Study On Preparation By A Layered Precursor Method And Catalytic Performance Of Magnetic Nano-Scale Solid Base Catalyst

Nano-scale magnetic solid base catalysts with coated structure have been designed and prepared for more easily and high efficiency reclaim of the catalysts. Magnetic separation is thought to be a "green" process for the recovery and reuse of nano-scale catalysts at the end of the reaction in liquid systems. Layered double hydroxides (LDHs) are a large family of synthetic anion type of layered materials. In this thesis, novel MgO-based magnetic nano-scale catalysts have been prepared by thermal treatment of a single-source precursor of MgFe-layered double hydroxide (MgFe-LDH) at 400℃and 600℃. The structure, morphology, basic and magnetic properties of the MgO-based magnetic nano-scale catalysts was characterized by series of instruments. The aldol condensation of citral with acetone was chosen as a probe reaction.From the results of characterization, we can know that the catalysts remained the same sheet morphology as the LDHs precursors; the catalysts calcined at 400℃had larger BET surface areas than the ones calcined at 600℃; the catalysts were mesoporous materials; all the catalysts contained surface sites of strong basicity, and Mg2F-400 had the largest total alkali content 1.383 mmol·g-1; catalyst M3F-600 has the largest saturation magnetization Ms=4.272 emu·g-1, catalysts all had good superparamagnetic properties.Catalytic reaction results showed that the most suitable molar ratio of citral and acetone was 5, and for catalyst M2F-600 the conversion of the citral was 83.6%, the selectivity of pseudoionone was 72.0%; when molar ratio of citral and acetone was 5, the catalyst calcined at 400℃had higher catalytic activity than ones calcined at 600℃; the catalyst M3F-400 exhibited no deactivation after the catalyst is recycled for three times.