脂肪酸甲酯环氧化反应及催化体系研究

【作者】 杨华；

【导师】 冯树波；

【作者基本信息】 河北科技大学 ， 工业催化， 2010， 硕士

【摘要】 以钨酸钠、磷酸、H2O2和氯代十六烷基吡啶为原料制备了磷钨杂多酸季铵盐相转移催化剂。考察了溶剂和制备条件对催化剂制备过程的影响,发现溶剂乙酸乙酯可使催化剂高度缔合析出,催化剂分离工序简单。以二氯乙烷为溶剂考察了反应温度、反应时间、H2O2添加方式、H2O2浓度和用量、催化剂用量等因素对脂肪酸甲酯环氧化和H2O2利用率的影响。结果表明,反应结束并降温后催化剂自动沉淀析出,催化剂回收率达到90%以上,重复使用八次催化活性基本不变。采用FT-IR对催化剂和环氧化产物进行了表征。采用磷钨杂多酸季铵盐相转移催化剂和H2O2(30%,质量分率)氧源,分别在乙酸乙酯和1, 2-二氯乙烷两种溶剂中考察了环氧脂肪酸甲酯合成工艺,并利用正交实验的方法对脂肪酸甲酯环氧化反应工艺条件进行了优化,得出对应的较佳反应条件分别为:乙酸乙酯15mL,反应时间1h,催化剂量0.1g,催化剂类型为3:1:4,分四次加入30wt%H2O21.57g,反应温度65℃,脂肪酸甲酯5.0g时,原料碘值为100的脂肪酸甲酯经环氧化,产品环氧值可达5.13%;二氯乙烷20mL,反应时间2.5h,催化剂量0.3g,分三次加入30wt%H2O23.5g,反应温度65℃,脂肪酸甲酯5.0g时,原料碘值为100的脂肪酸甲酯经环氧化,产品环氧值可达5.78%。以甲酸为活性氧载体,硫酸为催化剂和H2O2为氧源研究了有机过酸催化的脂肪酸甲酯环氧化。考察了H2O2滴加时间、环氧化反应保温时间、温度、H2O2用量、甲酸用量和硫酸用量等因素对反应的影响。结果表明,脂肪酸甲酯40g(含C=C157.48mmol)反应温度55℃,35% H2O218.36g(与双键摩尔比为1.2:1),甲酸6g,搅拌转速210r·min-1,H2O2滴加时间0.5h,反应3h,产品环氧值可达4.27%,对应的H2O2有效利用率为69.27%;达到最高环氧值后继续反应2h,二醇产率达到88.05%,3h达到95.17%。动力学研究表明,环氧化反应为一级反应,表观活化能为45.97 kJ/mol。更多还原

【Abstract】 A heteropolyphosphatotungstate for the epoxidation of fatty acid methyl esters was prepared using sodium tungstate, phosphoric acid, hydrogen peroxide and cetyl pyridinium chloride. It was found that catalysts prepared by dissolving cetyl pyridinium chloride with ethyl acetate aggregate between the interface of organic phase and water phase. The catalyst was separated by simple filtration. The action of the title catalyst with H2O2 leads to a formation of homogeneous phase and an accelerated reaction rate. The catalyst will precipitate in solid particles with the consumption of H2O2 and the decreasing temperature, its recovery is up to 90% and catalytic activity is almost unchanged after eight consecutive uses. The catalyst structures before and after epoxidation reaction were characterized by FT-IR.Fatty acid methyl ester epoxide was synthesized and the effect of reaction conditions on the epoxidation and H2O2 utilization was investigated, respectively using using ethyl acetate and 1, 2-dichloroethane as solvent. Optimal synthesis conditions obtained using orthogonal design of experiments are as follows. For 1, 2-dichloroethane system, the product epoxy value is up to 5.78%, double bond epoxidation selectivity 81.9% and H2O2 utilization 86% under the conditions of reaction time 1 h,catalyst 0.1g,stepwise addition of 30wt% H2O2 1.57g,reaction temperature 65℃,1,2-dichloroethane 15mL and FAMEs 5.0g. For ethyl acetate system, the product epoxy value is up to 5.13% under the conditions of reaction time 2.5h,catalyst 0.3g,stepwise addition of 30wt% H2O2 3.5g(30.88mmol),reaction temperature 65℃,1,2-dichloroethane 20mL and FAMEs 5.0g(22.84mmol double bond).With formic acid as oxygen carriers, sulfuric acid as catalyst and hydrogen peroxide as oxidant, the influence of drops time of H2O2, reaction time, reaction temperature, H2O2 amount, formic acid amount and sulphuric acid dosage on the reaction was investigated. Results showed that suitable conditions are as follows: 40g FAMEs(iodine value=100), reaction temperature: 55℃, 35% H2O2 18.36g(corresponding with the ratio of H2O2 to double bond 1.2:1), 6g formic acid, stirring velocity :210r·min-1, drops time of H2O2:0.5 h, reaction time: 3h, the epoxy value of products could reach 4.27% and hydrogen peroxide utilization was 69.27%. After the highest epoxy value, the reaction continued to proceed for 2h and 3h, glycol yield could reach 88.05% and 95.17%, respectively. Kinetics of epoxidation were measured and well represented by the first-order reaction model, its apparent activation energy was 45.97 kJ/mol.更多还原