Synthesis And Hydrodesulfurization Properties Of Multiple Pore ZSM-5 Zeolite

ZSM-5 zeolite is a new type of zeolite molecular sieve which is widely used in petrochemical industry nowadays.Its advantages are high thermal stability,high catalytic efficiency and excellent pore structure.The pore channel of porous ZSM-5zeolite is more stable than that of conventional single-pore ZSM-5 zeolite,and the catalytic efficiency is higher.The macromolecules can be diffused and transformed well.Therefore,porous ZSM-5 zeolite is a very ideal catalyst in petrochemical industry.The main research content of this paper is the synthesis method of ZSM-5 porous zeolite,which is planned to be realized through the synthesis of polyquaternary ammonium salt surfactants first and then the final product.The physicochemical properties of the products were analyzed by various chemical testing methods,and the desulfurization efficiency of 4,6-DM-DBT based on porous ZSM-5 zeolite-based catalysts was tested.The experimental results obtained in this paper are listed below:?1?The characteristic of polyquaternary ammonium salt surfactant is that the micelle is easy to form,the critical micelle concentration is not high,the internal positive charge is active,and it can react with aluminosilicate ion to grow zeolite precursor.This property makes its zeolites and templates for porous ZSM-5 zeolites.Under different synthesis paths,the structure of polyquaternary ammonium salt surfactants is very different.?2?Compared with conventional ZSM-5 zeolites,porous ZSM-5 zeolites have the advantage of abundant micromesoporous channels,so the total specific surface area is greatly increased,and the lift rate is about 82%,and the external specific surface area is about 13 times higher than that of conventional ZSM-5 zeolites.The mesoporous volume of porous ZSM-5 zeolite increases 10-fold,which makes it easier for macromolecules to pass through and react in it.In preparation,only polyquaternary ammonium salt can be used as template to synthesize ZSM-5 zeolite with both micropore and mesoporous structure.However,porous ZSM-5 zeolites could not be synthesized by bilayer polyquaternary ammonium salt template.?3?Because of its mesoporous structure and acidic center,porous Pd-5 can provide more active sites for catalytic reaction and isomerization reaction,and the prepared products can show higher hydrodesulfurization activity.The catalytic performance of the catalyst is better than that of conventional ZSM-5-based PD catalyst and?-Al₂O₃-based Pd catalyst,and the hydrodesulfurization process is completed after the methyl isomerization reaction takes place in 4,6-DM5-based DBT.