Study On Catalysts For Ethanol Synthesis From Syngas

Catalytic conversion of syngas to ethanol has great impact on China's energy structure,economic development and environmental protection.Rh-based catalyst is one of the most promising catalysts for ethanol synthesis.In this paper,the effects of promoters and their loadings on TiO₂ and Al₂O₃ supported Rh-based catalysts were investigated.Rh-Fe/TiO₂ catalysts were prepared by incipient wetness co-impregnation method.The effects of Fe on the catalytic performance of Rh-based catalysts were investigated by N2 adsorption,XRD,H2-TPR and CO-TPD.H2-TPR results showed that the addition of Fe facilitated the reduction of Rh.CO-TPD results indicated that the addition of Fe inhibited the formation of linear and bridged CO species and promoted the formation of gem-dicarbonyl CO species.Catalytic results showed that under the condition of 260? 2MPa,3600mL/?g·h?,CO conversion was 11.7%and ethanol selectivity was 22.6%with 4%Fe loading.Rh-Fe-Ce/TiO₂ catalysts were prepared by incipient wetness co-impregnation method.The effects of Ce on the catalytic performance of Rh-Fe catalysts were investigated by N2 adsorption,XRD,XPS,H2-TPR,CO-TPD and DRIFTS.XPS showed that Rh+ and Rh0 co-existed on the surface of reduced Rh-Fe-Ce/TiO₂ catalyst.The addition of Fe and Ce promoted the formation of Rh+ species.H2-TPR results suggested that the addition of Ce facilitated the reduction of Rh and Fe.CO-TPD and DRIFTS results indicated that the addition of Ce increased the CO adsorption.Proper Ce loading effectively facilitated the generation of linear,gem-dicarbonyl and bridged CO species.Catalytic results showed that under the condition of 260?,2MPa,3600mL/?g·h?,CO conversion was 12.5%and ethanol selectivity was 27.5%with 2%Ce loading.Rh-La/Al₂O₃ catalyst was prepared by incipient wetness co-impregnation method.The incorporation of La was beneficial to CO conversion and ethanol selectivity.Rh-based catalysts supported on Al₂O₃ and TiO₂ were compared.Catalytic results showed that TiO₂ supported Rh-based catalysts had better performance.H2-TPR showed that the presence of TiO₂ facilitated the reduction of Rh.CO-TPD showed that TiO₂ was beneficial to the formation of gem-dicarbonyl CO species,which was favorable for CO insersion,leading to the growth of ethanol selectivity.