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Ethanol conversion to C3+ olefins, especially propylene, using Zr-modified H-ZSM-5 catalysts was investigated. Zr-modification to H-ZSM-5 zeolite could improve the initial yield of C3+ olefins and propylene and could reduce the initial yield of ethylene. In general, catalysts exhibiting the higher initial yield of propylene showed the steeper decrease in propylene yield as the reaction proceeded. However, Zr-modification to H-ZSM-5 could depress the decrease in propylene yield for aqueous ethanol. As cause of catalytic deactivation, carbon deposition on catalyst and framework collapse of zeolite support can be considered. The addition of water to Zr-modified H-ZSM-5 catalyst could depress carbon deposition in some degree, and, as a result, the decrease in propylene yield could be depressed. [ABSTRACT FROM AUTHOR]

Abstract: Rh/Ce1−x Zr x O2 (x =0–1) samples (with 2wt% Rh loading) were prepared by a coprecipitation method using NH3·H2O as a precipitant. The resultant samples were used as catalysts for the synthesis of ethanol from syngas in a high-pressure fixed-bed flow reactor under typical reaction conditions of T =548K, P =2.4MPa, H2/CO=2/1, and W/F =10ghmol−1. XRD results indicated that Zr4+ ions entered in the CeO2 lattices when x was less than 0.2 in Rh/Ce1−x Zr x O2. TPR results indicated that the reducibility of CeO2 increased by inducing Zr4+ ions into the CeO2 lattices in Rh/Ce0.8Zr0.2O2. NH3-TPD and CO2-TPD results indicated that Rh/Ce0.8Zr0.2O2 contained both acid sites and base sites on the surface. Rh/CeO2 showed a CO conversion of 23.7%, which was higher than those over Rh/SiO2 (10.1%), Rh/MgO (10.8%), and Rh/ZrO2 (18.2%) at 548K because a strong interaction between support and metal (SISM) existed in Rh/CeO2. Moreover, the CO conversion over Rh/Ce0.8Zr0.2O2 (27.3%) was higher than that over Rh/CeO2 (23.7%) due to the smaller Rh particle size and the stronger reducibility in Rh/Ce0.8Zr0.2O2. The main oxygenated products were acetaldehyde and ethanol over neutral or acidic supports supported Rh catalysts (Rh/SiO2, Rh/ZrO2), and were methanol and ethanol over basic supports supported Rh catalysts (Rh/MgO, Rh/CeO2, Rh/Ce0.8Zr0.2O2). Rh/Ce0.8Zr0.2O2 showed the highest selectivity for ethanol among various catalysts because the Ce0.8Zr0.2O2 support simultaneously possesses reducibility, acidity and basicity. [Copyright &y& Elsevier]

Abstract: The catalytic performance of W-containing bimetallic Ni–W/Al2O3 catalyst and tri-metallic Ni–W–Ce/Al2O3 and Ni–Re–W/Al2O3 catalysts for oxidative steam reforming of gasoline to produce hydrogen has been studied. The bimetallic Ni–W/Al2O3 catalyst exhibits significantly superior activity maintenance compared to that of monometallic Ni/Al2O3 catalyst for highly efficient conversion of sulfur-containing gasoline fuel into hydrogen. The activity maintenance of tri-metallic Ni–W–Ce/Al2O3 catalyst with the suitable ratios of Ni/W/Ce is much better than those of bimetallic Ni–W/Al2O3 or Ni–Ce/Al2O3 catalysts for oxidative steam reforming of gasoline. The tri-metallic Ni–Re–W/Al2O3 catalyst exhibits better activity maintenance than bimetallic Ni–W/Al2O3 or Ni–Re/Al2O3 for oxidative steam reforming of gasoline to produce hydrogen. W acts as a promoter to improve the sulfur tolerance of W-containing bimetallic Ni–W/Al2O3 and tri-metallic Ni–W–Ce/Al2O3 and Ni–Re–W/Al2O3 catalysts for oxidative steam reforming of gasoline. [Copyright &y& Elsevier]

Abstract: The catalytic autothermal reforming (ATR) of liquid hydrocarbons to provide hydrogen for mobile or stationary fuel cells was carried out over a Ni/Sr/ZrO2 catalyst that is active for steam reforming (SR). The catalyst system was found to be active for the ATR reaction, although the hydrogen concentration obtained by ATR, under the conditions employed, was a little lower than that for SR. Addition of sulfur, introduced in the form of thiophene, reduced the catalytic stability of Ni/Sr/ZrO2, even at 1073K. The catalyst lifetime decreased with increasing sulfur concentration between 0 and 100ppm. Additives for improving the sulfur-tolerance of Ni/Sr/ZrO2 were examined, and additions of Re or La were found to be effective in improving the stability of the catalysts. The best catalyst was 5wt.% Re–Sr/Ni/ZrO2. This catalyst was used in the ATR of liquid hydrocarbon fuels such as commercial premium gasoline, hydrotreated FCC gasoline, reagent mixtures, and methylcyclohexane. For premium gasoline, the activity remained unchanged during 30h, but then diminished rapidly. With the other fuels, however, the catalyst showed a much improved performance, indicating that the presence of sulfur could be associated with catalyst stability. ATR coupled with the water–gas shift reaction led to a reduction in the CO concentration by up to 2800ppm. The catalyst''s activity remained constant even after cold-start runs with 853–423–853K temperature cycles under H2O/O2/N2 conditions. Thus, the Re–Sr/Ni/ZrO2 catalyst is effective for ATR of liquid hydrocarbon fuels. Further work is currently under way to extend the catalyst life. [Copyright &y& Elsevier]

Abstract: Heteropolyacid (HPA) and Pd(OAc)2 were immobilized through chemical bonds onto the functional organic groups modified solid surfaces of hexagaonal mesoporous silica (HMS) and polyimine (PIM). The obtained hybrid samples were used as heterogeneous catalysts for the oxidation of benzene to phenol by molecular oxygen and compared to the homogeneous catalytic system containing HPA and Pd(OAc)2 (denoted by HPA+Pd(OAc)2). The activity of various catalytic systems was in the order of HPA+Pd(OAc)2 >HMS–HPA+Pd(OAc)2 >PIM–HPA+Pd(OAc)2 >HPA+HMS–Pd(OAc)2 >HMS–HPA+HMS–Pd(OAc). Although the benzene conversions over the heterogeneous catalytic systems containing solid catalysts were lower than that over the homogeneous catalytic system HPA+Pd(OAc)2, HMS–HPA+Pd(OAc)2 gave the same maximum achievable yield of phenol as that over HPA+Pd(OAc)2 by extending the reaction time or increasing the catalyst amount. Moreover, HMS–HPA+Pd(OAc)2 was able to be reused after simple filtration without leaching HPA. The benzene conversion and the selectivity to phenol over the heterogeneous system HMS–HPA+Pd(OAc)2 did not decrease even after reused five times. [Copyright &y& Elsevier]