Sulfides catalysts for

A Molecular Approach to Synergy Generation in Co Mo Binary Sulfide Catalysts for Hydrodesulfurization... 

The use of nitrides, along with sulfides and carbides, as catalysts for hydroprocessing has recently been extensively reviewed by Furimsky and will not be discussed in detail here. Subsequently, Al-Megren et have published a comparison of the activities of bulk CoMo carbide, oxide, nitride and sulfide catalysts for pyridine hydrodenitrogenation. Of these, the sulfide catalysts were reported to possess more stable activity, with the carbide being next, followed... 

The presence of V3S4 crystals can only be attributed either to an autocatalytic mechanism of this type or the migration of the deposited metals. It is known that deposited Ni and V sulfides possess some catalytic activity (see Section IV). Slurry processes have been proposed which utilize Ni and V deposited from the oil onto a slurry material (Bearden and Aldridge, 1981). Studies have appeared in the literature demonstrating that nearly all of the transition metals are catalytically active for HDS reactions and presumably for HDM (Harris and Chianelli, 1984). Rankel and Rollmann (1983) impregnated an alumina catalyst base with Ni and V and concluded that these sulfides display an order of magnitude lower activity than the standard Co-Mo sulfide catalyst for HDS reactions, but exhibited similar activity for HDM reactions. 

Bender process a chemical treating process using lead sulfide catalyst for sweetening light distillates by which mercaptans are converted to disulfides by... 

Kushiyama et al (129) reported that phosphorus also promotes the activity of highly divided unsupported molybdenum and cobalt-molybdenum sulfide catalysts for HDS (and HDM) of crude oil, with a maximum at a P/(Co + Mo) atomic ratio of 2. This result warrants attention because it shows that phosphorus may directly modify the active sulfide phase(s) even in the absence of the alumina support. 

Catalysts were evaluated by means of different test reactions cyclohexane dehydrogenation, cyclopentane hydrogenolysis and coking reaction with cyclopentane at high pressure (15 bar). The reaction conditions are summarized in Table 1. Before performing the test reactions, presulfided catalysts were reduced at 500°C for 8 h and non-sulfided catalysts for 2 h. Coke... 

PREPARATION AND CATALYSIS OF HIGHLY DISPERSED METAL SULFIDE CATALYSTS FOR HYDRODESULFURIZATION... 

The promotional ratio is defined here as the ratio of the activity of the Co-Mo composite catalyst to that of the host Mo sulfide catalyst. The promotional ratio is plotted in Fig. 8 against N(Mo-Mo) of the host Mo sulfides. It is evident that the promotional ratio increases as the dispersion of the Mo sulfide increases. It is demonstrated that highly dispersed Mo sulfides lead to the formation of highly dispersed and highly active Co-Mo sulfide catalysts for HDS. 

Okamoto Y (1996) Preparation and catalysis of highly dispersed metal sulfide catalysts for hydrodesulfurization. In Absi-Halabi M (ed) Catalysts in petroleum refining and petrochemical industries. Elsevier, Amsterdam, p 77... 

J.D. Benck, Z. Chen, L.Y. Kuritzky, A.J. Forman, T.F. JaramiUo, Amorphous molybdenum sulfide catalysts for electrochemical hydrogen production insights into the origin of then-catalytic activity (ACS Catalysis, 2012), pp. 1916-1923... 

With respect to the metal recovery for reuse, the study of Lee et al deserves attention. These authors used the oil-soluble compounds of Mo, W, Ni and Co as the precursors for dispersed metal-sulfide catalysts. For single metals, the best performance was observed for the Mo catalyst. The combination of Co -1- Mo gave the most active catalyst for HDS, whereas Ni + Mo was best for HCR. In this study, the fixed bed of extmdates made either of the microporous AC or of y-Al203 was placed downstream of the reaction zone with the aim to remove metals from the product streams. For the former, the overall conversion increased with time on stream. This was attributed to the accumulation of metals on AC. Thus, the metal-deposited AC exhibited catalytic activity. It was noted that the efficiency of the metal removal using the AC extrudates was rather high. It is believed that there are a number of methods that are suitable for the recovery of metals that were trapped by the AC. For example, combustion of the AC will leave behind ash with a high concentration of metals. In this study, an AR containing 26 ppm of V + Ni was used as the feed. 

Different methods of preparation were also envisaged to avoid from using the complex sulfidation of oxides into sulfides that sometimes do not allow a perfect activation of sulfide catalysts. For example, Seiver and Chianelli [112] used low-temperature precipitation method for the preparation of group IVB, VB, and VIB binary sulfides. This low-temperature meta-thetical reaction allows controlling particle size and composition and occurs as follows ... 

Scheme 20.5 Selected sulfide catalysts for asymmetric epoxidation.

Tran PD, Chiam SY, Boix PP, Ren Y, Pramana SS, Fize J, Artero V, Barber J (2013) Novel cobalt/nickel-tungsten-sulfide catalysts for electrocatalytic hydrogen generation from water. Energy Environ Sci 6 2452-2459... 

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