金属改性对钛硅分子筛TS-1上油酸甲酯环氧化性能的影响

Effect of metal modification on titanium silicalite TS-1 for methyl oleate epoxidation

环氧植物油可广泛用作各种化工材料,为提高植物油环氧化催化剂钛硅分子筛TS-1的活性,采用沉淀沉积法制备了系列金属改性的TS-1催化剂(M/TS-1,M为Mn、Fe、Cu、Mg),对其进行了表征,并以油酸甲酯环氧化为探针反应,考察了金属改性对TS-1上油酸甲酯环氧化性能的影响。结果表明:Fe和Cu的引入提高了TS-1的催化活性,但Mg和Mn改性却抑制了油酸甲酯的环氧化,Cu/TS-1催化剂的催化活性最高;结合多种表征结果发现,Cu/TS-1催化剂的高活性归因于Cu的引入有效地改变了Ti活性中心的电子环境,并增加了新的中强酸性位点;Cu/TS-1催化油酸环氧化的最佳工艺条件为反应温度80℃、H_(2)O_(2)与油酸甲酯物质的量比3∶1、油酸甲酯与催化剂质量比10∶1~20∶1;Cu/TS-1重复使用5次后,油酸甲酯转化率和环氧油酸甲酯收率略有降低。综上,采用Cu改性TS-1可显著提高其催化活性,且Cu/TS-1具有良好的再生性能。

Epoxy vegetable oil has widely utilized as various chemical material.To improve the activity of titanium silicalite TS-1,a vegetable oil epoxidation catalyst,a series titanium silicalite TS-1 supported various metals catalysts(M/TS-1,M=Mn,Fe,Cu,Mg) were prepared by a deposition-precipitation method and characterized.The effect of metal modification on the epoxidation performance of methyl oleate on TS-1 was investigated using the epoxidation of methyl oleate as a probe reaction.The results showed that the introduction of Fe and Cu into TS-1 promoted the catalytic activity but Mg and Mn modification inhibited the methyl oleate conversion,and Cu/TS-1 catalyst showed the highest catalytic activity.Combined with various characterization results,the high activity of Cu/TS-1 catalyst was attributed to the introduction of Cu,which effectively changed the electronic environment of Ti active center and added new medium and strong acidic sites.The optimal process conditions for Cu/TS-1 catalyzed epoxidation of methyl oleate were obtained as follows:reaction temperature 80℃,molar ratio of H_2O_(2) to methyl oleate 3∶1,mass ratio of methyl oleate to catalyst 10∶1-20∶1.The conversion of methyl oleate and the yield of epoxy oleic methyl ester were slightly reduced after Cu/TS-1 was repeated for 5 times.In summary,TS-1 modified by Cu can significantly improve its catalytic activity and Cu/TS-1 has good regeneration performance.