Efficient Cu–Zn–Al/LDH Catalysts for CO2-to-Methanol Conversion

As a greenhouse gas, carbon dioxide is also a rich carbon resource that can be effectively utilized to tackle the global warming crisis. This paper presents an in-depth investigation of the impact of the Cu content on the structure of Cu–Zn–Al layered double hydroxides (LDHs) from a novel perspective. The CO2 hydrogenation performance of the derived catalyst, the LDO, is also evaluated in the methanol synthesis reaction. All catalysts were evaluated at 3.0 MPa, a carbon dioxide to hydrogen ratio of 3, and a space velocity of 3600 mL·g–1·h–1. The results from this work indicate that the catalyst with a Cu:Zn ratio of 11:4 exhibited the highest methanol selectivity of 63.9% at 230 °C. At 250 °C, the catalysts also yielded the highest methanol selectivity of 50% only, along with a CO2 conversion as high as 17.8%. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) data suggest that the CO2-to-methanol reaction follows the formate (HCOO*) mechanism for this catalyst. Results from this work offer a novel approach to designing Cu-LDH-based catalysts, which offers valuable insights for the efficient chemical utilization of CO2.