New hydrotreating NiMo catalysts supported on MCM-41 modified with phosphorus

A series of MCM-41 supports modified with phosphorus (0-5 wt.% P2O5) and their respective NiMo catalysts were prepared and characterized by N2 physisorption, XRD, ammonia TPD, temperature programmed reduction (TPR), UV-vis diffuse reflectance spectroscopy (DRS), chemical analysis and HRTEM. It was shown that phosphorus insertion in the siliceous MCM-41 causes a deterioration of the textural characteristics and some loss in the periodicity of the MCM-41 pore structure. However, the acidity of MCM-41 material increases with P loading. XRD, DRS, TPR and HRTEM show that the characteristics of oxide and sulfided Mo and Ni species change with P incorporation in the MCM-41 support. Hydrodesulfurization (HDS) of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) was used to evaluate the activity of the prepared catalysts. It was shown that the modification of MCM-41 with phosphorus results in high-performance NiMo catalysts especially for HDS of the most refractory dibenzothiophenes, such as 4,6-DMDBT. Catalysts of NiMo/P-MCM-41 series showed higher catalytic activity in 4,6-DMDBT HDS than the reference NiMo/Al2O3 counterpart. Maximum catalytic activity in this case was observed for the catalyst supported on MCM-41 with 1 wt.% P2O5. Reaction product analysis shows that phosphorus addition promotes hydrogenation pathway of HDS.