(60c) Zinc Carbonate Modification of Methanol Synthesis Catalyst for Single-Stage DME Production

In order to enhance the tolerance of the catalyst system to the high CO₂ content of CO₂-rich syngas, a carbonate modified dual-catalytic system between CuO/ZnCO₃/Al₂O₃ and γ-Al₂O₃ was successfully devised and developed using the SEAM’s proprietary condensed-phase reactive modification technology. The catalyst was selectively reconfigured based on a direct modification approach applied to a commercially available oxide-based catalyst before its reduction treatment. The study has established that: 1) supercritical carbon dioxide (sc-CO₂) is a good medium to carry out the conversion of CuO/ZnO/Al₂O₃to CuO/ZnCO₃/Al₂O₃; 2) the modified catalyst exhibits a reduced CuO crystallite size and an increased internal surface area when compared with the original unmodified catalyst; 3) the ZnCO₃ modified catalyst provides a superior resistance to mechanical attrition during the slurry reactor operation; and 4) the modified catalyst shows substantially enhanced anti-leaching characteristics against both water and a 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, which was not possible with the post-reduction modification approach.