Abstract

In order to develop an active and selective catalyst for the selective esterification of glycerol with fatty acid to monoglycerides, zirconia was incorporated into mesoporous MCM-41 support using two methods, i.e., impregnation and precipitation. The zirconia loading was varied between 10 and 30 wt. % to demonstrate its effect on the properties and activity of the modified catalysts. The catalysts were then characterized by N₂-adsorption surface analysis, SEM/EDX, FTIR, and TGA. The catalytic activity was then demonstrated in the selective esterification of glycerol with either lauric or palmitic acid at 160 °C for 6 h with glycerol/fatty acid molar ratios of 1:1, 4:1, and 6:1 and catalyst loadings up to 5 wt. %. Fatty acid conversion as well as monoglyceride selectivity and yield were monitored to measure the extent of reaction leading to the formation of the desired products. Correlations between the activity and the characteristics of the catalysts under various reaction conditions were successfully established. Relatively slower zirconia incorporation in the impregnation method caused more internal incorporation of the acidic component. MCM-41 catalyst with 30 wt. % zirconia loading that was prepared by impregnation method with a surface area of 589 m²/g and an acid site concentration of 6.83 µmol/g showed a lauric acid conversion of 98.6% and a monolaurin selectivity of 57.2%. An increase in the molar ratio exceeding 4:1 did not bring about the desired effect due to the dilution effect of the limiting reactant. Lower activity was demonstrated by stearic acid due to its higher molecular size and viscosity to mainly affect the mass transfer during the reaction.

摘要

为了开发用于甘油与脂肪酸选择性酯化为甘油单酯的活性和选择性催化剂，使用两种方法将氧化锆掺入介孔MCM-41载体中，即浸渍和沉淀。氧化锆负载量在 10 到 30 wt 之间变化。% 以证明其对改性催化剂的性能和活性的影响。然后用N _{2表征催化剂}-吸附表面分析、SEM/EDX、FTIR 和 TGA。然后在甘油与月桂酸或棕榈酸在 160 °C 下选择性酯化 6 小时，甘油/脂肪酸摩尔比为 1:1、4:1 和 6:1 且催化剂负载量高达5重量。%。监测脂肪酸转化率以及单酸甘油酯选择性和产率以测量​​导致所需产物形成的反应程度。成功建立了各种反应条件下催化剂的活性和特性之间的相关性。浸渍方法中相对较慢的氧化锆掺入导致酸性组分更多的内部掺入。MCM-41 催化剂与 30 wt。通过浸渍法制备的氧化锆负载百分比为 589 m² /g 和 6.83 µmol/g 的酸位点浓度表明月桂酸转化率为 98.6%，单月桂酸甘油酯选择性为 57.2%。由于限制性反应物的稀释作用，超过 4:1 的摩尔比增加不会产生预期的效果。硬脂酸由于其较高的分子尺寸和粘度主要影响反应过程中的传质而表现出较低的活性。