Probing Hydrophobization of a Cu/ZnO Catalyst for Suppression of Water–Gas Shift Reaction in Syngas Conversion

Abstract

Due to the complexity of the structure and surface property of metal oxide catalysts, hydrophobization of metal oxide catalysts is a great challenge. The hydrophobization strategy and effects of hydrophobization on the surface property and catalytic performance of metal oxide catalysts deserve rigorous investigations. Herein, we adopt stearic acid to functionalize the surface of a Cu/ZnO catalyst by bridging stearic acid molecules with the Cu/ZnO catalyst surface. After functionalization, the hydrophobicity of the Cu/ZnO catalyst is greatly reinforced, while its structure and catalytic performance remain nearly unchanged. The hydrophobic Cu/ZnO catalyst exhibits a very positive inhibitory effect on the unfavorable water–gas shift reaction (WGSR) in one-step synthesis of dimethyl ether (DME) from syngas (CO + H2), while the catalytic activity of the hydrophobic Cu/ZnO catalyst for methanol synthesis is not affected. Lower CO2 selectivity and higher DME selectivity over the hydrophobic Cu/ZnO-4 catalyst, better than those of untreated catalyst, are obtained facilely. The promoted catalytic performance of the hydrophobic Cu/ZnO catalyst demonstrates that the surface hydrophobicity of heterogeneous catalysts is worthy of more attention for enriching their catalytic roles.