Study On The Cu-Co Based Catalyst For Synthesis Of Higher Alcohol From Syngas

Synthesis of higher alcohol (C1～C6) from syngas (CO+H2) is one of the important way for clean utilization of coal resources. Higher alcohol not only can be used as alternative fuels and clean gasoline additives, also can be used as chemicals and chemical raw materials. In recent years, higher alcohol’s applied value in the field of energy、chemical industry and environmental protection gradually highlights, related research has become increasingly active. In the current development of higher alcohol catalyst system, CuCo based catalysts for its mild reaction condition, high activity and high selectivity of C2+OH is considered to be one of the catalyst with most industrial application prospect. The CuCo catalysts were prepared by co-impregnation method, this paper selected the rare earth metal Ce as additives, as Ce has the promoting effect for the synthesis of higher alcohol, the effect of different supporters of catalyst was investigated. Later, the effect of impregnation solvents and different Ce contents were investigated. The catalysts were characterized by XRD, H2-TPR, N2 adsorption/stripping, CO-TPD and TEM, binding their activity data and a variety of characterization results to analyse the catalyst performances. The main conclusions were as follows:(1) CuCo base catalysts with different supports have different effects on the synthesis of higher aclcohol from syngas. The catalyst support on CNTs can markedly improve the catalyst activity and the selectivity of alcohol.(2) The form of active species of catalysts with different supports were different and the active sites for alcohols were not the only. The interaction between CuO and CU2O may be one of the reasion for its good catalytic performance of CuCo-Ce/CNTs.(3) CNTs have a larger specific surface area which is conducive to the dispersion of active components and the formation of active sites, at the same time can significantly improve the reduction performance of catalyst.(4) Impregnation solvents have a certain impact on the reduction performance of catalysts. Using water or ethanol as solvent can promote the reduction of active metal and improve the reduction performance of catalysts.(5) Impregnation solvents have a significant impact on the CO adsorption of the catalysts. Using water as solvent can markedly increase the adsorbed capacity of CO and promote the transformation of CO and hydrogenation reaction, thus is advantageous to the synthesis of higher alcohol.(6) The addition of an appropriate amount of Ce facilitates the dispersion of Cu, reduces the grain size of Cu species, promotes the reduction of the catalysts and can significanty increase the strong adsorption active sites of CO and raise the activation adsorption quantity of CO species.(7) Using co-impregnation method and open-CNTs as the support can prepare CuCo/CNTs catalysts with high activity and high alcohols selectivity. At a Ce content of 3%, the catalyst has the highest catalytic activity, the formation rate and selectivity of alcohol reached 696.4 mg·gcat-1·h-1 and 59.7%, where the content of ethanol is 46.8% in the total of alcohols.