| Synthesis of higher alcohols(C1-C6) from syngas(CO+H2) is one of the important way for clean utilization of coal resources. Higher alcohols is widely used with its high economic value. Because of its complete combustion with emissions of little CO, NOx, hydrocarbons and others, higher alcohol can be used as environmentally friendly alternative fuels.And it can be used as fuels additives.At the same time it also can be used as chemical products and chemical raw materials. In the current catalyst system for CO hydrogenation to alcohols, F-T elements modified catalysts are the most promising catalysts. Co and Fe are two kinds of the active components of the catalysts.But this kinds of catalysts show some disadvantages in catalytic performance and economy. Developing catalysts with good performance is difficult and critical for CO hydrogenation to higher alcohols.The graphene is a new two-dimensional material. It can act as a catalyst carrier. Meanwhile, the graphene has the advantage such as huge surface area, stronger electrical conductivity and thermal conductivity as well as stable structure, which make catalysts using grapheme as a carrier exhibit relatively excellent catalytic activity. In this paper, CuZn Al catalysts were prepared by completely liquid method with the F-T component of Fe as promoter. And the catalytic reaction was carried out in fixed bed reaction. The effect of Fe content and ultrasound treatment on catalyst structure and catalytic performance were studied. CuCoCe/Gr catalysts were also preprared by impregnation method. The effect of Gr content and Ce content on catalyst structure and catalytic performance were studied. And catalysts were characterized using XRD, H2-TPR, BET, NH3-TPD and XPS. Combined characterization data with activity data the related conclusions were as follows:1. Fe modified CuZnAl catalyst prepared by complete liquid phase technology has an ability to promote the synthesis of higher alcohols. The addition of Fe favors producing long carbon chain alcohols and improving the selectivity of C2+OH.2. Fe promoted CuZnAl catalyst has a higher specific surface area and pore volume, which can increase the selectivity of C2+OH. The ratio of Cu and Zn and Al content on catalyst surface can increase with the increase of Fe content, which makes methanol selectivity decrease and hydrocarbon selectivity increase.3. The ultrasound treatment has no effect on catalyst phase but it is beneficial to the increase of the pore size of the catalyst, which makes the selectivity of higher alcohols increase.4. For CuZn Al catalysts treated by ultrasound a certain amount of Fe can change the interaction between Cu species and the support, and increase the specific surface area as well as the amount of weak acid, thus increase the CO conversion catalyst and C2+OH selectivity.5. The graphene as a carrier can increase specific surface area of the catalysts, improve the reducibility of the catalysts, then increase the selectivity of higher alcohols. What’s more, the suitable amount of graphenes can increase the selectivity of ethanol. The graphene can limit the growth of the carbon chain, which makes methanol and ethanol become the main ones in alcohol products.6. The suitable amount of Ce can improve the dispersion of Cu species, be conductive to increasing specific surface area of the catalyst, significantly improve the reduction performance of the catalysts, which can be contributed to promote the synthesis of the active sites of alcohols.7. For CuCoCe/Gr catalysts, the bigger pore size is bebeficial to the diffusion of molecules in the reaction. Suitable content of Ce can improve catalytic activity, and increase the selectivity of the higher alcohols as well as ethanol. |
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