Surface modification and catalytic performance study of Cu-based carbon dioxide to methanol hydrogenation catalyst
Development of effective copper-based catalyst for CO2 hydrogenation to methanol is of great significance,considering the utilization of this greenhouse gas.In this work,a series of surface promoter-modified(Mn,In,Mo,Mg,Zr)catalyst were synthesized by coprecipitation-post impregnation method and evaluated for CO2 hydrogenation to methanol in fixed-bed reactor.The role of metal modifier on the physicochemical properties of Cu/ZnO/Al2O3(CZA)were investigated through CO2-TPD,XRD,XPS and H2-TPR.In addition,the catalytic mechanism for CO2-to-methanol hydrogenation was revealed by employing in situ IR.The results showed that the Mn-modified CZA with good reduction behavior,excellent CO2 adsorption capacity and suitable Cu+/Cu0 ratio exhibited the best performance.The metal element loaded on catalyst strengthened the interactions between the copper and support,suppressing the growth of Cu.The appropriate Cu+/Cu0 ratio facilitates the stabilization and conversion of methoxy,resulting in increased methanol production.Compared to the untreated CZA catalyst,the Mn-modified catalyst has more medium strong base sites on the surface,which helps to adsorb more CO2 for further hydrogenation to form formate,methoxyl and other intermediates.The incorporation of metal component in CZA facilitated the catalyst reduction ability.The catalytic mechanism follows the formate pathway and the methoxyl species is the crucial intermediate.The Cu nanoparticles on the catalyst surface showed an increased capacity for H2 dissociation when using Mn-modified CZA catalysts.This is due to stronger metal-carrier interactions.The presence of interstitial H in the carriers contributed to the generation of formate species.The dissociated H atoms from the surface Cu nanoparticles replenished the consumed interstitial H.The modified catalyst's interstitial H presence and enhanced H2 dissociation ability accelerated the formation and conversion of intermediate species,promoting methanol generation.
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维普
