【作者】 赵静；

【导师】 王晓红；

【作者基本信息】 东北师范大学 ， 无机化学， 2013， 硕士

【摘要】 环境友好型、高效酸型催化剂的研究与开发是绿色化学研究的一个重要方向。多金属氧酸盐（也称为多酸）以其独特的酸性能、氧化还原性能以及催化性能的可调控性受到人们的广泛关注，在均相、非均相催化反应中有重要的应用。但由于多酸的比表面积小、极易溶于极性溶剂中，设计合成非均相催化剂是实现其应用的有效方法，其催化性能也将大大改善。另外，固体多酸催化剂在催化酯化、酯交换反应中常遇到底物原料中游离酸脂肪酸（FFA）和水分的不利影响，因此耐酸、耐水催化剂的设计合成更有意义。本文利用自组装思想设计合成了几种基于多酸的非均相催化剂，以酸催化反应如酯化和酯交换反应做为模型反应，分别考察了这些催化材料在非均相催化反应中的催化性能。具体研究内容如下：1.采用溶胶-凝胶技术合成了H₃PW₁₂O₄₀/Agarose （Agarose，琼脂糖）薄膜，并通过元素分析等手段对其结构进行了表征。结果表明，固载型催化剂H₃PW₁₂O₄₀/Agarose中催化活性位点H₃PW₁₂O₄₀基本结构未发生改变，Agarose固载H₃PW₁₂O₄₀后能形成均匀的膜，由于氢键作用使H₃PW₁₂O₄₀在膜中分散比较均匀、机械性能好，其担载量最高可达到38%。在酸催化酯化反应中，醇酸摩尔比为13:1，反应温度为65oC，催化剂使用量仅为0.25g时，7h后就能获得转化率96.8%，重复利用5次后活性略降低；在催化酯交换反应中，38wt%H₃PW₁₂O₄₀/Agarose在醇油摩尔比95:1，温度65oC，催化剂用量仅用0.50g时，连续反应12h后能最终实现芸芥油高效转化为四种主要的单脂，总产率可达85.1%，重复利用五次后催化剂活性仅降低0.8%，活性组分H₃PW₁₂O₄₀的脱落量小于5%。H₃PW₁₂O₄₀/Agarose （Agarose，琼脂糖）膜催化剂的活性源于酸催化位点H₃PW₁₂O₄₀和膜分离功能使产物和副产物从体系中自行分离出来，催化一步完成。2.利用长链季铵盐表面活性剂为结构导向剂合成了(C₁₆TA)H₄PW₁₁TiO₄₀(C₁₆TA为十六烷基三甲基铵盐)，通过元素分析等进行表征。结果表明(C₁₆TA)H₄PW₁₁TiO₄₀是具有Keggin结构的、同时具有Br nsted酸性和Lewis酸性双亲性分子且在极性溶剂中自组装为纳米级的胶束。系统考察不同条件对催化酯化反应活性的影响，发现在具有Br nsted酸性和Lewis酸性的(C₁₆TA)H₄PW₁₁TiO₄₀催化剂作用下，醇酸摩尔比为20:1，温度65oC，催化剂使用量仅为3.81mmol/L时，连续反应6h后就能获得96.8%的转化率，重复利用六次后活性略降低。耐水性实验发现(C₁₆TA)H₄PW₁₁TiO₄₀比母体H₅PW₁₁TiO₄₀碳链长而显示强耐水性。3.考察了硼钨多酸H₅BW₁₂O₄₀对于酯化反应的催化活性。H₅BW₁₂O₄₀是一种高电荷的质子酸，在极性溶剂中质子分步电离，得到高于H₃PW₁₂O₄₀的酸强度。因此系统研究了H₅BW₁₂O₄₀对酯化反应的催化活性，对于指导设计基于多酸的酸性催化剂有指导作用。结果表明：H₅BW₁₂O₄₀表现出强的Br nsted酸性，并在催化酯化反应中表现高的活性，其最佳反应条件为：醇酸比10:1，反应温度65oC，反应时间3h，催化剂用量为10.9mmol/L时，棕榈酸的转化率达到最高98.6%。催化剂利用乙醚萃取法从反应混合体系中分离出来，重复使用六次后活性降低1.9%。4.基于H₅BW₁₂O₄₀高于H₃PW₁₂O₄₀的催化活性，并且在酯化反应中H₅BW₁₂O₄₀作为均相催化剂，面临分离回收困难的问题，因此利用长链季铵盐类表面活性剂为结构导向剂，合成了(C₁₆TA)H₄BW₁₂O₄₀。结果表明：(C₁₆TA)H₄BW₁₂O₄₀表现出强Br nsted酸性，并在催化酯化反应中表现出高活性，其最佳反应条件为：醇酸比18:1，反应温度65oC，反应时间5h，催化剂用量为4.4mmol/L时，棕榈酸转化率达到最高98.7%。催化剂利用乙醚萃取法从反应混合体系中分离出来，重复使用六次后活性降低2.0%。5.基于H₇BW₁₁TiO₄₀的高活性，本实验合成具有Br nsted酸性和Lewis酸性双亲性分子。系统考察不同条件对催化酯化反应活性的影响。发现在具有Br nsted酸性和Lewis酸性的H₇BW₁₁TiO₄₀催化剂作用下，醇酸摩尔比为25:1，温度65oC，催化剂使用量仅为4.68mmol/L时，反应1h后就能获得99.9%的转化率，重复利用六次后活性略降低。双酸中心的催化剂H₅BW₁₁TiO₄₀的活性要高于单纯的Br nsted酸性的H₅BW₁₂O₄₀，原因是由于引入Lewis酸中心Ti，使得多酸的酸性有很大提高。更多还原

【Abstract】 Eco-friendly and efficient catalysts have been a focus of a much recent research.Polyoxometalates（POMs, also named heteropolyacids, HPAs） have attractedsignificant attention because of their unique properties such as high Br nsted acidity,redox property and modificability of catalytic activity, which make them available forapplications in homogeneous and heterogeneous reactions. However, POMs exhibitedlow surface area, and low thermal stability and easy solubility in polar solvents, whichlimit their utility in many catalytic reactions. The environmental friendly catalysts ofpolyoxometalates play an important roles in the heterogeneous system. In thisdissertation, a several solid POM catalysts had been designed, and had been evaluatedtheir catalytic activity in esterification and transesterification reactions. The mainresults of this work are as follows:1. H₃PW₁₂O₄₀/Agarose were prepared by sol-gel process and characterized byElemental analysis and so on. It was proved that the catalytic activity sites ofH₃PW₁₂O₄₀/Agarose did not change. It was identified that strong interaction betweenpolyhydroxyl site of agarose and H₃PW₁₂O₄₀by hydrogen bonds resulted in thehomogenous distribution of H₃PW₁₂O₄₀as well as the good mechanical properties ofthe nanocomposite films. With the help of38wt%H₃PW₁₂O₄₀/Agarose, molar ratio ofmethanol/palmitic13:1,65oC, mass of catalyst only0.25g, the highest catalyticactivity of catalyst can be obtained after7hours, and the reuse activity of catalystbeing still very good after five times; with the help of best loadings of38wt%H₃PW₁₂O₄₀/Agarose, molar ratio of methanol/Eruca sativa Gars. Oils95:1,65oC,mass of catalyst only0.50g, the highest catalytic activity of catalyst can be obtainedafter12hours, the reuse activity of catalyst being still very good after five times,active component of H₃PW₁₂O₄₀loss amount is less than5%. The thin film of38wt%H₃PW₁₂O₄₀/Agarose could be separated from mixture and H₃PW₁₂O₄₀providedcatalytic activity sites.2.(C₁₆TA)H₄PW₁₁TiO₄₀were precipitated by using long chain quaternaryammonium salt surfactants for structure-directingagent and characterized byElemental analysis and so on. It was proved that (C₁₆TA)H₄PW₁₁TiO₄₀had Br nstedacid and Lewis acid sites with Keggin structure. In a polar solvent it could formself-assembly nanoscale micelles. With the help of (C₁₆TA)H₄PW₁₁TiO₄₀, molar ratio of methanol/palmitic20:1,65oC, mass of catalyst only3.81mmol/L, the highestcatalytic activity of catalyst can be obtained after6hours, and the reuse activity ofcatalyst being still very good after six times.3. The activity of H₅BW₁₂O₄₀in esterification was investigated. H₅BW₁₂O₄₀wasproton acid which owned high charge,the proton was ionized step by step in polarsolvent and the acid strength was higher than H₃PW₁₂O₄₀. So we conducted asystematic study of the catalytic activity of H₅BW₁₂O₄₀in esterification reaction and itplayed a guiding role in designing heteropolyacid catalysts. With the help of Br nstedand high protons acid H₅BW₁₂O₄₀, molar ratio of methanol/palmitic10:1,65oC, massof catalyst only10.9mmol/L, the highest catalytic activity of catalyst can be obtainedafter3hours. The catalyst was separated from the mixture by ether extraction methodand the reuse activity of catalyst lost only2.0%after six times.4. The homogeneous catalyst H₅BW₁₂O₄₀used in esterification had problems ofseparation、reusing, so we made an effort to use long chain quaternary ammonium saltsurfactants for structure-directingagent to synthetize (C₁₆TA)H₄BW₁₂O₄₀. With thehelp of Br nsted and high protons acid (C₁₆TA)H₄BW₁₂O₄₀, molar ratio ofmethanol/palmitic18:1,65oC, mass of catalyst only4.4mmol/L, the highest catalyticactivity of catalyst can be obtained after3hours. The catalyst was separated from themixture by ether extraction method and the reuse activity of catalyst lost only1.9%after six times.5. The activity of H₅BW₁₂O₄₀in esterification was very high,so the catalyst ofH₇BW₁₁TiO₄₀owing Br nsted acid and Lewis acid sites played an important role inreaction. It was proved that H₇BW₁₁TiO₄₀still kept Keggin structure. With the help ofH₇BW₁₁TiO₄₀, molar ratio of methanol/palmitic25:1,65oC, mass of catalyst only4.68mmol/L, the highest catalytic activity of catalyst can be obtained after1hours,and the reuse activity of catalyst being still very good after six times. The double acidcatalyst H₇BW₁₁TiO₄₀performed higher activity than H₅BW₁₂O₄₀due to theintroduction of Lewis acid sites Ti4+.更多还原