| Calcium carbonate, zinc carbonate and aluminum hydroxide were prepared by coprecipitation method using calcium nitrate, zinc nitrate and aluminum nitrate as raw materials and sodium carbonate as precipitant, then calcium-zinc-aluminum solid base catalyst was obtained by aging, filtration, washing, drying and roasting.The effects of catalyst preparation conditions on the catalytic activity were investigated by orthogonal experiment with methanolysis reaction of castor seed oil as model reaction and castor seed oil conversion rate as the activity evaluation index. The catalyst and its precursor were characterized by Hammett indicator method, TG, XRD, SEM and BET.The results showed that the optimal conditions for the preparation of the catalyst were obtained as follows:n(Ca)∶?n(Zn)∶?n(Al)=2.5∶?0.5∶?1, with sodium carbonate as precipitant, calcination temperature 800?℃ and calcination time 8 h. Under the optimal conditions, the castor seed oil conversion rate was up to 95.4%. The catalyst precursor had a significant weight loss step at 700-850?℃, and the mass did not change with temperature higher than 850?℃. The alkali strength of the solid base catalyst was between 7.2 and 11.2, the total alkali amount was 9.740 mmol/g, mainly constituted by two kinds of crystals, CaO and ZnO.The shape of the solid base catalyst was porous continuous irregular solid, and the specific surface area was 30.75 m2/g, and the pore volume was 0.051 64 cm3/g. |
