合成条件对磷钨酸负载的金属有机框架催化剂氧化脱硫性能的影响

通过一步水热合成法制备了大比表面积、高脱硫活性的磷钨酸(HPW)负载的金属有机框架HPW@MIL-101(Cr)催化剂,对其进行了FT-IR、XRD和氮吸附等表征,并研究了合成时间、合成温度、酸碱度及HPW负载量等参数对催化剂脱硫性能的影响。结果表明,随着合成时间的延长、合成温度的提高,HPW@MIL-101(Cr)孔道有序度提高;合成温度低于等于140℃时,不能形成M IL-101(Cr)晶体结构;酸性合成条件合成的HPW@M IL-101(Cr)的孔道有序度降低;随着HPW负载量的增加,HPW@MIL-101(Cr)的催化性能呈现先升高后降低的趋势。在12 h、220℃和中性条件下制备得到的负载量为3.5 g的HPW@MIL-101(Cr)催化剂具有最佳脱硫活性;在模拟油20 mL、催化剂用量0.24 g、氧硫比为8和50℃条件下反应120 min,对苯并噻吩、二苯并噻吩和4,6-二甲基二苯并噻吩脱硫率分别为99%、100%和99%;与HPW相比,苯并噻吩脱硫率提高了2.4倍。

Effect of synthesis conditions on the catalytic performance of phosphotungstic acid encapsulated metal-organic framework in the oxidative desulfurization

A series of phosphotungstic acid (HPW) encapsulated metal-organic HPW@MIL-101(Cr) catalysts, with high surface area and high activity in the oxidative desulfurization (ODS), were synthesized by one-step hydrothermal method and characterized by FT-IR, XRD and nitrogen physisorption. The influences of synthesis time, temperature, HPW loading, and acidity/alkalinity on the catalytic performance of HPW@MIL-101(Cr) in ODS were then investigated. The results indicated that the order degree of channels in HPW@MIL-101(Cr) is improved with the increase of synthesis time and temperature. The crystal structure of MIL-101(Cr) cannot be formed at a synthetic temperature below 140℃ and the channel order of HPW@MIL-101(Cr) decreases under an acidic synthetic environment. The catalytic activity of HPW@MIL-101(Cr) displays a trend of first increasing and then decreasing with the increase of HPW loading. The HPW@MIL-101(Cr) catalyst with a HPW loading of 3.5 g, synthesized at 220℃ under neutral environment for 12 h, exhibits the highest activity in ODS. At 50℃, with a catalyst dosage of 0.24 g, an model oil of 20 mL, and an O/S molar ratio of 8, the desulfurization rates over the HPW@MIL-101(Cr) catalyst towards benzothiophene, dibenzothiophene, and 4,6-dimethyl dibenzothiophene after reaction for 120 min reach 99%, 100% and 99%, respectively; in particular, the desulfurization rate for benzothiophene is 2.4 times higher than that obtained over HPW.