Study On Synthesis And Catalytic Application Of Organized Mesoporous Alumina

Organized mesoporous alumina shows high specific surface area, narrow pore distribution and strong surface acidity. It is valuable to be applied in the process of large molecular hydrocarbon catalysis processing, heterogeneous catalysis and adsorbing separation. The research on its synthesis and catalytic application is significant.Synthesis and catalytic application of organized mesoporous alumina have been studied in detail. Organized mesoporous aluminas with different structure were prepared by different methods in different source of alumina. The structure was characterized by several measuring technology. The influence of reaction conditions on structure of organized mesoporous alumina has been investigated. Scale-up preparation of mesoporous alumina was firstly completed by HIGEE technology. Organized piling mechanism was creatively provided to explain the synthesis process of mesoporous alumina properly by theory. Nickel was supported on organized mesoporous alumina by different impregnation method. Several techniques were used to detect the structural characterization of catalyst. In order to discuss the influence of mesoporous structure on catalyst, the Ni-containing catalysts were tested activity for the methanation of carbon monoxide and compared with y-alumina. The Al-SBA-15was prepared by coating alumina on the surface of SBA-15mesoporous molecular sieve and loaded nickel. Its structure and catalytic activity were characterized and tested with comparison to synthesized organized mesoporous alumina.Organized mesoporous alumina has been prepared by hydrolysis of two organic alumina alkoxide. P123and Triton-100were used as co-template. Specific surface area exceeds400m2/g. Total pore volume is about1cm3/g, pore diameter up to8nm and narrow pore size distribution less than15nm. The pore exhibited organized in some extent. Its specific surface area, total pore volume and pore diameter were far larger than γ-alumina. Assistant template can effectively improve the mesoporous structure. Mesoporous alumina with high specific surface area and organized pore structure was formed by adjusting proportion of alumina source and water. Solvent, aging time, aging temperature and manner can affect the mesoporous structure evidently.Organized mesoporous alumina was synthesized by precipitation of inexpensive inorganic aluminium salts. PEG1540was used as template, monoamonium phosphate as assistant solvent. Specific surface area reaches250-300m2/g. Total pore volume is0.3-0.5cm3/g, pore diameter up to4-6nm and narrow pore size distribution less than4nm. The pore exhibits wormhole channel motifs and uniform in size and shape. The method overcomes the shortcut of expensive template and alumina source in the synthesis of mesoporous alumina for its simple technology and inexpensive cost. PEG1540can make the direct-piling and support function in the formation of mesopore. Assistant solvent can improve the mesoporous structure. The pH value of reaction terminal of different inorganic aluminium salts affected on mesoporous structure in different extent. The change of aging, cleaning and calcination condition can also produce important influence on mesoporous structure.HIGEE technology was firstly applied in the synthesis of organized mesoporous alumina. Organized mesoporous alumina has been prepared by precipitation of inorganic aluminium salts in bulk trial. Specific surface area reaches250-300m2/g. Total pore volume is0.3cm3/g, pore diameter up to4nm and narrow pore size distribution obtained. The pore exhibited wormhole channel motifs and uniform in size and shape. HIGEE technology has greatly intensified mass transfer and mixing. The reaction system is in the state of high disperse, high turbulence resistance and quick replacement boundary surface. It can easily control the generation and piling rate of inorganic precursor that is favorable to the formation of the organized mesoporous structure. The concentration and time of reaction, aging process have remarkable influence on the organized mesoporous structure. HIGEE technology can be applied to prepared organized mesoporous alumina in scale, with simple technology, inexpensive cost and small scaling effect. It founded the basis of industrialization production for organized mesoporous alumina and provided an engineering technology for preparation of mesopourous materials.On the basis of study on synthesis of organized mesoporous alumina, organized piling mechanism of organized mesoporous alumina synthesis was provided. The inorganic precursor (hydroxide), which was synthesized by hydrolysis or precipitation from different source of alumina, equably piled the organized mesoporous structure at an even rate in the indirection of template. It is the key to control the generation rate, piling rate of inorganic precursor, removing rate of template and water. The macroscopical measure is to regulate the source of alumina, ration of reactant, reaction time and mixing intensity. Template can not make the direct assembly function as in the synthesis of silicic mesoporous molecular sieve. It can make the direct-piling and support function. Organized piling mechanism logically explains the principle of organized mesoporous alumina synthesis by HIGEE technology. It is important to the research of industrialization production for organized mesoporous alumina.Nickel supported on two synthesized organized mesoporous alumina has been prepared by the overloading and equivalent-volume impregnation method. The results show that Ni-containing catalysts supported on two organized mesoporous alumina are much more active than the y-alumina in the methanation of carbon monoxide. The organized mesoporous alumina synthesized from hydrolysis of organic alumina alkoxide is suitable for preparation of high-loading metal catalyst. It can attribute to its high surface area, strong adsorption ability to metal, higher capacity of nickel, strong interaction between metal and carrier. The organized mesoporous alumina synthesized from precipitation inorganic alumina salts may be valuable in shape selective catalysis for its organized stable structure with narrow pore distribution. The different impregnation method has important influence on the structure, interaction between metal and carrier, catalysis of Ni-containing catalyst supported on mesoporous alumina.SBA-15mesoporous molecular sieve was synthesized by hydrolysis of ethyl silicate with regular pore channel. The agreement of pore exhibits annual zone. P123and Tritonx-100were used as co-template. Specific surface area reaches643m2/g. Al-SBA-15was prepared by coating alumina on the surface of SBA-15mesoporous molecular sieve at vacuum and subzero by aluminum nitrate. Specific surface area reached601m2/g. Total pore volume was about Icm3/g and pore diameter up to6.9nm. Coating alumina had no influence on the organized structure. NiAl-SBA-15was prepared by over-loading impregnation method. The characterization results indicated that coating alumina strengthened the surface adsorption of SB A-15and higher capacity of nickel. It was much more active than the γ-alumina and mesoporous alumina synthesized from precipitation inorganic alumina salts in the methanation of carbon monoxide. Al-SBA-15is valuable in catalysis field for its silicic framework and surface acid of alumina...