Effect of the electronic properties of Mo sulfide phase on the hydrotreating activity of catalysts supported on Al2O3, Nb2O5 and Nb2O5/Al2O3

Abstract

Activity in thiophene hydrodesulfurization (HDS) and in the three routes of 2,6-dimethylaniline (DMA) decomposition was examined on Mo sulfide catalysts supported on Al 2 O 3 , Nb 2 O 5 and Nb 2 O 5 -Al 2 O 3 . Catalysts activity is enhanced when Mo phase is deposited on niobium-containing support. For HDS and for the hydrogenation route of DMA decomposition, the niobiumcontaining support strongly contributes to the catalyst activity whereas the activity of the Mo phase per Mo atom decreases with the increase of niobium amount in the support. By contrast, as for the DMA route, which leads to xylene formation (XYL), the activity of the Mo sulfide phase per Mo atom is strongly enhanced. The electronic properties of the MoS 2 phase were studied by means of IR spectroscopy of CO adsorption. Comparison of m(CO/Mo) wavenumbers reveals an upward shift when Mo sulfide phase is deposited on Nb-containing support. The modification of the electronic properties of the sulfide phase is related to an interaction Mo-Nb either through the formation of a mixed Mo-Nb sulfide phase, or through the interaction MoS 2 slabs -support whose strength depends on the support acidity. Hence, the beneficial effect for xylene formation route is attributed to a decrease of the electron density of the Mo sulfide phase that should strengthen the DMA adsorption on the sulfide phase.

Hydrotreatment of heavy oil from coal liquefaction on Sulfided Ni - W Catalysts

“…The relative hydrogenation activity of Ni-W was higher than that of Ni-Mo. Such difference in hydrogenation may be attributed to the difference in the 23 Then, the synergy effect between Ni and W is stronger than that of Ni and Mo. All the results above indicate that the higher hydrogenation activity of sulfided catalysts for coal-derived heavy oil upgrading is associated not only with the nature of active sites and larger pore size but also with the strong acidic sites, metal sulfide crystallite size and the formation of S anion vacancies.…”

Support effect in the hydrodesulfurization of thiophene over rhodium sulfide

“…Niobium oxide hydrate HY-340 from CBMM has been used as Nb 2 O 5 precursor in previous works on HDS. Depending on the temperature of calcination (450-500°C), the surface area achieved varied in the range 30-70 m 2 g -1 (for instance papers [16,17]). We used a rather low calcination temperature of 350°C and short time of 45 min and obtained somewhat higher S BET (99 m 2 g -1 ), which was, however, still not above 100 m 2 g -1 .…”

Unsupported trimetallic Ni(Co)-Mo-W sulphide catalysts prepared from mixed oxides: Characterisation and catalytic tests for simultaneous tetralin HDA and dibenzothiophene HDS reactions

“…The activity and selectivity results of catalytic tests for simultaneous HDS of DBT and HDA of THN are shown in Table 6 for both Ni and Co promoted unsupported catalysts. For comparison, the results for an alumina-supported NiMo catalyst with a 1:1 nickel to molybdenum ratio, whose characterisation was already reported [31,36], are also shown.…”

“…The NiMo layered precursor (Ni1.6-Mo-am), its corresponding mixed oxide (Ni1.6-Mo-ca) and sulphided catalyst (Ni1.6-Mo-s) have been studied in previous work [31], where the simultaneous HDS/HDA activity of the latter was compared with that of an aluminasupported NiMo material synthesised in our laboratory [36].…”