A team around CAS Academician LIU Zhongmin at CAS Dalian Institute of Chemical Physics has developed a ZnAlOx & H-ZSM-5 catalyst, a nano-spinel structured ZnAlOx oxide mixed with nano-H-ZSM-5a zeolite of a high silicon-to-aluminum ratio. This catalyst provided 73.9 % selectivity for aromatics formation from carbon dioxide hydrogenation, with only 0.4 % selectivity from methane. Mechanism studies showed that carbon dioxide is hydrogenated on ZnAlOx to form dimethyl ether and methanol, which diffuse into the pores of the molecular sieve to form olefins, which in turn form aromatic hydrocarbons. Compared to carbon monoxide hydrogenation, carbon dioxide hydrogenation leads to more formate species on the surface of ZnAlOx, leaving less metal active sites. These factors all contribute to the formation of aromatics with high unsaturation.
CAS news release, September 10, 2018