Preparation Of Acidic Mesoporous Molecular Sieves And Their Catalytic Property For Rosin And Turpentine Reactions

The esterification of terpineol, the hydration and polymerization of α-pinene , the dimerization of rosin and the Friedel-Crafts acylation are important processes in the fine chemical industry. These reactions are concerned with larger molecule reactants using strong acid as catalysts. The traditional catalysts used in the processes are AlCl₃,H₂SO₄ and H3PO4 which are of some drawbacks such as too large amounts of usage, more environmental problems, serious corrosion to equipment and non-regenerable. Therefore, more and more attentions have been paid to using zeolites and solid super acids as catalysts for the reactions in recent years.The mesoporous molecular sieve MCM-41 possesses a hexagonal arrangement of uniformly sized unidimensional mesoporous with diameters which can be systematically varied from 1.5 to 10 nm, larger surface area of more than 700m²/g, and should therefore be a potential catalyst for the reactions concerned with larger molecule reactants. However, the acidity of MCM-41 is weak and is of low catalytic activity for the reaction using strong acid catalysts. Therefore, enhancing the acidity of MCM-41 is the key to using it as catalysts for the reactions.In this study, several mesoporous molecular sieves such as Zr-MCM-41 and Mo-MCM-41, were synthesized by hydrothermal system and some strong acid groups like BO₃^3-, SO₄^2-and AlCl₃, were incorporated into the frame of the mesoporous molecular sieves to obtain the strong acid mesoporous molecular sieves catalysts. The obtained materials were characterized by XRD, FT-IR, BET, ESR and NH₃-TPD.The results show that the obtained materials are of the characteristics of mesoporous molecular sieves, better long-range order and crystallinity, and that strong acid groups have been combined with the frame of mesoporous molecular sieve so that the acidity of the sieve is improved.The synthesized mesoporous molecular sieves were tried to use as catalysts in five model reactions, such as the esterification of terpineol, the hydration and the polymerization of α-pinene, the dimerization of rosin and the Friedel-Crafts acylation of 2-methoxynaphalene. The catalysts that are of best catalytic activities to different model reactions have been found to be SO₄^2-/Zr-MCM-41, AlCl₃/Zr-MCM-41, ZrO₂/BO₃^3-/Mo-MCM-41 and BO₃^3-/Mo-MCM-41. The effects of preparing conditions of catalysts and the reaction conditions on the reaction results were examined and the optimum conditions were obtained.