The Preparation And Catalytic Studies Of Supported Heteropoly Acids Catalyst For Synthesis Of Isopropyl Acetate

Isopropyl acetate is a kind of important organic chemical material, and has excellent alkali,this is widely used as organic solvent, drug extraction agent, dehydrating agent, extractant,perfume ingredients etc. Isopropyl acetate is commonly prepared with acetate and isopropylalcohol by sulfuric acid catalyst industry at present. But, serious corrosion of equipment, sidereactions and production expensive are caused with this process. With the growing ecologicaland environmental protection and catalytic rapid development of science, the esterificationcatalyst and process conditions was researched by many researchers at abroad,environmentally friendly solid heteropoly acid catalysts is focused on research focus. Becausesuch processes easily separated recyclable catalyst, and no environmental pollution andequipment corrosion and other problems, which are called green technology. However, sincethe solid heteropoly acid catalyst surface area is small, the catalytic activity can not be fullyexpensive, limiting its applications in catalysis, it is difficult in industrial production has beenwidely applied. Therefore, research and development supported heteropoly acid catalystbecomes particularly important. The heteropolyacid supported on a suitable effective carriercan greatly improve the specific surface area, not only can improve the catalytic activity andselectivity, but also diversify the homogeneous catalytic reaction, the product is easy toseparate the catalyst readily recycled. This approach simplifies the production process,opening up a new world of catalytic applications.This paper chooses cheap kaolin as the carrier, using the hot reflux impregnation,phosphorus tungsten heteropoly silicotungstic acid load to the modified kaolin, preparation ofsupported phosphotungstic acid and silicotungstic acid heteropoly acid catalyst, for increasingthe surface area of the catalyst, the catalytic activity and selectivity. By scanning electronmicroscopy (SEM), X ray diffraction (XRD), Fourior transform infrared spectroscopy (FT-IR),thermogravimetry and differential scanning calorimetry (TG-DSC) and other measurements,the surface morphology of the catalyst, the crystal structure, loading of active components andcomposition test. Studies have shown that supported phosphotungstic acid, silicon tungstateheteropoly acid catalyst has high catalytic activity and selectivity. Acetic acid is0.2mol, theoptimum process conditions of supported phosphotungstic acid catalyst for the2g catalyst,molar ratio is2:1, reflux time of4h, the highest yield is69.08%; Supported silicotungstic acid catalyst the optimum catalyst2g, alkyd ratio of2:1, reflux time3h, the highest yield of63.67%. Its synthesis of isopropyl acetate esterification of acetic acid and isopropanol hashigh catalytic activity and selectivity.The paper also compares the liquid acid catalysts, solid acid catalyst and supportedheteropoly acid catalyst, the effects of the amount of catalyst, the molar ratio, reflux time onyield of ester. Catalytic efficiency from high in the end of the sequence: load phosphotungsticacid, phosphotungstic acid load silicotungstic acid, silicon tungstate.