Hydrodesulfurization

Schuman, S.C.; Shalit, H.

doi:10.1080/01614947108075491

Cited by 131 publications

(44 citation statements)

References 40 publications

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“…Several excellent reviews of HDS reactions and processes are available (Schuman and Shalit, 1970;Schuit and Gates, 1973;Weisser and Landa, 19734).…”

Section: Hydrodesulfurization (Hds)mentioning

confidence: 98%

Interactions between catalytic hydrodesulfurization of thiophene and hydrodenitrogenation of pyridine

1975

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Pyridine hydrodenitrogenation (HDN) is more difficult than thiophene hydrodesulfurization (HDS), and there is a thermodynamic limitation on the first step of the HDN reaction mechanism which occurs, for example, at 5 to 11 bars, at temperatures above about 350°C. Pyridine inhibits the HDS reaction as previously reported, but sulfur compounds have a dual effect on HDN. At low temperatures, thiophene inhibits the reaction by competing with pyridine for hydrogenation sites on the catalyst. This retards the hydrogenation of pyridine to piperidine, reducing the overall reaction rate. At high temperatures the dominant effect is interaction of hydrogen sulfide, an HDS reaction product, with the catalyst to improve its hydrogenolysis (hydrocracking) activity. This increases the rate of piperidine hydrogenolysis, which is rate determining at the latter conditions, and enhances the overall rate of HDN. CHARLES N. SATT'ERFIELD SCOPEThe hydroprocessing of fuels containing relatively large amounts of organonitmgen compounds will become increasingly important in the future in the upgrading of synthetic fuels from oil shale and coal or processing of lower grades of crude petroleum. Organosulfur compounds are present, and the inhibiting effeet of organonitrogen compounds on catalytic hydrodesulfurization is established. However, very little has been published on the effect of organosulfur compounds on hydrodenitrogenation. These two groups of effects were explored by using as model compounds thiophene and PFidine which represent some of the less reactive organosulfur and organonitrogen compounds, respectively.Studies were made with a flow microreactor at temperatures of 200" to 500°C, 4.4 and 11.2 bars pressure, on commercial catalysts consisting of CoMo/Al,03, NiMo/ A1203, NiW/AI2O3 and NiW/SiO2-AlzO3. CONCUSIONS A N D SIGNIFICANCEPyridine, a basic nitrogen compound, severely inhibits the hydrodesulfurization of thiophene on sulfided cobaltmolybdate type of catalysts, in agreement with previous studies. The pattern of this inhibition suggests there are two types of HDS sites involved. The first are postulated to be very active for HDS but very sensitive to nitrogen bases. Sufficient quantities of these bases will completely block these sites and render them inactive for HDS. The second type of sites are much less active for HDS, but they are also less susceptible to pyridine poisoning. These latter sites are responsible for HDS activity after the first type of sites have been blocked.The hydrodenitrogenation of pyridine is more difficult than thioohene HDS, and there appears to be a thermodynamic limitation to the first step in the reaction mechanism. Sulfur compounds have a twofold effect on HDN. At low temperatures they are postulated to compete with pyridine for hydrogenation sites on the catalyst, thereby inhibiting the rate of the hydrogenation step in the pyridine decomposition mechanism. At high temperatures the HDS reaction product hydrogen sulfide interacts with the catalyst to improve the hydrogenolysis activity. Thi...

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“…Several excellent reviews of HDS reactions and processes are available (Schuman and Shalit, 1970;Schuit and Gates, 1973;Weisser and Landa, 19734).…”

Section: Hydrodesulfurization (Hds)mentioning

confidence: 98%

Interactions between catalytic hydrodesulfurization of thiophene and hydrodenitrogenation of pyridine

1975

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“…Details of light distillate processes are given in reviews by Docksey and Gilbert (1967) and Schuman and Shalit (1970). An account given by Lister ( 1965) concerns commercial operating experiences, including details of reactor design, construction, and operation.…”

Section: Process Designmentioning

confidence: 99%

Chemistry and engineering of catalytic hydrodesulfurization

1973

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SCOPEThe chemistry of catalytic hydrodesulfurization is not well understood although the hydrodesulfurization of petroleum distillates has been practiced industrially for years. The subject remains a neglected area of research, although there has been a recent surge in process development motivated by air pollution control standards requiring low sulfur fuel oils. The developments focus on processing of high-molecular-weight feeds, including residual oils. The results include large scale fixed-and fluidizedbed residuum hydrodesulfurization processes.This review emphasizes the recent literature in summarizing the catalytic chemistry of hydrodesulfurization and identifying the process engineering problems.The subject of reaction intermediates in hydrodesulfurization is reviewed thoroughly; kinetics for pure compounds and petroleum feedstocks are summarized; and structures of alumina-based catalysts (especially Ni/W and Co/Mo) are given in detail, leading to consideration of the catalytic sites.The engineering literature of the new processes is sparse; consequently, the review is qualitative and speculative. The unique problems are related to plugging of catalyst pores by inorganic reaction products and to the possibility of unstable operation with exothermic reactions of explosive mixtures. CONCLUSIONS AND SIGNIFICANCEReaction networks prevailing in catalytic hydrodesulfurization are known for only a few reactants, and results are not easily generalized; thiophene is desulfurized to butadiene before it is hydrogenated, but benzothiophenes are more rapidly hydrogenated than desulfurized. Rates of hydrodesulfurization vary greatly among feeds, being lowest for high-molecular-weight aromatic compounds like benzothiophene. Hydrodesulfurization of many reactants over a wide range of conditions is first order in reactant concentration and in hydrogen partial pressure; reaction is inhibited by product H2S and by strongly adsorbed hydrocarbons.Catalysts have been described in terms of two models, the intercalated sulfide model in which the catalytic sites for hydrogenation and possibly hydrodesulfurization involve W " + ions adjacent to vacancies at crystal edges and the monolayer model with catalytic sites involving M o~+ ions octahedrally coordinated in a surface layer which is stabilized by the presence of promoter Co*+ ions located in tetrahedral sites of the underlying support.The processes for hydrodesulfurization of petroleum distillates are well established, and until recently there had been little incentive for improvement of catalysts. The more challenging problems of hydrodesulfurizing residual feeds stem from the lack of reactivity of the heavier sulfur compounds and the presence of organometallic feed components; these react to form inorganic products, which can permanently plug the pores of catalysts and contribute to plugging of the interstices of fixedbed reactors. The catalyst aging phenomena have been countered by catalyst-and reactor-designs maximizing the capacity for unwanted products and optimizing th...

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“…Metal catalysed carbon-sulphur bond cleavage reactions are important in synthetic chemistry [1][2][3][4][5][6][7][8][9]. There are numerous examples of metal complexes that catalytically cleave carbon-sulphur bonds [10][11][12][13][14][15][16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Iron(II) and Manganese(II) Complexes of 2-{2-(3-Carboxypyridin-2-yl)disulfanyl}pyridine-3-carboxylic acid Through C–S Bond Cleavage

2012

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Two psuedopolymorphs of iron(II) complexes, namely [Fe(phen) 3 ](HL 2 ) 2 ÁH 2 O (1); [Fe(phen) 3 ](H 2 L 2 )(L 2 )Á 7H 2 O (2) and a manganese(II) carboxylate coordination polymer [Mn(L 2 )(py) 2 (MeOH) 2 ] n (3) (H 2 L 2 = 2-(2-(3-carboxypyridin-2-yl)disulfanyl)pyridine-3-carboxylic acid, phen = 1,10-phenanthroline, py = pyridine) were prepared via in situ generation of H 2 L 2 through concomitant C-S bond cleavage and S-S bond formation reactions of 2-(3-methyl-1,4-dihydro-naphthalen-2-yl-sulfanyl)nicotinic acid (L 1 ). The complex 1 has, a = 26.945(3) Å ; b = 11.6895 (10) Å ; c = 20.708(2) Å ; a = 90.008; b = 123.228(13)8; c = 90.008 and volume = 5456.0(12) Å 3 , Z = 4; the complex 2 has, a = 11.575(7) Å ; b = 21.530(12) Å ; c = 23.212(13) Å ; a = 90.008; b = 90.13(2)8; c = 90.008; volume = 5785(6) Å 3 ; Z = 4 and the coordination polymer 3 has a = 14.7154(11) Å ; b = 9.0292(11) Å ; c = 20.568 (2) Å ; a = 90.00(4)8; b = 93.032(9)8; c = 90.008; volume = 2729.0(5) Å 3 ; Z = 4.

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Hydrodesulfurization

Cited by 131 publications

References 40 publications

Interactions between catalytic hydrodesulfurization of thiophene and hydrodenitrogenation of pyridine

Interactions between catalytic hydrodesulfurization of thiophene and hydrodenitrogenation of pyridine

Chemistry and engineering of catalytic hydrodesulfurization

Iron(II) and Manganese(II) Complexes of 2-{2-(3-Carboxypyridin-2-yl)disulfanyl}pyridine-3-carboxylic acid Through C–S Bond Cleavage

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