Direct conversion of blast furnace gas to dimethyl ether over Cu-ZnO-Ga2O3/γ-Al2O3 hybrid catalyst: Optimum mass ratio of the catalyst

Abstract

The objective of this study is to develop a catalyst in a packed-bed reactor for direct synthesis of dimethyl ether ((CH3)2O, DME) from blast furnace offgas (CO-CO2-H2-N2, BFG). Physically-admixed (hybrid) catalysts of Cu-ZnO-Ga2O3 for CH3OH synthesis and γ-Al2O3 for its dehydration were experimentally studied, in which the influence of mixing ratio of the two catalysts on both yield and selectivity of DME was mainly examined for the same catalyst mass. The results showed that the developed hybrid catalyst is very effective in producing DME directly from BFG without equilibrium limit of methanol. Interestingly, the yield of DME had a significant dependence of mixing ratio, and the hybrid catalyst with only 5 mass% γ-Al2O3 showed the highest yield with 99.3% selectivity of DME+methanol. This implies that methanol formation governs the rate of this series reaction (BFG→CH3OH→DME) due to fast dehydration of methanol to DME.