改性膨润土催化剂的制备及催化有机反应研究

【作者】 杨兆磊；

【导师】 赵斌； 张恒；

【作者基本信息】 曲阜师范大学 ， 有机化学， 2012， 硕士

【摘要】 改性膨润土负载型催化剂是一类良好的环境友好型催化剂，在现代有机催化合成中有广泛应用。它具有制备简单且无污染、价格低、催化活性高、选择性好、容易与反应体系分离及可循环利用等优点。本文系统地考察了改性膨润土催化剂的制备条件与其结构和性能的关系，研究了催化剂在烷基化和氢胺化等有机合成反应中的应用。1.改性膨润土催化剂的制备和表征将钙基膨润土经提纯、钠化等处理后，负载质子酸、Lewis酸（Cl₂ZnCl₂）及KF制备负载型催化剂，考察催化剂制备条件对其结构和性能的影响。利用FT-IR、XRD、BET、NH3-TPD等测试技术对催化剂的晶相结构、酸位中心性质以及比表面积等进行了表征。结果显示，膨润土经适当浓度质子酸改性，可显著增大比表面积，增加表面酸量；经CuCl₂、ZnCl₂等Lewis酸改性能够与表面羟基形成新的催化活性物种。膨润土负载KF后，比表面积有所降低，层间距随焙烧温度的升高而逐渐减小。2.改性膨润土催化剂催化有机反应研究考察了酸改性膨润土催化剂对烯烃氢胺化反应的催化效果。以经盐酸酸化改性的膨润土为催化剂，常压下催化环己烯与对甲苯磺酰胺的氢胺化反应。系统考察了酸化条件、溶剂及其用量、催化剂用量及反应时间等因素对N-环己基对甲苯磺酰胺收率的影响。结果表明，经2mol/L盐酸酸化的膨润土催化活性最高，以甲苯为溶剂常压回流反应2h，N-环己基对甲苯磺酰胺的收率达到83.7%。研究了膨润土负载CuCl₂、ZnCl₂等Lewis酸催化剂对活泼亚甲基化合物烷基化反应的催化效果。结果表明，CuCl₂/膨润土催化剂对丙二酸二乙酯与二苯甲醇的反应具有最好的催化性能，2-（二苯甲基）丙二酸二乙酯的收率达到85%以上。以溴代正丁烷与乙酰乙酸乙酯的烷基化反应为探针反应，考察优化了KF/膨润土催化剂的制备条件，在KF：膨润土=1：5（质量比）和焙烧温度400C下制备的催化剂活性最好。在乙酰乙酸乙酯：溴代正丁烷=1：2、反应温度为85C的条件下催化反应4小时，2-正丁基乙酰乙酸乙酯的收率达到38.6%，体现出此催化剂对活泼亚甲基的烷基化反应具有良好的活性。更多还原

【Abstract】 Modified bentonite is a kind of good environmental friendly catalyst, which plays animportant role in organic catalysis, and are widely applied in modern organic synthesis. Thereare many advantages, such as simple preparation process, low pollution level, low price, highcatalytic activity and good selectivity, easy separation from reaction system, and repeated use,for the use of modified bentonite catalysts. This paper describes the preparation andcharacterization of new modified bentonite catalysts, e.g. inorganic acid modified bentonitecatalysts, Lewis acid loaded bentonite catalysts and KF loaded bentonite catalysts. The catalyticactivities of these catalysts are evaluated through the different organic reactions.1. The preparation and characterization of modified bentonite catalystsFirst the raw bentonite were purified, acidized and sodium treated, and acidic treatmentconditions were optimized. Then, the well-purified active bentonite were chosen for furtherloading of active components, and inorganic acid （HNO₃, HCl, H₂SO₄） modified bentonitecatalysts, Lewis acid （ZnCl₂, CuCl₂） loaded bentonite catalysts and KF-loaded bentonitecatalysts were prepared. The internal structure, specific surface area and acid center etc. of thesecatalysts were characterized by FT-IR, XRD, BET, NH3-TPD. The results show that there is nodamage of bentonite layer-shape structure in the inorganic acid-modified bentonite catalystsobtained in a range of appropriate concentration of acid change, the bentonite pore structuresbecome loose, the specific surface areas increase, the surface acidity is enhanced. In the Lewisacid-loaded bentonite catalysts, the Lewis acids are bonded to bentonite with surface hydroxylgroups, forming new active catalytic centers. In the KF-loaded bentonite catalyst, the specificsurface areas decrease, the layer distances reduce with the increasing of roasting temperature.2. The evaluation of catalytic activities of the modified bentonite catalystsThe HCl-modified bentonite catalysts （HCl/bentonite） were used for catalyzing thepreparation reaction of N-cyclohexyl-p-toluenesulfonamide from cyclohexene andtoluenesulfonamide, and the reaction conditions including the amount of catalyst, reaction timeand other effect factors were explored. The results show that the HCl-modified bentonite catalyst,obtained by the treatment of2mol/L hydrochloric acid, has the best catalytic activity. The yieldof N-cyclohexyl p-toluenesulfonamide is as high as83.7%in toluene solvent at atmosphericpressure.Lewis acid-loaded bentonite catalysts show good catalytic performance in alkylationreaction of active methylene. In the Lewis acid-loaded bentonite catalyzed reaction of diethylmalonate and diphenyl methanol, the yield of diethyl2-（diphenyl）methylmalonate reached more than85%.Using the alkylation reaction of bromobutane and ethyl acetoacetate as a probe, thepreparation conditions of KF/bentonite catalysts were optimized. The preparation condition forKF/bentonite catalysts is KF/bentonite=1:5, and the roasting temperature400C. The catalyticreaction of bromobutane and ethyl acetoacetate was also studied, and the results indicate that, inthe condition of ethyl allylacetoacetate: bromobutane=1:2, the reaction temperature85C, andthe reaction time4h, KF/bentonite catalyst0.4g, the yield of ethyl2-n-butylacetoacetate reached38.6%.更多还原