Abstract:

Phytosteryl oleate synthesized from stigmasterol and oleic acid using the composite catalysts of potassium bisulfate and metal oxide was investigated. By comparing with other sulfates, potassium bisulfate was proved to be more suitable for the esterification of oleic acid and stigmasterol in an efficient and safe way. Taking into account the high catalytic efficiency of metal oxide, the combination of potassium bisulfate and different metal oxides as a kind of composite catalyst may be promising. The catalyst comparative experiments suggested that the composite catalyst of KHSO₄-ZnO was the best catalyst in terms of the esterification yields. When the esterification reaction was carried out at 150℃ for 7 h with oleic acid and stigmasterol in a molar ratio of 1.8:1 and 3.0% KHSO₄ + 1.0% ZnO catalyst (based on the mass of stigmasterol) under the protection of nitrogen, the highest esterification yield was 92.17%. In the presence of the composite catalyst of KHSO₄-ZnO, a new process for the synthesis of stigmasterol oleate with high esterification yield is acquired.

Key words: composite catalyst, metal oxide, potassium bisulfate, esterification, phytosteryl oleate

摘要：

以油酸和豆甾醇为原料,研究了以硫酸氢钾-金属氧化物为组合的复合催化剂在酯化合成中的应用。首先,通过与其他硫酸盐的酯化效果进行比较,筛选出KHSO₄是适用于酯化合成中高效且安全的催化剂,并将其和不同的金属氧化物进行组合作为复合催化剂进一步探究酯化效果。通过实验结果比较,得到KHSO₄-ZnO作催化剂的酯化率最高。然后,将KHSO₄-ZnO作为复合催化剂,针对催化剂用量、反应温度、反应时间、酸醇摩尔比等因素进行考察,探究油酸和豆甾醇的最佳酯化条件。得到最佳工艺条件为:在通高纯氮气条件下,选用3.0%KHSO₄+1.0%ZnO(以豆甾醇的质量分数计)为催化剂,油酸和豆甾醇的摩尔比为1.8:1,反应的温度为 150℃,反应的时间为7 h,酯化率达到92.17%。本工艺利用KHSO₄-ZnO作为复合催化剂,得到较高的酯化率,实现了一条合成油酸豆甾醇酯的新工艺路线。

关键词: 复合催化剂, 金属氧化物, 硫酸氢钾, 酯化合成, 甾醇酯