Modification Of Urea Aqueous Solution For γ-Al₂O₃ And Its Impact On Catalysis Of La₂O₃/γ-Al₂O₃ In MPV Reaction Of Cinnamaldehyde

In thesis, some experimental methods, including chemical reaction, measurement of ? potential of solid particles in liquid, probes-TPD, probes-IR ect., were used to research into following content mainly.1. The MPV reaction conditions of cinnamaldehyde and 2-propanol （La₂O₃ loading amount of catalyst, solvent, temperature and time） catalyzed La₂O₃/γ-Al₂O₃.2. Urea aqueous solution treatment for γ-Al₂O₃, and its impact on the y-Al₂O₃ surface acid-base properties.3. As support of La203/y-Al₂O₃ catalysts, impact of γ-Al₂O₃ on result of catalytic cinnamaldehyde MPV reaction.Through the research, some conclusions are drawn as followings:（1） For the MPV reaction of cinnamaldehyde with 2-propanol （hydrogen transfer reagent） catalyzed by 10.43wt.% La₂O₃/γ-AL₂O₃, perfect reaction conditions were given as amount of 2-propanol 5 mL; the reaction temperature and time were 100 ℃ and 150 min respectively under the experimental condition.（2） After modified by urea solutions with various concentrations, the amount of charge and the intensity distribution of acid and base sites changed on γ-AL₂O₃ surface. In Na₂SO₄ aqueous solution, absolute value of ? potential of γ-AL₂O₃ increased with increasing the concentration of urea solution; When MPV reaction of cinnamaldehyde with 2-propanol was catalyzed by modified γ-Al₂O₃, selectively of product cinnamyl alcohol decreased with increasing the concentration of urea solution; When modified γ-Al₂O₃ was used as the support of La₂O₃/γ-Al₂O₃ catalysts prepared by impregnation method, the content of La₂O₃ on γ-Al₂O₃ decreased.（3） On surface of γ-Al₂O₃ samples which were modified by the urea solution, then calcined, and La₂O₃/γ-Al₂O₃ samples which were prepared by using modified γ-Al₂O₃ as supports, there were Lewis acid sites, Lewis base sites and Bronstead acid sites. On surface of these γ-Al₂O₃ and La₂O₃/γ-Al₂O₃ samples, intensity distribution and amount of acid and base sites had changed.（4） In reuse of La₂O₃/γ-Al₂O₃ catalyst, the performance of the catalyst decreased with the increasing of use times, However, modification of urea solution for γ-Al₂O₃ support was helpful to improve the stability of La₂O₃/γ-Al₂O₃ catalysts.（5） Modification of urea solution and loading of lanthanum oxide can not change the crystalline structure of γ-Al₂O₃. La₂O₃ is highly dispersed on the surface of γ-Al₂O₃.