金属改性分子筛催化剂的制备及其对异戊醇催化性能研究

发布时间：2018-06-20 15:16

  本文选题：异戊醇 + 选择性氧化　； 参考：《西北大学》2017年硕士论文

【摘要】：伴随对环境问题重视度的提高,醇类绿色氧化的发展也被越来越广泛关注。本文制备了一系列改性HMS催化剂,并在以分子氧(O2)为氧化剂以及无溶剂条件下将所制备的催化剂用于异戊醇催化氧化制备异戊酸的研究当中,探讨所制备的催化剂用于异戊醇制备异戊酸的性能差异,并将部分催化剂表征进行分析。论文所讨论的问题主要包括:(1)利用溶胶-凝胶方式制备HMS分子筛以及金属掺杂分子筛Al-HMS和Co-HMS,并以此为载体将ZnO负载于载体之上获得负载型分子筛催化剂。运用不同表征分析了所获得的催化剂,并研究了所得到的催化剂对异戊醇催化氧化的反应性能。结果发现:金属杂原子掺杂改性后的分子筛载体能够提高负载于其上的ZnO物种的分散度,其中Co-HMS效果更加明显;催化剂5wt%ZnO/Co-HMS(100)对异戊醇催化氧化制异戊酸的性能最佳,使异戊醇的转化率、异戊酸的收率以及选择性分别达到了 43.6%、18.9%、43.3%。(2)以5wt%的ZnO物种负载量,金属Co掺杂分子筛为载体考察了金属Co的掺杂量对催化剂催化性能的影响,并将部分催化剂通过表征进行了分析。结果显示:金属Co的引入量会对催化剂的结构性质造成影响。适量金属Co的掺杂能够改善负载的活性物种的分散度,提高催化剂的反应活性。当Si/Co的值等于100时,获得的催化剂的催化效果较佳。(3)讨论了 ZnO物种的负载量、焙烧温度以及ZnO前驱体种类对催化剂效果的影响。研究表明:当ZnO的负载量为3wt%,550℃下焙烧,以Zn(N03)2·6H20作为ZnO的前驱体时,制备的催化剂对催化异戊醇氧化制异戊酸的性能最佳。(4)通过对制备条件的讨论,我们筛选出了最佳的催化剂3wt%ZnO/Co-HMS(100)。并用3wt%ZnO/Co-HMS(100)进行优化异戊醇氧化合成异戊酸的反应条件。实验结果表明,合成反应的工艺条件明显影响着底物异戊醇的转化率以及目标产物异戊酸的收率和选择性。当底物的加入量为15mL、使用0.5g催化剂在120℃下反应8h时,异戊醇的转化率、目标产物异戊酸的收率以及选择性达到最高值,分别为52.2%、26.9%、51.5%。催化反应动力学的结果表明,催化剂3wt%ZnO/Co-HMS(100)的使用能够明显降低该催化反应体系的活化能,使异戊醇的氧化反应可以在较为温和的条件下顺利进行。
[Abstract]:With the increasing attention to environmental problems, the development of green oxidation of alcohols has been paid more and more attention. A series of modified HMS catalysts were prepared in this paper. The catalysts were used in the catalytic oxidation of isopentanol to isopentanoic acid under the conditions of molecular oxygen O _ 2 as oxidant and solvent free. The properties of the catalysts used in isoamyl alcohol to prepare isopentanoic acid were discussed, and some of the catalysts were characterized and analyzed. The main problems discussed in this paper include the preparation of HMS molecular sieve and metal doped molecular sieve Al-HMS and Co-HMS by sol-gel method. The catalysts obtained were analyzed by different characterizations and the catalytic performance of the catalysts for the catalytic oxidation of isopentanol was studied. The results showed that the molecular sieve carrier doped with metal hetero-atom could increase the dispersion of ZnO species loaded on it, and the Co-HMS effect was more obvious, and the catalyst ZnO / Co-HMS100 had the best performance in the catalytic oxidation of isoamyl alcohol to isovaleric acid, and the effect of Co-HMS on the catalytic oxidation of isopentanol to isopentanoic acid was found to be the best. The conversion of isoamyl alcohol, the yield and selectivity of isovaleric acid were 43.6and 18.9%, respectively. The effect of doping amount of Co on the catalytic performance of the catalyst was investigated with 5 wt% ZnO species loading and Co doped molecular sieve as the carrier. Some of the catalysts were characterized and analyzed. The results show that the addition of Co has an effect on the structure and properties of the catalyst. Proper amount of Co doping can improve the dispersion of the supported active species and increase the reaction activity of the catalyst. When the value of Si / Co is equal to 100, the effect of the supported amount of ZnO species, calcination temperature and the type of ZnO precursor on the catalyst effect is discussed. The results showed that when ZnO was calcined at 550 鈩，

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