Na₂WO₄/SiO₂浸渍磷改性催化剂制备及其反应动力学模型探索

Preparation and Exploration of Reaction Kinetics Model of Phosphate Modified Na2WO4/SiO2 Catalyst

摘要: 本文采用浸渍法制备Na2WO4P2.5/SiO2催化剂，并以SiO2为载体，对催化剂进行了X射线衍射(XRD)，扫描电镜(SEM)和比表面积(BET)表征分析。采用噻吩/石油醚为模拟油，氧气为氧化剂，考察了催化剂P/W摩尔比及焙烧温度对脱硫效果的影响。实验表明，P/W摩尔比为2.5，600℃焙烧得到的Na2WO4P2.5/SiO2催化剂的脱硫效果最好。在噻吩/石油醚模拟油20 mL、催化剂用量0.12 g、氧气流量120 mL/min、氧化温度60℃，氧化时间40 min条件下，将所得到的产物，采用剂油比为1:1(体积)的甲醇、在萃取温度20℃下萃取10 min，脱硫率可以达到96.6%。在所研究的温度范围内，噻吩的氧化脱硫过程符合3/2级反应，Arrhenius活化能Ea = 25.914 kJ/mol，指前因子A = 470.4078 s−1。

Abstract: Na2WO4P2.5/SiO2 catalysts were prepared with the SiO2 supported by the impregnation method. The catalysts were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and specific surface area (BET) analysis. The effects of P/W molar ratio and calcination temperature on the catalytic oxidation desulfurization of cata-lyst were investigated on the catalytic oxidation desulfurization of catalyst using O2 as oxidant, thiophene/thiophene as raw material. The result showed that the Na2WO4P2.5/SiO2 catalyst with P/W molar ratio 2.5, calcination temperature of 600°C was found to be optimal. Under the conditions of thiophene/petroleum ether model oil 20 mL, catalyst 0.12 g, oxygen 120 mL/min, at 60°C, react for 40 min, the reactants extracted using methanol with the volume ratio of sol-vent/oil of 1:1, at 20°C with 10 min, the desulfurization ratio reached to 96.6%. Under the reaction temperature range concerned, kinetics of the catalytic oxidation desulfurization of thiophene met the 3/2 order model with the Arrhenius activation energy Ea = 25.914 kJ/mol, A = 470.4078 s−1.