Preparation Of Mesoporous ?-Al₂O₃ And Application In Hydrodesulfurization Of Diesel

China's oil compound become heavy and deep hydrogenation for the strong steric structure of fused ring sulfide,the catalyst supportshould have higher surface area,enlarge pore volume and increase average pore size,so as to provide more active centers,smooth reaction diffusion and more space to storage coke,sulfur and metal.The ordinary commercial alumina usually have low surface area andsmall pore volume sothat this alumina can not well meet the demand of hydrodesulfurizationprocess.Underhydrodesulfurization of heavy oil refining trend,the development of a?-Al₂O₃support with high surface area and large pore volume has important significance.First of all,this thesis adopts double hydrolysis method?NaAlO₂-AlCl₃system?to synthesize mesoporous?-Al₂O₃by using P123 as the surfactant.By controlingreaction conditions of precipitation pH value,reaction temperature and surfactant mass,we understood how these conditions influencealumina surface area,pore volume and pore size distribution,so we can select the appropriate parameters of the synthesis.The experimental results show that the synthesis process of mesoporous?-Al₂O₃has an optimal range ofprecipitation pH value,during precipitation pH value in the range of 9 to10.5,?-Al₂O₃samples surface area can up to425.5 m²/g and the pore volume is 1.59 cm³/g.When the pH value of precipitation increases or decreases,the pore structure properties of materials become poor.The addition of surfactant not only increases the pore volume and pore size of the role,but also improve the surface area,and a certain surfactant mass range,with the increase of surfactant mass,the pore volume and pore size increased.The size can be adjusted from 5nm to 11nm by controlling the precipitation pH value and the amount of surfactant used.After that,this thesis used precipitation method?NaOH-AlCl₃system?to synthetize fibrous ultra large mesoporous volume?-Al₂O₃ materials.The surface area of mesoporous?-Al₂O₃is512.2 m²/g andpore volume can up to 2.05cm³/g and the materials have good thermal stability.TEM characterizationshows that the materialshave fibrous structure.By using thissynthesis method,we selectedseveral different surfactants to prepare mesoporous?-Al₂O₃materials andthis materials showed good pore structure.So this synthesis method is universalapplicability.Finally,we selectedsome mesoporous?-Al₂O₃ samples and commercial?-Al₂O₃to prepareNiO-MoO3/?-Al₂O₃catalysts.By using 4,6-DMDBT as model compounds,hydrodesulfurization reaction happened in MR-A-6miniature high pressure catalytic reaction device.The experimental results show that the high surface area,large pore volume mesoporous?-Al₂O₃materials have a better reaction performance in 4,6-DMDBTremoval thancommercial?-Al₂O₃,removal efficiency has been increased 7%-11%and alumina with bigger pore volume show a better reaction performance.