Synthesis,Characterization And Application Of High Performance Alumina Catalytic Materials

Alumina,as a common catalyst carrier,can be synthesized as functionalized alumina or modified for conventional alumina for different fields of application.With the increasing trend of heavy and poor quality crude oil worldwide,the reaction performance of heavy oil catalytic cracking catalysts is increasingly required on the one hand,and on the other hand,a significant reduction of pollutants（such as NO_x,SO₂,and CO₂）emitted from catalytic cracking flue gas is required.Special alumina and its modified products play a pivotal role in the development of high efficiency heavy oil catalytic cracking catalysts and catalyst development for reducing catalytic cracking flue gas pollutant emissions,therefore,the synthesis and modification of high-performance alumina and application development are of great research value and practical significance.In this paper,we designed and synthesized various alumina and its modified samples,evaluated the reaction performance of the prepared series catalysts,and obtained optimized catalyst ratios centered around improving the heavy oil conversion capacity of catalytic cracking catalysts and reducing catalytic cracking flue gas pollutants.On this basis,the conformational relationship between their physicochemical properties and catalytic performance is explored to reveal the reaction mechanism.This provides a favorable foundation for the development of valuable catalysts for heavy oil catalytic cracking and NO_x removal.The main research contents and results are as follows:（1）Silica-modified Pseudo boehmite（Si-PB）was synthesized in situ based on the double aluminum neutralization method using sodium silicate as the silicon source,and heavy oil cracking catalyst samples were prepared to study the effect of the catalyst synthesized by Si-PB on the catalytic cracking of heavy oil.The results show that the synthesized Si-PB has significant specific surface area,pore volume,surface acid density and micro-anti-activity.the introduction of Si can provide a certain amount of B-acid center to construct a tetra-ligand type of silica-alumina structural unit,which will be beneficial to the catalytic cracking reaction.the catalysts synthesized by 30%Si-PB exhibit excellent heavy oil conversion efficiency and resistance to metal contamination before and after heavy metal contamination.the Si-PB novel catalysts provide favorable reference value for solving crude oil problems.（2）The effects of Zn and Mg on the SCR of NO by C₃H₆ were investigated by introducing diatomic Zn and Mg into the Ag/Al₂O₃ catalyst.The results showed that the bimetallic Zn and Mg modified Ag/Al₂O₃ catalysts increased the ratio of Zn Al₂O₄ and Mg Al₂O₄ spinel,which facilitated the generation of active components and improved the adsorption capacity of NO.The enol and acetate produced by C₃H₆ in the presence of H₂ will react with NO+O₂ to form more-NCO and-CN intermediate species,which facilitated the improvement of N₂ selectivity.Ag2.5Zn2.5Mg Al exhibited more than 95%NO_x conversion,excellent water resistance and sulfur resistance at 300°C(GHSV=100 000 h^-1).The developed Ag Zn Mg Al new catalytic material has excellent reaction performance in reducing NO_x emission from catalytic cracking flue gas and has good application prospects.（3）The effect of I on the SCR of NO by C₃H₆ was investigated by introducing I into the Ag/Al₂O₃ catalyst using rotary evaporation.The results show that the targeted targeting of Ag by I enhances the binding ability of Ag to the terminal hydroxyl group of alumina,which improves the dispersion of Ag and increases the proportion of active sites.The enol substances,carboxylates and acetates produced by C₃H₆ in the presence of H₂ will react with nitrate species to produce more-NCO and-CN important intermediate species,which facilitates the formation of N₂.Ag1.5IAl at 300°C(GHSV=100 000 h^-1)to achieve 100%NO_x conversion,showing excellent water and sulfur resistance.This process promotes the development of flue gas treatment technology and the application of related products.