Organometallic catalysts, hydrodesulfurization

Figure 4.23. Infrared spectra of NO probe molecules on sulfided Mo, Co, and Co-Mo hydrodesulfurization catalysts. The peak assignments are supported by the IR spectra of organometallic model compounds. These spectra allow for a quantitative titration of Co and Mo sites in the Co-Mo catalyst.

Residua and heavy oils contain impurities other than sulfur, nitrogen, and oxygen, and the most troublesome of these impurities are the organometallic compounds of nickel and vanadium. The metal content of a residuum or heavy oil can vary from several parts per million (ppm) to more than 1000 parts per million (Table 6-15), and there does seem to be more than a chance relationship between the metals content of a feedstock and its physical properties (Reynolds, 1997 Speight, 1999). In the hydrodesulfurization of the heavier feedstocks the metals (nickel plus vanadium) are an important factor since large amounts (over 150 ppm) will cause rapid deterioration of the catalyst. The free metals, or the sulfides, deposit on the surface of the catalyst and within the pores of the catalyst, thereby... 

P. Mills, S. Korlaim, M.E. Bussell, M.A. Reynolds, M.V. Ovchinnikov, R.J. Angelici, C. Stinner, T. Weber R. Prins (2001). J. Phys. Chem. A, 105, 4418-4429. Vibrational study of organometallic complexes with thiophene ligands Models for adsorbed thiophene on hydrodesulfurization catalysts. 

A. Hydrodesulfurization and hydrodenitrogenation catalysis. The supported metal sulfides used as catalysts for hydroprocessing reactions have been characterized by many techniques, but the nature of the catalytically active sites is still a matter of controversy which makes it difficult to understand the mechanisms, and relevant organometallic models need to be developed. 

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