Conversion Of CO/CO₂+H₂ To Higher Alcohols Over Co-Ga Based Catalysts

Faced with various kinds of environmental problems,such as greenhouse effect,haze etc.and along with the severe scarcity of fossil fuels,synthesis of alternative energy sources is particularly important.Higher alcohols as a clean energy have been studied by scholars.The main research work of this paper is to explore the catalystic performance and structure concerning the Co-Ga based catalyst for syngas and carbon dioxide hydrogenation to produce low carbon alcohols.Combining the citrate complexing method with incipient impregnation,19%LaCoO₃/ZrO₂,xLaCo_0.65Ga_0.35O₃/ZrO₂?x=25%,30%,35%?,Co₃O₄-Ga₂O₃/ZrO₂were prepared.According to XPS,XRD,STEM,TG and other characterization methods and activity testing,it is showed that 30%LaCo_0.65Ga_0.35O₃/ZrO₂ has the best performance.After reduction,the 30%LaCo_0.65Ga_0.35O₃/ZrO₂ catalyst was transformed to Co NPs/LaGaO₃-La₄Ga₂O₉ supported on ZrO₂,which showed CO conversion 17%,alcohol selectivity 52.1%and C₂₊OH=76.1%under the reaction condiction:T=300?,P=4 MPa,CHSV=3900 h^-1.It has not deactivation phenomenon under 200h stability test.Adding gallium can improve ethanol selectivity,the very good resistance and the high resistance to carbon deposition.A series of catalysts of 30%LaCo_0.65Ga_0.35O₃/Ce_xZr_1-xO₂ were synthesized.According to BET,XRD and H₂-TPR and the activity test,it is shown that 30%LaCo_0.65Ga_0.35O₃/Ce_xZr_1-xO₂ are good catalysts for CO₂ hydrogenation.30%LaCo_0.65Ga_0.35O₃/Ce_0.5Zr_0.5O₂ catalyst exhibits excellent ethanol selectivity compared to 30%LaCo_0.65Ga_0.35O₃/CeO₂ and 30%LaCo_0.65Ga_0.35O₃/ZrO₂ catalysts,which showed CO₂ conversion 12.9%,alcohol selectivity 40.1%and C₂₊OH=76.5%under the reaction condiction:T=290?,P=4 MPa,CHSV=3000 h^-1.The reason is that the addition of Zr is beneficial to enhance its resistance to sintering.Secondly,Ce_0.5Zr_0.5O₂ support has the basic character,so having appropriate acid sites,conducive to the further adjustment of the conversion of carbon dioxide,the formation of alcohols and the C₂₊OH formation.Meanwhile,CeO₂ is benefical to reverse water gas shift reaction to generate CO.CO hydrogenation generate higher alcohol.