Modulating the surface composition of CuZnOx catalysts via doping Al for catalyzing CO2 hydrogenation reaction

For the industrially promising reaction of CO 2 hydrogenation toward methanol, Cu/Zn/Al-based catalysts present a potential candidate, where the surface active structure dictates the catalytic performance, guiding ongoing research into structure–activity relationships. Herein, a series of CuZn x Al y  (where the mol ratio of Zn/Cu =  x , mol ratio of Al/Cu =  y ) catalysts with varying compositions was synthesized via a coprecipitation method. Physicochemical characterization revealed that a small amount of Al (CuZn 0.56 Al 0.04 ) enhanced the specific surface area, improved the dispersion of Cu and Zn species, and optimized the Cu + /Cu 0 ratio, as evidenced by N 2  physisorption, XRD, and XPS analyses. In contrast, excessive Al content (CuZn 0.23 Al 0.83 ) led to a decline in surface area, pore volume, and surface exposure of active Cu and Zn species. Catalytic performance tests showed that CuZn 0.56 Al 0.04  achieved the highest CO 2  conversion (16.2%), methanol selectivity (56.3%), and methanol space–time yield (STY) (438  g MeOH  kg cat −1  h −1 ), outperforming that of the commercial CuZnAl catalyst. In situ DRIFTS studies confirmed that methanol synthesis proceeded via a formate (HCOO) mediated pathway, with the optimal catalyst demonstrating superior efficiency in converting key intermediates (HCO 3 *, CO 3 *, HCOO*) to the final product. The study establishes that tailored Al content is crucial for modulating catalyst surface properties and ultimately promoting catalytic performance for methanol synthesis from CO 2 . Graphical abstract An optimal Al content in co-precipitated CuZn x Al y catalysts optimizes the surface active structure, enabling efficient CO 2 -to-methanol hydrogenation via the formate pathway.