Hydrodesulfurization activities

Figure 9.7. The hydrodesulfurization activity oftransition metal sulfides obeys Sabatier s principle (Section 6.5.3.5) the curve is a so-called volcano plot. [Adapted from T.A. Pecoraro and R.R. Chianelli.J, Catal. 67 (1981) 430 P.Raybaud,). Hafner, G. Kresse,...

Coulier, L. Kishan, G. van Veen, J. A. R., and Niemantsverdriet, J. W., Surface science models for CoMo hydrodesulfurization catalysts Influence of the support on hydrodesulfurization activity. Journal of Vacuum Science Technology A Vacuum, Surfaces, and Films, 2001. 19(4) pp. 1510-1515. 

Xu, W., et ah, Low-temperature plasma-assisted preparation of graphene supported palladium nanoparticles with high hydrodesulfurization activity. Journal of Materials Chemistry, 2012. 22(29) p. 14363-14368. 

Catalysts NiMo-124 have been prepared according to this patent and have been investigated. The hydrodesulfurization activity showed indeed a pronounced decrease on calcination at 650°C in comparison with the 480°C calcined sample. 

Figure 1. The effects of a series of Mo/AljOj catalysts with varying Mo loading (0-10%(m/m)) on the coke selectivity and the hydrodesulfurization activity. The HDS activity has been expressed as a second-order rate constant ( hds)< Process conditions temperature 450 C, pressure 30 bar, H2/oil ratio 900 Nl/kg, WHSV 1.3 kg/(kg h) and run length 180 h.

Figure 1. Volcano plot showing the effect of the heat of formation of metal sulfides on the dibenzothiophene hydrodesulfurization activity of various mono- and bimetallic catalysts. Adapted from Chianelli et al. [6] and reprinted with permission of John Wiley Sons from L. L. Hegedus, ed., Catalyst Design— Progess and Perspectives, p. 1. Wiley, New York (1987) [1]. Copyright 1987, John Wiley Sons.

In industrial practice, catalytic surfaces are often very complex, not only structurally but also chemically. An example is shown in Fig. 1 from Chianelli et al. [6] for hydrodesulfurization catalysts. The data indicate that maximum dibenzothiophene hydrodesulfurization activity is achieved at intermediate heats of formation of metal sulfides, i.e., at intermediate metal-sulfur bond strengths. Again, while such surface energetic considerations do not have ab initio predictive ability, they are valuable tools for catalyst synthesis and prescreening. 

Figure 24. Hydrodesulfurization activity of catalysts (Procata-lyse HR 306) activated according to different procedures at different temperatures (RS) simultaneous reduction sulfidation (15% H2S in H2) - except for the experiment at 573 K, the samples were first reacted for 4 h at 673 K, then progressively heated to the temperature indicated in the figure and maintained at this temperature for 4h (R + RS) successive reduction in H2 (4h) and reduction-sulfidation, as above (4h), both at the temperature indicated (R + RS ) reduction at the temperature indicated (4 h) followed by reduction-sulfidation at 673 K (4 h) as above (S + RS) sulfidation by pure H2S (4 h) followed by reduction sulfidation as above (4 h), both steps at the temperature indicated. The reaction with hydrogen with a feed containing 0.5% thiophene and 30% cyclohexene in cyclohexane was made under a total pressure of 3 MPa [138, 152],...

The noble metal component may be either palladium or platinum the effect of the concentration of both metals on methylpentane as well as on dimethylbutane selectivity in C6 hydroisomerization on lanthanum and ammonium Y-zeolite with Si/Al of 2.5 has been studied by M.A. Lanewala et al. (5). They found an optimum of metal content for that reaction between 0.1 and 0.4 wt.-%. The noble metal has several functions (i) to increase the isomerization activity of the zeolite (ii) to support the saturation of the coke precursors and hence prevent deactivation, as was shown by H.W. Kouvenhoven et al. (6) for platinum on hydrogen mordenite (iii) to support the hydrodesulfurization activity of the catalysts in sulfur containing feedstocks. 

To study the benzene saturation under high sulfur conditions, the same feed, but spiked with 30 ppmw of sulfur (as ethyl mercaptan), has been used (4). Sulfur in the effluent was analyzed to calculate the hydrodesulfurization activity. 

Coulier, L., V. H. J. de Beer, J. A. R. van Veen, and J W. Niemantsverdriet, Correlation between Hydrodesulfurization Activity and Order of Ni and Mo Sulfidation in Planar Silica-Supported NiMo Catalysts the Influence of Chelating Agents , J. Catal 197, Issue 1,1 January 2001, pp 26-33. 

Since hydrogen sulfide suppresses the activity of hydrodesulfurization catalysts, the downstream pan of the bed operates under suboptimal conditions, which is particularly disadvantageous since the conversion of the more refractive sulfur-containing compounds in this part of the bed calls for the highest catalytic activity. The suppression of hydrodesulfurization activity by hydrogen sulfide is illustrated by the experimental data in Fig. 2. 

Rodriguez JA, Kim JY Hanson JC, Sawhill SJ, Bussell ME (2003) Physical and chemical properties of MoP, Ni P, and MoNiP hydrodesulfurization catalysts Time-resolved X-ray diffraction, density functional, and hydrodesulfurization activity studies. J Phys Chem B 107 6276... 

It is interesting to note that Reddy and Manohar could show that M0S2 did also spread on the surface of AI2O3 supports. The resulting material developed a thiophene hydrodesulfurization activity which was identical to that measured on a conventionally impregnated and sulfided catalyst. 

Kaluza, L. and Zdrazil, M. Carbon-supported Mo catalysts prepared by a new impregnation method using a Mo03/water slurry Saturated loading, hydrodesulfurization activity and promotion by Co. Carbon, 2001, 39, 2023. 

Lecrenay, E., Sakanishi, K., Mochida, I., and Suzuka, T. Hydrodesulfurization activity of CoMo and NiMo catalysts supported on some acidic binary oxides. Applied Catalysis. A, General, 1998, 175, 237. 

The quality of the regenerated catalyst was studied by means of Surface Area (SA) and Dynamic Oxygen Chemisorption (DOC). DOC has been proven previously to be an elegant technique for the evaluation of hydrotreating catalysts. Hydrodesulfurization activity has been correlated with the amount of oxygen chemisorbed at low temperature (5, 6). 

Gil Llainbias, EJ. et al.. Hydrodesulfurization activity of WOj/y-alumina prepared by the equilibrium adsorption method, Appl. Catal.,, 59, 185, 1990. 

The catalysts were characterized by N2 physisorption, XRD, thermodesorption of Py (FT-IR), NH3 TPD, TPR and NO chemisorption. The DBT and 4,6-DMDBT hydrodesulfurization activity tests were conducted in a 300 ml batch reactor at 300°C and 7.3 MPa total pressure. Before the activity tests, the catalysts were sulfided ex-situ in a tubular reactor at 400 C, 4 h, in a stream of H2S (15 vol%)-H2. The course of the reaction was followed by taking liquid samples and analyzing them by GC or GC-MS. 

Vazquez A, Pedraza F, Fuentes S. Influence of sulfidation on the morphology and hydrodesulfurization activity of palladium particles on silica. J Mol Catal. 1992 75(1) 63. Feuerriegel U, Klose W, Sloboshanin S, Goebel H, Schaefer JA. Deactivation of a ptilladium-supported alumina catalyst by hydrogen sulfide during the oxidation of methtme. Langmuir. 

Similar reactivity to Pt in alcohol synthesis, methane dehydrogenation, and hydrocarbon isomerization Excellent hydrodesulfurization activity Promotes the water gas shift (WGS) reaction at low temperatures High resistance to coking even under stoichiometric fuel reforming conditions Shows the potential of being sulfur-tolerant High selectivity for hydrocarbon conversions... 

Hilsenbeck, S. J. McCarley, R. E. Goldman, A. I. et al. Hydrodesulfurization Activity and EXAFS Characterization of Novel Ternary Tin and Lanthanum Molybdenum Sulfide Catalysts. Chem. Mater. 1998, 10, 125-134. 

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