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目的:环氧化物是多种有机合成反应的重要中间体,也可作为环氧树脂、染料和表面活性剂的原料。传统的环氧化存在催化剂分离难、氧化剂成本高和过程含有溶剂等缺点。本文旨在探讨纳米金和多金属氧酸盐负载非均相催化剂用于无溶剂条件下环辛烯环氧化的反应条件对催化性能的影响。创新点:1.把纳米金颗粒和多金属氧酸盐(即BW11)结合并负载在固体载体上制备出了一种新型复合催化剂材料;2.采用分子氧作为氧化剂而不是传统的有机酸或者过氧酸;3.在温和条件下可获得良好的转化率和较高的环氧化物选择性;4.催化反应体系未使用有机溶剂;5.催化剂稳定并可循环使用。方法:1.根据文献中所述方法制备BW11;2.采用标准沉积沉淀法合成Au/Al2O3;3.采用湿式浸渍法制备催化剂Au/BW11/Al2O3;4.环辛烯环氧化使用叔丁基过氧化氢(TBHP)作为引发剂,氧气作为氧化剂,在高压反应釜中进行反应;5.采用扫描电镜和X射线衍射等对催化剂进行表征。结论:1.提高焙烧温度可改善催化反应性能;2.随着催化剂量增加到0.2 g,转化率也随之增加(图8);3.反应的最佳温度为80°C(表1);4.随着反应时间的增加直到24 h,转化率逐渐增加,环氧化物选择性也增加到约87%(图9);5.催化剂可适用于多种氧化剂(表2);6.无溶剂下转化率和选择性相对较大(表3);7.催化剂可以有效活化分子氧和环辛烯;8.催化剂可以再生,在使用三次后,其活性损失不大。
OBJECTIVE: Epoxides are important intermediates for many organic synthesis reactions. They are also used as raw materials for epoxy resins, dyes and surfactants. Traditional epoxidation has the disadvantages of difficult catalyst separation, high cost of oxidant and process containing solvent. The purpose of this paper is to investigate the effects of reaction conditions on the catalytic performance of cyclooctene epoxidation using gold nanoparticles and polyoxometalate-supported heterogeneous catalysts under solvent-free conditions. Innovative points: 1. The nano-gold particles and polyoxometalates (ie, BW11) combined and supported on a solid support to prepare a new composite catalyst material; 2. The use of molecular oxygen as an oxidant rather than the traditional organic acid or Peroxyacid; 3. Good conversions and higher epoxide selectivity under mild conditions; 4. No organic solvent used in the catalytic reaction system; 5. The catalyst is stable and recyclable. Method: 1. Prepare BW11 according to the method described in the literature; 2. Prepare Au / Al2O3 by standard deposition precipitation method; 3. Prepare catalyst Au / BW11 / Al2O3 by wet impregnation method; 4. Cyclooctene epoxidation using tert-butyl Hydrogen peroxide (TBHP) as an initiator, oxygen as an oxidant in the autoclave for reaction; 5 using scanning electron microscopy and X-ray diffraction and other catalysts were characterized. CONCLUSIONS: 1. Increasing the calcination temperature improves the catalytic performance. 2. The conversion increases with increasing catalyst amount to 0.2 g (Figure 8). 3. The optimal reaction temperature is 80 ° C (Table 1) ; 4. With the increase of reaction time until 24 h, the conversion rate gradually increased, the epoxide selectivity increased to about 87% (Figure 9); 5. The catalyst can be applied to a variety of oxidants (Table 2); Without solvent conversion and selectivity is relatively large (Table 3); 7. The catalyst can effectively activate molecular oxygen and cyclooctene; 8. The catalyst can be regenerated, in the use of three times, the activity loss is not.