GB896440A - Separation of nitrogen compounds from hydrocarbon mixtures - Google Patents

Abstract

A hydrocarbon contaminated with organic nitrogen compounds is purified by contacting it with a solid zeolitic metallo aluminosilicate molecular sieve adsorbent having substantially uniform pores at least 7 Angstrom units in diameter so that at least a portion of the organic nitrogen compounds become adsorbed thereon. The feedstock may be crude petroleum, a petroleum distillate (e.g. natural gasoline, petroleum naphtha or kerosene), a refined petroleum product (e.g. cracked, reformed or aromatized gasoline or naphtha, cycle oil or coker distillate), an oil derived from coal (e.g. crude coal tar oil, hydrogenated coal oil or a coal tar distillate) or an oil derived from shale (e.g. crude shale oil, a shale oil distillate or a shale oil coker distillate). Sulphur-containing feedstocks may first be desulphurized by catalytic hydrogenation before contacting them with the adsorbent. The feedstock may be in vapour or liquid form when it is contacted with the adsorbent and there may be one or more contact stages; the adsorbent bed may be static or fluidized. The spent adsorbent may be regenerated by burning off the sorbed nitrogen compounds in the presence of an oxygen-containing gas, or by stripping off the sorbed nitrogen with the aid of a gaseous or liquid non-adsorbable stripping fluid or with the aid of heat or reduced pressure. If the adsorbent has been contacted with liquid hydrocarbon feedstock, it is desirable to wash the spent adsorbent free of occluded hydrocarbon (e.g. with the aid of liquid butane or pentane) before regenerating. Instead of regenerating the spent adsorbent, the nitrogen compounds may be displaced from it with the aid of a gas or liquid which, under the conditions employed, is preferentially sorbed by the adsorbent. The adsorbent then contains adsorbed displacement exchange fluid, and when the adsorbent is contacted with the feedstock in the next succeeding cycle of operation, the nitrogen compounds in the feedstock displace the displacement exchange fluid. When the feedstock is of relatively wide boiling range, a portion of the feedstock itself can be employed as the displacement exchange fluid. Thus, a feedstock may be fractionally distilled to obtain a low-boiling fraction and a high-boiling fraction, and the two fractions contacted alternately with the adsorbent. In the examples, (3) petroleum naphtha is first desulphurized by catalytic hydrogenation (using a cobalt oxide/molybdenum oxide p catalyst supported on silica-stabilized alumina), then contacted (without removing the hydrogen) with the molecular sieve adsorbent and finally catalytically reformed in the presence of the hydrogen (using a fluorine-promoted platinum catalyst), hydrogen from the reforming zone being recycled to the desulphurization zone; (7) light reformed gasoline is contacted with the molecular sieve adsorbent and then deatomized by contact with silica gel. Specification 777,233 is referred to.ALSO:A hydrocarbon fraction to be reformed which is contaminated with organic nitrogen compounds is purified by contacting it with a solid zeolitic metallo aluminosilicate molecular sieve adsorbent having substantially uniform pores at least 7 ngstrome units in diameter so that at least portion of the organic nitrogen compounds become adsorbed thereon. The feedstock may be crude petroleum, a petroleum distillate, a refined petroleum product, or an oil derived from coal or shale. The feedstock may be in vapour or liquid form when it is contacted with the adsorbent and there may be one or more contact stages; the adsorbent bed may be static or fluidized. Methods of regenerating the spent adsorbent or of displacing the sorbed nitrogen compounds therefrom are described (see Group III). In an example, (3) petroleum naphtha is first desulphurized by catalytic hydrogenation (using a cobalt oxide molybdenum oxide catalyst supported on silica-stabilized alumina), then contacted (without removing the hydrogen) with the molecular sieve adsorbent and finally catalytically reformed in the presence of the hydrogen (using a fluorine-promoted platinum catalyst), hydrogen from the reforming zone being recycled to the desulphurization zone.