Hydrodenitrogenation process

Transition metal complexes containing coordinated small molecules such as CO, 02, and N2 have been known for many decades and are of critical importance in industrial and biological processes and coordination chemistry as a whole (Table 1.1). Of all the industrially relevant molecules, H2 is arguably the most important. Catalytic hydrogenation reactions represent the most massive man-made chemical reactions in the world All crude oil is treated with hydrogen to remove sulfur and nitrogen in hydrodesulfurization/hydrodenitrogenation processes. Ten billion tons of ammonia is produced worldwide by the Haber process ... 

Hydrodenitrogenation. Heterocyclic compounds containing nitrogen in coal liquids are either basic (pyridines, quinolines and acridines) or non-basic (pyrroles, indoles and carbazoles). Attempts have been made to study these model compounds to highlight the mechanism involved in hydrodenitrogenation process. 

Catalysts based on MoSi are used to remove sulfur and nitrogen from organic molecules in hydrodesulfurization and hydrodenitrogenation processes. 

Hydrodenitrogenation (HDN) is an important process in petroleum refining. It removes nitrogen from oil distillates, so that less NOx pollutes the air when oil is burned and poisoning of the subsequent refining catalysts is reduced when the oil is processed further. Although HDN has been studied intensively and different reaction mechanisms, catalytic active sites, and functions of the catalytic components have been proposed, there are stiU many questions to be answered in order to better mderstand the reaction and the catalyst (1-4). 

Satterfield, C. N., and Yang, S. H., Catalytic Hydrodenitrogenation of Quinoline in A Trickle-Bed Reactor. Comparison With Vapor Phase Reaction. Ind. Eng. Chem. Process Des. Dev, 1984. 23 pp. 11-19. 

In general, it can be concluded, that although a large scale biphasic solution process for hydrodesulfurization and hydrodenitrogenation is not likely to come soon, there are promising results in homogeneous catalysis which can lead to constmction of such processes in the future. 

Actually, catalytic hydrodenitrogenation is an industrially applicable process for reducing the level of nitrogen content in mineral feed-stocks. For this reason, catalytic pyrolysis was investigated as an alternative process also, in order to minimize the problems of heterogeneity of the products (132). 

Virtually all of these processes rely on promoted molybdenum sulfide (MoS2) catalysts. Hydrodenitrogenation catalysts are usually nickel-promoted... 

Hydrodenitrogenation (HDN) processes in current industry are not separated from the other hydrotreatments, viz, HDS, HDO, and HDM. A clear description of the HDS processes for conventional petroleum distillation was... 

Prins summarizes advances in understanding of the reactions in catalytic hydrodenitrogenation (HDN), which is important in hydroprocessing of fossil fuels. Hydroprocessing is the largest application in industrial catalysis based on the amount of material processed. The chapter addresses the structures of the oxide precursors and the active sulfided forms of catalysts such as Ni-promoted Mo or W on alumina as well as the catalytically active sites. Reaction networks, kinetics, and mechanisms (particularly of C-N bond rupture) in HDN of aliphatic, aromatic, and polycyclic compounds are considered, with an evaluation of the effects of competitive adsorption in mixtures. Phosphate and fluorine promotion enhance the HDN activity of catalysts explanations for the effect of phosphate are summarized, but the function of fluorine remains to be understood. An account of HDN on various metal sulfides and on metals, metal carbides, and metal nitrides concludes this chapter. 

In a number of petrochemical processes, a gas (hydrogen) is present as reactant. In hydrodesulfurization (HDS), hydrocracking (HC), and hydrodenitrogenation (HDN), the reaction products H2S and ammonia, respectively, are known to decrease the catalyst activity, but are partly transferred to the gas phase. Therefore, also these processes profit from reactive stripping. 

A trickle-bed reactor was used to study catalyst deactivation during hydrotreatment of a mixture of 30 wt% SRC and process solvent. The catalyst was Shell 324, NiMo/Al having monodispersed, medium pore diameters. The catalyst zones of the reactors were separated into five sections, and analyzed for pore sizes and coke content. A parallel fouling model is developed to represent the experimental observations. Both model predictions and experimental results consistently show that 1) the coking reactions are parallel to the main reactions, 2) hydrogenation and hydrodenitrogenation activities can be related to catalyst coke content with both time and space, and 3) the coke severely reduces the pore size and restricts the catalyst efficiency. The model is significant because it incorporates a variable diffusi-vity as a function of coke deposition, both time and space profiles for coke are predicted within pellet and reactor, activity is related to coke content, and the model is supported by experimental data. 

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