| In modern chemical engineering, inorganic acids and metal haloids are wildly used as catalysts in esterification, such as sulfuric acid, phosphoric acid and AlCh, SnCU, TiCU. But these traditional catalysts have so many disadvantages as equipment corrosion, pollution, many vice-reactions, and low selectivity. Solid superacids as SO42VZrO2 can overcome these disadvandages, and perform higher activity and better selectivity in esterification. In recent years, with the development of nano technology, nano-sized SO42"/ZrO2 was more concerned as solid superacid catalyst, for its high specific surface and catalytic activity. But in liquid reaction nano-sized catalysts are difficult in separation from reaction system and recovery. If the nano-sized catalyst particles were moulded into congregate shape, not only the surface area of the catalyst and the reaction interface would decrease, but also the mass transmittion resistance would increase. In this dissertation, we propose the new idea of endowing magnetism with solid superacid catalysts. Application of the magnetic superacid catalyst in esterification gives very good results.In this dissertation, we synthesized highly scattered magnetic substrate of Co0 sFe2 sO4 magnetic liquid by the method of chemical precipitation, and then synthesized magnetic solid acid ZrO2 -Co0.5Fe2.5O4 by liquid phase precipitation, after immersing in aquaeous solution of ammonium sulfate, we attained magnetic solid superacid SO427ZrO2Coo.5Fe2.5O4. Character -istics of the catalyst such as crystal construction, crystal size, and crystallization temperature were measured with XRD, TEM, DTA, IR etc.. Results showed the mean size of synthesized magnetic solid superacids is between 30 nm~50 nm, and we found that the addition of magnetism to the substrates delayed the transformation from ZrO2(t)to ZrO2(m), and increased crystallization temperature, and benefited born and perfect of ZrO2(t) ( ZrO2(t) was main component of catalyst).We inveistigated the influence of calcining temperature, calcining time, andthe content of magnetic substrates in magnetic solid superacid on catalytic activity in synthesizing reaction of butyl acetate in which SC>427 ZrOa -Coo.5Fe2.sO4 were used as catalysts. We got the optimized conditions of the reaction are: reaction time, 3 h; ratio of acid to alcohol, 1:2 (molar ratio); content of catalyst, 1.2wt%; content of water-taking agent in reactant, 9.0(wt)%; activation temperature of catalysts, 600 癈; activation time, 3 h; concentration of immersing liquid of ammonium sulfate, 0.5 mol/L; molar fraction of magnetic substrates in catalysts, 2.44%. Experiments showed that catalytic activity of magnetic solid superacids could attain above 97%, and selectivity of reaction 100%, which illustrated the choiceness of these catalysts in esterifications. We also investigated life span and recovery of catalysts, and experimental results showed that after catalysts were used 6 times, their catalytic activity was 81.69%, and after they were re-activited, catalytic activity was 96.25%, which explained magnetic solid superacids had higher life span and could be totally recovered and re-sued.Recovery ratio of the magnetic solid superacid we synthesized was above 85%, 36.6% high than the non-magnetical superacid solid. These figures illustrated that the magnetic superacid solid catalysts could be separated from the reaction system and recovered by exerting magmetic field. The experiments have reached the aim of our imagination, so we concluded that this kind of magnetic superacid solid catalysts were of great importance in the application of nano-catalysts.
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