Journal of Chemical Engineering of Japan, Vol.36, No.2, 126-131, 2003
Comparison of single-stage and two-stage CO2 hydrogenation for methanol synthesis gain and phase margins
A two-stage CO2 hydrogenation reaction was conducted to increase methanol yield. At the first-stage, CO2 was converted to CO by the reverse water-gas shift reaction with Cu/ZnO/Al2O3, Fe2O3/Cr2O3, or MoS2/TiO2 catalyst, and then at the second-stage, methanol was synthesized from the effluents of the first-stage with a commercial methanol synthesis catalyst, Cu/ZnO/Al2O3. In the case of the two-stage CO2 hydrogenation reaction, CO that was produced by the first-stage reverse water-gas shift reaction contributed to the methanol synthesis, increasing the methanol yield. Especially, with the two-stage CO2 hydrogenation reaction, methanol yield obtained was two or three times higher than that of the single-stage one. It was found that to increase the methanol yield in the two-stage hydrogenation reaction, more CO2 should be converted to CO at the first-stage. The XRD patterns of the Cu/ZnO/Al2O3 catalyst before and after reaction showed the presence of metallic bulk Cu and the absence of other bulk Cu species.
Keywords:CO2 hydrogenation;CO hydrogenation;methanol synthesis;single-stage reaction;two-stage reaction