Highly Selective CO₂ Conversion to Methanol in a Bifunctional Zeolite Catalytic Membrane Reactor

The hydrogenation of sequestrated CO₂ to methanol can reduce CO₂ emission and establish a sustainable carbon circuit. However, the transformation of CO₂ into methanol is challenging because of the thermodynamic equilibrium limitation and the deactivation of catalysts by water. In the present work, different reactor types have been evaluated for CO₂ catalytic hydrogenation to methanol. Best results have been obtained in a bifunctional catalytic membrane reactor (CMR) based on a zeolite LTA membrane and a catalytic Cu-ZnO-Al₂O₃-ZrO₂ layer on top. Due to the in situ and rapid removal of the produced water from the catalytic layer through the hydrophilic zeolite LTA membrane, it is effective to break the thermodynamic equilibrium limitation, thus significantly increasing the CO₂ conversion (36.1 %) and methanol selectivity (100 %). Further, the catalyst deactivation by the produced water can be effectively inhibited, thus maintaining a high long-term activity of the CMR.