Effect of TiO2 on hydrodenitrogenation performances of MCM-41 supported molybdenum phosphides

The effect of TiO2 on the hydrodenitrogenation (HDN) performance of MoP/MCM-41 was investigated using quinoline and decahydroquinoline as the model molecules. The catalysts were characterized by XRD, CO chemisorption, TEM, TPR and pyridine FT-IR. Addition of TiO2 enhanced the C–N bond cleavage activity of MoP/MCM-41 but inhibited its dehydrogenation activity. A maximum HDN activity was observed when the TiO2 loading was 5 wt%. The characterization results indicated that introduction of TiO2 did not affect the formation of MoP phase. The TiO2-containing catalysts possessed higher CO uptake than MoP/MCM-41, but no significant differences in the acid properties and particle size distributions were observed for all the catalysts. XPS results revealed a surface enrichment of TiO2 in Ti-containing catalysts and small amount of these surface TiO2 can be partially reduced to Tin+ (n < 4). It is suggested that these Tin+ (n < 4) species may be responsible for the promoting effect of TiO2 on the HDN performance of MoP/MCM-41.