Investigation of co-effect of 12-tungstophosphoric heteropolyacid, nickel citrate and carbon-coated alumina in preparation of NiW catalysts for HDS, HYD and HDN reactions

Mesoporous zeolite-supported metal sulfide catalysts with high activities in the deep hydrogenation of phenanthrene

“…In contrast, the band at 895 cm À1 is not observed on the NiMo/MZSM-5 sample, while the (Fig. 9a), the overlapping profiles in the temperature range of 367-690°C can be assigned to the reduction of Ni 2+ and Ni octahedral species (Ni oct 2+ ) [64,65]. The very small profiles with peak at 210°C may be associated with the superficial reduction of nickel oxide [66].…”

“…This result suggests that the intrinsic activities of the metal sulfide catalysts could correlate with the morphology (length and stacking number) of MoS 2 crystallites. Nikulshin and co-workers also reported that the hydrogenation activity of the NiW and Co(Ni)Mo catalysts supported on c-Al 2 O 3 increased with the decrease in slab length and Ni/W(Mo) edge ratio of the active phase [65,78]. In addition, the MoS 2 particles with shorter slab length and relatively less stacking could provide more exposure of the edge of MoS 2 slabs, leading to an increase in the available sites for Ni promotion [65].…”

“…Compared with the reduction behavior of the Mo/MZSM-5 and Ni/MZSM-5 samples, the profile with a peak at 370°C should involve the reduction of octahedral Mo and Ni 2+ species, and the profile with a peak at 561°C should be attributed to the further reduction of the octahedral Mo species and Ni oct 2+ species for the NiMo/MZSM-5 sample (Fig. 9c) [53,64,65]. Similarly, the reduction profile in the relatively low temperature range of 325-625°C is also observed on the NiMo/c-Al 2 O 3 sample, which should be attributed to the reduction of the octahedral Mo species and all Ni 2+ species (Fig.…”

“…Generally, the stacking and slab length of the MoS 2 crystallites strongly influence the intrinsic activity of the catalyst [56,65,78]. Because the stacking and slab length of the MoS 2 crystallites could be controlled by varying the Mo loadings on the support, it is possible to establish the relationship between the slab length and stacking of the MoS 2 and hydrogenation activity by using different Mo loading catalysts.…”

Sulfide Catalysts Supported on Porous Aromatic Frameworks for Naphthalene Hydroprocessing

“…In general, two methods for obtaining sulfide catalysts are used: impregnation of different supports by metal salts with post-sulfidizing [2][3][4][5], and usage of metal sulfides as catalyst precursors with conversion to a catalytically-active form during the reaction [6][7][8][9]. The mechanisms, by which metal sulfides decompose to their active form were investigated in several studies [10,11].…”