Co-reporter:Limin Chen, Yunfeng Bao, Yuhai Sun, Ding Ma, Daiqi Ye and Bichun Huang
Catalysis Science & Technology 2016 vol. 6(Issue 1) pp:98-106
Publication Date(Web):21 Sep 2015
DOI:10.1039/C5CY01091H
A variety of PtFeNi catalysts supported on carbon materials have been prepared and tested for CO preferential oxidation (PROX) in excess hydrogen. 100% O2 and CO conversions have been achieved over carbon black (CB) and carbon nanotube (CNT) supported PtFeNi catalysts at room temperature in a feed gas containing 1% CO, 0.5% O2 (volume ratio) and H2 balance gas. N2 adsorption, temperature-programmed desorption (TPD) and transmission electron microscopy (TEM) studies indicate that the carbon textural properties and surface chemistry determine the catalyst particle size distribution and mean size; but the mean particle size does not have a great influence on the catalytic performance within the investigated particle size range. X-ray diffraction (XRD), resistance measurements and the designed catalytic reaction results reveal the ability of graphitic carbon to capture and shuttle electrons from the noble metal to spatially different sites in the FeNi species through the π–π network, enables the indirect interactions between Pt and the FeNi species, leading to a strengthened synergistic effect, enhancing the CO oxidation activity at room temperature, increasing the Pt utilization efficiency, and apparently decreasing the Pt loading level.
Co-reporter:Guannan Wang, Limin Chen, Yuhai Sun, Junliang Wu, Mingli Fu and Daiqi Ye
RSC Advances 2015 vol. 5(Issue 56) pp:45320-45330
Publication Date(Web):12 May 2015
DOI:10.1039/C5RA04774A
Methanol synthesis from CO2 hydrogenation in a fixed-bed plug flow reactor was investigated over Cu–ZrO2 catalysts supported on CNTs bearing various functional groups. The highest methanol activity (turnover frequency 1.61 × 10−2 s−1, space time yield 84.0 mg gcat−1 h−1) was obtained over the Cu/ZrO2/CNTs catalyst (CZ/CNT-3) with CNTs functionalized by nitrogen-containing groups and Cu loading only about 10.3 wt% under the reaction conditions of 260 °C, 3.0 MPa, V(H2):V(CO2):V(N2) = 69:23:8 and GHSV of 3600 h−1. The catalysts were fully characterized by N2 physisorption, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), H2-temperature-programmed reduction (H2-TPR) and temperature-programmed desorption of H2 (H2-TPD) techniques. The excellent performance of CZ/CNT-3 is attributed to the presence of nitrogen-containing groups on the CNTs surface, which increase the dispersion of copper oxides, promote their reduction, decreases the crystal size of Cu, and enhances H2 and CO2 adsorption capability, thus leading to good catalytic performance towards methanol synthesis.
Co-reporter:Dr. Jinzhu Chen;Shengpei Wang;Jing Huang;Dr. Limin Chen;Dr. Longlong Ma;Dr. Xing Huang
ChemSusChem 2013 Volume 6( Issue 8) pp:1545-1555
Publication Date(Web):
DOI:10.1002/cssc.201200914
Abstract
Cellulose and cellobiose were selectively converted into sorbitol over water-tolerant phosphotungstic acid (PTA)/metal– organic-framework-hybrid-supported ruthenium catalysts, Ru-PTA/MIL-100(Cr), under aqueous hydrogenation conditions. The goal was to investigate the relationship between the acid/metal balance of bifunctional catalysts Ru-PTA/MIL-100(Cr) and their performance in the catalytic conversion of cellulose and cellobiose into sugar alcohols. The control of the amount and strength of acid sites in the supported PTA/MIL-100(Cr) was achieved through the effective control of encapsulated-PTA loading in MIL-100(Cr). This design and preparation method led to an appropriately balanced Ru-PTA/MIL-100(Cr) in terms of Ru dispersion and hydrogenation capacity on the one hand, and acid site density of PTA/MIL-100(Cr) (responsible for acid-catalyzed hydrolysis) on the other hand. The ratio of acid site density to the number of Ru surface atoms (nA/nRu) of Ru-PTA/MIL-100(Cr) was used to monitor the balance between hydrogenation and hydrolysis functions; the optimum balance between the two catalytic functions, that is, 8.84<nA/nRu<12.90, achieves maximum conversion of cellulose and cellobiose into hexitols. Under the applied reaction conditions, optimal results (63.2 % yield in hexitols with a selectivity for sorbitol of 57.9 % at complete conversion of cellulose, and 97.1 % yield in hexitols with a selectivity for sorbitol of 95.1 % at complete conversion of cellobiose) were obtained using a Ru-PTA/MIL-100(Cr) catalyst with loadings of 3.2 wt % for Ru and 16.7 wt % for PTA. This research thus opens new perspectives for the rational design of acid/metal bifunctional catalysts for biomass conversion.
Co-reporter:Dr. Limin Chen; Ding Ma;Dr. Zhen Zhang;Yuanyuan Guo; Daiqi Ye; Bichun Huang
ChemCatChem 2012 Volume 4( Issue 12) pp:1960-1967
Publication Date(Web):
DOI:10.1002/cctc.201200365
Abstract
Carbon black (CB) supported PtAg non-alloy bimetal catalysts were prepared by incipient wetness impregnation and evaluated for CO preferential oxidation in excess H2 (PROX). PtAg/CB catalysts exhibited an evident synergistic effect. The catalyst support selection is crucial to the synergistic effect. X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning TEM energy dispersive X-ray analysis (STEM-EDX) characterization indicates no alloy was formed over the PtAg/CB catalyst after activation in H2 at 500 °C for 2 h. However, temperature-programmed reduction (TPR) and XRD data evidenced strong interactions between platinum and silver, as a result of their simultaneous reduction and high temperature activation. The PtAg interactions result in high catalytic performance and the synergistic effects. This is another example of model catalyst research translating to real world catalysis. PtAg non-alloy catalysts may also be effective in eliminating or alleviating catalyst poisoning by CO-like intermediates in direct liquid fuel cells.
Co-reporter:Limin Chen;Ding Ma;Zhen Zhang;Yuanyuan Guo;Daiqi Ye;Bichun Huang
Catalysis Letters 2012 Volume 142( Issue 8) pp:975-983
Publication Date(Web):2012 August
DOI:10.1007/s10562-012-0850-0
The commercial carbon nanotubes (CNTs-o) and purified carbon nanotubes (CNTs-p) have been utilized to prepare Pt(FeNi)/CNTs catalysts for CO preferential oxidation (PROX) in H2 rich stream. The 3 wt%Pt0.41 %Fe 0.35 %Ni/CNTs-p catalyst after activation at 500 °C in H2 can almost completely remove CO at 6 °C in feed gas containing 1 % CO, 0.5 % O2 (volume ratio) and H2 balance. CNTs-o supported 3 wt% Pt can also remove CO almost completely at room temperature, after activation at 500 °C in the feed gas. And this catalyst can keep high activity, high selectivity and high stability for PROX of CO at room temperature. These catalysts are the most effective catalysts for PROX of CO with much lower Pt loading until so far. H-TPR, XRD, HRTEM and reaction results indicate that the Fe and/or Ni precursors have been reduced to metallic state after activation in H2 which can be oxidized to coordinatively unsaturated FeOx and/or NiOx active species after exposure to feed gas. XPS data point out that over oxidation of Fe and Pt species will deactivate the catalysts seriously. The high catalytic performance is mainly due to the promotion effects of in situ formed coordinatively unsaturated FeOx and/or NiOx species and the unique properties of CNTs.
Co-reporter:Limin Chen, Yunfeng Bao, Yuhai Sun, Ding Ma, Daiqi Ye and Bichun Huang
Catalysis Science & Technology (2011-Present) 2016 - vol. 6(Issue 1) pp:NaN106-106
Publication Date(Web):2015/09/21
DOI:10.1039/C5CY01091H
A variety of PtFeNi catalysts supported on carbon materials have been prepared and tested for CO preferential oxidation (PROX) in excess hydrogen. 100% O2 and CO conversions have been achieved over carbon black (CB) and carbon nanotube (CNT) supported PtFeNi catalysts at room temperature in a feed gas containing 1% CO, 0.5% O2 (volume ratio) and H2 balance gas. N2 adsorption, temperature-programmed desorption (TPD) and transmission electron microscopy (TEM) studies indicate that the carbon textural properties and surface chemistry determine the catalyst particle size distribution and mean size; but the mean particle size does not have a great influence on the catalytic performance within the investigated particle size range. X-ray diffraction (XRD), resistance measurements and the designed catalytic reaction results reveal the ability of graphitic carbon to capture and shuttle electrons from the noble metal to spatially different sites in the FeNi species through the π–π network, enables the indirect interactions between Pt and the FeNi species, leading to a strengthened synergistic effect, enhancing the CO oxidation activity at room temperature, increasing the Pt utilization efficiency, and apparently decreasing the Pt loading level.
