Hydrodenitrogenation of Petroleum

Abstract

A high level of hydrodenitrogenation (HDN) is required to achieve a desirable conversion of other hydroprocessing reactions. This results from a strong adsorption of nitrogen-containing compounds on catalytic sites that slows down the hydrogen activation process and hinders the adsorption of other reactants. Studies on model compounds and real feeds indicate that less than 50 ppm of nitrogen in the feed can poison catalytic sites. Kinetic studies determined adsorption constants of various nitrogen-containing compounds and concluded that at least four different catalytic sites are required to interpret experimental observations in contrast with a dual site site ffi concept, which only considered two sites. The advancements in experimental techniques allowed identification of products formed during very early stages of hydrodenitrogenation. These results confirmed that the removal of the amino group from saturated amines, as the last step in hydrodenitrogenation, is governed by the type of carbon to which the amino group is attached rather than the number of hydrogen atoms attached to carbon in a and b position to nitrogen Performance of conventional Co(Ni)Mo(W)/Al 2 O 3 catalysts during hydrodenitrogenation was enhanced by combination with various additives and by replacing the traditionally used g-Al 2 O 3 support with novel supports. Catalytic functionalities could be modified by using different precursors of active metals and varying conditions during preparation. Progress has been made in the development of catalysts possessing a high selectivity for hydrodenitrogenation. In this case, the nonconventional catalysts based on the carbides and nitrides of transition metals exhibited high activity and selectivity. Noble metal sulfides alone or supported on different supports were active for HDN as well. Feedstocks used for catalyst evaluation included model compounds and mixtures of model compounds as well as real feeds. The challenges in the development of catalysts for hydrodenitrogenation of heavy feeds containing asphaltenes and metals have been identified.In general, compared to Q, conversions were little affected by a methyl (Me) on the aromatic ring, while being lower for Me on the N-ring, except for 2-MeQ. It is evident that Me substitution in the 2-position had little effect on HDN over the NiMoP/Al 2 O 3 catalyst, whereas it actually enhanced the HDN rate over the CoMo/Al 2 O 3 catalyst. For both catalysts the HDN rate was suppressed in 6-MeQ and particularly in 3-MeQ and 4-MeQ. The distribution of N-containing intermediates was influenced by the ring substitution and the type of catalyst. This suggests that several factors influence the overall HDN mechanism of Qs. This should be kept in mind while analyzing differences in the networks proposed by different authors.The preceding discussion on the HDN of Q mostly referred to conventional catalysts. A number of studies on the HDN of Q were conducted over unconventional catalysts. For example, 3-and 4-MeQs were more reactive than Q over the unsupported Zr,...

β-Molybdenum nitride: synthesis mechanism and catalytic response in the gas phase hydrogenation of p-chloronitrobenzene

“…4,5 Conventional preparative routes have involved either (a) high temperature (1400-1900 K) reaction of the base metal and elemental nitrogen, 6 (b) carbothermal nitridation of metal oxides 6 or (c) a self-propagating high temperature synthesis. 7 Alternative methods that can operate under milder reaction conditions have drawn on controlled temperature programmed procedures.…”

Catalytic hydrodenitrogenation of propionitrile over supported nickel phosphide catalysts as a model reaction for the transformation of pyrolysis oil obtained from animal by-products

“…In order to model industrial HDN conditions most studies concern the HDN of model compounds in the presence of sulfur compound in the feed, usually over supported or non-supported transition metal sulfides or phosphides. The ammonia was substantiated to be released from quaternized ammonium compound, formed by protonation of primary amine, on the attack of a nucleophilic HS -or S -species on the catalyst surface [5].…”

“…Numerous studies have been devoted to catalytic heteroatom removal from feedstocks and model compounds by hydroprocessing, including the HDN of organic N-compounds [5][6][7].…”

Szerves nitrogénvegyületek katalitikus hidrodenitrogénezése (HDN) hordozós nikkel-foszfid katalizátorokon

“…Ezekben a frakciókban fémtartalmú komplex vegyületek (elsősorban V és Ni) és aszfaltének is előfordulnak. A kőolaj szerves kéntartalmát főleg merkaptánok, szulfidok, diszulfidok és tiofének [20], míg szerves nitrogéntartalmát az erős bázis piridin-és a kevésbé bázikus pirrolszármazékok adják [26].…”

“…A rendszerint 300-400°C hőmérsékleten, 10-70 bar hidrogénnyomáson végzett hidrogénező finomítás során a betáplált anyag minőségétől függően számos reakció játszódhat le egy időben, így például a hidrogénező kéntelenítés (HDS), nitrogénmentesítés (HDN), oxigénmentesítés (HDO), fémmentesítés (HDM) és aromástartalom-csökkentés (HDA) [20,26].…”