Synthesis and characterization of P-modified mesoporous CoMo/HMS–Ti catalysts

Competitive HDS and HDN reactions over NiMoS/HMS-Al catalysts: Diminishing of the inhibition of HDS reaction by support modification with P

“…Noticeably, the catalyst with a largest P content (2.0 wt.%), showed a small decrease of its average pore diameter with respect to P-free one (from 2.9 to 2.4 nm) suggesting that its micropores were blocked by P species. The large decrease in the surface area, pore diameter and pore volume at high P-loadings suggests the formation of large MoS 2 particles partially blocking support structure, in agreement with previous published reports [13,18].…”

“…In this sense, it is known that the mesoporous silica materials, such as hexagonal mesoporous silica (HMS), exhibit a much lower metal-support interaction. Moreover, the enhancement of the catalyst hydrogenation function was observed after modification of HMS substrate with Al 3+ ions [13]. This prompted us to study the effect of modification of the HMS substrate with both P and Al on the catalytic response of NiMo catalysts in simultaneous HDS+HDN reaction.…”

Morphological investigation of nanostructured CoMo catalysts

“…However, a comparison of the N 2 adsorption-isotherms of the HMS-Ti and P/HMS-Ti materials (not shown here) excluded this possibility [14]. Since the calculation of the normalized specific surface area indicated that the P species are located exclusively on the external surface of the P/HMS-Ti, the much lower S BET of SIM-P sample with respect to SUC-P catalyst (634 vs. 793 m 2 g cat À 1) is more likely to be due to the deposition of metal oxides in the pores of P/HMS-Ti support when the successive impregnation method is employed [14]. Fig.…”

“…Since XPS techniques reveal the surface exposure of molybdenum species in the oxide precursors, whereas HRTEM shows the bulk morphology of the sulfide catalyst, such correlation indicates that MoS 2 phase has its origin in the MoO 3 species located on the catalyst surface. Indeed, we previously reported a correlation between molybdenum species surface exposure in the freshly sulfided catalysts and their catalytic response in the HDS of DBT reaction performed in a batch reactor [14]. Since all oxide precursors in this study have a similar Mo/Si atomic ratio indicating similar molybdenum oxide species surface exposure (Table 3), the correlation observed previously [14] indicates that the surface exposure of Mo oxide species changes slightly after sulfidation at 673 K. However, it is noteworthy that all catalysts proved to be stable under on-stream conditions (see Fig.…”

“…The second goal was to determine whether there is a correlation between the activity of sulfided catalysts in the HDS of DBT reaction and the dispersion of the MoS 2 phases, as determined by HRTEM. Since the catalyst might undergo poisoning by the H 2 S evolved from DBT transformation when the HDS reaction takes place in a batch reactor [14], the HDS of DBT reaction in this study has been performed in a continuous-flow reactor.…”