Preparation and application of Cu/ZnO catalyst by urea hydrolysis method for low-temperature methanol synthesis from syngas

- Urea method achieved higher carbon conversion of catalyst than coprecipitation method.
- The increase of precipitation temperature obtained the highly dispersed Cu particles.
- The optimum content of urea benefits the formation of homogeneously fine crystals.
- The increased surface area of BET and metallic Cu0 promoted the catalyst activity.

The Cu/ZnO catalyst prepared by urea hydrolysis method was investigated for low-temperature methanol synthesis from syngas containing CO2. Concurrently, the activity of the conventional Cu/ZnO catalyst prepared by co-precipitation method was also compared. The effects of precipitation temperature, urea content, stirring speed and the introduction of Al on the catalytic performance of Cu/ZnO were deeply studied. It was found that the total carbon conversion of the Cu/ZnO catalyst prepared by urea hydrolysis method was increased to 45.0% from 32.8%, comparing with that of the catalyst prepared by co-precipitation method. The structure, BET surface area, surface morphology of the catalyst were characterized by XRD, BET, EDX and SEM. The catalyst prepared by urea method obtained higher BET surface area and larger metallic surface area of Cu than those of the co-precipitation method. The crystals sizes of Cu by urea method were smaller than those of co-precipitation method. Surface structure prepared by urea method had needle shape, and it could increase the surface area, different from the catalyst by co-precipitation method. Both the increased BET surface area of the catalysts and the enhanced metallic surface area of Cu0 promoted the catalyst activity for the low-temperature methanol synthesis. The deactivation of the Cu-ZnO catalysts prepared by urea method was not observed in low-temperature methanol synthesis here.