Hydrodesulfurization catalysts for

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

Mossbauer spectroscopy is one of the techniques that is relatively little used in catalysis. Nevertheless, it has yielded very useful information on a number of important catalysts, such as the iron catalyst for Fischer-Tropsch and ammonia synthesis, and the cobalt-molybdenum catalyst for hydrodesulfurization reactions. The technique is limited to those elements that exhibit the Mossbauer effect. Iron, tin, iridium, ruthenium, antimony, platinum and gold are the ones relevant for catalysis. Through the Mossbauer effect in iron, one can also obtain information on the state of cobalt. Mossbauer spectroscopy provides valuable information on oxidation states, magnetic fields, lattice symmetry and lattice vibrations. Several books on Mossbauer spectroscopy [1-3] and reviews on the application of the technique on catalysts [4—8] are available. 

Molybdena catalysts have been with us for quite a long time. The term molybdena is used here to denote a composite catalyst consisting of molybdenum oxide supported on an activated support, commonly alumina. Early it was found that certain transition metals, notably cobalt and nickel, promote the molybdena catalyst for hydrodesulfurization (HDS) reactions. 

A new catalyst for hydrodesulfurization of 36 percent Kuwait atmospheric tower bottom (KATB) was tested. The reaction conditions used were temperature = 400 C C, pressure = 136 atm, liquid hourly space velocity (LHSV) =1 h", and hydrogen circulation rate = 1.4 x 10s cm3 bb 1 (at STP). The reactor was a 6.35-cm i.d. stainless-steel tube equipped with a 0.635-cm o.d. axial thermowell mounted in the center of the reactor. The catalyst size was 8-14 mesh. 

Pawelec, B., Mariscal, R., Fierro, J.L.G., Greenwood, A., and Vasudevan, P.T. Carbon-supported tungsten and nickel catalysts for hydrodesulfurization and hydrogenation reactions. Applied Catalysis. A, General, 2001, 206, 295. 

Reddy, K.M., Wei, B.L., and Song, C.S. Mesoporous molecular sieve MCM-41 supported Co-Mo catalyst for hydrodesulfurization of petroleum resids. Catalysis Today, 1998, 43, 261. 

Song, C. and Reddy, K.M. Mesoporous zeolite-supported Co-Mo catalyst for hydrodesulfurization of dibenzothiophene in distillate fuels. American Chemical Society, Division of Petroleum Chemistry, 1996, 41, 567. 

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

Table 2 shows the process conditions applied in the pilot plant tests. Figure 1 gives the catalyst configurations. The two demetallization catalysts, KFRll and KFR 10 have a very high metal absorption capacity. KFR 11 is more metal tolerant than KFR 10. KFR 30 is a dual function catalyst for hydrodesulfurization and demetallization which is used as an intermediate stage in the catalyst system. KFR 50 is used as a downstream catalyst that has a high activity for desulfurization and is more coke resistant... 

NiMo/HNaY(x)-Al203 catalysts for hydrodesulfurization of hindered dibenzothiophenes effect of the preparation method... 

It can be concluded that the modification of SBA-15 supports with Z1O2 species results in high-performance NiMo catalysts for hydrodesulfurization of hindered dibenzothiophenes. Zirconia loading in the catalyst support leads to an increase in the dispersion of oxidic Mo species and promotes the HYD pathway of 4,6-DMDBT hydrodesulfurization. 

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... 

Ternan, M. and M.J. Whalley. Presulfiding of Catalysts for Hydrodesulfurization and Hydrodenitrogenation in a Bottom Feed Liquid Phase Reaction. Canad. J. Chem. Engg. 54 (Dec. 1976) 642. 

Song, C., and Reddy, K. M. Mesoporous Zeolite-Supported Co-Mo Catalyst for Hydrodesulfurization of Dibenzothiophene in DistUlate Fuels. ACS Div. Petrol. Chem. Preprints, 1996,41, 567-573. 

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