Preparation Of Rare Earth Solid Superacid And Catalysis On The Esterification Reactions

Traditional esterification commonly use liquid acid as catalyst such as sulfuric acid, Although the technology is mature also has got some achievem- ents, but there are many defects, such as by-products, more serious environm- ent pollution, equipment corrosion severe and product loss, etc. With the development of Green Chemistry and less pollution technology solid acid catalyst will instead liquid acid catalyst. The acidity of solid super acid is stronger than the concentrated sulfuric acid (H0<-11.93).It can catalyze many difficult chemical reactions, It has many advantages such as non-corrosive, non-polluting, easy separation, high activity and high selectivity, It will beco- me catalysis research hot spot. In recent years, domestic and foreign scholars has made a great progress in development of new environmentally friendly solid acid catalyst material from molecular sieve, heteropoly acid and solid super acid.(1)Nanometer hybrid rare earth solid superacid has prepared by Sol-Gel method. Tetrabutyl titanate was hydrolyzed and condensation polymerized, then doped with rare earth elements Ce and La respectively by immersion process, and activated under the certain temperatures to give a nanometer hybrid rare earth solid superacid catalyst. It also proved that the rare earth solid superacid catalysts exhibit high catalytic activity for the esterification of stearic acid and n-buoh. Contacting the esterification reaction it has researche- d the influence of H₂SO₄ concentration, rare earth ions concentration and cal- cination temperature on the activity of the catalyst respectively.(2)The structure, specific surface area, crystal form, acid strength and m- orphology of samples have been characterized and analysed by FT-IR, BET,XRD, Hammette indicator and SEM respectively .(3)The paper used self-made rare earth solid super acid SO₄^2-/TiO₂/Ce4+ and SO₄^2-/TiO₂/La³⁺ to synthesize methyl stearate, ethyl stearate, butyl stear- ate,α-chlorinated methyl esters of stearic acid. In experiments the reaction time, temperature, alcohol to acid mole ratio, and the dosage of catalyst have been investigated respectively, then the optimum reaction conditions has been concluded.(4)Contacting the esterification reaction of stearic acid and n-buoh, the deactivation mechanism and regeneration conditions of the catalyst have been preliminarily discussed by series control experiments.