2024 AIChE Annual Meeting

(500e) Hydrophobic h-BN Supported Cu/ZnO Catalysts for CO2 Hydrogenation to Methanol

Authors

Wu, J. - Presenter, National Taiwan University
Hu, J. C., National Taiwan University
Hsu, H. Y., Industrial Technology Research Institute
Chen, Y. C., Industrial Technology Research Institute
Methanol (CH3OH) is widely used as a common chemical feedstock for industrial purposes. Because of its high hydrogen-to-carbon ratio and being liquid under ambient conditions, methanol is widely recommended as hydrogen energy carrier in literature. CO2 hydrogenation to methanol not only stores hydrogen as methanol but also achieves the purpose of CO2 recycling. Industrially, Cu/ZnO/Al2O3 catalyst is used in CO2 hydrogenation to methanol, which needs to be operated under very high pressure (5-10 MPa) from the thermodynamic point of view. In addition, water, an inevitable by-product during the reaction, not only decreases the methanol selectivity but also promotes the oxidation of Cu and the aggregation of ZnO, resulting in the deactivation of the catalyst.

In this study, we used hydrophobic material, hexagonal boron nitride (h-BN), as the support of Cu/ZnO catalyst for CO2 hydrogenation to methanol. h-BN was pretreated by sonication or modified Hummers method to increase the adhesion of metal oxide. Cu/Zn metals were loaded on h-BN by the deposition-precipitation method. We designed different procedures and loading parameters to synthesize catalysts, including h-BN pretreatment method, catalyst synthesis method, metal loading, and promoter. The reaction was carried out at 230 oC and 1 MPa. The result indicated that all catalysts using h-BN as support showed higher methanol selectivity compared with those by Al2O3 support. We found that the catalyst using 40 wt% Cu/ZnO/La2O3 with 0.3 mol% Mg loaded on h-BN pretreated with modified Hummers’ method showed the highest activity in this study. The space-time yield of methanol reached 105 mgMeOH/gcat/hr at 1.0 MPa and 200 oC. The instruments XRD, SEM, EDS, H2-TPR, CO2-TPD, XPS, and contact angle were applied to evaluate the characteristics of catalysts and explain the activity test results. Chemical kinetic analysis was conducted based on the results obtained under different reaction conditions. Furthermore, a high-pressure reaction was carried out at the Industrial Technology Research Institute (ITRI) to confirm the excellent catalyst performance under industrial high-pressure operation, thus worth the further development of h-BN-supported catalysts.