The changing nature of the active site of Cu-Zn-Zr catalysts for the CO2 hydrogenation reaction to methanol

• Differently prepared Cu-Zn-Zr catalysts were used in CO 2 hydrogenation reaction. • Catalyst composition and preparation method affect the physico-chemical properties. • The gel-oxalate coprecipitated catalyst showed high CH 3 OH productivity and stability. • The interaction of sites at metal-oxide interface plays a key catalytic role. The effects of the most largely employed preparation methods (i.e . , coprecipitation with sodium bicarbonate, complexation with citric acid, gel-oxalate coprecipitation) on the structure and catalytic behaviour of Cu-Zn-Zr systems for methanol synthesis from hydrogenation of carbon dioxide have been studied. The characterization data of the dried, calcined and reduced catalysts showed that the physico-chemical properties can be controlled by varying composition and preparation method. The catalyst obtained by the gel-coprecipitation procedure showed the highest catalytic activity in the T R range 453–513 K, 3.0 MPa and 10,000 h −1 , due to a superior functionality in the CO 2 and H 2 activation. An adequate balance between metal and oxide surface sites, in correspondence of a well defined particle size, was proposed to be crucial to design active and selective catalysts for such reaction. The good performance of the gel-oxalate coprecipitated catalyst was confirmed by an endurance test (≈200 h), in which a constant and remarkable methanol space–time-yield value of 1200 g kg cat −1 h −1 at ≈10% CO 2 conversion was obtained ( T R , 513 K; P R , 3.0 MPa).