CO2 hydrogenation to methanol at high reaction temperatures over In2O3/ ZrO2 catalysts: Influence of calcination temperatures of ZrO2 support

This work investigated the role of calcination temperatures (600, 700, 800, 900 and 1000 degrees C) of ZrO2 support on the physicochemical properties of In2O3/ZrO2 catalysts (denoted as 20In/Zr-X with X, calcination temperature of ZrO2 support) as well as their catalytic activity in CO2 hydrogenation to methanol at high reaction temperatures (320-400 degrees C). The calcination temperature played a crucial role on crystal structure of In2O3 and ZrO2, reducibility of In2O3 and adsorption-desorption of CO2 and H-2. XRD analysis revealed that cubic In2O3 and amorphous ZrO2 were presented in 20In/Zr-600. With increasing calcination temperature of ZrO2 support from 600 to 1000 degrees C, the tetragonal ZrO2 was formed and the In2O3 and ZrO2 crystallite sizes were enlarged. The degree of In2O3 reduction was found to gradually decrease with increasing the calcination temperature of ZrO2 support due to the increase of In2O3 crystallite size. The adsorption strength of CO2 and H-2 with the catalysts surface was found to be as follows: ZrO2 > 20In/Zr-1000 > 20In/Zr-900 > 20In/Zr-800 > 20In/Zr-700 > 20In/Zr600 > In2O3. The different calcination temperatures of ZrO2 support did not significantly affect the formation of CO but strongly dominated the yield of CH3OH and CH4. At reaction temperatures of 320-340 degrees C, the 20In/Zr-800 provided the maximum yield of CH3OH. However, as the reaction temperature was further increased, the maximum yield of CH3OH was obtained over the 20In/Zr-900, indicating that higher adsorption strength of CO2 and H-2 enhanced the formation of CH3OH at higher reaction temperatures. Moreover, the strong interaction of H-2 and CO2 with the catalysts surface suppressed the formation of CH4.

Automated summary

The calcination temperature of ZrO2 support plays a crucial role in the crystal structure and reducibility of In2O3, as well as in the formation of methane and methanol. Different calcination temperatures of ZrO2 support significantly affect the yield of methane and methanol.