Two-stage process for purifying a hydrogen gas and recovering liquifiable hydrocarbons from hydrocarbonaceous effluent streams

#The present invention is related to methods for recovering a hydrogen-rich gas stream from a hydrogen and hydrocarbon effluent of a catalytic hydrocarbon conversion zone. In addition this invention improves the recovery of liquifiable hydrocarbons from hydrogen and hydrocarbon effluent streams.

#Various types of catalytic hydrocarbon conversion reaction systems have found widespread utilization throughout the petroleum and petrochemical industries for effecting the conversion of hydrocarbons to different products. The reactions employed in such systems are either exothermic or endothermic, and of more importance to the present invention, often result in either the net production of hydrogen or the net consumption of hydrogen. Such reaction systems, as applied to petroleum refining, have been employed to effect numerous hydrocarbon conversion reactions including those which predominate in catalytic reforming, ethylbenzene dehydrogenation to styrene, propane and butane dehydrogenation, etc.

#Petroleum refineries and petrochemical complexes customarily comprise numerous reaction systems. Some systems within the refinery or petrochemical complex may result in the net production of hydrogen. Because hydrogen is relatively expensive, it has become the practice within the art of hydrocarbon conversion to supply hydrogen from reaction systems which result in the net production of hydrogen to reaction systems which are net consumers of hydrogen. Occasionally, the net hydrogen being passed to the net hydrogen-consuming reactions systems must be of high purity due to the reaction conditions and/or the catalyst employed in the systems. Such a situation may require treatment of the hydrogen from the net hydrogen-producing reaction systems to remove hydrogen sulfide, light hydrocarbons, etc. from the net hydrogen stream.

#FIG. 1 illustrates a reforming process and a prior art separation arrangement for recovering a hydrogen-rich product and a liquid reformate.

#FIG. 2 shows a reforming process with a system for recovering a hydrogen-rich gas product and a reformate liquid product arranged in accordance with this invention.

#FIG. 3 is another reforming process with a system for recovering a hydrogen-rich product and a liquid reformate arranged in accordance with an alternate embodiment of this invention.

#The process of this invention is suitable for use in hydrocarbon conversion reaction systems which may be characterized as single or multiple reaction zones in which catalyst particles are disposed as fixed beds or movable via gravity flow. Moreover, the present invention may be advantageously utilized in hydrocarbon conversion reaction systems which result in the net production or the net consumption of hydrogen. Although the following discussion is specifically directed toward catalytic reforming of naphtha boiling range fractions, there is no intent to so limit the present invention.

#The art of catalytic reforming is well known to the petroleum refining and petrochemical processing industry. Accordingly, a detailed description thereof is not required herein. In brief, the catalytic reforming art is largely concerned with the treatment of a petroleum gasoline fraction to improve its anti-knock characteristics. The petroleum fraction may be a full boiling range gasoline fraction having an initial boiling point of from about 50.degree. to about 100.degree. F. and an end boiling point from about 325.degree. to about 425.degree. F. More frequently the gasoline fraction will have an initial boiling point of about 150.degree. to about 250.degree. F. and an end boiling point of from about 350.degree. to 425.degree. F., this higher boiling fraction being commonly referred to as naphtha. The reforming process is particularly applicable to the treatment of those straight-run gasolines comprising relatively large concentrations of naphthenic and substantially straight-chain paraffinic hydrocarbons which are amenable to aromatization through dehydrogenation and/or cyclization. Various other concomitant reactions also occur, such as isomerization and hydrogen transfer, which are beneficial in upgrading the anti-knock properties of the selected gasoline fraction. In addition to improving the anti-knock characteristics of the gasoline fraction, the tendency of the process to produce aromatics from naphthenic and paraffinic hydrocarbons makes catalytic reforming an invaluable source for the production of benzene, toluene, and xylenes which are all of great utility in the petrochemical industry.

#Widely accepted catalysts for use in the reforming process typically comprise platinum on an alumina support. These catalysts will generally contain from about 0.05 to about 5 wt. % platinum. Certain promoters or modifiers, such as cobalt, nickel, rhenium, germanium and tin, have been incorporated into the reforming catalysts to enhance its performance.