Study On The Preparation Of La₂O₃/AAO Solid Base Catalyst For Catalytic Distillation

Catalytic Distillation (CD) is a new type of chemical green process intensification technology that combines heterogeneous reaction and fractionation in a single column. Among them, the development and research of the catalyst of CD is a key element. A type of reasonable catalyst can not only broaden the application of CD, but also highlight the advantages of CD achieving energy conservation and sustainable development.Studies have shown that the most common catalysts used for CD are ion exchange resins which generally have temperature limits of 60～120℃.In the case of a supported catalyst, the temperature limit can be much higher (depending on the coating) so that CD can be applied to a greater number of reactions. Considering the strong separation and mass transfer, low cost and easy machining of raschig ring, we make sure to prepare the solid base catalyst with raschig rings assisted for CD.In this study, the highly-ordered anodic aluminum oxide (AAO) support is prepared by a one-step anodization. A type of filler La2O3/AAO solid base catalyst for catalytic distillation is prepared via a hydrothermal synthesis route. The catalytic activity of La2O3/Al2O3-Al is evaluated by self-condensation of acetone as a probe reaction. The product is characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy disperse spectroscopy (EDS) and thermogravimetric analysis (TGA).The results show that the optimum condition is as follows:the molar ratio of La (NO3)3·nH2O to NH3·H2O is 1:8, the heating temperature is 160℃ , the oil bath time is 10 h, the calcination temperature is 550℃ and the calcination time is 2 h in an N2 flow. Under the above conditions, the conversion of acetone is 4.1% and the selectivity towards diacetone alcohol is 98%. The active ingredient La2O3 nanoscale particles with high crystallinity are uniformly distribute on the template surface. We find that:the precursor solution enter the channels and forms stable nuclei, the particles deposit on other particles and form bigger groups in the channels under a hydrothermal condition, the La2O3 nanowires form under heating treatment. The diameter of La2O3 nanowires depends on the nanochannel diameter of template.