| In recent years,with the development and progress of industry,the use of fossil fuels has become more and more frequent,accompanied by more and more serious environmental pollution,among which the most striking is CO2,a large number of continuous emissions of CO2 will cause greenhouse effect,but at the same time CO2 is also an important resource.Therefore,the hydrogenation of CO2 into valuable chemicals is of great significance and high demand,but the process still faces great challenges.Both "carbon reduction" and "carbon use" are needed.Therefore,it is an important scientific research strategy for researchers to use CO2 conversion process to realize carbon resource recycling.Low carbon alcohol(C1-C3)is not only a common resource in people’s work and life,but also indispensable in industrial production.Therefore,the preparation of CO2 into low carbon alcohol is also a general trend.This paper mainly studied the reaction performance of polymetallic catalyst used in the preparation of low carbon alcohol,and studied the performance of the modified catalyst,the specific content is as follows:1.A series of MnxCu/Fe3O4 catalysts were prepared by coprecipitated method.The fixed bed equipment was used to evaluate and test the effects of different Mn content on the structural properties of the catalysts and on the synthesis performance of low carbon alcohols.The catalysts were characterized by XRD,CO2-TPD and H2-TPR.It was found that when the Mn content reached 0.006,the selectivity of low carbon alcohols,especially C3 alcohols,was the highest.The results showed that the interaction between the carbonate species generated on the catalyst surface was conducive to the production of low carbon alcohols,and the Fe7C3 species generated on the catalyst surface was also conducive to the formation of alcohol hydroxyl groups,promoting the reaction.The conversion of CO2 and the selectivity of low carbon alcohols with different Mn content changed obviously at different temperatures.At 240℃ to 320℃,the overall conversion rate of CO2 basically remained at 60%-70%.When the reaction temperature was 280℃,Mn0.006Cu/Fe3O4,the total alcohol of C1-C3 reached the maximum value,and the selectivity was 52.5%.2.The co-precipitation method was used to modify Mn0.006CuX/Fe3O4,in which X=(Zn,Co,Zr,Y,Ce).Based on the optimal conditions(280℃-320℃)conducive to the formation of alcohols in the previous chapter,the catalyst was studied and analyzed,and the experimental results ensured that the substance content of metal X was maintained at 0.015 mol.It is found that the addition of transition metals can change the electron transfer ability of elements,and promote the reduction peak shift to high temperature,that is,the interaction between metals is strengthened.Through various characterization analysis and evaluation,it was found that the catalysts with Zn and Co introduced maintained good catalytic activity at 280℃ to 320℃,which was mainly attributed to the promotion of the formation of alcohol hydroxyl on the surface.Meanwhile,combined with CO2-TPD and BET analysis,it was found that the introduction of metal could promote the increase of specific surface area.At the same time,an appropriate amount of alkaline sites is conducive to the reaction.The catalyst containing Zr and Ce has no liquid phase product in the reaction temperature range(280℃ to 320℃),and the main product is CO,while the catalyst containing Y has the same phenomenon at 320℃.The results showed that the selectivity of C1-C2 alcohols was significantly improved by the catalyst with the introduction of Zn,Co and Y.At 280℃,the selectivity of total alcohol between C1 and C3 reached the optimal 50.28%. |
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