Co-Based Bimetallic Catalyst For Synthesis Of Ethanol And Higher Alcohols From Syngas

Synthesis of ethanol and higher alcohols from syngas is one of the major subjects in C1 chemistry field. Ethanol and higher alcohols used as liquefaction fuels and/or feedstocks for chemicals could be of great significance if they could be be efficiently synthesized from the transformation of the biomass-based syngas. For the fact that Co has prominent chain growth ability and lower activity towards water-gas shift (WGS), Co-based catalysts have been attracting renewed scientific interest. However, sole Co site encounters low selectivity towards alcohols due to the deficiency of CO non-dissociation sites. Therefore, another centre on which CO adsorption is associative rather than dissociative is needed to be introduced and cooperates with Co0 to yield ethanol and higher alcohols. This work is focused on both of the structure and catalytic performance of the uniformly distributed CoCu catalyst and novel CoGa catalyst.(1) As the metal cations in the layer distributed in atom scale and ion inter the layer dispersed orderly as well as the controlled component, the CoCuZnAl-CO3-LDHsLDHs and CoZnAl-Cu(C2O4)2-LDHs are synthesized as precursors. By the reduction of the as-synthesised LDHs, CoCu(intercalated)-ZnAl2O4 and CoCu(layered)-ZnAl2O4 are produced. It is found that the CoCu catalysts derived from LDHs show a better uniformly distributed structure of Co and Cu compared with CoCu/ZnAl2O4 prepared by impregnation method, which boost their activity and selectivity towards ethanol and higher alcohols. Furthermore, the effect of the introduction method of Cu on the distribution of Co and Cu in the CoCu catalysts is discussed, as well as the relationship of uniformly distribution and synergetic catalysis.(2) CoZnGaAl-LDHs are synthesised in situ on the y-Al2O3 support. Benifiting from the trap effect of LDHs, a uniformly dispersed CoGa catalyst CoGa-ZnAl-LDO/y-Al2O3 with CoGa particles trapped into the oxide support is produced by in situ reduction of as-synthesised CoZnGaAl-LDHs. Such CoGa catalyst exhibits excellet performance in ethanol and higher alcohols synthesis from syngas. The catalytic performance is improved by the well distributed CoGa particles when comparing with the supported CoGa catalysts produced by impregnation method. Furthermore, research on the interaction of Co and Ga in the CoGa-ZnAl-LDO/y-Al2O3 is carried out for the understanding of the mechanism for the designed CoGa catalyst.