Influence of the secondary metals on structure of the Cu/LDH catalyst for carbon dioxide-to-methanol reaction

CO 2 -to-methanol is a promising process for carbon utilization to produce sustainable fuel and chemicals. Catalytic performance of Cu-based Layered Double Hydroxide (LDH)-derived catalysts for CO 2 hydrogenation to produce methanol was investigated in this work. Various secondary metallic components, Al, Ga, Cr, In, Sm and La were employed to prepare a series of Me-Cu/LDH type of catalyst for CO 2 -to-methanol reaction. The catalysts were synthesized using a co-precipitation method, followed by calcination and reduction activation. Impact of the secondary metals on the structure of the prepared catalyst and their reaction performance was studied in fixed-bed reactor. The CO₂ hydrogenation activity and methanol selectivity of the prepared LDO catalyst were evaluated at 3.0 MPa and a gas hourly space velocity (GHSV) of 3.6 L·g⁻¹·h⁻¹, using a CO₂/H₂ ratio of 3. Synthesis conditions, including temperature and aging time, significantly affected the catalyst structural properties and catalytic performance. The results showed that the CuAl catalyst yielded the highest CO 2 conversion up to 20%, while the CuIn catalyst generated the highest methanol selectivity above 74%. It can be reasonably proposed that the highly dispersed copper active sites in the CuAl catalyts contributed to the improved CO 2 conversion, whereas the high concentration of oxygen vacancies in the CuIn catalyst promoted methanol formation. Furthermore, these catalysts showed good stability with no noticeable carbon deposition. These findings highlight the potential of LDH-based catalysts in CO 2 hydrogenation and provide valuable insights for optimizing their structure and composition to enhance catalytic efficiency.