Hydrogenation of CO 2 into Methanol and Dimethyl Ether on a Mixture of Commercial CuO/ZnO/MgO and HZSM5 Catalysts: Effect of Optimizing the Temperature Profile along the Reactor

The optimal temperature progression (OTP) theory was applied to the catalytic hydrogenation of CO 2 into methanol and dimethyl ether. The reaction kinetics was studied experimentally on a mixture of the CuO/ZnO/Al 2 O 3 /MgO (CZA-C) catalyst and HZSM-5 zeolite between 26 and 36 bar and at temperatures between 463 and 583 K. Isothermal and OTP behaviors of the reactors were compared in terms of CO 2 conversion and production of valuable molecules. OTP depends heavily on the inlet temperature and demonstrated its significant advantage over an isothermal reactor operation in a simple reversible and balanced reaction. However, in the case of a complex scheme involving several exothermic and endothermic reactions, the benefits were more moderate. Extrapolation to industrial scale demonstrated the feasibility of designing an OTP reactor, enhancing CO 2 conversion and productivity by continuously promoting the methanol synthesis, and reducing the competing reverse water gas shift reaction rate along the reactor by lowering the outlet temperature.