(599b) Co-Production of Methanol and Dimethyl Ether Using a Zinc Carbonate Modified Catalyst System

A carbonate modified dual-catalytic system of Cu/ZnCO₃/Al₂O₃ andγ- Al₂O₃ was successfully devised and developed using the SEAM’s proprietary condensed-phase reactive modification technology. This catalyst system was also experimentally investigated in a fully continuous, proof-of-concept mini-pilot scale system for a process engineering study of single-stage syngas-to-dimethylether (ssDME) process. The preliminary experimental results have revealed that (1) the modified catalyst exhibits a good potential to maintain the initial catalytic activity for a prolonged time in a typical reaction environment; (2) the catalyst exhibits high CO₂ tolerance and reactivity for the CO₂-rich feed syngas; and (3) the catalyst possesses an enhanced attrition resistance. This study has also shown that 1) supercritical carbon dioxide is a good medium to convert the conventional Cu/ZnO/Al₂O₃to the modified Cu/ZnCO₃/Al₂O₃; 2) the modified catalyst exhibits a reduced CuO crystallite size, and a larger surface area when compared with the original unmodified catalyst; 3) the ZnCO₃ modified catalyst provided a better resistance to mechanical attrition during harsh reactor operation; and 4) the modified catalyst shows substantially enhanced anti-leaching characteristics against both water and slurry medium of high-boiling mineral oil. The current concept of pre-reduction modification of the catalyst enables the modified catalyst to be commercially producible as an added benefit.