Recent advances in the science and technology of ultra low sulfur diesel (ULSD) production

High aromatic content in diesel fuel has been recognized both to lower the fuel quality and to contribute significantly to the formation of undesired emissions in exhaust gases [1, 2]. Because of the health hazards associated with these emissions, environmental regulations governing the composition of diesel fuels are being tightened in both Europe and the United States, leading to limitations on aromatics [3, 4].

Aromatic Hydrogenation Catalysis: A Review

Deactivation of hydroprocessing catalysts

Etude de la structure d'un catalyseur utilise pour une hydrodesulfuration et plus particulierement etude de la localisation et de la structure des ions molybdene et cobalt a la surface de l'alumine. Discussion sur le role d'un promoteur modifiant un catalyseur, notamment determination du nombre de sites actifs

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Structure and Function of the Catalyst and the Promoter in Co—Mo Hydrodesulfurization Catalysts

The elimination of specific oxygenated groups of biomass-derived pyrolysis oils (bio-oils) is necessary for improving their stability. These are mainly unsaturated groups like alkene, carbonyl and carboxylic functions, as well as guaiacyl groups. For practical applications, it is desirable that the reactions are performed selectively in order to avoid excessive hydrogen consumption. The reactions must be done at relatively low temperature in order to limit competitive thermal condensation reactions. In this study, model oxygenated compounds were used, namely 4-methylacetophenone, diethyldecanedioate and guaiacol. They were tested simultaneously in one reaction test in the presence of sulfided cobalt-molybdenum and nickel-molybdenum supported on gamma-alumina catalysts in a batch system. Their reactivity and conversion scheme were determined. The ketonic group is easily and selectively hydrogenated into a methylene group at temperatures higher than 200 degrees C. Carboxylic groups are also hydrogenated to methyl groups, but a parallel decarboxylation occurs at comparable rates. A temperature around 300 degrees C is required for the conversion of carboxylic groups as well as for the conversion of the guaiacyl groups. The main reaction scheme of guaiacol is its transformation in hydroxyphenol which is subsequently converted to phenol. But in batch reactor conditions, guaiacol gives a high proportion of heavy products. CoMo and NiMo catalysts have comparable activities and selectivities. However, the NiMo catalyst has a higher decarboxylating activity than CoMo and also leads to a higher proportion of heavy products during the conversion of guaiacol.

Study of the Hydrodeoxygenation of Carbonyl, Carboxylic and Guaiacyl Groups Over Sulfided Como/gamma-al2o3 and Nimo/gamma-al2o3 Catalysts .1. Catalytic Reaction Schemes

Some effects of sulfiding of a NiMoAl2O3 catalyst on its activity for hydrodenitrogenation of quinoline

Studies at 350, 375, and 390/sup 0/C and 6.9 MPa showed that the presence of H/sub 2/S (generated in situ from CS/sub 2/) in the overall reaction network somewhat inhibits hydrogenation and dehydrogenation reactions but markedly accelerates hydrogenolysis reactions, for a net increase in the overall rate of hydrodenitrogenation (HDN). These effects are similar to those observed previously in vapor-phase reactions. H/sub 2/S has little effect on the activation energies for the hydrogenation and dehydrogenation reactions, but it significantly reduces those for the hydrogenolysis reactions. Certain plugging problems encountered upon reacting 5,6,7,8-tetrahydroquinoline are attributed to formation of a trimer imine as an intermediate. The presence of Tetralin in the liquid inhibits the overall hydrodenitrogenation reaction, indicating that inhibition by competitive adsorption is more important than the accelerating hydrogen-donor capability that Tetralin exhibits in some homogeneous reactions.

Catalytic hydrodenitrogenation of quinoline in a trickle-bed reactor. Effect of hydrogen sulfide

Studies over a commercial NiMo/Al/sub 2/O/sub 3/ catalyst at 350, 375, and 390/sup 0/C and 6.9 MPa using quinoline or various intermediate reaction products showed that the reaction rate constants for the various hydrodenitrogenation (HDN) reactions in the presence of an inert paraffin liquid are very similar to those for the same reactions in the vapor phase, although the liquid tends to equalize the adsorptivities of the various N-compounds present. Over a wide range, for a specified pressure and temperature, the percent conversion as a function of contact time is remarkably similar for liquid- and vapor-phase processing. In both cases, the overall HDN reaction is essentially zero order under the conditions studied. Equilibrium between quinoline and 1,2,3,4-tetrahydroquinoline is rapidly attained in both vapor-phase and liquid-phase processing. Homogeneous reactions were negligible except for the hydrogenation of quinoline to 1,2,3,4-tetrahydroquinoline.

Shan Hsi Yang

Papers

Some effects of sulfiding of a NiMoAl2O3 catalyst on its activity for hydrodenitrogenation of quinoline

Catalytic hydrodenitrogenation of quinoline in a trickle-bed reactor. Effect of hydrogen sulfide

Catalytic hydrodenitrogenation of quinoline in a trickle-bed reactor. Comparison with vapor phase reaction

Simultaneous hydrodenitrogenation and hydrodeoxygenation of model compounds in a trickle bed reactor