Preparation And Catalytic Performance Of Immobilized Lewis Acid Catalysts

Traditional Lewis acid catalysts such as anhydrous AlCl3, SnCl4, SnCl2etc, were widely used in industry, since their mild reaction conditons and the high reaction conversion. However, these homogeneous catalysts pose considerable problems such as equipment corrosion, disposal problems due to large amount of acidic effluents, and difficulties in product isolation. In this thesis, The immobilized AlCl3catalysts and immobilized SnCl2catalysts were prepared and studied. The main content include:①AlCl3was immobilized on zeolites, which were used to isomerization of endo-tetrahydrodicyclopentadiene(endo-TCD), the reaction mechanism was studied, and the amplified experiment of catalytic reaction was proceeding;(2)SiO2,SiO2-Al2O3,Al2O3were used as supports for preparation of immobilized SnCl2catalysts, which were used for Prins condensation reaction of isobutene with formaldehyde.The immobilized AlCl3catalysts which were prepared by using different zeolites as support were used in the isomerization reaction of endo-TCD, it focuses on the effects of acid type, acid strength and reaction temperature on the catalytic performance of the catalysts for isomerization of endo-TCD, exploring reaction mechanism. The main results are as follows:(1) The pore structure and acidity of the catalyst greatly influence the reaction activity and products selectivity. There is no catalytic activity over HM since its smaller pore diameter. The acid strength of the catalyst has effect on the selectivity of the products; the strong acidity of HP is beneficial for ADH formation.(2) After immobilization of AlCl3, the surface acidity and the catalytic performance of the catalysts were remarkably enhanced. Strong acid sites of the catalysts play a major role for endo-TCD conversion. The strong Bronsted acid sites are beneficial for the formation of adamantane.(3) Diffusion dynamics has great effect on the catalytic performance of the solid acid catalyst. AlCl3/Hβ possesses stronger acidity, but the lower catalytic activity and ADH yield in lower reaction temperature might be ascribed to the effect of diffusion.(4) AlCl3/γ-Al2O3catalyst possessed superior stability and reaction activity, after reacted100h on the fixed-bed reactor, the endo-TCD conversion was still above98%.In the Prins condensation reaction of isobutene with formaldehyde which was catalyzed by immobilized SnCl2catalysts, N2adsorption/desorption and ICP-OES were used to characterize SnCl2/SiO2, SnCl2/SiO2-Al2O3, and SnCl2/Al2O3. After immobilized SnCl2, the specific surface area, pore volume and pore diameter of SiO2, SiO2-Al2O3, and Al2O3decreased. The catalysts activity, MBOH selectivity and yield all followed the order:SnCl2/Al2O3> SnCl2/SiO2-Al2O3>SnCl2/SiO2.