Copper and Iron Cooperation on Micro-Spherical Silica during Methanol Synthesis via CO2 Hydrogenation

A series of mono- and bi-metallic copper and iron samples were prepared by impregnation method on micro-spherical silica and used for the synthesis of methanol via CO2 hydrogenation. Compared with conventional carrier oxides, micro-spherical silica has obvious advantages in terms of absorption capacity and optimal distribution of active phases on its surface, also exhibiting excellent heat resistance properties and chemical stability. The prepared catalysts were characterized by various techniques including XRF, XRD, SEM, TEM, H-2-TPR and CO2-TPD techniques, while catalytic measurements in CO2 hydrogenation reaction to methanol were performed in a fixed bed reactor at a reaction pressure of 30 bar and temperature ranging from 200 to 260 degrees C. The obtained results revealed that the mutual interaction of copper-iron induces promotional effects on the formation of methanol, especially on systems where Fe enrichment on the silica support favours the presence of a larger concentration of oxygen vacancies, consequently responsible for higher CO2 adsorption and selective methanol production. Surface reconstruction phenomena rather than coke or metal sintering were responsible for the slight loss of activity recorded on the catalyst samples during the initial phase of reaction; however, with no appreciable change on the product selectivity.

Automated summary

In this study, a series of mono- and bimetallic copper and iron samples were prepared on micro-spherical silica as a carrier through impregnation method, and used for the methanol synthesis via CO2 hydrogenation. Micro-spherical silica demonstrated advantages in absorption capacity and optimal distribution of active phases on its surface, as well as excellent heat resistance properties and chemical stability. The mutual interaction of copper and iron was found to promote the formation of methanol, especially when iron enrichment on the silica support favored the presence of a larger concentration of oxygen vacancies, leading to higher CO2 adsorption and selective methanol production. Surface reconstruction phenomena rather than coke or metal sintering were responsible for the slight loss of activity recorded on the catalyst samples during the initial phase of reaction, with no significant change in the product selectivity.