(617do) Cobalt-Copper Alloy Nanoparticle Catalysts for Higher Alcohol Synthesis from Syngas
Co2.5Cu alloy nanoparticles were synthesized by a polyol synthesis in which metal acetates are reduced in refluxing diethylene glycol with a polyvinylpyrrolidone capping agent to control particle size. The nanoparticle catalysts were then supported on a variety of metal oxides and tested in a packed bed reactor under Fischer-Tropsch conditions (250° C, 40 bar, 2:1 H2:CO) to evaluate their activity and selectivity. The best performing sample, supported on alumina, had a 11.3% carbon selectivity towards higher alcohols, primarily ethanol. Nanoparticle composition and structure, both before and after reaction, were confirmed ex situ using a combination of transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), x-ray photoelectron spectroscopy (XPS), and x-ray diffraction (XRD). A consistent alloy phase and composition was observed prior to reaction, suggesting the synthesis successfully reduced the metal precursors to the cobalt-copper alloy phase. After reaction, new phases were observed to have formed via metal segregation and cobalt carbide formation. The alumina-supported sample, which had the highest performance, also showed minimal formation of these new phases, indicating a possible correlation between the observed performance and the extent of alloy degradation. Future investigations are focused on improving the stability of the desired alloy phase under reaction conditions.
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