SBA-15 and HMS supported chromia catalysts were prepared and characterized. Chromia is highly dispersed on the mesoporous supports when its loading is 7 wt%. The supported catalysts display high activity, selectivity ...SBA-15 and HMS supported chromia catalysts were prepared and characterized. Chromia is highly dispersed on the mesoporous supports when its loading is 7 wt%. The supported catalysts display high activity, selectivity and stability for dehydrogenation of ethylbenzene and propane. ESR measurement of the catalysts before and after reaction shows that the active species for dehydrogenation reaction might be Cr3+ species on the catalyst surface, and the activity of the catalyst is probably correlated with the dispersion of Cr3+ species.展开更多
ZSM-5 zeolite membrane reactor was used in ethylbenzene dehydrogenation to styrene under the circumstances of commercial production.The experimental results indicated that the conversion of ethylbenzene in the membran...ZSM-5 zeolite membrane reactor was used in ethylbenzene dehydrogenation to styrene under the circumstances of commercial production.The experimental results indicated that the conversion of ethylbenzene in the membrane reactor increased with increasing pressure of the membrane tube.Using the inert sweep gas instead of vacuumizing, the result of long term steady operation under the same condition showed that the selectivity of styrene increased and the conversion of ethylbenzene in the membrane reactor increased by 7.52% in comparison with the fixed-bed reactor.展开更多
Dehydrogenation of ethylbenzene （EB） to styrene （ST） in the presence of CO2, in which EB dehydrogenation is coupled with the reverse water-gas shift （RWGS）, was investigated extensively through both theoretical ...Dehydrogenation of ethylbenzene （EB） to styrene （ST） in the presence of CO2, in which EB dehydrogenation is coupled with the reverse water-gas shift （RWGS）, was investigated extensively through both theoretical analysis and experimental characterization. The reaction coupling proved to be superior to the single dehydrogenation in several respects. Thermodynamic analysis suggests that equilibrium conversion of EB can be improved greatly by reaction coupling due to the simultaneous elimination of the hydrogen produced from dehydrogenation. Catalytic tests proved that iron and vanadium supported on activated carbon or Al2O3 with certain promoters are potential catalysts for this coupling process. The catalysts of iron and vanadium are different in the reaction mechanism, although ST yield is always associated with CO2 conversion over various catalysts. The two-step pathway plays an important role in the coupling process over Fe/Al2O3, while the one-step pathway dominates the reaction over V/Al2O3. Coke deposition and deep reduction of active components are the major causes of catalyst deactivation. CO2 can alleviate the catalyst deactivation effectively through preserving the active species at high valence in the coupling process, though it can not suppress the coke deposition.展开更多
文摘SBA-15 and HMS supported chromia catalysts were prepared and characterized. Chromia is highly dispersed on the mesoporous supports when its loading is 7 wt%. The supported catalysts display high activity, selectivity and stability for dehydrogenation of ethylbenzene and propane. ESR measurement of the catalysts before and after reaction shows that the active species for dehydrogenation reaction might be Cr3+ species on the catalyst surface, and the activity of the catalyst is probably correlated with the dispersion of Cr3+ species.
文摘ZSM-5 zeolite membrane reactor was used in ethylbenzene dehydrogenation to styrene under the circumstances of commercial production.The experimental results indicated that the conversion of ethylbenzene in the membrane reactor increased with increasing pressure of the membrane tube.Using the inert sweep gas instead of vacuumizing, the result of long term steady operation under the same condition showed that the selectivity of styrene increased and the conversion of ethylbenzene in the membrane reactor increased by 7.52% in comparison with the fixed-bed reactor.
基金The authors are grateful for the financial support of The Sate Key Fundamental Research Project and the Natural Science Foundation of China.
文摘Dehydrogenation of ethylbenzene （EB） to styrene （ST） in the presence of CO2, in which EB dehydrogenation is coupled with the reverse water-gas shift （RWGS）, was investigated extensively through both theoretical analysis and experimental characterization. The reaction coupling proved to be superior to the single dehydrogenation in several respects. Thermodynamic analysis suggests that equilibrium conversion of EB can be improved greatly by reaction coupling due to the simultaneous elimination of the hydrogen produced from dehydrogenation. Catalytic tests proved that iron and vanadium supported on activated carbon or Al2O3 with certain promoters are potential catalysts for this coupling process. The catalysts of iron and vanadium are different in the reaction mechanism, although ST yield is always associated with CO2 conversion over various catalysts. The two-step pathway plays an important role in the coupling process over Fe/Al2O3, while the one-step pathway dominates the reaction over V/Al2O3. Coke deposition and deep reduction of active components are the major causes of catalyst deactivation. CO2 can alleviate the catalyst deactivation effectively through preserving the active species at high valence in the coupling process, though it can not suppress the coke deposition.
基金Supported by the National Basic Research Program of China (973 Program,2006CB806103)the National Natural Science Foundation of China (20773027,20633030)the Shanghai Research Institute of Petrochemical Technology,and the Science and Technology Commission of Shanghai Municipality (08DZ2270500)
