Catalysts hydrotreating

Hydrotreating catalysts comprise oxides of either Mo or W and either Co or Ni on a support comprised of y-alumina. Usually, CoMo catalysts are used for HDS. NiMo catalysts are used for HDS and HDN. NiW catalysts are especially active for the saturation of aromatics. T57)ical physical properties are shown in Table 9. 

Hydrotreating catalyst particles are surprisingly small, with diameters of 1.5 to 3.0 mm and length/diameter ratios of 3 to 4. In many units, ceramic balls and/or successively larger catalyst particles are loaded on top of the first catalyst bed. This graded bed protects the bulk of the catalyst by filtering particulate matter out of the feed. 

Synthesis of Solid Catalysts. Edited by K.P. de Jong 2009 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim ISBN 978-3-527-32040-0 

Owing largely to research over the last twenty years, the sulfided C0-M0/AI2O3 system is one of the best-characterized industrial catalysts [H. Topsoe, B.S. Clausen and F.E. Massoth, Hydrotreating Catalysis (1996), Springer-Verlag, Berlin]. A combination of methods, such as Mbssbauer spectroscopy, EXAFS, XPS, and infrared spectroscopy, has led to a picture in which the active site of such a catalyst is known in almost atomic detail. 

Molybdenum disulfide has a layered structure. Each layer is a sandwich consisting of between two layers of ions (Fig. 9.5). The sulfur ions form trigonal prisms and half of the prisms contain a molybdenum ion in the middle. The chemical reactivity of M0S2 is associated with the edges of the sandwich, whereas the basal planes are much less reactive. The edges form the sites where gases adsorb and where the catalytic activity resides. 

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Volume 50 Hydrotreating Catalysts. Preparation, Characterization and Performance. 

FCC feed hydrotreating Gasoline end point reduction FCC gasoline hydrotreating Catalyst additives Bio-catalytic desulfurization... 

Mossbauer spectroscopy is a specialist characterization tool in catalysis. Nevertheless, it has yielded essential information on a number of important catalysts, such as the iron catalyst for ammonia and Fischer-Tropsch synthesis, as well as the CoMoS hydrotreating catalyst. Mossbauer spectroscopy provides the oxidation state, the internal magnetic field, and the lattice symmetry of a limited number of elements such as iron, cobalt, tin, iridium, ruthenium, antimony, platinum and gold, and can be applied in situ. 

However, residuum hydrotreating catalysts themselves are susceptible to irreversible deactivation caused by the accumulation of sulfided metal impurities. The gradual buildup of these impurities in the pores of a hydroprocessing catalyst causes plugging and deactivation. 

Lebreton, R. Brunet, S. Perot, G., et al., Influence of sulfur containing compounds on high temperature coke formation on hydrotreating catalyst. Studies in Surface Science and Catalysis, 2000. 130 p. 2861. 

Bogdanort, J. M., and Rase, H. F., Characteristics of a Commercially Aged Ni-Mo/AL203 Hydrotreating Catalyst Component Distribution, Coke Characteristics, and Effects of Regeneration. Ind. Eng. Chem. Prod. Res. Dev, 1986. 25 pp. 220-230. 

Miller, J.T., Marshall, C.L., and Kropf, A.J. 2001. (Co)MoS2/alumina hydrotreating catalysts An EXAFS study of the chemisorption and partial oxidation with 02. J. Catal. 202 89-99. 

Hydrotreating Catalysts, Occelli, M. L. and Anthony, R. G., Eds., Elsevier, Amsterdam, 1989. Topsoe, H., Clausen, B. S., Massoth, F. E., Hydrotreating Catalysis Science and Technology, Springer-Verlag, Berlin, 1996. 

OptiCAT-plus A process for regenerating hydrotreating catalysts. It uses a fluidized-bed pretreatment to control the initial exotherms found in regeneration, followed by a moderate heat soak to eliminate sulfur and carbon. Developed in the 1990s by the Criterion Catalyst Company. 

If reaction (2-13) follows reaction (2-12) instantaneously, the effect will not be noticeable in the H2 signal [12]. In spite of these limitations, we conclude that TPS with mass spectrometric detection is a highly useful technique for studying the sulfidation of hydrotreating catalysts. We shall return to the sulfidation of molybdenum oxides in the chapters on photoemission (Chapter 3), ion spectroscopy (Chapter 4), and in a case study on hydrodesulfurization catalysts in Chapter 9. 

Figure 4.14 Kinematic factors Ej/E, for He and Ne scattering as a function of scattering angle for the elements present in a hydrotreating catalyst, calculated with (4-4).

X-Ray Absorption Fine Structure, Mossbauer, and Reactivity Studies of Unsupported Cobalt-Molybdenum Hydrotreating Catalysts... 

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