A Ni–Fe alloy supported by active carbon efficiently promotes the vapor phase catalytic carbonylation of ethanol

Abstract

Vapor phase carbonylation of ethanol is an effective way to produce propionic acid. Monometallic nickel-based catalysts stand out because of their low preparation cost and relatively high catalytic performance. However, the monometallic nickel-based catalysts have the disadvantages of easy sintering of the metal, poor dispersibility and insufficient number of active centers. In this study, Ni–Fe/AC catalysts were prepared by changing the proportion of Ni–Fe loading for the vapor phase carbonylation of ethanol. The physicochemical properties of the Ni–Fe/AC catalysts were characterized by XRD, TEM, XPS, H₂-TPR and BET. It was found that Ni–Fe alloy was formed in the catalyst after Fe was introduced into Ni/AC. The strong interaction between Ni and Fe inhibits the sintering of the metal and improves the dispersibility of the metal particles. The H₂-TPR results showed that the synergy between Ni and Fe reduced the reduction temperature of NiO and promoted the reduction of NiO. The content of Ni⁰ on the catalyst surface was further characterized by XPS. The results showed that the content of active centers Ni⁰ increased from 10.49% to 20.46% (1Ni–1Fe/AC) after the promoter metal Fe was introduced, which provided more active sites. The experimental results showed that the 1Ni–1Fe/AC catalyst (Ni : Fe = 1 : 1, wt%) displayed the highest catalytic performance, and the co-selectivity of propionic acid (PA) and ethyl propionate (EP) increased by 11%, and the space-time yield (STY) of PA and EP was about twice that of the Ni/AC catalyst.