Preparation and Characterization of Ni-CaO Catalyst for One Step Synthesis of MIBK (Methyl isobutyl ketone) from Acetone

摘要

One step synthesis of MIBK (methyl isobutyl ketone) from acetone over co-impregnated Ni-CaO catalyst and Ni effect on the thermal decomposition of CaCO_3 into CaO were studied. Bulk calcium acetate, one of catalyst precursors, decomposed into CaCO_3 and acetone at 400 - 450 °C, and CaCO_3 into CaO and CO_2 at 700 °C. But, when nickel acetate for 2 wt% Ni was added into calcium acetate, the decomposition temperature of CaCO_3 was decreased to 500 °C in H_2/N_2 stream but not in O_2/N_2 stream or air, and in case of 20 wt% Ni, this phenomenon was more drastic. From TPD-MS experiment, we found out that Ni-added CaCO_3 did not decompose directly into CaO and CO_2 but via the route of CaCO_3 + 4H_2 → CaO + CH_4 + 2H_2O, supposed to have a relatively low activation barrier. CaO can be formed even at 500 °C with the aid of Ni and H_2. When 2 wt% NiCaO reduced at 500 °C for one step synthesis of MIBK was used, 60 - 80% of acetone overall conversion and 50 - 60% of MIBK selectivity were obtained.