KIT-5负载离子液体催化甲缩醛和三聚甲醛合成聚甲醛二甲醚

采用包埋法将离子液体封装在分子筛KIT-5孔笼内,制备了四种负载型离子液体催化剂,用于甲缩醛和三聚甲醛合成聚甲醛二甲醚(PODE_n),研究了不同条件对三聚甲醛转化率和目标产物PODE_(3-5)选择性的影响。结果表明,催化合成PODEn的最佳反应条件为:反应时间2 h、100℃、甲缩醛与三聚甲醛物质的量比1.5、催化剂含量3%,在此条件下,四种催化剂均表现出了很好的催化效果。与离子液体催化剂相比,负载型催化剂的催化活性基本保持不变,而且性能稳定,可多次使用,具有一定的实用价值。

Synthesis of polyoxymethylene dimethyl ethers from dimethoxymethane and trioxane catalyzed by ionic liquids encapsulated in caged mesoporous KIT-5 material

Four kinds of supported ionic liquid catalysts were prepared by encapsulation of ionic liquids within the nanocage of KIT-5 and were used in the synthesis of polyoxymethylene dimethyl ether (PODE_n) from dimethoxymethane and trioxane; the effects of conditional parameters on the conversion of trioxane and the selectivity to targeted PODE_3-5 were systematically investigated. The results show that the optimum reaction parameters for the synthesis of polyoxymethylene dimethyl ether were: reaction time of 2 h, 100 ℃, dimethoxymethane to trioxane molar ratio of 1.5, and catalyst content of 3%. Under the optimum conditions, the encapsulated catalysts are efficient in the synthesis of polyoxymethylene dimethyl ether, with a similar catalytic activity to the homogeneous counterparts. Moreover, the encapsulated catalysts can be reused several times without remarkable loss of activity and product selectivity, which makes it a promising catalyst for practical applications.