不同硅源对NiW/Al2O3-SiO2催化剂加氢脱硫性能的影响

 分别以硅溶胶、SiO₂粉、正硅酸乙酯(TEOS)为硅源与Al₂O₃粉制备成硅铝载体，然后采用孔饱和法制备负载型NiW催化剂NiW/Al₂O₃-SiO₂。采用TPR、XPS和TEM手段对各硫化态NiW/Al₂O₃-SiO₂催化剂进行了表征。在微反装置中，以4,6-二甲基二苯并噻吩(4,6-DMDBT)为模型硫化合物，评价其加氢脱硫活性，并与NiW/Al₂O₃比较。结果表明，采用无机硅源制备的NiW/Al₂O₃-SiO₂催化剂的加氢脱硫活性高于NiW/Al₂O₃；而由正硅酸乙酯制备的NiW/Al₂O₃-SiO₂催化剂仅在SiO₂质量分数为5%时，其加氢脱硫活性才高于NiW/Al₂O₃。同时，不同硅源制备的NiW/Al₂O₃-SiO₂催化剂对其上4,6-DMDBT加氢脱硫反应的直接脱硫和加氢脱硫两条路径的促进作用也不相同，由无机硅源制备的NiW/Al₂O₃-SiO₂催化剂对直接脱硫路径的促进作用强于对加氢路径的促进作用；而由正硅酸乙酯制备的催化剂对直接脱硫路径无促进作用。NiW/Al₂O₃-SiO₂加氢脱硫性能的提高与其容易还原和硫化的性能相关。

EFFECT OF SILICA SOURCE ON HYDRODESULFURIZATION PERFORMANCE OF NiW/Al2O3-SiO2 CATALYST

A series of NiW/Al2O3-SiO2 catalysts were prepared by incipient wetness impregnation with silica sol，silica powder and tetraethyl orthosilicate (TEOS) as the silica source, respectively, which were then characterized by the means of TPR, XPS and TEM after their sulfurization. The 4,6-dimethyldibenzothiophene (4,6-DMDBT) was used as the model to test the hydrodesulfurization activity of these NiW/Al2O3-SiO2 catalysts in microreactor. The evaluation results were compared to that of NiW/Al2O3. It is shown that the silica source played an important role on HDS performance of NiW/Al2O3-SiO2. The NiW/Al2O3-SiO2 catalyst prepared from inorganic silca source exhibited higher HDS activity than NiW/Al2O3, and the NiW/Al2O3-SiO2 catalyst prepared from TEOS showed higher HDS activity than NiW/Al2O3 only when its silica mass fraction was 5%. In addition, the silica source also had different effects on the two routes of 4,6-DMDBT desulfurization. The NiW/Al2O3-SiO2 catalyst prepared from inorganic silica had more positive effect on direct desulfurization (DDS) route of 4,6-DMDBT than on hydrogenation desulfurization (HYD) route. However, the NiW/Al2O3-SiO2 catalyst prepared from TEOS had no positive effect on DDS route of 4,6-DMDBT. It was also noticed that the enhancement of desulfurization ability for NiW/Al2O3-SiO2 catalyst related to its properties of easy reduction and sulfurization.