C sub(2)-C sub(4) hydrocarbons synthesis from syngas over CuO-ZnO-Al sub(2)O sub(3)/SAPO-34 bifunctional catalyst

BACKGROUND The synthesis of C sub(2)-C sub(4) hydrocarbons from coal or biomass-derived syngas has received increasing attention because of the resource constraints of petroleum. The present study explores direct production of hydrocarbons from syngas over bifunctional catalyst containing methanol synthesis catalyst CuO-ZnO-Al sub(2)O sub(3) (CZA) and SAPO-34 zeolite. RESULTS The synthesis of C sub(2)-C sub(4) hydrocarbons from syngas was investigated over CZA/SAPO-34 bifunctional catalyst at temperatures ranging from 240 to 440 degree C. The results indicate that higher temperatures aggregate Cu metal and lead to the deactivation of CZA. The predominant products are dimethyl ether (DME) and methanol at temperatures from 280 to 360 degree C and a small amount of hydrocarbons are found due to the deactivation of SAPO-34 caused by a type of coke named 'inert coke'. While 96.5% selectivity of C sub(2)-C sub(4) hydrocarbons in products of all hydrocarbons can be obtained at 400 degree C with less coke named 'active coke'. CONCLUSION Reaction temperatures have significant effect on the selectivity of C sub(2)-C sub(4) hydrocarbons and coke species of SAPO-34. The 'active coke' of poly methyl-substituted benzene/naphthalene (MB/MN) acts both as an intermediate and as coke deposition. The 'inert coke' of poly methyl-substituted adamantine (MA) and other groups-substituted benzene/naphthalene acts only as coke depositions. Comprehensive consideration of the characteristics of this bifunctional catalyst, shows that a moderate temperature for C sub(2)-C sub(4) hydrocarbons synthesis from syngas might be approximately 400 degree C. copyright 2014 Society of Chemical Industry