Methanol synthesis by catalytic hydrogenation of carbon dioxide on CuO-ZnO-Al2O3 and CuO-ZnO-Al2O3-Ga2O3-MgO catalysts

The purpose of the study is to develop a practical catalyst for the convers ion of carbon dioxide to methanol by hydrogenation. The activity and durabi lity of a CuO-ZnO-Al2O3 catalyst and a CuO-ZnO-Al2O3-Ga2O3-MgO catalyst wer e investigated using a bench-scale test plant. It is found that the CuO-ZnO -Al2O3-Ga2O3-MgO catalyst shows better activity and durability than the CuO -ZnO-Al2O3 catalyst. Addition of Ga and Mg is effective to especially impro ve durability of the CuO-ZnO-Al2O3 catalyst. CO2 conversion to methanol of the CuO-ZnO-Al2O3-Ga2O3-MgO catalyst has been over 95% for 2,000 h at a pre ssure of 9 MPa, a temperature of 503 K and a recycle ratio of four by recyc ling unconverted reactants. Assuming that the CuO-ZnO-Al2O3-Ga2O3-MgO catal yst 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 5.5 in the case of catalyst exchange after 16,000 h of use, and 10 MPa at a recycle ratio of 5 in the case of catalyst exchange after 32,000 h of use.