Abstract: Normal paraffins are separated from a gas oil-containing hydrocarbon vapor feed stream having 16 to 25 carbon atoms per molecule in a constant pressure process employing a molecular sieve adsorbent and n-hexane for purging and for dilution of gas oil-containing feedstock. Cocurrent purge effluent is used to provide a source of such n-hexane diluent, thereby reducing the equipment size and energy consumption for processing of the n-hexane purge recycle stream and increasing adsorbent utilization or the efficiency of the adsorption process.

Abstract: Normal paraffins are separated from a gas oil-containing hydrocarbon vapor feed stream having 16 to 25 carbon atoms per molecule in a constant pressure process employing a molecular sieve adsorbent and n-hexane for purging and for dilution of gas oil-containing feedstocks. Countercurrent purge effluent is used to provide a source of such n-hexane diluent, thereby effecting a savings in the amount of energy necessary to process the purge recycle stream and the size of the equipment used therefor.

Abstract: The hot effluent from the catalytic steam reforming of a major portion of a fluid hydrocarbon feed stream in the reformer tubes of a primary reformer, or said effluent after secondary reforming thereof, is mixed with the hot effluent from the catalytic steam reforming of the remaining portion of the feed discharged from the reformer tubes of a primary reformer-exchanger. The combined gas steam is passed on the shell side of the reformer-exchanger countercurrently to the passage of feed in the reformer tubes thereof, thus supplying the heat for the reforming of the portion of the feed passed through the reformer tubes of the reformer-exchanger. At least about 2/3 of the hydrocarbon feed stream is passed to the reformer tubes of said primary reformer, heated by radiant heat transfer and/or by contact with combustion gases, at a steam/hydrocarbon mole ratio of about 2-4/1.

Abstract: One portion comprising about 30-80% of a hydrogen-containing feed gas having a relatively high carbon dioxide content is preheated to remove a substantial portion of said carbon dioxide therefrom. The thus - preheated stream is passed to a pressure swing adsorption bed from which a purified hydrogen stream is withdrawn. Upon completion of this step, the unpretreated portion of the feed gas is passed to the feed end of the bed, with purified hydrogen continuing to be withdrawn from the bed. In cyclic pressure swing adsorption operations employing such a two-feed process, the recovery of purified hydrogen is enhanced as compared with operations in which none of the feed gas is pretreated for carbon dioxide removal or in which all of the feed gas is so treated for removal of carbon dioxide therefrom.

Abstract: In an adiabatic pressure swing process for separation of feed gas mixtures such as H.sub.2 containing CO.sub.2 and N.sub.2 impurities, at least seven adsorbent beds are employed of which at least two are receiving feed gas during the entire cycle, and with at least three pressure equalization stages.