Hydrophilicity-reduced hexagonal-BN supported Cu/ZnO-based catalyst for CO2 hydrogenation to methanol

Cu/ZnO/Al 2 O 3 has been a common catalyst for CO 2 hydrogenation to methanol. However, this catalyst suffered from water deactivation by the reaction product water, leading to reduced catalyst activity. In this research, hexagonal boron nitride (hexagonal-BN) was used as a hydrophilicity-reduced support for Cu/ZnO-based catalyst, with pretreatment of modified Hummers’ method to perform exfoliation and OH-group functionalization on hexagonal-BN to form H-hBN. Cu/ZnO-based catalyst with Al, La, or Ga as promoter metal and a trace amount of Mg was synthesized by the co-precipitation method. The results showed that CuZnAlMg/H-hBN catalyst exhibited the utmost methanol space-time yield among others at 230 °C and 5 MPa, and could achieve an even higher methanol space-time yield value at 270 °C and 5 MPa, reaching 201.1 mg CH3OH /g cat -h. Catalyst characterization indicated that catalysts with H-hBN as a support could exhibit reduced hydrophilicity and increased water-removal ability. Moreover, using H-hBN could increase the catalyst's Cu dispersion, thereby improving catalyst activity. Therefore, CuZnAlMg/H-hBN showed a high percentage of active Cu sites, resulting in its high methanol space-time yield. In summary, hexagonal BN is an innovative catalyst support that reduces catalyst hydrophilicity and increases water-removal capacity, leading to enhanced CO 2 hydrogenation for methanol production.