Efficient Conversion of Syngas into Ethanol by Tandem Catalysis

Syngas conversion into ethanol by tandem catalysis has exhibited its potential for the selective production of ethanol. For practical applications, it is desired to develop a robust catalyst system to enhance the CO conversion while maintaining high selectivity to ethanol. Here, we report an efficient and stable triple-tandem catalyst system consisting of CuZnAlOx/γ-Al2O3, pyridine-modified H-MOR zeolite (Py-HMOR), and Cu1Zn2AlOx, which catalyzes syngas to dimethyl ether (DME), DME carbonylation to methyl acetate (MA), and MA hydrogenation to ethanol in tandem. Both high CO conversion (52%) and satisfying selectivity to ethanol (62%, excluding CO2) were achieved simultaneously, leading to an unprecedently high ethanol space-time yield of 6.5 mmol g–1 h–1. In situ DRIFT and control catalytic tests were designed to elucidate the intrinsic reason of the high activity and stability of Py-HMOR in the tandem system. The developed tandem catalyst system presents a promising prospect for the direct ethanol manufacture from syngas.