Co-reporter:Wen Hua Fu, Xiao Min Liang, Haidong Zhang, Yi Meng Wang and Ming Yuan He
Chemical Communications 2015 vol. 51(Issue 8) pp:1449-1452
Publication Date(Web):02 Dec 2014
DOI:10.1039/C4CC08784D
In the synthesis of polyoxymethylene dimethyl ethers (PODEn) catalyzed by ordered supermicroporous aluminosilicates, shape selectivity was observed and the high selectivity for target products (PODE3–8) was attributed to the particular pore diameter.
Co-reporter:Teng Xue, Huaping Liu and Yi Meng Wang
RSC Advances 2015 vol. 5(Issue 16) pp:12131-12138
Publication Date(Web):09 Jan 2015
DOI:10.1039/C4RA14874F
Zeolite ferrierite aggregates with hierarchical porosity were synthesized using TMAOH and piperidine as cooperative structure-directing agents (co-SDAs). The effect of the relative amount of TMAOH and piperidine on the crystalline phase and textural properties of the products was investigated. Ferrierite aggregates synthesized herein were ca. 10–15 μm in size, comprised of nanosheets with thickness of less than 50 nm. The ferrierite aggregates possessed similar acidity and crystallinity with respect to the bulk ferrierite prepared using only piperidine as SDA, but exhibited more than 3 times higher mesopore surface area. The ferrierite aggregates with hierarchical porosity were found to be more efficient in catalytic LDPE cracking due to improved accessibility of large polymer molecules to the active sites.
Co-reporter:Bhupendra K. Singh, Dongdong Xu, Lu Han, Jian Ding, Yimeng Wang, and Shunai Che
Chemistry of Materials 2014 Volume 26(Issue 24) pp:7183
Publication Date(Web):December 3, 2014
DOI:10.1021/cm503919h
A single-crystalline mesoporous ZSM-5 (SCMZ) with sheetlike pores, a uniform thickness of ∼2 nm, and a wide range of lengths (5–50 nm) along the a-axis and c-axis was synthesized using an amphiphilic template with three diquaternary ammonium-terminated alkyl chain branches that were bound to a benzene ring at positions 1, 3, and 5. The triply branched diquaternary ammonium head groups of the template broke the extension of the lamellar assembly along the a-axis and c-axis, which led to the formation of SCMZ with three-dimensional mesopores having abundant crystal faces along the a-axis, b-axis, and c-axis. By increasing the length of the hydrophobic chain, we obtained the mesoporous ZSM-5 with intercrossed nanosheets (MZIN) with only a–c planes, whose mesopores were maintained after calcination because of the structural connectivity around the crossed joints. The SCMZ exhibited catalytic efficiencies significantly higher than those of and unique selectivity compared with those of the conventional MFI and MZIN.
Co-reporter:Wen Hua Fu, Sai Jin Wu, Yi Meng Wang and Ming Yuan He
Journal of Materials Chemistry A 2014 vol. 2(Issue 36) pp:14908-14917
Publication Date(Web):18 Jul 2014
DOI:10.1039/C4TA02269F
Highly ordered supermicroporous silicas and aluminosilicates with cubic Pm3n symmetry were prepared under weakly alkaline condition using alkyltrimethylammonium bromide with a short hydrophobic chain and relatively small hydrophilic head as a template. As the length of the carbon chain was increased from C10 to C16, the surfactant packing parameter increased and the favored symmetry of the silicas shifted from cubic Pm3n to hexagonal P6mm. Different mineral acids used to pre-hydrolyze TEOS could tune the silica mesostructures when dodecyltrimethylammonium bromide (C12TMAB) was used as the template: sulfuric acid (H2SO4) led to cubic Pm3n symmetry and nitric acid (HNO3) resulted in hexagonal P6mm symmetry. Under similar conditions, octyltrimethylammonium bromide (C8TMAB) templating led to a disordered structure. The Pm3n symmetry could be well preserved after Al was incorporated into the framework and the molar ratio of SiO2/Al2O3 in the aluminosilicates reached as low as 25. The pore size of the cubic Pm3n silicas and aluminosilicates was in the supermicroporous range. All the silica and aluminosilicate samples exhibited high specific area and large pore volume. Compared to zeolite USY-1 and AlSBA-1 catalysts synthesized in concentrated acid solution, aluminosilicates prepared herein exhibited more pronounced resistance to deactivation, higher reactivity for the acetalization of cyclohexanone with pentaerythritol, and a higher yield of 4-t-butyl-catechol in the tert-butylation of catechol.
Co-reporter:Wen Qian Jiao, Xiao Min Liang, Yi Meng Wang and Ming-Yuan He
CrystEngComm 2014 vol. 16(Issue 16) pp:3348-3358
Publication Date(Web):28 Jan 2014
DOI:10.1039/C4CE00068D
Boehmite nanostructures with different morphologies were prepared through polymorphic transformation of bayerite in the dry-gel conversion process with acetic acid solutions as steam source. The evolution of the crystalline structures and morphologies of nanoparticles tightly relied on the composition of the steam source, where H2O in the vapor offered the hydrothermal environment for the formation of boehmite crystalline structure and preferred the flake-like morphology while HAc adjusted the particle morphologies from flakes to nano-rods. Notably, the nano-structured particles aggregated together and led to the formation of microsized hierarchical boehmite structures. After dehydration, the boehmite can transform to γ-Al2O3 with the hierarchical structures well preserved, resulting in good textural properties.
Co-reporter:Hong Li Chen, Jian Ding and Yi Meng Wang
New Journal of Chemistry 2014 vol. 38(Issue 1) pp:308-316
Publication Date(Web):11 Oct 2013
DOI:10.1039/C3NJ00785E
Hierarchical porous ZSM-11 composites were hydrothermally synthesized through a one-step route using binary templates of cetyltrimethylammonium tosylate (CTATos) and tetrabutylammonium hydroxide (TBAOH). Influences of aluminum content and crystallization temperature on the morphology and structure were investigated. Powder X-ray diffraction (XRD) and N2 physisorption results show that the mesoporous ZSM-11 composites possess both a considerable mesoporous structure and zeolitic MEL-structure. Moreover, a large amount of aluminum in the gel composition slows the rate of zeolite crystallization, while a high SiO2/Al2O3 ratio is beneficial for the synthesis of mesoporous ZSM-11 without any phase separation. Mesoporous ZSM-11 aluminosilicates were compared to pure ordered mesoporous materials, zeolites and a mechanical mixture of meso and microphases for their catalytic activity in low-density polyethylene (LDPE) pyrolysis. The results suggest that all mesoporous ZSM-11 composites show higher catalytic performance for LDPE cracking.
Co-reporter:Wen Qian Jiao, Wen Hua Fu, Xiao Min Liang, Yi Meng Wang and Ming-Yuan He
RSC Advances 2014 vol. 4(Issue 102) pp:58596-58607
Publication Date(Web):30 Oct 2014
DOI:10.1039/C4RA11042K
Hierarchically structured Y zeolites were prepared by a post-synthetic strategy, where the as-made NaY zeolite was sequentially treated by a lactic acid solution and an alkaline solution containing cetyltrimethyl ammonium bromide (CTAB). Many techniques, including X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), N2 adsorption–desorption, Fourier-transform infrared spectroscopy (FT-IR), Thermogravimetric analysis (TG-DTG) and NH3 Temperature Programmed Desorption (NH3-TPD), were applied to characterize the chemical and textural properties of the samples. The results show that lactic acid pre-modification of NaY zeolite may cause on the one hand Na+ cation removal by proton exchange and on the other hand the dealumination of the zeolite framework with the formation of amorphous silicon-rich species offering nutrients for the fabrication of mesoporosity. After alkaline treatment in the presence of surfactant CTAB, mesoporosity can be successfully introduced into the NaHY zeolites with the microporous structures well preserved. Furthermore, the hierarchically structured Y zeolites exhibit much better performances in the acetalization reactions with large sized molecules involved. This could be attributed to the enhanced diffusion ability of large sized guest molecules through the combination of mesoporosity and microstructures compared with pure microporous Y zeolites.
Co-reporter:Dr. Haidong Zhang;Yu Zou; Yi-Meng Wang;Dr. Yu Shen; Xuxu Zheng
Chemistry - A European Journal 2014 Volume 20( Issue 25) pp:7830-7841
Publication Date(Web):
DOI:10.1002/chem.201402136
Abstract
Immobilised Mn(salen) catalysts with two different linkages were studied in the asymmetric epoxidation of cis/trans-β-methylstyrene using NaClO as oxidant. The immobilised Mn(salen) complexes inside nanopores can lead to different catalytic behaviour compared with that of homogeneous Jacobsen catalyst. The rigidity of the linkage was found to be a key factor affecting the catalytic performance of immobilised catalysts. The immobilised catalyst with a rigid linkage exhibited comparable chemical selectivity, enantioselectivity and cis/trans ratio of product formation to that obtained with homogeneous Jacobsen catalysts. In contrast, the immobilised catalyst with a flexible linkage gave remarkably lower chemical selectivity, enantioselectivity and inverted cis/trans ratio compared with the results obtained with the homogeneous Jacobsen catalyst and the immobilised catalyst with rigid linkage. Thus, for immobilised Mn(salen) catalysts, a rigid linkage connecting active centres to the support is essential to obtain activity and enantioselectivity as high as those obtained in homogeneous systems.
Co-reporter:Wen Hua Fu, Yi Meng Wang and Ming Yuan He
RSC Advances 2013 vol. 3(Issue 40) pp:18519-18528
Publication Date(Web):06 Aug 2013
DOI:10.1039/C3RA43022G
Highly ordered supermicroporous aluminosilicates with cubic Pm3n symmetry were prepared for the first time in weakly acidic solutions of succinic acid and malonic acid using dodecyltriethylammonium bromide as a template. The polycarboxylic acids acted as auxiliaries for fabricating the cubic Pm3n structure as well as weak acids. Thermally stable aluminosilicates with a high utilization ratio of Al could be obtained in the presence of succinic acid by either facilely adding aluminum source into the initial synthesis gel or by grinding the as-made silica-surfactant composite with aluminum nitrate. In contrast, thermally stable aluminosilicates could only be prepared via a post-synthesis approach in the presence of malonic acid, probably because of the powerful coordination tendency between malonic acid and Al cations. The thermal stability of the aluminosilicates was enhanced because of the incorporation of Al into the framework or grafting of Al onto the pore walls. Aluminosilicates prepared via the post-synthesis approach preserved the cubic Pm3n structure better than the directly-synthesized ones. In spite of the kind of polycarboxylic acids or the preparation methods, Al was predominantly tetrahedrally coordinated. The aluminosilicates showed a high specific area and pore volume, especially for the post-synthesized ones. The pore size was in the supermicroporous range evidenced by N2 physisorption, though that of the aluminosilicates prepared via the post-synthesis approach was larger. TEM images verified the Pm3n symmetry of the materials herein. The cubic Pm3n aluminosilicates prepared in our research exhibited equal reactivity but a much pronounced deactivation resistance property in the acetalization of cyclohexanone with pentaerythritol.
Co-reporter:Wen Qian Jiao, Yi Meng Wang, Ming-Yuan He
Microporous and Mesoporous Materials 2013 Volume 181() pp:123-131
Publication Date(Web):15 November 2013
DOI:10.1016/j.micromeso.2013.07.026
•Basic di-carboxylate and neutral tri-carboxylate salts were synthesized.•The influence of organic acid used to the sample morphology was investigated.•All the aluminum carboxylate salts can pseudomorphically transform to aluminas.•γ-Al2O3 displays a significantly high pore volume and high thermal stability.•The alumina particle sizes and aggregation degrees greatly affect the sintering.Aluminum carboxylate salts are synthesized by the reaction of aluminum isopropoxide and lower aliphatic acid. The crystalline structures and the morphologies can be easily controlled by tuning the organic acid used. When formic acid or acetic acid is used as both solvent and reactant, basic aluminum di-carboxylate can be obtained, while neutral aluminum tripropionate forms if propionic acid is used. And the morphological changes of the products are also investigated when the mixture of acetic and propionic acids with different ratios is used. After the calcination, all the aluminum carboxylates can transform to aluminas with the morphology retained. The thermal transformation process is monitored using TG-DTG, XRD and N2 adsorption–desorption measurements. The resultant γ-Al2O3 displays a good textural properties (SBET = 158 m2 g−1, Vtotal = 1.35 cm3 g−1, d = 46 nm) and high thermal stability, where the γ-Al2O3 sample can endure calcination at 1000 °C without any changes of crystalline structure.
Co-reporter:Ming Bo Yue, Teng Xue, Wen Qian Jiao, Yi Meng Wang
Materials Letters 2013 Volume 91() pp:115-117
Publication Date(Web):15 January 2013
DOI:10.1016/j.matlet.2012.09.104
Mesoporous silica-doped aluminas (MSAs) have been prepared with carbon as template. The addition of silica dopant modulated the textural and structural evolution of the alumina and the obtained MSA exhibited high surface area (216 m2 g−1) and uniform pore size distributions (around 8 nm) after calcination at 800 °C. The properties of nickel passivation were studied by hydrogen temperature programmed reduction (H2-TPR) and X-ray diffraction (XRD). XRD showed that the nickel transformed into NiAl2O4 by interacting with Al2O3 on the surface of the MSA. The H2-TPR results showed that silica-doped aluminas could be an alternative nickel passivator with improved efficiency. The obtained MSA can passivate nickel below 10,000 ppm effectively.Graphical abstractHighlights► Mesoporous silica-doped aluminas (MSAs) are prepared with carbon as template. ► MSA shows high surface areas after calcinations at 800 °C. ► MSA exhibits a mechanism to passivate nickel up to 10,000 ppm.
Co-reporter:Wen Hua Fu, Yi Meng Wang, Ming-Yuan He
Materials Letters 2013 Volume 109() pp:127-129
Publication Date(Web):15 October 2013
DOI:10.1016/j.matlet.2013.07.080
•Well-ordered cubic Pm3n supermicroporous silicas and aluminosilicates are obtained.•Supermicroporous aluminosilicates should be prepared at low temperature.•The SiO2/Al2O3 molar ratio in products could be achieved as low as 32.•The supermicroporosity of these materials is proved by N2 sorption data.Ordered cubic Pm3n supermicroporous silica and aluminosilicate materials were synthesized using dodecyltriethylammonium bromide as template and sodium silicate as silicon source under alkaline condition. The cubic Pm3n structures were confirmed by XRD patterns and TEM images. Ordered supermicroporous silica could be obtained facilely at room temperature. As the incorporation of Al resulted in a decrease in the cubic ordering, ordered supermicroporous aluminosilicates should be synthesized at lower temperature. A series of aluminosilicates was prepared and the SiO2/Al2O3 molar ratio in products could be achieved as low as 32 with the cubic Pm3n structure well-preserved. Nitrogen sorption data further proved the supermicropore size of the materials.
Co-reporter:Ming Bo Yue, Na Yang, Wen Qian Jiao, Yi Meng Wang, Ming-Yuan He
Solid State Sciences 2013 20() pp: 1-7
Publication Date(Web):
DOI:10.1016/j.solidstatesciences.2013.03.001
Co-reporter:Ming Bo Yue, Teng Xue, Wen Qian Jiao, Yi Meng Wang, Ming-Yuan He
Microporous and Mesoporous Materials 2012 Volume 159() pp:50-56
Publication Date(Web):1 September 2012
DOI:10.1016/j.micromeso.2012.04.027
A new strategy to dealumination, silicon insertion and H-proton exchange of NaY in one step with acid ethanol solution is reported in this article. The removal of framework aluminum is controlled by modulating the acid through adjusting the water amounts in the ethanol, and the formed cationic non-framework aluminum species are solved in the solution by complexation with hydroxy carboxylate. Substitution of framework silicon for aluminum (stabling the zeolite structure) and the H-proton exchanges with sodium are completed in this dealumination process simultaneously. By using tartaric acid as leaching agent in ethanol solution, 78% of the framework aluminum atoms can be released with 94% exchange of the sodium cations in this dealumination process. This new strategy displays two advantages: firstly, excluding the NH4+ pollution by using acid to exchange sodium cation directly, and secondly, energy- and time-saving by combining the dealumination, silicon insertion and H-proton exchange in one step.Graphical abstractHighlights► Dealumination and H-proton exchange of NaY were combined in one step. ► This strategy excluded the NH4+ pollution by using acid to exchange sodium cation. ► The removal of aluminum is controlled by adjusting the water amounts in the ethanol. ► Seventy eight percentage of the framework aluminum atoms release and 94% exchange of the sodium cations.
Co-reporter:Teng Xue, Yi Meng Wang, Ming-Yuan He
Microporous and Mesoporous Materials 2012 Volume 156() pp:29-35
Publication Date(Web):1 July 2012
DOI:10.1016/j.micromeso.2012.02.014
High crystalline nano-sized NH4-ZSM-5 zeolites with a wide SiO2/Al2O3 ratio range were directly synthesized through seed-induced approach. The products were characterized using X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), N2-sorption experiment, thermal gravimetry (TG) analysis, ammonium temperature programmed desorption (NH3-TPD), inductively coupled plasma atomic emission spectroscopy (ICP-AES) and 27Al and 29Si MAS NMR. The crystal sizes could be controlled by simply adjusting the amount of seeding suspension. The as-prepared NH4-ZSM-5 can be converted the acid H-form by a single calcination.Graphical abstractNano-sized NH4-ZSM-5 zeolites with a wide SiO2/Al2O3 ratio range were directly synthesized through seed-induced approach. The crystal sizes could be controlled by simply adjusting the seeding gel amount.Highlights► One-step synthesis of nano-sized NH4-ZSM-5 via seed-induced approach was reported. ► This approach decreased the organic template used. ► Crystal sizes could be controlled by tuning the seeding gel amount. ► The as-prepared NH4-ZSM-5 could be converted the acid H-form by simple calcination. ► The products showed similar properties to that synthesized in the alkali-system.
Co-reporter:Wen Qian Jiao, Ming Bo Yue, Yi Meng Wang, Ming-Yuan He
Microporous and Mesoporous Materials 2012 Volume 147(Issue 1) pp:167-177
Publication Date(Web):January 2012
DOI:10.1016/j.micromeso.2011.06.012
Aluminum hydroxides were synthesized through the acidification of sodium aluminate solution using single organic diester or diacid as pH adjustor and aluminum chelating agent. The obtained alumina hydrates are investigated by XRD, SEM, IR and TG. Bayerite firstly formed at room temperature, and its morphology greatly varied with the pH adjustors used, which probably attributes to different kinetics of the acidification. The bayerite can evolve to gibbsite and boehmite after the hydrothermal treatment at 100 °C and 145 °C, respectively, where these alumina hydrates show diverse morphologies. After the calcination, these alumina hydrates of bayerite, gibbsite and boehmite could pseudomorphically transform to the corresponding η-, χ- and γ-aluminas, respectively, exhibiting different structural and textural properties. Interestingly, the transition aluminas derived from the aluminum tri-hydroxides, bayerite and gibbsite, both display locally organized mesopores, while no such meso-structure can be observed in γ-alumina obtained from the aluminum mono-hydroxide, boehmite. The changes of bayerite during calcination are investigated detailed. The dehydration of non-porous bayerite accompanied with the formation of meso-structured transition aluminas, where the meso-structure becomes more and more clearly defined and pore size expands with the calcination temperature increasing.Graphical abstractHighlights► Morphology-controlled aluminum hydroxides were synthesized. ► The pH adjustor affects the morphology of aluminum hydroxides. ► The alumina hydrates pseudomorphically transformed to corresponding aluminas. ► The pore size of aluminas expands with the calcination temperature increasing.
Co-reporter:Teng Xue, Li Chen, Yi Meng Wang, Ming-Yuan He
Microporous and Mesoporous Materials 2012 Volume 156() pp:97-105
Publication Date(Web):1 July 2012
DOI:10.1016/j.micromeso.2012.02.022
Mesoporous ZSM-5 aggregates were synthesized with wide SiO2/Al2O3 ratio range using tetrapropylammonium hydroxide as single template through seed-induced route. The influences of SiO2/Al2O3 ratio, Na2O/SiO2 ratio and seeding gel amount on the textural properties of the mesoporous ZSM-5 aggregates were investigated and the possible formation mechanism was brought forward. The mesoporous ZSM-5 aggregates of approximately 2.0 μm in diameter were formed by nanosized crystals several tens nanometers in size, which avoid the filtration difficulties for nanosized crystals. This synthesis process is facile and much less expensive while the prepared mesoporous ZSM-5 aggregates possess large external surface area and large mesopore volume.Graphical abstractHighlights► Mesoporous ZSM-5 aggregates were synthesized through the seed-induced approach. ► Template/SiO2 ratio could be reduced to as small as 0.005. ► The aggregates possessed mesopore volume as large as 0.20 cm3 g−1. ► This process is much facile and covers much wider range of SiO2/Al2O3 ratios.
Co-reporter:Teng Xue, Yi Meng Wang, Ming-Yuan He
Solid State Sciences 2012 Volume 14(Issue 4) pp:409-418
Publication Date(Web):April 2012
DOI:10.1016/j.solidstatesciences.2012.01.023
Using silicalite-1 suspension as seed crystals and a small amount of tetraallkylammonium bromide as additional structure-directing agent, highly crystallized ZSM-5 with SiO2/Al2O3 ratios higher than 100 was obtained. The crystal sizes could be easily tuned from tens of nanometers to about several micronmeters by merely adjusting the amount of the seeding suspension. Seeding suspension synthesized from different silica sources and the additional structure-directing agent may also affect the crystal sizes. The synthesized samples were characterized by powder X-ray diffraction, scanning electron microscopy, N2 adsorption–desorption and inductively coupled plasma. When tetraethylammonuim bromide was used as additional structure-directing agent, crystals with silica-rich cores were observed, while additional nucleation could be found when tetrapropylammonium bromide was used as auxiliary template.Highlights► High-silica ZSM-5 zeolites were synthesized via the seed-induced approach. ► TPABr or TEABr were used as auxiliary structure-directing agent. ► Crystal sizes could be facilely tuned by the relative amount of seeds and template. ► This process has wide potential for large-scale production of ZSM-5 for various uses.
Co-reporter:Yejun Guan;Damin Zhang
Catalysis Letters 2012 Volume 142( Issue 10) pp:1225-1233
Publication Date(Web):2012/10/01
DOI:10.1007/s10562-012-0891-4
A one-step synthesis of cyclohexanone acetals from phenol/alcohol mixtures has been explored using bifunctional aluminum borates supported Pd catalysts. Three aluminum borates have been prepared via either a high temperature calcination (9Al2O3·2B2O3) or a self-pressured thermal synthesis (PKU-1 and ABO-X) using various aluminum precursors and boric acid. Well dispersed Pd nanoparticles loaded on these materials show excellent phenol hydrogenation activity in both water and ethanol. The reactivity follows the trend of Pd/ABO-X > Pd/9Al2O3·2B2O3 > Pd/PKU-1, which is similar to the sequence of BO4/BO3 ratio presented in the aluminoborates as shown by NMR spectra. When ethanol is used as a solvent, 13.5 % yield of cyclohexanone diethyl acetal has been obtained under the conditions investigated on Pd/ABO-X, which is attributed to its high activity in both hydrogenation and acetalization for the one-step synthesis of cyclohexanone acetals.
Co-reporter:Wen Qian Jiao;Ming Bo Yue;Yi Meng Wang;Ming-Yuan He
Journal of Porous Materials 2012 Volume 19( Issue 1) pp:61-70
Publication Date(Web):2012 February
DOI:10.1007/s10934-010-9448-3
Organized mesoporous γ-alumina samples were prepared by cationic-anionic double hydrolysis (CADH) method using the mixture of cationic and anionic surfactants as template. The intermediate aluminum oxyhydroxides were characterized by XRD, SEM, TEM, FT-IR and TG. Boehmite could easily form under the given synthetic conditions, where an increase in the crystallization temperature favored the formation of well-crystallized boehmite. After the calcination, organized mesoporous γ-Al2O3 was obtained by dehydroxylation between AlOOH octahedron structures. After being characterized by N2 adsorption–desorption, the obtained γ-Al2O3 was of excellent textural properties, i.e., large pore volume (0.79 cm3 g−1), and large pore size (12.1 nm) with narrow pore size distribution which can be used as good candidates for catalyst support in the processing of heavy petroleum. In this modified CADH method, the mixture of cationic and anionic surfactants plays a key role in the formation of relatively large mesopore.
Co-reporter:Hong Li Chen, Kun Zhang, Yi Meng Wang
Materials Research Bulletin 2012 47(7) pp: 1774-1782
Publication Date(Web):
DOI:10.1016/j.materresbull.2012.03.029
Co-reporter:Kun Zhang;Hong-Li Chen;Belén Albela;Jin-Gang Jiang;Yi-Meng Wang;Ming-Yuan He;Laurent Bonneviot
European Journal of Inorganic Chemistry 2011 Volume 2011( Issue 1) pp:59-67
Publication Date(Web):
DOI:10.1002/ejic.201000754
Abstract
Highly ordered 2D hexagonal mesostructured silicas with thick pore walls have been directly hydrothermally synthesized at high temperatures in a range from 130 to 175 °C by using the new surfactant cetyltrimethylammonium tosylate (CTATos) as template. The mesoporous structure of the synthesized MCM-41 could be maintained after heating it to reflux in boiling water for at least 24 h. The crystallization temperature, the nature of surfactants, and the relative amount of TAAOH (tetraalkylammonium hydroxide, such as TMAOH and TEAOH) to surfactant were found to be critical parameters that affect the ordering of mesophases. On the basis of the combined characterizations of X-ray diffraction (XRD), N2 adsorption, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG), 13C cross-polarization magic-angle spinning (CPMAS) solid-state NMR spectroscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM), a new mechanism was proposed to understand the formation mechanism of highly ordered MCM-41 silicas. The enlargement of pore-wall thickness is attributed to the migration and subsequent deposition of the silicate species in the inner pore channel. This process was accelerated by the ion-exchange interaction of tetraalkylammonium cations (TAA+) on CTA+ cations.
Co-reporter:Ming Bo Yue, Teng Xue, Wen Qian Jiao, Yi Meng Wang, Ming-Yuan He
Solid State Sciences 2011 Volume 13(Issue 2) pp:409-416
Publication Date(Web):February 2011
DOI:10.1016/j.solidstatesciences.2010.12.003
Mesoporous γ-aluminas are prepared via a facile one-pot hydrothermal method using aluminum sulfate as a precursor, urea as precipitating agents, sodium tartrate and CTAB (cetyltrimethylammonium bromide) as co-templates respectively. Characterizations of the intermediate aluminum oxyhydroxides by IR, XRD, element analysis and TG show that the amounts of CTAB occluded in the as-prepared mesoporous aluminum oxyhydroxides are determined by molar ratio of sodium tartrate to aluminum (ST/Al). Especially, no sodium tartrate is added, no CTAB is occluded in the mesoporous aluminum oxyhydroxides. The structures of obtained mesoporous aluminas are characterized by XRD, nitrogen adsorption analysis, and scanning electron micrographs (SEM). And the surface areas, mesopore volume and the order of meso-structure are enhanced with an increase in ST/Al molar ratio. Sodium citrate and sodium succinate are also used as additives to study the formation mechanism of organized mesoporous aluminas. The formation mechanisms are proposed that tartrate interacts with aluminum and CTAB simultaneously to form an intermediate as the building blocks of the final meso-structured hybrid.
Co-reporter:Li Chen, Shu Yan Zhu, Hai Man Wang, Yi Meng Wang
Solid State Sciences 2011 Volume 13(Issue 11) pp:2024-2029
Publication Date(Web):November 2011
DOI:10.1016/j.solidstatesciences.2011.08.033
Highly active, hierarchical zeolite ZSM-5 aggregates have been prepared in a one-step synthesis using alkanolamine as single template. The effects of SiO2/Al2O3, pH and H2O/SiO2 on the aggregate morphology of the ZSM-5 nanocrystals were investigated. The obtained aggregate zeolites characterized by SEM, TEM and BET possessed significant textual porosity (up to 0.22 cm3/g), which could be tuned by the number of substituents in the alkanolamine molecules and the amount of aluminum in the synthetic mixtures. These zeolite aggregates showed high activities for Friedel–Crafts alkylations and may curtail the filtration difficulties during the synthesis and applications to some extent.
Co-reporter:Li Chen, Yi Meng Wang, Ming-Yuan He
Materials Research Bulletin 2011 46(5) pp: 698-701
Publication Date(Web):
DOI:10.1016/j.materresbull.2011.01.015
Co-reporter:Li Chen;Yi Meng Wang;Ming-Yuan He
Journal of Porous Materials 2011 Volume 18( Issue 2) pp:211-216
Publication Date(Web):2011/04/01
DOI:10.1007/s10934-010-9372-6
Fiber-like or rod-like mesoporous SBA-15 silicas with different lengths and diameter of macrostructures and pore diameter could be synthesized by the self-assembly of silica-surfactant (commonly used Pluronic P123 (EO20-PO70EO20) as a structure-directing agent) through careful control of the synthetic temperature and stirring time without any additives. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and nitrogen adsorption–desorption isotherms are used to characterize these mesoporous silica materials. Compared with those reports on conventional SBA-15, our work is focused on one-step synthesis and the morphological control of ordered mesoporous silica synthesized at low temperature under low concentration of P123 (0.67 wt%) without the addition of inorganic salts, where pre-hydrolyzed silica species may favor the self-assembly of silica-polymer hybrid micelles. Moreover, the pore diameter of fiber-like SBA-15 synthesized at 40 °C is slightly smaller than that of conventional SBA-15, revealing that the average micellar radius of P123 micelles in this low concentration of P123 solution was almost same as that for the conventional synthesis of SBA-15.
Co-reporter:Li Chen, Shu Yan Zhu, Yi Meng Wang and Ming-Yuan He
New Journal of Chemistry 2010 vol. 34(Issue 10) pp:2328-2334
Publication Date(Web):29 Jul 2010
DOI:10.1039/C0NJ00316F
Hierarchical zeolite microspheres were synthesized via a one-step method using a diamine with a linear carbon chain as the single template, where no secondary template and additives were added. The obtained microspheres possessed significant textual porosity (up to 0.24 cm3 g−1), which was tuneable by carefully choosing diamines with different length hydrocarbon chains and the amount of aluminium in the synthetic mixture. The zeolite microspheres not only possessed high activities in catalytic applications but also curtailed to some extent filtration difficulties in their preparation and application. During the hydrothermal synthesis, zeolite nanocrystals (50 nm) were formed and spontaneously assembled into uniform microspheres in size of 5–8 μm following a particle–particle aggregation mechanism.
Co-reporter:Ming Bo Yue, Wen Qian Jiao, Yi Meng Wang, Ming-Yuan He
Microporous and Mesoporous Materials 2010 Volume 132(1–2) pp:226-231
Publication Date(Web):July 2010
DOI:10.1016/j.micromeso.2010.03.002
A new strategy was introduced to synthesize mesoporous γ-Al2O3 by double hydrolysis method using hydroxyl polyacids and CTAB (cetyltrimethylammonium bromide) as co-templates. The intermediate aluminum hydroxides were characterized by IR, XRD and TG. A formation mechanism of the meso-structure is suggested, where hydroxyl polyacids interact with aluminum species and CTAB simultaneously and bridge the interaction between aluminum and CTAB micelle in favor of the genesis of ordered meso-structure. Characterizations by XRD and N2 sorption measurements showed that the resulted mesoporous alumina with γ-Al2O3 phase possessed high surface area (398 m2 g−1), large pore volume (0.59 cm3 g−1) and exhibited good catalytic activity for cyclohexene epoxidation.
Co-reporter:Shu-Ping Liu, Li Chen, Yi Meng Wang
Solid State Sciences 2010 Volume 12(Issue 7) pp:1070-1075
Publication Date(Web):July 2010
DOI:10.1016/j.solidstatesciences.2010.04.025
Zeolite Beta Aggregates have been synthesized by the self-assembly of Beta nanoparticles without the use of second template or additive, where the large zeolitic aggregates avoided the filtration difficulties and the presence of mesopore reduced the diffusion limitation. The samples were characterized by XRD, N2-sorption, SEM, TEM, thermogravimetric analysis, IR spectroscopy and temperature programmed desorption of ammonia. The results showed that the SiO2/Al2O3 ratio played a key role on the particle size, mesopore volume and particle–particle aggregation process of zeolite Beta. The sample with SiO2/Al2O3 ratio below 60 had improved textual and acidic properties and exhibited the best catalytic activity to the alkylation of phenol with tert-butanol.
Co-reporter:Kun Zhang, Yi Meng Wang, Belén Albela, Li Chen, Ming-Yuan He and Laurent Bonneviot
New Journal of Chemistry 2009 vol. 33(Issue 12) pp:2479-2485
Publication Date(Web):28 Oct 2009
DOI:10.1039/B9NJ00331B
Mesoporous lamellar aluminosilicate–surfactant nanoparticles as small as 50 nm can be hydrothermally synthesized at 140 °C using a mixture of cationic and anionic surfactants as a templating agent and tetrapropylammonium cations (TPA+), known to be the structure directing agent of the MFI type of zeolite. The nanophases exhibit some ill-resolved atomic ordering after 1 to 3 d of crystallization. A definitive ZSM-5 ordering occurs for longer crystallization times, concomitant with a progressive contraction of the lamellar array. In most cases, calcination at 550 °C leads to a collapse of the lamellar structure, while the zeolitic ordering is preserved. For short crystallization times, the lamellar structure with its atomic ordering is maintained when the aluminium source is the nitrate salt, instead of Al(OH)3 or Boehmite. Then, after 3 d of crystallization, highly porous systems are produced with a surface area of ∼650 m2 g−1 and pore volume of ∼1.1 cm3 g−1. For longer crystallization time, the collapse of the lamellar phase under calcination does not affect the well-defined ZSM-5-like atomic ordering and leads to non-faceted nanoparticles of ca. 200 nm size with rugged shapes. These conclusion are supported by cross investigations using X-ray diffraction patterns, infrared spectra, scanning electron microscopy and high-resolution transmission electron microscopy with selected area electron diffraction. The ordering of the inorganic sheet of the aluminosilicate–surfactant mesophase is likely favoured by the high diffusion rate of TPA+ in the nanosized particles.
Co-reporter:Gang Li, Wen Hua Fu, Yi Meng Wang
Catalysis Communications (5 March 2015) Volume 62() pp:10-13
Publication Date(Web):5 March 2015
DOI:10.1016/j.catcom.2014.12.016
•Partially crystalline zirconosilicate is synthesized at 120 °C.•Partially crystalline zirconosilicate shows high activity in the MPV reduction.•Critical factors are Lewis acid amount, mesopore volume and surface hydrophobicity.•Surface hydrophobicity of samples determines their water tolerance ability.Partially crystalline zirconosilicate was prepared at low crystallization temperature of 120 °C using amorphous zirconosilicate as solid sources of both zirconium and silicon. Partially crystalline zirconosilicate showed relatively high activity in the Meerwein–Ponndorf–Verley (MPV) reduction of cyclohexanone with 2-propanol. Lewis acid amount, mesopore volume and surface hydrophobicity are the three critical factors for its catalytic activity. Furthermore, partially crystalline zirconosilicate exhibited certain water tolerance ability, most probably related to the surface hydrophobicity that originates from the zeolitic units.
Co-reporter:Wen Hua Fu, Xiao Min Liang, Haidong Zhang, Yi Meng Wang and Ming Yuan He
Chemical Communications 2015 - vol. 51(Issue 8) pp:NaN1452-1452
Publication Date(Web):2014/12/02
DOI:10.1039/C4CC08784D
In the synthesis of polyoxymethylene dimethyl ethers (PODEn) catalyzed by ordered supermicroporous aluminosilicates, shape selectivity was observed and the high selectivity for target products (PODE3–8) was attributed to the particular pore diameter.
Co-reporter:Wen Hua Fu, Sai Jin Wu, Yi Meng Wang and Ming Yuan He
Journal of Materials Chemistry A 2014 - vol. 2(Issue 36) pp:NaN14917-14917
Publication Date(Web):2014/07/18
DOI:10.1039/C4TA02269F
Highly ordered supermicroporous silicas and aluminosilicates with cubic Pm3n symmetry were prepared under weakly alkaline condition using alkyltrimethylammonium bromide with a short hydrophobic chain and relatively small hydrophilic head as a template. As the length of the carbon chain was increased from C10 to C16, the surfactant packing parameter increased and the favored symmetry of the silicas shifted from cubic Pm3n to hexagonal P6mm. Different mineral acids used to pre-hydrolyze TEOS could tune the silica mesostructures when dodecyltrimethylammonium bromide (C12TMAB) was used as the template: sulfuric acid (H2SO4) led to cubic Pm3n symmetry and nitric acid (HNO3) resulted in hexagonal P6mm symmetry. Under similar conditions, octyltrimethylammonium bromide (C8TMAB) templating led to a disordered structure. The Pm3n symmetry could be well preserved after Al was incorporated into the framework and the molar ratio of SiO2/Al2O3 in the aluminosilicates reached as low as 25. The pore size of the cubic Pm3n silicas and aluminosilicates was in the supermicroporous range. All the silica and aluminosilicate samples exhibited high specific area and large pore volume. Compared to zeolite USY-1 and AlSBA-1 catalysts synthesized in concentrated acid solution, aluminosilicates prepared herein exhibited more pronounced resistance to deactivation, higher reactivity for the acetalization of cyclohexanone with pentaerythritol, and a higher yield of 4-t-butyl-catechol in the tert-butylation of catechol.
