NMR Studies Of Solid Acid Catalysts

This dissertation is concentrated on the applications of solid-state NMR techniques to heterogeneous catalysis. Some fundamental studies on synthesis, modifications and characterizations of solid acid catalyst matrials have been carried out.Using zeolite Y seeds and organotrialkoxysilane as silica sources, hydrothermally stable thiol- and sulfonic functionalized mesoporous silicas of MSU structure were prepared by a one-pot synthesis involving co-condensation of organotrialkoxysilane and tetraalkoxysilane and post oxidation. It should be noted that inexpensive reactant, mainly including sodium silicate and sodium aluminate, used in the preparation of zeolite Y seeds provided a low-cost route for the synthesis of hydrothermally stable organo-functionalized mesoporous silicas.Tin oxide supported molybdena (MoO₃/SnO₂) was prepared by impregnation process using SnCl4.xH2O and ammonium heptamolybdate as initial materials. MoO₃/SnO₂ is a widely used catalyst for oxidation reactions, and a solid acid as well.The structure and acidity of sulfonic group functionalized mesoporous materials with MSU structure were characterized in detail using multinuclear NMR technique in combination with other approaches such as XRD, N₂ adsorption and desorption, as well as density function theory (DFT) calculation. Our experimental and theoretical calculation results indicate that functionalized MSU-SO3H materials with well-ordered mesostructure have been successfully synthesized and the materials have acid strength slightly weaker than that of microporous zeolite HZSM-5. It can be expected that MSU-SO3H may probably satisfy some catalytic applications involving larger molecules...