Effects of Al introduction methods for Al-SBA-15 on NiMoS active phase morphology and hydrodesulfurization reaction selectivities

Abstract

A series of Al-SBA-15 were synthesized with three Al introduction methods and different Si/Al molar ratios. The introduction methods included the direct synthesis (DS), post-synthesis grafting (PG) and impregnation synthesis (IM) method. The Si/Al molar ratios of Al-SBA-15 materials were 20, 10 and 5 respectively. The corresponding NiMoS catalysts were performed by hydrodesulfurization (HDS) recations of dibenzothiophene (DBT) to analyze reaction behavior. The characterization results of N2-physisorption, X-ray diffraction and 27Al NMR presented that the Al introduction method has a direct effect on the physical and chemical properties of Al-SBA-15. PG method could introduce most of Al atoms into the framework of parent- material, which was opposed to the IM method. The DS method could better maintain the pore structure advantages of the Al-SBA-15. The PG-NiMo catalyst had the strongest metal-support interaction, and the NiMoS slabs presented the lowest average stacking number over this catalyst. The reaction results showed that DS-NiMo catalyst obtained the highest HDS activity, and PG-NiMo catalyst presented the highest HDS hydrogenolysis selectivity of DBT. It is speculated that the frame-work Al has strong metal interaction with metal oxide precursor, and the morphology of NiMoS Phase has important effect on the selectivity of DBT HDS.