g-C_3N_4固载磷钨酸催化剂的制备及催化性能

Preparation and catalytic performance of phosphotungstic acid immobilized on g-C_3N_4

以磷钨酸(PTA)和g-C_3N_4为原料,水热法制备g-C_3N_4固载磷钨酸(PTA/g-C_3N_4)催化剂。采用红外(FT-IR)、X-射线衍射(XRD)、扫描电子显微镜(SEM)、热重分析仪(TGA)、全自动比表面积及微孔物理吸附仪(BET)对制备的催化剂结构进行分析。将其应用于油酸和甲醇酯化制备生物柴油,以生物柴油收率为指标,考察该催化剂的催化性能。结果表明:PTA成功固载在gC_3N_4表面,固载后的PTA仍具有Keggin结构;在磷钨酸固载量40%、反应时间2 h、反应温度80℃、醇酸摩尔比10∶1、催化剂用量7.5%条件下,催化剂的催化性能最好,生物柴油收率达到98.4%。

Phosphotungstie acid（PTA） immobilized on g - C3N4 as catalyst （ PTA/g - C3N4 ） was pre- pared via hydrothermal method using phosphotungstic acid and g - C3 N4 as raw materials. Also, the structure of the catalyst was characterized by Fourier transform infrared spectroscopy （ FT - IR）, X - ray diffraction （XRD）, scanning electron microscopy （SEM）, thermogravimetric analysis （TGA） and auto- matic specific surface area and microporous physical adsorption （BET）. Furthermore, the obtained cata- lyst was applied to the esterification of oleic acid and methanol to prepare biodiesel, and the catalytic per- formance of the catalyst was studied with the yield of biodiesel as index. The results showed that Keggin structure of PTA active species was still kept after being immobilized on the g - C3 N4 surface. Under the conditions of immobilization amount of phosphotungstic acid 40%, reaction time 2 h, reaction temperature 80℃, molar ratio of methanol to oleic acid 10：1 and catalyst dosage 7.5%, the catalyst had the best catalytic performance, and the yield of biodiesel reached 98.4%.