Zhang;Dr. Jincan Kang;Xiaobo Peng;Dr. Qinghong Zhang;Dr. Ye Wang
Chemistry - A European Journal 2015 Volume 21( Issue 5) pp:
Publication Date(Web):
DOI:10.1002/chem.201590016
Co-reporter:Dr. Kang Cheng;Lei Zhang;Dr. Jincan Kang;Xiaobo Peng;Dr. Qinghong Zhang;Dr. Ye Wang
Chemistry - A European Journal 2015 Volume 21( Issue 5) pp:1928-1937
Publication Date(Web):
DOI:10.1002/chem.201405277
Abstract
Bifunctional Fischer–Tropsch (FT) catalysts that couple uniform-sized Co nanoparticles for CO hydrogenation and mesoporous zeolites for hydrocracking/isomerization reactions were found to be promising for the direct production of gasoline-range (C5–11) hydrocarbons from syngas. The Brønsted acidity results in hydrocracking/isomerization of the heavier hydrocarbons formed on Co nanoparticles, while the mesoporosity contributes to suppressing the formation of lighter (C1–4) hydrocarbons. The selectivity for C5–11 hydrocarbons could reach about 70 % with a ratio of isoparaffins to n-paraffins of approximately 2.3 over this catalyst, and the former is markedly higher than the maximum value (ca. 45 %) expected from the Anderson–Schulz–Flory distribution. By using n-hexadecane as a model compound, it was clarified that both the acidity and mesoporosity play key roles in controlling the hydrocracking reactions and thus contribute to the improved product selectivity in FT synthesis.
Co-reporter:Weiping Deng;Qinghong Zhang
Science China Chemistry 2015 Volume 58( Issue 1) pp:29-46
Publication Date(Web):2015 January
DOI:10.1007/s11426-014-5283-8
The catalytic transformation of cellulose into key building-block or platform chemicals such as 5-hydoxymethylfurfural (HMF), levulinic acid, and lactic acid under mild conditions, has attracted much attention in recent years, as these conversions can be operated without consumption of hydrogen or oxygen and thus are more economical compared to the hydrogenolysis or oxidation of cellulose. This review article highlights recent advances in the development of novel catalysts or catalytic processes for the conversion of cellulose and its derived carbohydrates into HMF, levulinic acid, and lactic acid or their esters under inert atmosphere. We also analyze efficient catalytic systems for HMF production, in particular Lewis acids combined with ionic liquid or biphasic systems. For the formations of levulinic and lactic acids or their esters, we focus on the reactions in aqueous and alcohol media catalyzed by multifunctional catalysts that combine the functions of hydrolysis, isomerization, and dehydration-rehydration or retro-aldol reactions. The reaction mechanism for each process will also be discussed to gain insights into the activation of C-O and C-C bonds in the absence of hydrogen or oxygen.
Co-reporter:Zhen Guo, Bin Liu, Qinghong Zhang, Weiping Deng, Ye Wang and Yanhui Yang
Chemical Society Reviews 2014 vol. 43(Issue 10) pp:3480-3524
Publication Date(Web):20 Feb 2014
DOI:10.1039/C3CS60282F
Oxidation catalysis not only plays a crucial role in the current chemical industry for the production of key intermediates such as alcohols, epoxides, aldehydes, ketones and organic acids, but also will contribute to the establishment of novel green and sustainable chemical processes. This review is devoted to dealing with selective oxidation reactions, which are important from the viewpoint of green and sustainable chemistry and still remain challenging. Actually, some well-known highly challenging chemical reactions involve selective oxidation reactions, such as the selective oxidation of methane by oxygen. On the other hand some important oxidation reactions, such as the aerobic oxidation of alcohols in the liquid phase and the preferential oxidation of carbon monoxide in hydrogen, have attracted much attention in recent years because of their high significance in green or energy chemistry. This article summarizes recent advances in the development of new catalytic materials or novel catalytic systems for these challenging oxidation reactions. A deep scientific understanding of the mechanisms, active species and active structures for these systems are also discussed. Furthermore, connections among these distinct catalytic oxidation systems are highlighted, to gain insight for the breakthrough in rational design of efficient catalytic systems for challenging oxidation reactions.
Co-reporter:Xiaoyue Wan, Chunmei Zhou, Jiashu Chen, Weiping Deng, Qinghong Zhang, Yanhui Yang, and Ye Wang
ACS Catalysis 2014 Volume 4(Issue 7) pp:2175
Publication Date(Web):May 26, 2014
DOI:10.1021/cs5003096
The aerobic oxidation of 5-hydroxymethylfurfural (HMF), a key platform compound in cellulose transformation, into 2,5-furandicarboxylic acid (FDCA), a promising renewable alternative to petroleum-derived terephthalic acid, is one of the most attractive reactions for establishing biomass-based sustainable chemical processes. Supported Au catalysts have shown encouraging performance for this reaction, but the need of an excess amount of base additives makes the process less green and less cost-effective. Here, we report a stable and efficient carbon nanotube (CNT)-supported Au–Pd alloy catalyst for the aerobic oxidation of HMF to FDCA in water without any bases. The functionalization of CNT surfaces is crucial for FDCA formation. We have clarified that the CNT containing more carbonyl/quinone and less carboxyl groups favors FDCA formation by enhancing the adsorption of the reactant and reaction intermediates. Significant synergistic effects exist between Au and Pd in the alloy for the base-free oxidation of HMF to FDCA through three tandem steps. The present work provides understanding of the support-enhanced adsorption effect and the alloying effect for supported Au-based bimetallic catalysts, and this knowledge may help develop efficient catalysts for the aerobic oxidation of relatively complicated organic compounds with different functional groups in water.Keywords: 5-hydroxymethylfurfural; aerobic oxidation; alloying effect; carbon nanotube; gold catalysis; sustainable chemistry
Co-reporter:Shunji Xie, Yu Wang, Qinghong Zhang, Weiping Deng, and Ye Wang
ACS Catalysis 2014 Volume 4(Issue 10) pp:3644
Publication Date(Web):September 5, 2014
DOI:10.1021/cs500648p
The photocatalytic reduction of carbon dioxide with water to fuels and chemicals is a longstanding challenge. This article focuses on the effects of cocatalysts and reaction modes on photocatalytic behaviors of TiO2 with an emphasis on the selectivity of photogenerated electrons for CO2 reduction in the presence of H2O, which has been overlooked in most of the published papers. Our results clarified that the reaction using H2O vapor exhibited significantly higher selectivity for CO2 reduction than that by immersing the photocatalyst into liquid H2O. We examined the effect of noble metal cocatalysts and found that the rate of CH4 formation increased in the sequence of Ag < Rh < Au < Pd < Pt, corresponding well to the increase in the efficiency of electron–hole separation. This indicates that Pt is the most effective cocatalyst to extract photogenerated electrons for CO2 reduction. The selectivity of CH4 in CO2 reduction was also enhanced by Pt. The size and loading amount of Pt affected the activity; a smaller mean size of Pt particles and an appropriate loading amount favored the formation of reduction products. The reduction of H2O to H2 was accelerated more than the reduction of CO2 in the presence of Pt, leading to a lower selectivity for CO2 reduction and limited increases in CH4 formation rate. We demonstrated that the addition of MgO into the Pt–TiO2 catalyst could further enhance the formation of CH4. The formation of H2 was suppressed simultaneously, suggesting the increase in the selectivity for CO2 reduction in the presence of MgO. Furthermore, the MgO- and Pt-modified TiO2 catalyst exhibited a higher CH4 selectivity in CO2 reduction.Keywords: carbon dioxide; cocatalyst; methane; photocatalysis; preferential reduction; titanium oxide
Co-reporter:Weiping Deng, Enze Zhu, Mi Liu, Qinghong Zhang and Ye Wang
RSC Advances 2014 vol. 4(Issue 81) pp:43131-43141
Publication Date(Web):01 Sep 2014
DOI:10.1039/C4RA05939E
Cellulose and inulin, two important biomasses, can be transformed to polyols using bifunctional catalysts combining acid sites for hydrolysis and metal nanoparticles for hydrogenation. Here, we report that Ru nanoparticles loaded on a Keggin-type polyoxometalate, i.e., Cs3PW12O40, without intrinsic Brønsted acidity exhibit superior catalytic performances for the transformation of inulin and cellulose into hexitols in water in the presence of H2. We demonstrated that new Brønsted acid sites were generated from H2 on the Ru/Cs3PW12O40 catalyst. The H2-originated reversible Brønsted acid sites were robust during the transformation of biomass under hydrothermal conditions. We further found that the mean size of Ru nanoparticles determined the product selectivity in the conversion of inulin under H2. The catalyst with larger Ru nanoparticles favoured the formation of fructose, the hydrolysis product, while the major products were hexitols over the catalyst with a smaller Ru particle size. We clarified that, as compared to that of inulin hydrolysis, the rate of fructose hydrogenation increased more rapidly upon decreasing the Ru particle size.
Co-reporter:Zhenchen Tang;Weiping Deng;Yanliang Wang;Enze Zhu;Xiaoyue Wan;Qinghong Zhang;Dr. Ye Wang
ChemSusChem 2014 Volume 7( Issue 6) pp:1557-1567
Publication Date(Web):
DOI:10.1002/cssc.201400150
Abstract
The transformation of cellulose or cellulose-derived carbohydrates into platform chemicals is the key to establish biomass-based sustainable chemical processes. The systems able to catalyze the conversion of cellulose into key chemicals in water without the consumption of hydrogen are limited. We report that simple vanadyl (VO2+) cations catalyze the conversions of cellulose and its monomer, glucose, into lactic acid and formic acid in water. We have discovered an interesting shift of the major product from formic acid to lactic acid on switching the reaction atmosphere from oxygen to nitrogen. Our studies suggest that VO2+ catalyzes the isomerization of glucose to fructose, the retro-aldol fragmentation of fructose to two trioses, and the isomerization of trioses, which leads to the formation of lactic acid under anaerobic conditions. The oxidative cleavage of CC bonds in the intermediates caused by the redox conversion of VO2+/VO2+ under aerobic conditions results in formic acid and CO2. We demonstrate that the addition of an alcohol suppresses the formation of CO2 and enhances the formic acid yield significantly to 70–75 %.
Co-reporter:Dr. Qinghong Zhang;Kang Cheng;Dr. Jincan Kang;Dr. Weiping Deng ;Dr. Ye Wang
ChemSusChem 2014 Volume 7( Issue 5) pp:1251-1264
Publication Date(Web):
DOI:10.1002/cssc.201300797
Abstract
Fischer–Tropsch synthesis is a key reaction in the utilization of non-petroleum carbon resources, such as methane (natural gas, shale gas, and biogas), coal, and biomass, for the sustainable production of clean liquid fuels from synthesis gas. Selectivity control is one of the biggest challenges in Fischer–Tropsch synthesis. This Minireview focuses on the development of new catalysts with controllable product selectivities. Recent attempts to increase the selectivity to C5+ hydrocarbons by preparing catalysts with well-defined active phases or with new supports or by optimizing the interaction between the promoter and the active phase are briefly highlighted. Advances in developing bifunctional catalysts capable of catalyzing both CO hydrogenation to heavier hydrocarbons and hydrocracking/isomerization of heavier hydrocarbons are critically reviewed. It is demonstrated that the control of the secondary hydrocracking reactions by using core–shell nanostructures or solid-acid materials, such as mesoporous zeolites and carbon nanotubes with acid functional groups, is an effective strategy to tune the product selectivity of Fischer–Tropsch synthesis. Very promising selectivities to gasoline- and diesel-range hydrocarbons have been attained over some bifunctional catalysts.
Co-reporter:Wenqing Fan, Qinghong Zhang, Weiping Deng, and Ye Wang
Chemistry of Materials 2013 Volume 25(Issue 16) pp:3277
Publication Date(Web):July 28, 2013
DOI:10.1021/cm400192q
This paper reports a novel bottom-up hydrothermal route for the synthesis of niobic acid nanosheets. This route is simpler and greener than the conventional top-down and multistep route for the synthesis of hydrated metal oxide nanosheets via exfoliation of layered compounds, which typically requires the use of bulky organic cations. We have clarified that the pH of the suspension for hydrothermal treatment, the hydrothermal temperature and time, and the presence of NH4+ play roles in determining the morphology of the product. We propose that the nanosheet is formed from amorphous niobic acid nanoparticles through a dissolution–crystallization mechanism. The obtained niobic acid nanosheets are uniform with a thickness of ∼2 nm and uniquely possess mainly Brønsted acid sites. As compared to the conventional amorphous niobic acid and several other typical solid acid catalysts, the niobic acid nanosheet synthesized by our bottom-up method exhibits significantly higher activity and selectivity for the Friedel–Crafts alkylation of anisole with benzyl alcohol. We have further demonstrated that our niobic acid nanosheet is a water-tolerant and efficient catalyst for the hydrolysis of inulin, a polysaccharide-based biomass, into fructose.Keywords: Brønsted acid; green chemistry; hydrothermal synthesis; nanosheet; niobic acid;
Co-reporter:Shunji Xie, Yu Wang, Qinghong Zhang, Wenqing Fan, Weiping Deng and Ye Wang
Chemical Communications 2013 vol. 49(Issue 24) pp:2451-2453
Publication Date(Web):07 Feb 2013
DOI:10.1039/C3CC00107E
Photocatalytic activity in the reduction of CO2 with H2O to CH4 was significantly enhanced by simply adding MgO to TiO2 loaded with Pt. A positive correlation between CH4 formation activity and basicity was observed. The interface between TiO2, Pt and MgO in the trinary nanocomposite played a crucial role in CO2 photocatalytic reduction.
Co-reporter:Wenqing Fan, Qinghong Zhang and Ye Wang
Physical Chemistry Chemical Physics 2013 vol. 15(Issue 8) pp:2632-2649
Publication Date(Web):17 Dec 2012
DOI:10.1039/C2CP43524A
Semiconductor-based photocatalysis has attracted much attention in recent years because of its potential for solving energy and environmental problems that we are now facing. Among many photocatalytic reactions, the splitting of H2O into H2 and O2 and the reduction of CO2 with H2O into organic compounds such as CH4 and CH3OH are two of the most important and challenging reactions. Many studies have been devoted to designing and preparing novel photocatalytic materials for these two reactions. This article highlights recent advances in developing semiconductor-based nanocomposite photocatalysts for the production of H2 and the reduction of CO2. The systems of semiconductor–cocatalyst, semiconductor–carbon (carbon nanotube or graphene) and semiconductor–semiconductor nanocomposites have mainly been described. It has been demonstrated that the design and preparation of nanocomposites with proper structures can facilitate charge separation/migration and decrease the charge recombination probability, thus promoting the photocatalytic activity. Keeping the reduction and oxidation processes in different regions in the nanocomposite may also enhance the photocatalytic efficiency and stability. The location and size of cocatalysts, the interfacial contact between semiconductor and carbon materials, and the heterojunctions between different semiconductors together with the suitable alignment of band edges of semiconductors are key factors determining the photocatalytic behaviours of the nanocomposite catalysts.
Co-reporter:Qingge Zhai;Shunji Xie;Wenqing Fan;Dr. Qinghong Zhang;Yu Wang;Dr. Weiping Deng ;Dr. Ye Wang
Angewandte Chemie International Edition 2013 Volume 52( Issue 22) pp:5776-5779
Publication Date(Web):
DOI:10.1002/anie.201301473
Co-reporter:Kang Cheng, Jincan Kang, Shuiwang Huang, Zhenya You, Qinghong Zhang, Jiansheng Ding, Weiqi Hua, Yinchuan Lou, Weiping Deng, and Ye Wang
ACS Catalysis 2012 Volume 2(Issue 3) pp:441
Publication Date(Web):February 8, 2012
DOI:10.1021/cs200670j
Mesoporous beta (meso-beta) zeolites prepared by post-treatment of H-beta with NaOH aqueous solution were studied as supports of Ru catalysts for Fischer–Tropsch (FT) synthesis. The size and volume of the mesopores increased with the concentration of NaOH. The Brønsted acidity declined because Na+ ions were exchanged into the meso-beta during the post-treatment, and a further ion exchange of the meso-beta with NH4+ followed by calcination, forming H-meso-beta, could recover the Brønsted acidity. The use of H-meso-beta or meso-beta instead of H-beta or Na-beta as the support for FT synthesis decreased the selectivities to CH4 and heavier hydrocarbons (C12+) and increased that to C5–C11 hydrocarbons. The C5–C11 selectivity depended on the concentration of NaOH used for meso-beta preparation. Under an optimum NaOH concentration, a C5–C11 selectivity of 77%, significantly higher than the maximum expected from Anderson–Schulz–Flory distribution (∼45%), was attained with a ratio of isoparaffins to n-paraffins being 2.7. The mesoporosity and the unique acidity of the meso-beta probably contribute to the selective hydrocracking of the primary heavier hydrocarbons formed on Ru nanoparticles into gasoline-range liquid fuels.Keywords: Fischer−Tropsch synthesis; gasoline; mesoporous zeolite; ruthenium nanoparticles; selectivity control; synthesis gas;
Co-reporter:Aihua Ye, Wenqing Fan, Qinghong Zhang, Weiping Deng and Ye Wang
Catalysis Science & Technology 2012 vol. 2(Issue 5) pp:969-978
Publication Date(Web):23 Jan 2012
DOI:10.1039/C2CY20027A
CdS–graphene (GR) and CdS–carbon nanotube (CNT) nanocomposites prepared by a hydrothermal method were studied as photocatalysts for the evolution of hydrogen and the degradation of methyl orange (MO) under visible-light irradiation. The incorporation of GR or CNT into CdS significantly enhanced the photocatalytic activities for both reactions. The photocatalytic activities depended on the mass ratio of CdS:GR or CdS:CNT in the nanocomposites. Under optimized mass ratios, the CdS–GR was more efficient than the CdS–CNT. Our characterizations suggested that CdS nanoparticles of ∼35 nm in size were dispersed on the graphene sheets or CNT surfaces in the nanocomposites. Significant band-gap narrowing was observed due to the incorporation of GR or CNT into CdS, indicating the strong interactions between CdS and GR or CNT. The transient photocurrent response studies suggested a more efficient separation of photogenerated electrons and holes. The stronger interaction or larger contact interface between CdS and GR was proposed to accelerate the transfer of photogenerated electrons from CdS to GR more efficiently, resulting in higher photocatalytic activities of the CdS–GR composite.
Co-reporter:Weiping Deng, Qinghong Zhang and Ye Wang
Dalton Transactions 2012 vol. 41(Issue 33) pp:9817-9831
Publication Date(Web):01 May 2012
DOI:10.1039/C2DT30637A
Efficient utilisation of renewable biomass resources, particularly lignocellulosic biomass, for the production of chemicals and fuels has attracted much attention in recent years. The catalytic conversion of cellulose, the main component of lignocellulosic biomass, selectively into a platform chemical such as glucose, 5-hydroxymethyl furfural (HMF), sorbitol or gluconic acid under mild conditions is the most desirable route. Acid catalysis plays a crucial role in the conversion of cellulose via the cleavage of its glycosidic bonds. Owing to their unique features such as strong acidity, water-tolerance, low corrosiveness and recoverability, polyoxometalates have shown promising performances in transformations of cellulose into platform chemicals both in homogeneous and heterogeneous systems. This article highlights recent studies on polyoxometalates and polyoxometalate-based bifunctional catalysts or catalytic systems for the selective conversions of cellulose and cellobiose, a model molecule of cellulose, into platform chemicals.
Co-reporter:Weiping Deng;Yanliang Wang;Qinghong Zhang
Catalysis Surveys from Asia 2012 Volume 16( Issue 2) pp:91-105
Publication Date(Web):2012 June
DOI:10.1007/s10563-012-9136-1
The efficient utilization of renewable lignocellulosic biomass has attracted much attention in recent years. One of the most desirable routes for the transformation of cellulose, the main component of lignocellulosic biomass, is to convert cellulose under mild conditions selectively into a value-added chemical or into a platform compound, which can be easily converted to versatile chemicals or fuels in the subsequent step. The activation of cellulose, typically starting by the cleavage of its glycosidic bonds, under mild conditions and the selective formation of a particular molecule are critical challenges. Bifunctional catalysts coupling the acid sites for the activation of the glycosidic bonds via hydrolysis and the metal nanoparticles for the hydrogenation or oxidation of glucose intermediate have shown promising performances for the conversion of cellulose or cellobiose into hexitols or gluconic acid in water under mild conditions. This short review has summarized some recent studies on the development of such bifunctional catalysts or catalytic systems. The following two kinds of bifunctional catalysts or catalytic systems have mainly been discussed: (1) a liquid acid in combination with a supported metal catalyst, (2) solid acid-supported metal nanoparticles. Emphases have been laid on the conversions of cellulose or cellobiose into sorbitol and gluconic acid catalyzed respectively by ruthenium and gold nanoparticles loaded on carbon nanotubes bearing acid sites.
Co-reporter:Jieli He;Ting Xu;Zhihui Wang;Dr. Qinghong Zhang;Dr. Weiping Deng ;Dr. Ye Wang
Angewandte Chemie International Edition 2012 Volume 51( Issue 10) pp:2438-2442
Publication Date(Web):
DOI:10.1002/anie.201104071
Co-reporter:Wenjing Long;Qingge Zhai;Jieli He;Dr. Qinghong Zhang;Dr. Weiping Deng ;Dr. Ye Wang
ChemPlusChem 2012 Volume 77( Issue 1) pp:27-30
Publication Date(Web):
DOI:10.1002/cplu.201100050
Co-reporter:Dr. Dongli An;Aihua Ye;Dr. Weiping Deng;Dr. Qinghong Zhang ;Dr. Ye Wang
Chemistry - A European Journal 2012 Volume 18( Issue 10) pp:2938-2947
Publication Date(Web):
DOI:10.1002/chem.201103262
Abstract
Gold nanoparticles loaded onto Keggin-type insoluble polyoxometalates (CsxH3−xPW12O40) showed superior catalytic performances for the direct conversion of cellobiose into gluconic acid in water in the presence of O2. The selectivity of Au/CsxH3−xPW12O40 for gluconic acid was significantly higher than those of Au catalysts loaded onto typical metal oxides (e.g., SiO2, Al2O3, and TiO2), carbon nanotubes, and zeolites (H-ZSM-5 and HY). The acidity of polyoxometalates and the mean-size of the Au nanoparticles were the key factors in the catalytic conversion of cellobiose into gluconic acid. The stronger acidity of polyoxometalates not only favored the conversion of cellobiose but also resulted in higher selectivity of gluconic acid by facilitating desorption and inhibiting its further degradation. On the other hand, the smaller Au nanoparticles accelerated the oxidation of glucose (an intermediate) into gluconic acid, thereby leading to increases both in the conversion of cellobiose and in the selectivity of gluconic acid. The Au/CsxH3−xPW12O40 system also catalyzed the conversion of cellulose into gluconic acid with good efficiency, but it could not be used repeatedly owing to the leaching of a H+-rich hydrophilic moiety over long-term hydrothermal reactions. We have demonstrated that the combination of H3PW12O40 and Au/Cs3.0PW12O40 afforded excellent yields of gluconic acid (about 85 %, 418 K, 11 h), and the deactivation of the recovered H3PW12O40–Au/Cs3.0PW12O40 catalyst was not serious during repeated use.
Co-reporter:Qinghong Zhang, Weiping Deng and Ye Wang
Chemical Communications 2011 vol. 47(Issue 33) pp:9275-9292
Publication Date(Web):2011/05/31
DOI:10.1039/C1CC11723H
The size of the active phase is one of the most important factors in determining the catalytic behaviour of a heterogeneous catalyst. This Feature Article focuses on the size effects in two types of reactions, i.e., the metal nanoparticle-catalysed dehydrogenation of alcohols and the metal oxide nanocluster-catalysed selective oxidation of hydrocarbons (including the selective oxidation of methane and ethane and the epoxidation of propylene). For Pd or Au nanoparticle-catalysed oxidative or non-oxidative dehydrogenation of alcohols, the size of metal nanoparticles mainly controls the catalytic activity by affecting the activation of reactants (either alcohol or O2). The size of oxidic molybdenum species loaded on SBA-15 determines not only the activity but also the selectivity of oxygenates in the selective oxidation of ethane; highly dispersed molybdenum species are suitable for acetaldehyde formation, while molybdenum oxide nanoparticles exhibit higher formaldehyde selectivity. CuII and FeIII isolated on mesoporous silica are highly efficient for the selective oxidation of methane to formaldehyde, while the corresponding oxide clusters mainly catalyse the complete oxidation of methane. The lattice oxygen in iron or copper oxide clusters is responsible for the complete oxidation, while the isolated CuI or FeII generated during the reaction can activate molecular oxygen forming active oxygen species for the selective oxidation of methane. Highly dispersed CuI and FeII species also function for the epoxidation of propylene by O2 and N2O, respectively. Alkali metal ions work as promoters for the epoxidation of propylene by enhancing the dispersion of copper or iron species and weakening the acidity.
Co-reporter:Mi Liu, Weiping Deng, Qinghong Zhang, Yanliang Wang and Ye Wang
Chemical Communications 2011 vol. 47(Issue 34) pp:9717-9719
Publication Date(Web):25 Jul 2011
DOI:10.1039/C1CC12506K
Ru
nanoparticles loaded on a Keggin-type polyoxometalate (Cs3PW12O40), which did not possess strong intrinsic acidity, efficiently catalysed the conversions of cellobiose and cellulose into sorbitol in water medium in H2 at ≤433 K. The Brønsted acid sites generated in situ from H2 have been demonstrated to play a key role in the formation of sorbitol.
Co-reporter:Wenhao Fang;Jiashu Chen;Dr. Qinghong Zhang;Dr. Weiping Deng ;Dr. Ye Wang
Chemistry - A European Journal 2011 Volume 17( Issue 4) pp:1247-1256
Publication Date(Web):
DOI:10.1002/chem.201002469
Abstract
Gold nanoparticles with uniform mean sizes (≈3 nm) loaded onto various supports have been prepared and studied for the oxidant-free dehydrogenation of benzyl alcohol to benzaldehyde and hydrogen. The use of hydrotalcite (HT), which possesses both strong acidity and strong basicity, provides the best catalytic performance. Au/HT catalysts with various mean Au particle sizes (2.1–21 nm) have been successfully prepared by a deposition–precipitation method under controlled conditions. Detailed catalytic reaction studies with these catalysts demonstrate that the Au-catalyzed dehydrogenation of benzyl alcohol is a structure-sensitive reaction. The turnover frequency (TOF) increases with decreasing Au mean particle size (from 12 to 2.1 nm). A steep rise in TOF occurs when the mean Au particle size becomes smaller than 4 nm. Our present work suggests that the acid–base properties of the support and the size of Au nanoparticles are two key factors controlling the alcohol dehydrogenation catalysis. A reaction mechanism is proposed to rationalize these results. It is assumed that the activation of the β-CH bond of alcohol, which requires the coordinatively unsaturated Au atoms, is the rate-determining step.
Co-reporter:Dr. Jincan Kang;Kang Cheng;Lei Zhang;Dr. Qinghong Zhang;Jiansheng Ding;Dr. Weiqi Hua;Dr. Yinchuan Lou;Qingge Zhai;Dr. Ye Wang
Angewandte Chemie International Edition 2011 Volume 50( Issue 22) pp:5200-5203
Publication Date(Web):
DOI:10.1002/anie.201101095
Co-reporter:Wenqing Fan ; Qinghua Lai ; Qinghong Zhang
The Journal of Physical Chemistry C 2011 Volume 115(Issue 21) pp:10694-10701
Publication Date(Web):May 9, 2011
DOI:10.1021/jp2008804
Nanocomposites of titanium dioxide (P25) and reduced graphene oxide (RGO), which were prepared by several techniques including UV-assisted photocatalytic reduction, hydrazine reduction, and hydrothermal method, were studied as photocatalysts for the evolution of hydrogen from alcohol solution under UV–vis irradiation. The incorporation of RGO into P25 significantly enhanced the photocatalytic activity for H2 evolution, and the P25–RGO composite prepared by the hydrothermal method exhibited the best performance. The optimum mass ratio of P25 to RGO in the composite was 1/0.2. The P25–RGO composite was stable and could be used recyclably, and it could also catalyze the evolution of H2 from pure water. Our characterizations suggested that P25 nanoparticles with diameters of 20–30 nm were dispersed on the RGO sheet in the composite, and the stronger interaction between P25 and RGO provided a better photocatalytic activity. The intimate contact between P25 and RGO was proposed to accelerate the transfer of photogenerated electrons on P25 to RGO, suppressing the recombination of charge carriers and thus increasing the photocatalytic performance.
Co-reporter:Wenhao Fang, Qinghong Zhang, Jing Chen, Weiping Deng and Ye Wang
Chemical Communications 2010 vol. 46(Issue 9) pp:1547-1549
Publication Date(Web):27 Jan 2010
DOI:10.1039/B923047E
Hydrotalcite-supported gold nanoparticles with sizes of less than 5 nm are highly efficient and reusable catalysts for the oxidant-free dehydrogenation of alcohols to carbonyl compounds and hydrogen.
Co-reporter:Weiping Deng, Mi Liu, Qinghong Zhang, Xuesong Tan and Ye Wang
Chemical Communications 2010 vol. 46(Issue 15) pp:2668-2670
Publication Date(Web):06 Feb 2010
DOI:10.1039/B925723C
Cellulose can be transformed into methyl glucosides in methanol with yields of 50–60% in the presence of several acid catalysts under mild conditions (≤473 K); H3PW12O40 provides the highest turnover number (∼73 in 0.5 h) for the formation of methyl glucosides among many acid catalysts examined.
Co-reporter:Ye Wang;DongLi An;QingHong Zhang
Science China Chemistry 2010 Volume 53( Issue 2) pp:337-350
Publication Date(Web):2010/02/01
DOI:10.1007/s11426-010-0045-8
Co-reporter:Dr. Qinghong Zhang;Jincan Kang ;Dr. Ye Wang
ChemCatChem 2010 Volume 2( Issue 9) pp:1030-1058
Publication Date(Web):
DOI:10.1002/cctc.201000071
Abstract
Fischer–Tropsch synthesis is a heterogeneous catalytic process for the production of clean hydrocarbon fuels or chemicals from synthesis gas (CO+H2), which can be derived from non-petroleum feedstocks such as natural gas, coal, or biomass. Fischer–Tropsch synthesis has received renewed interests in recent years because of the global demand for a decreased dependence on petroleum for production of fuels and chemicals. The product distributions with conventional Fischer–Tropsch catalysts usually follow the Anderson–Schulz–Flory distribution and are typically unselective with regards to the formation of hydrocarbons from methane to waxes. Selectivity control is one of the key challenges of research into Fischer–Tropsch synthesis. This Review article summarizes the effects of key factors on catalytic properties, particularly the product selectivity, and highlights recent developments of novel Fischer–Tropsch catalysts and new strategies with an aim at controlling the product selectivity.
Co-reporter:Xuesong Tan, Weiping Deng, Mi Liu, Qinghong Zhang and Ye Wang
Chemical Communications 2009 (Issue 46) pp:7179-7181
Publication Date(Web):14 Oct 2009
DOI:10.1039/B917224F
Gold nanoparticles loaded on nitric acid-pretreated carbon nanotubes are efficient for the selective oxidation of cellobiose by molecular oxygen to gluconic acid in aqueous medium without pH control; a gluconic acid yield of 80% has been obtained at 145 °C.
Co-reporter:Baomin Lin, Qinghong Zhang and Ye Wang
Industrial & Engineering Chemistry Research 2009 Volume 48(Issue 24) pp:10788
Publication Date(Web):October 16, 2009
DOI:10.1021/ie901227p
Among 11 kinds of molecular sieves examined, H−ZSM-5 exhibited the highest activity for the direct conversion of ethylene to propylene. The conversion of ethylene was 58% and the selectivities to propylene and butenes were 42% and 21%, respectively, over H−ZSM-5 at 723 K. Our studies demonstrate that the conversion of ethylene increases with the degree of H+ exchange in the H−Na−ZSM-5 series of samples with different H+ exchange degrees and the Al content in the H−ZSM-5 samples with different Si/Al ratios. The strong Brønsted acid sites are proposed to account for the conversion of ethylene. The modification of H−ZSM-5 with phosphorus or boron could enhance the selectivity of propylene but decreased the conversion of ethylene due to the decreased acidity. In situ FT-IR studies confirm the reaction of ethylene molecules with the Brønsted acid sites associated with −Si−(OH)−Al− groups. In situ FT-IR results further suggest the occurrence of oligomerization of ethylene on the surface of H−ZSM-5. We speculate that the cracking of the oligomeric intermediates may lead to the formation of propylene.
Co-reporter:Weiping Deng;Xuesong Tan;Wenhao Fang;Qinghong Zhang
Catalysis Letters 2009 Volume 133( Issue 1-2) pp:
Publication Date(Web):2009 November
DOI:10.1007/s10562-009-0136-3
Cellulose samples with different crystallinities (33–85%) were prepared by treating a commercial cellulose (crystalline, 85%) with phosphoric acid under different conditions. Supported Fe, Co, Ni, Pd, Pt, Rh, Ru, Ir, Ag, and Au catalysts were examined for the conversion of cellulose with a crystallinity of 33% in water medium in the presence of hydrogen, and Ru was found to be the most effective catalyst for the formation of sorbitol. We demonstrated that carbon nanotubes (CNTs) were the most efficient support of Ru for cellulose conversion, and the mean size of Ru nanoparticles over CNT was ~8.8 nm. NH3-TPD and H2-TPD characterizations suggest that plenty of acid sites and unique hydrogen species over the Ru/CNT are important for sorbitol formation through hydrolysis and hydrogenation of cellulose. A 40% yield of hexitols (including 36% of sorbitol) could be achieved over the Ru/CNT catalyst for the conversion of the commercial cellulose (crystalline, 85%), and this yield was the highest one reported to date for the direct conversion of cellulose into sugar alcohols.
Co-reporter:Jincan Kang;Shuli Zhang;Qinghong Zhang Dr. Dr.
Angewandte Chemie International Edition 2009 Volume 48( Issue 14) pp:2565-2568
Publication Date(Web):
DOI:10.1002/anie.200805715
Co-reporter:Feng Li, Jing Chen, Qinghong Zhang and Ye Wang
Green Chemistry 2008 vol. 10(Issue 5) pp:553-562
Publication Date(Web):06 Mar 2008
DOI:10.1039/B715627H
Ruthenium catalysts supported on various metal oxides and Co3O4-supported various transition metal catalysts prepared by an adsorption-precipitation method were examined for the aerobic oxidation of benzyl amine. We found that the Co3O4-supported ruthenium catalyst exhibited the best catalytic performance. The Co3O4-supported ruthenium catalyst was also effective for the aerobic oxidation of several other amines. The present catalyst could be used recyclably and be operated under solvent-free conditions. The activity of the present catalyst for the aerobic oxidation of benzyl amine depended less on the oxygen pressure, and the catalyst was also efficient even when air was used as an oxidant. The content of ruthenium and the size of Co3O4 particles played crucial roles in determining the catalytic performance. We have clarified that the supported hydrous ruthenium oxide (RuO2·xH2O) is the active species for the aerobic oxidation of benzyl amine, whereas the supported metallic ruthenium (Ru°) and supported ruthenium chloride (RuCl3) are inactive, and the supported anhydrous ruthenium oxide (RuO2) only exhibits a lower activity.
Co-reporter:Wenming Zhu ; Qinghong Zhang
The Journal of Physical Chemistry C 2008 Volume 112(Issue 20) pp:7731-7734
Publication Date(Web):April 29, 2008
DOI:10.1021/jp800927y
We found that a simple K+-modified CuOx−SiO2 catalyst prepared by a sol−gel method was efficient for the epoxidation of propylene by oxygen. The catalyst did not require prereduction, and propylene oxide (PO) could be formed with a selectivity of 78% under oxygen-rich conditions. We demonstrated that Cu(I) formed during the reaction over the K+-modified CuOx−SiO2 catalyst was the active site for propylene epoxidation by oxygen. Cu(I) was proposed to account for the activation of oxygen, generating an active oxygen species for propylene epoxidation, while K+enhanced the PO selectivity probably by neutralizing the Lewis acid sites on catalyst surface. The enhanced dispersion of copper species due to the interaction with K+ may also contribute to the increase in PO selectivity.
Co-reporter:Yang Li, Dongli An, Qinghong Zhang and Ye Wang
The Journal of Physical Chemistry C 2008 Volume 112(Issue 35) pp:13700-13708
Publication Date(Web):2017-2-22
DOI:10.1021/jp804168y
While copper is the active center of particulate methane monooxygenase in methanotrophic bacteria, there are few studies to utilize synthetic copper catalysts for the selective oxidation of methane by oxygen. In this work, we have found that the copper ions attached on mesoporous silica SBA-15 with high dispersion can catalyze the selective oxidation of methane to formaldehyde by oxygen efficiently. The catalyst with a copper content of 0.008 wt % (Si/Cu = 13200) exhibits the best catalytic performance, and the specific site rate for formaldehyde formation can reach 5.6 mol (mol Cu)−1 s−1, significantly higher than those reported to date for other catalysts. We have elucidated that the oxidation of methane produces formaldehyde as a major primary product together with a small amount of carbon dioxide, while carbon monoxide is formed mainly via the consecutive oxidation of formaldehyde over our copper-based catalyst. Pulse reaction studies have indicated that methane molecules can react with the lattice oxygen of the catalyst, producing carbon oxides, and CuII in the catalyst is reduced at the same time. Detailed pulse reaction studies combined with EPR characterizations suggest that the reduced copper (probably CuI) sites generated by methane molecules during the reaction account for the activation of molecular oxygen, forming active oxygen species for the selective oxidation of methane to formaldehyde.
Co-reporter:Qiang Yuan;Weiping Deng;Qinghong Zhang
Advanced Synthesis & Catalysis 2007 Volume 349(Issue 7) pp:
Publication Date(Web):18 MAY 2007
DOI:10.1002/adsc.200600438
Various transition metal chlorides including FeCl3, CoCl2, RuCl3, RhCl3, PdCl2, OsCl3, IrCl3, H2PtCl6, CuCl2 and HAuCl4 were studied for the selective oxidations of methane and ethane with hydrogen peroxide in aqueous medium. Among the metal chlorides investigated, osmium(III) chloride (OsCl3) exhibited the highest turnover frequency (TOF) for the formation of organic oxygenates (mainly alcohols and aldehydes) from both methane and ethane. For the OsCl3-catalyzed oxidation of methane with hydrgen peroxide, methyl hydroperoxide was also formed together with methanol and formaldehyde. The effects of various kinetic factors on the catalytic behavior of the OsCl3-H2O2 system were investigated, and TOF values of 12 and 41 h−1 could be obtained for oxygenate formation during the oxidations of methane and ethane, respectively. In the presence of OsCl3, NaClO, NaClO4 or NaIO4 as oxidant was incapable of oxidizing methane and ethane to the corresponding oxygenates, and the use of tert-butyl hydroperoxide (TBHP) instead of H2O2 provided remarkably lower rates of formation of oxygenates. UV-Vis spectroscopic measurements suggested that OsCl3 was probably oxidized into an Os(IV) species by H2O2 in aqueous medium, and the Os(IV) species might be involved in the oxygenation of methane or ethane. The result that the conversions of both methane and ethane to oxygenates were suppressed by the addition of a radical scavenger suggested that the reactions proceeded via a radical pathway.
Co-reporter:Ping Wang;Jincan Kang;Qinghong Zhang
Catalysis Letters 2007 Volume 114( Issue 3-4) pp:178-184
Publication Date(Web):2007 April
DOI:10.1007/s10562-007-9062-4
Among various microporous and mesoporous materials investigated, the Li+-exchanged zeolite faujasite has been found to be the most efficient support of iron catalyst for producing C5+ hydrocarbon fuels via Fischer-Tropsch synthesis. The location of iron species in the catalyst is a key issue in obtaining high selectivities to C5+ hydrocarbons. It is proposed that the Li+ cation and the supercage structure of zeolite faujasite both play important roles in improving the selectivities to C5+ hydrocarbons over the Fe catalyst.
Co-reporter:Weiping Deng, Qinghong Zhang, Ye Wang
Journal of Energy Chemistry (September 2015) Volume 24(Issue 5) pp:595-607
Publication Date(Web):1 September 2015
DOI:10.1016/j.jechem.2015.08.016
The catalytic transformation of cellulose, the major component of abundant and renewable lignocellulosic biomass, into building-block chemicals is a key to establishing sustainable chemical processes. Cellulose is a polymer of glucose and a lot research effort has been devoted to the conversion of cellulose to six-carbon platform compounds such as glucose and glucose derivatives through CO bond activation. There also exist considerable studies on the catalytic cleavage of CC bonds in biomass for the production of high-value chemicals, in particular polyols and organic acids such as ethylene glycol and lactic acid. This review article highlights recent advances in the development of new catalytic systems and new strategies for the selective cleavage of CC bonds in cellulose and its derived carbohydrates under inert, reductive and oxidative atmospheres to produce C1C5 polyols and organic acids. The key factors that influence the catalytic performance will be clarified to provide insights for the design of more efficient catalysts for the transformation of cellulose with precise cleavage of CC bonds to high-value chemicals. The reaction mechanisms will also be discussed to understand deeply how the selective cleavage of CC bonds can be achieved in biomass.Recent advances in catalytic transformation of cellulose or its derived carbohydrates into chemicals involving CC bond cleavage have been reviewed.Download high-res image (189KB)Download full-size image
Co-reporter:Jieli He, Yang Li, Dongli An, Qinghong Zhang, Ye Wang
Journal of Natural Gas Chemistry (September 2009) Volume 18(Issue 3) pp:288-294
Publication Date(Web):1 September 2009
DOI:10.1016/S1003-9953(08)60120-6
FeOx-SiO2 catalysts prepared by a sol-gel method were studied for the selective oxidation of methane by oxygen. A single-pass formaldehyde yield of 2.0% was obtained over the FeOx-SiO2 with an iron content of 0.5 wt% at 898 K. This 0.5 wt% FeOx-SiO2 catalyst demonstrated significantly higher catalytic performances than the 0.5 wt% FeOx/SiO2 prepared by an impregnation method. The correlation between the catalytic performances and the characterizations with UV-Vis and H2-TPR suggested that the higher dispersion of iron species in the catalyst prepared by the sol-gel method was responsible for its higher catalytic activity for formaldehyde formation. The modification of the FeOx-SiO2 by phosphorus enhanced the formaldehyde selectivity, and a single-pass formaldehyde yield of 2.4% could be attained over a P-FeOx-SiO2 catalyst (P/Fe = 0.5) at 898 K. Raman spectroscopic measurements indicated the formation of FePO4 nanoclusters in this catalyst, which were more selective toward formaldehyde formation.
Co-reporter:Weiping Deng, Ye Wang, Ning Yan
Current Opinion in Green and Sustainable Chemistry (October 2016) Volume 2() pp:54-58
Publication Date(Web):1 October 2016
DOI:10.1016/j.cogsc.2016.10.002
Catalytic synthesis of valuable organic acids such as lactic acid, levulinic acid, formic acid, acetic acid, 2, 5-furandicarboxylic acid (FDCA), and sugar acids (e.g. gluconic acid and glucosaminic acid) from renewable carbon resources is of high interest for a sustainable chemical industry in the future. A number of efficient catalytic systems have been recently developed to convert biomass into organic acids. Herein we highlight new strategies and catalysts that are effective for the transformations. The mechanisms and catalyst functions involved in several typical reactions are analyzed for the rational design of more efficient catalytic systems.
Co-reporter:Bizhong Hu, Weiping Deng, Rongsheng Li, Qinghong Zhang, Ye Wang, Francine Delplanque-Janssens, Deschrijver Paul, Frederique Desmedt, Pierre Miquel
Journal of Catalysis (November 2014) Volume 319() pp:15-26
Publication Date(Web):1 November 2014
DOI:10.1016/j.jcat.2014.08.001
•Carbon materials are efficient supports of Pd catalysts for H2O2 synthesis.•H2O2 formation activity depends on the structure and property of carbon supports.•Higher graphitic degree and lower COOH-group density favor H2O2 selectivity.•Metallic Pd is more efficient than PdO for H2O2 formation.•Smaller Pd nanoparticles exhibit higher activity and H2O2 selectivity.Twelve kinds of carbon materials were studied as supports of palladium catalysts for the direct synthesis of hydrogen peroxide. The correlation between the catalytic performance and the structure and physicochemical properties of carbon materials suggested the important roles of the graphitic structure and the surface function groups in the selective formation of H2O2. The carbon material with a higher degree of graphitic structure and a lower density of surface COOH groups provided higher H2O2 selectivity and productivity. The chemical state and the mean size of Pd particles also affected the catalytic behavior. Metallic Pd was more efficient than PdO, and the catalyst with a smaller mean size of Pd nanoparticles exhibited higher activity and H2O2 selectivity. The presence of a mineral acid rather than a halide promoter and an organic solvent contributed to the selective formation of H2O2.Graphical abstractDownload high-res image (84KB)Download full-size image
Co-reporter:Ting Xu, Qinghong Zhang, Hang Song, Ye Wang
Journal of Catalysis (November 2012) Volume 295() pp:232-241
Publication Date(Web):1 November 2012
DOI:10.1016/j.jcat.2012.08.014
Among several typical zeolites, H-ZSM-5 was found to be a promising catalyst for the conversion of methyl halides (CH3Cl and CH3Br) into propylene. The increase in Si/Al ratio or Na+ exchange degree in ZSM-5 increased the selectivity of propylene but decreased the conversion of methyl halides. The treatment of H-ZSM-5 with ammonium fluoride followed by calcination significantly improved its catalytic performance. With a proper concentration of fluoride, not only the propylene selectivity but also the catalyst stability could be enhanced significantly. We have demonstrated that the acidity and the pore structure are two crucial factors determining the catalytic behaviors. The weaker acidity of the fluoride-treated H-ZSM-5 suppressed the hydrogen-transfer and aromatization reactions, leading to higher selectivity to light olefins. Larger micropores with sizes of 0.73–0.78 nm, which were generated after the fluoride treatment, changed the distribution of methylbenzenes in the “hydrocarbon pool” over catalyst and contributed to higher propylene selectivity.Graphical abstractThe fluoride-treated H-ZSM-5 catalyzes the conversion of methyl halides (CH3Cl or CH3Br) to propylene with high selectivity and stability.Download high-res image (158KB)Download full-size imageHighlights► Fluoride-treated H-ZSM-5 is highly selective for C3H6 formation from CH3Cl or CH3Br. ► Fluoride treatment decreases acidity, inhibiting secondary reactions of light olefins. ► Fluoride treatment generates larger micropores in ZSM-5, increasing C3H6 selectivity. ► Conversion of methyl halide to light olefins proceeds via hydrocarbon pool mechanism. ► Acidity and porous structure determine the catalytic conversion of methyl halides.
Co-reporter:Ye Wang
Journal of Energy Chemistry (March 2016) Volume 25(Issue 2) pp:169-170
Publication Date(Web):1 March 2016
DOI:10.1016/j.jechem.2016.03.001
The Bao group at Dalian Institute of Chemical Physics, Chinese Academy of Sciences has recently made a significant breakthrough in the direct conversion of syngas to light olefins by designing a new OX-ZEO process.Download high-res image (163KB)Download full-size image
Co-reporter:Jieli He, Qingge Zhai, Qinghong Zhang, Weiping Deng, Ye Wang
Journal of Catalysis (March 2013) Volume 299() pp:53-66
Publication Date(Web):1 March 2013
DOI:10.1016/j.jcat.2012.11.032
Among alkali metal ions, Cs+ was found to be the most efficient promoter of the CuOx/SiO2 catalyst for the epoxidation of propylene to propylene oxide (PO) by O2. Stronger interactions between Cs+ and CuOx nanoparticles were proposed to favor the selective formation of PO. Kinetic studies indicated that PO was formed as a primary product in parallel with acrolein over the CuOx/SiO2 catalyst, but PO readily underwent isomerization to allyl alcohol, followed by oxidation to acrolein, without Cs+ modification. The modification by Cs+ inhibited the isomerization of PO because of the weakened acidity, contributing to the increase in PO selectivity. The inhibition of the reactivity of the lattice oxygen in the presence of Cs+ also promoted PO selectivity by suppressing the allylic oxidation route. In situ X-ray diffraction, CO-adsorbed Fourier-transform infrared, and pulse-reaction studies suggest that CuI sites generated during the reaction account for the epoxidation of propylene by O2.Graphical abstractCuI generated over the CuOx/SiO2 catalyst with and without Cs+ modification during the reaction accounts for the formation of propylene oxide, while the lattice oxygen is responsible for acrolein formation.Download high-res image (58KB)Download full-size imageHighlights► The modification of CuOx/SiO2 catalyst by Cs+ promotes PO formation. ► PO is formed as a primary product in parallel with acrolein over CuOx/SiO2 catalyst. ► Modification by Cs+ inhibits the consecutive conversion of PO by decreasing acidity. ► Cs+ decreases the reactivity of lattice oxygen responsible for allylic oxidation. ► CuI generated during the reaction is involved in propylene epoxidation.
Co-reporter:Qinghong Zhang, Weiping Deng, Ye Wang
Journal of Energy Chemistry (January 2013) Volume 22(Issue 1) pp:27-38
Publication Date(Web):1 January 2013
DOI:10.1016/S2095-4956(13)60003-0
Catalytic conversion of synthesis gas (CO+H2) into hydrocarbons, also known as Fischer-Tropsch (FT) synthesis, is a crucial reaction for the transformation of non-petroleum carbon resources such as coal, natural gas, shale gas, coal-bed gas and biogas, as well as biomass into liquid fuels and chemicals. Many factors can influence the catalytic behavior of a FT catalyst. This review highlights recent advances in understanding some key catalyst factors, including the chemical state of active phases, the promoters, the size and the microenvironment of active phase, which determine the CO conversion activity and the product selectivity, particularly the selectivity to C5+ hydrocarbons.
Co-reporter:Weiping Deng, Mi Liu, Qinghong Zhang, Ye Wang
Catalysis Today (30 April 2011) Volume 164(Issue 1) pp:461-466
Publication Date(Web):30 April 2011
DOI:10.1016/j.cattod.2010.10.055
The alcoholysis of cellulose in methanol and ethanol media has been studied in the presence of various kinds of acid catalysts. Keggin-type tungstosilicious and tungstophosphoric acids (H4SiW12O40 and H3PW12O40) were found to be highly efficient for the alcoholysis of cellulose. Methyl and ethyl glucosides (both containing α and β isomers) could be obtained in methanol and ethanol with yields as high as 57% and 63%, respectively. The ratio of α and β isomers was ∼1.4–1.6 in both methyl or ethyl glucosides, suggesting the intermolecular transformations between α and β isomers. Our comparative studies show that the alcoholysis of cellulose in methanol or ethanol proceeds more efficiently than the hydrolysis of cellulose in water medium. Glucose yields of only about 5–10% were obtained in water in the presence of an acid catalyst under similar reaction conditions.
Co-reporter:Ye Wang, Hui Chu, Wenming Zhu, Qinghong Zhang
Catalysis Today (29 February 2008) Volume 131(Issues 1–4) pp:496-504
Publication Date(Web):29 February 2008
DOI:10.1016/j.cattod.2007.10.022
Among a series of SBA-15-supported transition metal oxides with and without modification, the CuOx/SBA-15 after K+ modification exhibited the best catalytic performance for the epoxidation of propylene by molecular oxygen. Potassium was the best modifier among various alkali and alkaline earth metal ions examined, and potassium acetate was a superior precursor of K+ for propylene oxide formation. The highest propylene oxide selectivity was obtained over a catalyst with copper content of 1 wt.% and K/Cu molar ratio of 0.7. Kinetic studies reveal that the allylic oxidation mainly proceeds over the CuOx/SBA-15 providing acrolein as the main partial oxidation product, and the K+ modification switches the main reaction route from allylic oxidation to epoxidation. The characterizations suggest that copper species with content of ≤5 wt.% are located in the mesoporous channels of SBA-15 existing mainly as CuOx clusters and Cu2+ ions, and there exists an interaction between K+ and the copper species. This interaction is proposed to play pivotal roles in epoxidation of propylene. As compared with other reported Cu-based catalysts for propylene epoxidation, the present catalyst possesses several distinct features.
Co-reporter:Yinchuan Lou, Huichun Wang, Qinghong Zhang, Ye Wang
Journal of Catalysis (25 April 2007) Volume 247(Issue 2) pp:245-255
Publication Date(Web):25 April 2007
DOI:10.1016/j.jcat.2007.02.011
The selective oxidation of ethane was investigated over SBA-15-supported molybdenum oxide catalysts. Our characterizations suggest that the MoOx species were dispersed mostly in mesoporous channels of SBA-15 at Mo content <9.5 wt%. At higher Mo content (15.4 and 20.1 wt%), MoOx nanoparticles together with small amount of MoO3 crystallites were found. The growth of MoOx species in mesoporous channels to MoOx nanoparticles causes the collapse of the silica wall of SBA-15. The rate of ethane conversion per Mo atom over the catalyst with Mo content of 9.5–20.1 wt% was significantly higher than that over the catalyst with lower Mo content, suggesting that polymeric MoOx clusters and MoOx nanoparticles are more active toward ethane activation. The catalysts with highly dispersed MoOx species favor the selectivity of acetaldehyde, whereas those containing polymeric MoOx clusters or MoOx nanoparticles show higher formaldehyde formation rates. Formaldehyde is likely produced through the consecutive oxidation of ethylene.
Co-reporter:Lüjuan Yang, Jieli He, Qinghong Zhang, Ye Wang
Journal of Catalysis (19 November 2010) Volume 276(Issue 1) pp:76-84
Publication Date(Web):19 November 2010
DOI:10.1016/j.jcat.2010.09.002
The modification of copper by vanadium significantly enhanced its catalytic performance of propylene epoxidation by oxygen. Synergistic effects existed between copper and vanadium, and the catalysts with V/Cu atomic ratios of 0.11–0.20 exhibited better propylene oxide (PO) formation activity. The dispersion of copper was enhanced by vanadium, and this might contribute to the increase in catalytic activity. The pre-reduction of catalyst resulted in better performances than the oxidative pretreatment, and an induction period was observed for PO formation over the reduced catalyst. In situ XRD measurements revealed that Cu0 in the reduced catalyst was partially transformed into Cu2O in propylene oxidation, and the presence of VOx promoted this transformation. Structure–performance correlations demonstrate that CuI accounts for propylene epoxidation. Vanadium species at lower valence states (VIII and VIV) may participate in the activation of oxygen. The presence of VOx also suppressed the reactivity of lattice oxygen in the working catalyst.Modification of unsupported copper by vanadium significantly enhances its catalytic activity for propylene epoxidation. CuI with cooperation of vanadium species at lower valance states is responsible for propylene oxide formation.Download high-res image (79KB)Download full-size image
Co-reporter:Weiping Deng, Mi Liu, Xuesong Tan, Qinghong Zhang, Ye Wang
Journal of Catalysis (12 April 2010) Volume 271(Issue 1) pp:22-32
Publication Date(Web):12 April 2010
DOI:10.1016/j.jcat.2010.01.024
Carbon nanotube (CNT)-supported ruthenium catalysts were studied for the hydrogenation of cellobiose in neutral water medium. The acidity of catalysts and the size of Ru particles played key roles in the conversion of cellobiose to sorbitol. A higher concentration of nitric acid used for CNT pretreatment provided a better sorbitol yield, suggesting an important role of catalyst acidity. The catalysts with larger mean sizes of Ru particles and abundant acidic sites exhibited better sorbitol yields, while those with smaller Ru particles and less acidic sites favored the formation of 3-β-d-glucopyranosyl-d-glucitol. We elucidated that cellobiose was first converted to 3-β-d-glucopyranosyl-d-glucitol via the hydrogenolysis, and then sorbitol was formed through the cleavage of β-1,4-glycosidic bond in 3-β-d-glucopyranosyl-d-glucitol over the catalysts. The catalyst with smaller Ru particles favored the first step but was disadvantageous to the second step due to the less acidity. Smaller Ru particles also accelerated the degradation of sorbitol.The mean size of Ru nanoparticles and the catalyst acidity are key factors for Ru/CNT-catalyzed hydrogenation of cellobiose to sorbitol in water. 3-β-d-Glucopyranosyl-d-glucitol is a main reaction intermediate.Download high-res image (91KB)Download full-size image
Co-reporter:Yinchuan Lou, Qinghong Zhang, Huichun Wang, Ye Wang
Journal of Catalysis (10 September 2007) Volume 250(Issue 2) pp:365-368
Publication Date(Web):10 September 2007
DOI:10.1016/j.jcat.2007.06.015
The selective oxidation of ethylene by oxygen produced formaldehyde with a single-pass yield of ∼30% at a temperature of 863 K and a contact time of 0.08 s g cm−3 over a mesoporous silica (SBA-15)-supported molybdenum oxide catalyst. Oligomeric MoOx species and polymeric MoOx clusters were responsible for this reaction. The exploitation of a double-bed catalytic reaction mode containing Dy2O3Li+MgOCl− and MoOx/SBA-15 as the upstream, and the downstream catalysts converted ethane directly to formaldehyde by oxygen with a single-pass yield of 14% at 863 K.
Co-reporter:Sufen Yang, Wenming Zhu, Qinghong Zhang, Ye Wang
Journal of Catalysis (10 March 2008) Volume 254(Issue 2) pp:251-262
Publication Date(Web):10 March 2008
DOI:10.1016/j.jcat.2008.01.002
The presence of boron significantly promoted propylene oxide (PO) formation over chlorine-free K+-modified FeOx/SBA-15 catalysts with K/Fe ratios ⩾2.5. Boron also improved the catalytic performances of Rb+- and Cs+-modified FeOx/SBA-15 catalysts, whereas it did not play significant roles over Li+- and Na+-modified catalysts. Boron-promoted K+–FeOx/SBA-15 exhibited the best catalytic performance for PO formation. Potassium ions could enhance the dispersion of FeOx clusters, forming active iron sites. The addition of K+ at a higher content destroyed the ordered mesoporous structure of SBA-15, likely causing the reaggregation of iron species. The modification by boron could keep the ordered mesoporous structure and the high dispersion of iron species, which were beneficial to PO formation. The addition of boron with a proper content also suppressed further conversion of PO by diminishing the acidity and basicity of the catalyst. We propose that the interactions among boron, potassium ions, and iron species play pivotal roles in enhancing PO formation.
Co-reporter:Sufen Yang, Wenming Zhu, Qinghong Zhang, Ye Wang
Journal of Catalysis (10 March 2008) Volume 254(Issue 2) pp:251-262
Publication Date(Web):10 March 2008
DOI:10.1016/j.jcat.2008.01.002
The presence of boron significantly promoted propylene oxide (PO) formation over chlorine-free K+-modified FeOx/SBA-15 catalysts with K/Fe ratios ⩾2.5. Boron also improved the catalytic performances of Rb+- and Cs+-modified FeOx/SBA-15 catalysts, whereas it did not play significant roles over Li+- and Na+-modified catalysts. Boron-promoted K+–FeOx/SBA-15 exhibited the best catalytic performance for PO formation. Potassium ions could enhance the dispersion of FeOx clusters, forming active iron sites. The addition of K+ at a higher content destroyed the ordered mesoporous structure of SBA-15, likely causing the reaggregation of iron species. The modification by boron could keep the ordered mesoporous structure and the high dispersion of iron species, which were beneficial to PO formation. The addition of boron with a proper content also suppressed further conversion of PO by diminishing the acidity and basicity of the catalyst. We propose that the interactions among boron, potassium ions, and iron species play pivotal roles in enhancing PO formation.
Co-reporter:Qinghong Zhang, Yang Li, Dongli An, Ye Wang
Applied Catalysis A: General (1 March 2009) Volume 356(Issue 1) pp:103-111
Publication Date(Web):1 March 2009
DOI:10.1016/j.apcata.2008.12.031
Co-reporter:Feng Li, Qinghong Zhang, Ye Wang
Applied Catalysis A: General (1 January 2008) Volume 334(Issues 1–2) pp:217-226
Publication Date(Web):1 January 2008
DOI:10.1016/j.apcata.2007.10.008
Co-reporter:Shunji Xie, Zebin Shen, Huamin Zhang, Jun Cheng, Qinghong Zhang and Ye Wang
Catalysis Science & Technology (2011-Present) 2017 - vol. 7(Issue 4) pp:NaN933-933
Publication Date(Web):2017/01/18
DOI:10.1039/C6CY02510B
Bismuth vanadate (BiVO4) single crystals with controllable facets and cocatalysts were synthesized and studied for photocatalytic coupling of formaldehyde into C2 compounds mainly including ethylene glycol and glycolaldehyde. By using chloride anions as a morphology-controlling agent, we succeeded in synthesizing BiVO4 single crystals with a uniform truncated tetragonal bipyramidal morphology enclosed with {010} and {110} facets. The ratio of exposed {010} and {110} facets could be regulated by changing the concentration of Cl−. BiVO4 with an equal fraction of exposed {010} and {110} facets exhibited the highest capability of electron–hole separation and the highest C2-compound yield. The loading of core–shell structured Pt@MoOx and MnOx particles onto {010} and {110} facets, respectively, further enhanced the formation of C2 compounds. Our studies suggested that the Pt core and the MnOx particles accelerated the separation of photogenerated electron–hole pairs, whereas the MoOx shell catalyzed the coupling of HCHO possibly via a redox mechanism. The yields of C2 compounds and ethylene glycol reached 21% and 11%, respectively, under irradiation with UV-vis light for 12 h. Quantum yields of 11% and 4.8% were achieved for the coupling products under ultraviolet (350 nm) and visible (450 nm) light irradiation, respectively.
Co-reporter:Weiping Deng, Qinghong Zhang and Ye Wang
Dalton Transactions 2012 - vol. 41(Issue 33) pp:NaN9831-9831
Publication Date(Web):2012/05/01
DOI:10.1039/C2DT30637A
Efficient utilisation of renewable biomass resources, particularly lignocellulosic biomass, for the production of chemicals and fuels has attracted much attention in recent years. The catalytic conversion of cellulose, the main component of lignocellulosic biomass, selectively into a platform chemical such as glucose, 5-hydroxymethyl furfural (HMF), sorbitol or gluconic acid under mild conditions is the most desirable route. Acid catalysis plays a crucial role in the conversion of cellulose via the cleavage of its glycosidic bonds. Owing to their unique features such as strong acidity, water-tolerance, low corrosiveness and recoverability, polyoxometalates have shown promising performances in transformations of cellulose into platform chemicals both in homogeneous and heterogeneous systems. This article highlights recent studies on polyoxometalates and polyoxometalate-based bifunctional catalysts or catalytic systems for the selective conversions of cellulose and cellobiose, a model molecule of cellulose, into platform chemicals.
Co-reporter:Qinghong Zhang, Weiping Deng and Ye Wang
Chemical Communications 2011 - vol. 47(Issue 33) pp:NaN9292-9292
Publication Date(Web):2011/05/31
DOI:10.1039/C1CC11723H
The size of the active phase is one of the most important factors in determining the catalytic behaviour of a heterogeneous catalyst. This Feature Article focuses on the size effects in two types of reactions, i.e., the metal nanoparticle-catalysed dehydrogenation of alcohols and the metal oxide nanocluster-catalysed selective oxidation of hydrocarbons (including the selective oxidation of methane and ethane and the epoxidation of propylene). For Pd or Au nanoparticle-catalysed oxidative or non-oxidative dehydrogenation of alcohols, the size of metal nanoparticles mainly controls the catalytic activity by affecting the activation of reactants (either alcohol or O2). The size of oxidic molybdenum species loaded on SBA-15 determines not only the activity but also the selectivity of oxygenates in the selective oxidation of ethane; highly dispersed molybdenum species are suitable for acetaldehyde formation, while molybdenum oxide nanoparticles exhibit higher formaldehyde selectivity. CuII and FeIII isolated on mesoporous silica are highly efficient for the selective oxidation of methane to formaldehyde, while the corresponding oxide clusters mainly catalyse the complete oxidation of methane. The lattice oxygen in iron or copper oxide clusters is responsible for the complete oxidation, while the isolated CuI or FeII generated during the reaction can activate molecular oxygen forming active oxygen species for the selective oxidation of methane. Highly dispersed CuI and FeII species also function for the epoxidation of propylene by O2 and N2O, respectively. Alkali metal ions work as promoters for the epoxidation of propylene by enhancing the dispersion of copper or iron species and weakening the acidity.
Co-reporter:Zebin Shen, Shunji Xie, Wenqing Fan, Qinghong Zhang, Zaiku Xie, Weimin Yang, Yangdong Wang, Jinchi Lin, Xuejiao Wu, Huilin Wan and Ye Wang
Catalysis Science & Technology (2011-Present) 2016 - vol. 6(Issue 17) pp:NaN6489-6489
Publication Date(Web):2016/07/29
DOI:10.1039/C6CY01468B
We report a novel and direct conversion of formaldehyde into C2 compounds, in particular ethylene glycol, via photocatalytic carbon–carbon coupling over BiVO4, a visible-light-responsive and robust semiconductor. The generation of V4+ on BiVO4 surfaces enhanced the photocatalytic formation of C2 compounds.
Co-reporter:Shunji Xie, Qinghong Zhang, Guodong Liu and Ye Wang
Chemical Communications 2016 - vol. 52(Issue 1) pp:NaN59-59
Publication Date(Web):2015/10/30
DOI:10.1039/C5CC07613G
The development of efficient artificial photocatalysts and photoelectrocatalysts for the reduction of CO2 with H2O to fuels and chemicals has attracted much attention in recent years. Although the state-of-the-art for the production of fuels or chemicals from CO2 using solar energy is still far from practical consideration, rich knowledge has been accumulated to understand the key factors that determine the catalytic performances. This Feature article highlights recent advances in the photocatalytic and photoelectrocatalytic reduction of CO2 with H2O using heterogeneous semiconductor-based catalysts. The effects of structural aspects of semiconductors, such as crystalline phases, particle sizes, morphologies, exposed facets and heterojunctions, on their catalytic behaviours are discussed. The roles of different types of cocatalysts and the impact of their nanostructures on surface CO2 chemisorption and reduction are also analysed. The present article aims to provide insights into the rational design of efficient heterogeneous catalysts with controlled nanostructures for the photocatalytic and photoelectrocatalytic reduction of CO2 with H2O.
Co-reporter:Aihua Ye, Wenqing Fan, Qinghong Zhang, Weiping Deng and Ye Wang
Catalysis Science & Technology (2011-Present) 2012 - vol. 2(Issue 5) pp:NaN978-978
Publication Date(Web):2012/01/23
DOI:10.1039/C2CY20027A
CdS–graphene (GR) and CdS–carbon nanotube (CNT) nanocomposites prepared by a hydrothermal method were studied as photocatalysts for the evolution of hydrogen and the degradation of methyl orange (MO) under visible-light irradiation. The incorporation of GR or CNT into CdS significantly enhanced the photocatalytic activities for both reactions. The photocatalytic activities depended on the mass ratio of CdS:GR or CdS:CNT in the nanocomposites. Under optimized mass ratios, the CdS–GR was more efficient than the CdS–CNT. Our characterizations suggested that CdS nanoparticles of ∼35 nm in size were dispersed on the graphene sheets or CNT surfaces in the nanocomposites. Significant band-gap narrowing was observed due to the incorporation of GR or CNT into CdS, indicating the strong interactions between CdS and GR or CNT. The transient photocurrent response studies suggested a more efficient separation of photogenerated electrons and holes. The stronger interaction or larger contact interface between CdS and GR was proposed to accelerate the transfer of photogenerated electrons from CdS to GR more efficiently, resulting in higher photocatalytic activities of the CdS–GR composite.
Co-reporter:Weiping Deng, Jiashu Chen, Jincan Kang, Qinghong Zhang and Ye Wang
Chemical Communications 2016 - vol. 52(Issue 41) pp:NaN6808-6808
Publication Date(Web):2016/04/26
DOI:10.1039/C6CC01490A
Functionalised carbon nanotube (CNT)-supported Au–Pd alloy nanoparticles were highly efficient catalysts for the aerobic oxidation of amines. We achieved the highest turnover frequencies (>1000 h−1) for the oxidative homocoupling of benzylamine and the oxidative dehydrogenation of dibenzylamine. We discovered a cooperative effect between Au–Pd nanoparticles and ketone/quinone groups on CNTs.
Co-reporter:Shunji Xie, Yu Wang, Qinghong Zhang, Weiping Deng and Ye Wang
Chemical Communications 2015 - vol. 51(Issue 16) pp:NaN3433-3433
Publication Date(Web):2015/01/20
DOI:10.1039/C4CC10241J
We successfully synthesized SrNb2O6 with nanoplate morphology by a facile hydrothermal method. The SrNb2O6 nanoplate without any promoters or co-catalysts exhibited promising photocatalytic performance for the preferential reduction of CO2 with H2O vapour to CO and CH4 due to its high electron–hole separation and high CO2 chemisorption abilities.
Co-reporter:Guodong Liu, Shunji Xie, Qinghong Zhang, Zhengfang Tian and Ye Wang
Chemical Communications 2015 - vol. 51(Issue 71) pp:NaN13657-13657
Publication Date(Web):2015/07/21
DOI:10.1039/C5CC05113D
The combination of polyaniline with TiO2 significantly enhanced the photocatalytic reduction of CO2 with H2O owing to the increased CO2 chemisorption and the facilitated separation of photogenerated electron–hole pairs. We discovered that CO2 played a unique role in enhancing the electron–hole separation and the photocatalytic activity for polyaniline-containing catalysts.
Co-reporter:Shunji Xie, Yu Wang, Qinghong Zhang, Wenqing Fan, Weiping Deng and Ye Wang
Chemical Communications 2013 - vol. 49(Issue 24) pp:NaN2453-2453
Publication Date(Web):2013/02/07
DOI:10.1039/C3CC00107E
Photocatalytic activity in the reduction of CO2 with H2O to CH4 was significantly enhanced by simply adding MgO to TiO2 loaded with Pt. A positive correlation between CH4 formation activity and basicity was observed. The interface between TiO2, Pt and MgO in the trinary nanocomposite played a crucial role in CO2 photocatalytic reduction.
Co-reporter:Weiping Deng, Mi Liu, Qinghong Zhang, Xuesong Tan and Ye Wang
Chemical Communications 2010 - vol. 46(Issue 15) pp:NaN2670-2670
Publication Date(Web):2010/02/06
DOI:10.1039/B925723C
Cellulose can be transformed into methyl glucosides in methanol with yields of 50–60% in the presence of several acid catalysts under mild conditions (≤473 K); H3PW12O40 provides the highest turnover number (∼73 in 0.5 h) for the formation of methyl glucosides among many acid catalysts examined.
Co-reporter:Xuesong Tan, Weiping Deng, Mi Liu, Qinghong Zhang and Ye Wang
Chemical Communications 2009(Issue 46) pp:NaN7181-7181
Publication Date(Web):2009/10/14
DOI:10.1039/B917224F
Gold nanoparticles loaded on nitric acid-pretreated carbon nanotubes are efficient for the selective oxidation of cellobiose by molecular oxygen to gluconic acid in aqueous medium without pH control; a gluconic acid yield of 80% has been obtained at 145 °C.
Co-reporter:Mi Liu, Weiping Deng, Qinghong Zhang, Yanliang Wang and Ye Wang
Chemical Communications 2011 - vol. 47(Issue 34) pp:NaN9719-9719
Publication Date(Web):2011/07/25
DOI:10.1039/C1CC12506K
Ru
nanoparticles loaded on a Keggin-type polyoxometalate (Cs3PW12O40), which did not possess strong intrinsic acidity, efficiently catalysed the conversions of cellobiose and cellulose into sorbitol in water medium in H2 at ≤433 K. The Brønsted acid sites generated in situ from H2 have been demonstrated to play a key role in the formation of sorbitol.
Co-reporter:Wenhao Fang, Qinghong Zhang, Jing Chen, Weiping Deng and Ye Wang
Chemical Communications 2010 - vol. 46(Issue 9) pp:NaN1549-1549
Publication Date(Web):2010/01/27
DOI:10.1039/B923047E
Hydrotalcite-supported gold nanoparticles with sizes of less than 5 nm are highly efficient and reusable catalysts for the oxidant-free dehydrogenation of alcohols to carbonyl compounds and hydrogen.
Co-reporter:Wenqing Fan, Qinghong Zhang and Ye Wang
Physical Chemistry Chemical Physics 2013 - vol. 15(Issue 8) pp:NaN2649-2649
Publication Date(Web):2012/12/17
DOI:10.1039/C2CP43524A
Semiconductor-based photocatalysis has attracted much attention in recent years because of its potential for solving energy and environmental problems that we are now facing. Among many photocatalytic reactions, the splitting of H2O into H2 and O2 and the reduction of CO2 with H2O into organic compounds such as CH4 and CH3OH are two of the most important and challenging reactions. Many studies have been devoted to designing and preparing novel photocatalytic materials for these two reactions. This article highlights recent advances in developing semiconductor-based nanocomposite photocatalysts for the production of H2 and the reduction of CO2. The systems of semiconductor–cocatalyst, semiconductor–carbon (carbon nanotube or graphene) and semiconductor–semiconductor nanocomposites have mainly been described. It has been demonstrated that the design and preparation of nanocomposites with proper structures can facilitate charge separation/migration and decrease the charge recombination probability, thus promoting the photocatalytic activity. Keeping the reduction and oxidation processes in different regions in the nanocomposite may also enhance the photocatalytic efficiency and stability. The location and size of cocatalysts, the interfacial contact between semiconductor and carbon materials, and the heterojunctions between different semiconductors together with the suitable alignment of band edges of semiconductors are key factors determining the photocatalytic behaviours of the nanocomposite catalysts.
Co-reporter:Zhen Guo, Bin Liu, Qinghong Zhang, Weiping Deng, Ye Wang and Yanhui Yang
Chemical Society Reviews 2014 - vol. 43(Issue 10) pp:NaN3524-3524
Publication Date(Web):2014/02/20
DOI:10.1039/C3CS60282F
Oxidation catalysis not only plays a crucial role in the current chemical industry for the production of key intermediates such as alcohols, epoxides, aldehydes, ketones and organic acids, but also will contribute to the establishment of novel green and sustainable chemical processes. This review is devoted to dealing with selective oxidation reactions, which are important from the viewpoint of green and sustainable chemistry and still remain challenging. Actually, some well-known highly challenging chemical reactions involve selective oxidation reactions, such as the selective oxidation of methane by oxygen. On the other hand some important oxidation reactions, such as the aerobic oxidation of alcohols in the liquid phase and the preferential oxidation of carbon monoxide in hydrogen, have attracted much attention in recent years because of their high significance in green or energy chemistry. This article summarizes recent advances in the development of new catalytic materials or novel catalytic systems for these challenging oxidation reactions. A deep scientific understanding of the mechanisms, active species and active structures for these systems are also discussed. Furthermore, connections among these distinct catalytic oxidation systems are highlighted, to gain insight for the breakthrough in rational design of efficient catalytic systems for challenging oxidation reactions.
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