Abstract: The nickel catalysts supported on activated carbon were prepared by the impregnation method. The effects of nickel precursors, such as Ni(NO3)2, NiAc2, and NiCl2, and solvents of dipping solution, such as water and ethanol, on the Ni dispersion degree were studied by X-ray diffraction(XRD) and thermogravimetry (TG). The XRD results showed that when the calcination temperature was 550 ℃ and water was used as the solvent, the nickel threshold was 0.065 g/g using Ni(NO3)2 as precursor and 0.058 g/g using NiAc2 as precursor. The threshold of the catalyst with the Ni(NO3)2 precursor was 0.082 g/g in methanol and larger than that in water. Anions of nickel salts and solvents of dipping solution influenced the interaction between the active substance and support, which resulted in different dispersion capacity. The threshold obtained by TG was smaller than that by XRD. The results of catalyst performance experiments indicated the threshold effect of supported Ni catalysts existed in the carbonylation of methanol to produce acetic acid.

Key words: nickel, precursor, activated carbon, supported catalyst, threshold, methanol, carbonylation, acetic acid