Synthesis Of Catalysis Pseudobohmite And Alumina From Aluminium Isopropoxide

As an important class of inorganic materials,high-purity alumina alumina is extensively applied in raw materials for fine ceramics,synthetic sapphire,and lithium battery separators.Aluminum alkoxide hydrolysis is considered to be the most environmentally friendly and efficient industrial technology for obtaining high-purity alumina.In China,aluminum alkoxide hydrolysis mainly produces alumina for sapphire,however,in the field of high-end catalytic applications,the intermediate product aluminum hydroxide cannot meet the application requirements due to high residual carbon content and low peptization index;In response to the above problems,firstly,the crystalline state and structure of aluminum hydroxide gel powders produced by the hydrolysis of aluminum alkoxides were controlled by inducing crystallization method to obtain pseudo-boehmite and alumina for catalysis with high peptization index and low carbon content.Then,based on the theory of high temperature peptization,high solid content alumina sol for catalysis was prepared;On this basis,the existing process was improved,using aluminum isopropoxide as the aluminum source,the direct hydrolysis conversion method is used in the water-rich system,and the carbon content of the pseudo-boehmite,the peptization index,and the pore structure of alumina are controlled by controlling the amount of water,the products obtained meet the standards for catalytic applications.In details:(1)Synthesis of pseudoboehmite and alumina for catalysis by inducing conversion of alkoxide aluminum hydroxide gel powder.Under optimized conditions,pseudo-boehmite is prepared from aluminum hydroxide gel powder produced by industrial hydrolysis of aluminum isopropoxide,peptization index?95%,carbon content reduced to less than 0.5%,meets catalytic application standards;Adding organic solvent during the process of induced transformation to achieve a wide range of alumina pore structure adjustment,maximum specific surface area 279.1 m~2/g,maximum pore volume 1.437 mL/g,maximum average pore diameter 20.6 nm.(2)Low acid content and high solid content aluminum sol preparation of aluminum hydroxide gel powder by peptizing alkoxide method.Aluminum sol with solid content of 15%,20%is prepared from aluminum hydroxide gel powder produced by industrial hydrolysis of aluminum isopropoxide,the effects of peptization temperature and acid-aluminum ratio on peptization index of aluminum sol were studied.Adjust the acid-aluminum ratio(0.05~0.1)and peptization temperature(100?~140?)to prepare a peptized,transparent and clear solid content 15%,20%aluminum sol.(3)Synthesis of pseudobohmite and alumina from aluminium isopropoxide.Under rich water system,direct hydrolysis conversion method is used to prepare pseudo-boehmite,which is then calcined at high temperature to obtain porous alumina.Systematic study of the effect of water consumption on the pore structure of pseudo-boehmite and alumina,the crystal form of the hydrolysate is affected by the amount of water,and the product is transformed from amorphous to pseudo-boehmite phase,with a peptization index up to 99%;The amount of water mainly affects the pore structure of alumina.With the increase of water consumption,the specific surface area and pore volume of alumina generally show a downward trend.