Influence of preparation method on supported Cu-Ni alloys and their catalytic properties in high pressure CO hydrogenation

Article abstract of DOI:10.1039/c3cy00546a

Silica supported Cu-Ni (20 wt% Cu + Ni on silica, molar ratio of Cu/Ni = 2) alloys are prepared via impregnation, coprecipitation, and deposition- coprecipitation methods. The approach to co-precipitate the SiO₂ from Na₂SiO₃ together with metal precursors is found to be an efficient way to prepare high surface area silica supported catalysts (BET surface area up to 322 m² g^-1, and metal area calculated from X-ray diffraction particle size up to 29 m² g^-1). The formation of bimetallic Cu-Ni alloy nanoparticles has been studied during reduction using in situ X-ray diffraction. Compared to impregnation, the coprecipitation and deposition-coprecipitation methods are more efficient for preparation of small and homogeneous Cu-Ni alloy nanoparticles. In order to examine the stability of Cu-Ni alloys in high pressure synthesis gas conversion, they have been tested for high pressure CO hydrogenation (50 bar CO and 50 bar H₂). These alloy catalysts are highly selective (more than 99 mol%) and active for methanol synthesis; however, loss of Ni caused by nickel carbonyl formation is found to be a serious issue. The Ni carbonyl formation should be considered, if Ni-containing catalysts (even in alloyed form) are used under conditions with high partial pressure of CO. The Royal Society of Chemistry.