Radioisotopic study of (Co)Mo/Al2O3 sulfide catalysts for HDS

Evolution and interlayer dynamics of active sites of promoted transition metal sulfide catalysts under hydrodesulfurization conditions

“…This model agrees with previously obtained results. Thus, in the course of radioisotopic examinations of the mechanism of poisoning of the CoMo/Al 2 O 3 sulfide catalysts by N-containing compounds [40] we showed that in the course of the HDS of thiophene and 4-methyl-and 4,6-dimethyldibenzothiophenes CoMoS catalysts demonstrate stronger resistance to poisoning in HYD reactions than in desulfurization (DS) ones. In the course of dibezothiophene HDS, catalysts demonstrate the opposite trend.…”

Description of coordinatively unsaturated sites regeneration over MoS2-based HDS catalysts using 35S experiments combined with computer simulations

“…Besides, 35 S radioactive tracer methods were developed to determine the sulfidation process of HDS catalysts as well as to describe the HDS reaction mechanism over various catalysts under real working conditions [32,34,35,[73][74][75][76][77][78][79][80]. On the other hand, with the recent developments of the computer simulations, new insights in the state of the HDS catalysts surface [81][82][83][84] as well as an overview of the HDS mechanism over the simulated surfaces were concurrently proposed [85,86].…”

35S Tracer Study of the Effect of Support on the Nature of the Active Sites of Co(Ni)Mo Sulphide Catalysts Supported on Al2O3and Activated Carbon

“…Figure 7 shows how the butane:butenes ratio, which is a characteristic of hydrogenating capacity, depends on the density of functioning vacancies (number of V's per 1000 SH groups) for the Mo/Al 2 O 3 and Mo/C catalysts. The hydrogenating capacity of these catalysts, like that of catalysts poisoned with N-containing compounds [31], depends linearly on the density of the vacancies responsible for desulfurization. This finding confirms the deduction that thiophene hydrogenation and desulfurization take place at the same sites.…”

“…It is, therefore, pertinent to make a more thorough analysis of the data relevant to the mobility and distribution of mobile sulfur in the active phase. It was demonstrated [31] that the active phase of the CoMo/Al 2 O 3 and NiMo/Al 2 O 3 bimetallic catalysts has two types of surface SH group differing in capacity for forming H 2 S (mobility) and, accordingly, two types of active site (AS) differing in reactivity. The more reactive sites (rapid AS's) are associated with Mo, and the less reactive sites (slow AS's) are associated with Co. Figure 10 plots S mob /Mo as a function of the promoter content r = Ni / (Ni + Mo) for the γ-Al 2 O 3 -and C-supported catalysts.…”

“…It is assumed that desulfurization and hydrogenation sites are different and no quantitative estimates have been reported for the properties of these sites. Application of the radioisotopic technique [29][30][31] enabled us to determine the number of surface SH groups, evaluate the reactivity of active sites, and correlate these data with the composition of the active phase of the sulfide catalyst. Here, we report a radioisotopic investigation of the dependence of catalyst activity in thiophene hydrogenolysis on the nature of the support.…”