Methanol Synthesis by Catalytic Hydrogenation of Carbon Dioxide on CuO-ZnO-Al_2O_3 and CuO-ZnO-Al_2O_3-Ca_2O_3-MgO Catalysts

摘要

The purpose of the study is to develop a practical catalyst for the conversion of carbon dioxide to methanol by hydrogenation. The activity and durability of a CuO-ZnO-Al_2O_3 catalyst and a CuO-ZnO-Al_2O_3-Ga_2O_3-MgO catalyst were investigated using a bench-scale test plant. It is found that the CuO-ZnO-Al_2O_3-Ga_2O_3-MgO catalyst shows better activity and durability than the CuO-ZnO-Al_2O_3 catalyst. Addition of Ga and Mg is effective to especially improve durability of the CuO-ZnO-Al_2O_3 catalyst. CO_2 conversion to methanol of the CuO-ZnO-Al_2O_3-Ga_2O_3-MgO catalyst has been over 95% for 2, 000 h at a pressure of 9 MPa, a temperature of 503 K and a recycle ratio of four by recycling unconverted reactants. Assuming that the CuO-ZnO-Al_2O_3-Ga_2O_3-MgO catalyst is applied to a conventional process, the optimum synthesis pressure to minimize the power consumption is estimated to be 7 MPa at a recycle ratio of 5 in the case of catalyst exchange after 32, 000 h of use.