磷钨酸/SBA-15催化氧化-萃取柴油脱硫

摘要

以自制的SBA-15为载体，磷钨酸为活性组分，用过量浸渍法制备了HPW/SBA-15催化剂，并采用SEM、BET 和 TG-DTA 对催化剂进行表征分析。H2O2为氧化剂，十六烷基三甲基溴化铵（CTAB）为相转移剂，以二苯并噻吩（DBT）的模型化合物（DBT 为溶质、正辛烷为溶剂）进行氧化脱除为探针反应，考察了磷钨酸负载量和HPW/SBA-15的焙烧温度对催化剂活性的影响，同时考察了氧化-萃取工艺条件对真实柴油脱硫效果的影响。实验结果表明，磷钨酸最佳负载量为30%，HPW/SBA-15在250℃焙烧处理时活性最高；在n(H2O2)∶n(S)=6、HPW/SBA-15用量为2.5%（基于柴油质量）、CTAB用量为0.4%（基于柴油质量）、萃取级数为4、温度60℃反应1.5h的条件下，柴油硫含量从1317mg/L降到39mg/L，脱硫率达到97.0%、收率不低于85.0%。气相色谱结果显示，该催化氧化脱硫体系容易脱除柴油中加氢难以脱除的二苯并噻吩及其衍生物。%A series of HPW/SBA-15 were prepared by supersaturated impregnation method with phosphotungstic acid loaded on SBA-15. The catalysts were characterized by means of BET,SEM and TG-DTA. The effects of HPW loading amount and calcination temperature on the desulfurization were investigated by studying the DBT desulfurization performance on the HPW/SBA-15 with H2O2 as oxidation and CTAB as phase transfer catalyst. Meanwhile,the effects of different oxidation-extraction conditions on diesel desulfurization were investigated. The results showed that the best mass percentage of HPW was 30% and HPW/SBA-15 showed the highest activity at 250℃. The sulfur content in the diesel oil decreased from 1317mg/L to 39mg/L and thesulfur removal rate reached 97.0% under the best condition ofn(H2O2)∶n(S)=6,the mass percentage of HPW/SBA-15 of 2.5% that of CTAB of 0.4%(both based on the diesel oil),extraction stage of 4,reaction temperature of 60℃ and reaction time of 1.5h. According to GC analysis,the HPW/SBA-15 catalytic oxidation-extraction method could easily remove dibenzothiophene and its derivatives,which were quite inert in diesel during its hydrodesulfurization.