Abstract:

Different nickel salt precursors, namely, nickel acetylacetone, nickel chlorate, nickel nitrate and nickel acetate, were used to prepare Ni/C catalysts for vapor phase carbonylation of ethanol. The activity testing results revealed that the Ni/C catalyst prepared from nickel acetate showed maximal catalytic activity for carbonylation of ethanol with the ethanol conversion of 96.1% and the propionic acid selectivity of 95.7% in comparison with that prepared with other nickel precursors, but the catalyst prepared from acetylacetone nickel showed minimum activity with the ethanol conversion of 68.9% and the propionic acid selectivity of 27.1%. The Ni/C catalysts were characterized by means of BET measurement, metal dispersion test, H2-TPR and XRD. It was found that the catalytic performances of the Ni/C catalysts depended in a great degree on the interaction between nickel species and active carbon support. The nickel acetate molecule was confirmed to be easily adsorbed on the surface of active carbon, leading to a stronger interaction between nickel species and active carbon support, thereby increasing the absorption capacity of CO. Meanwhile, a better dispersion of active component and smaller nickel crystallites were found.

Key words: ethanol, active carbon, nickel salt precursors, vapor-phase carbonylation, propionic acid