Light hydrocarbons hydrogen separation from

After cooling, the reactor effluent gas is compressed (3) and sent to the recovery section (4), where inert gases, hydrogen, and light hydrocarbons are separated from the compressed reactor effluent and C4 and heavier are rejected. The ethane, propane and propylene components are then sent to the product purification section deethanizer (5) and product splitter (6), where propylene product is separated from unreacted propane. The propane is recycled to the reactors. 

Dehydrogenation of isobutane to isobutylene is highly endothermic and the reactions are conducted at high temperatures (535—650°C) so the fuel consumption is sizeable. Eor the catalytic processes, the product separation section requires a compressor to facHitate the separation of hydrogen, methane, and other light hydrocarbons from-the paraffinic raw material and the olefinic product. An exceHent overview of butylenes is avaHable (81). 

The product coming out of the reactor consists of excess hydrogen and a reformate rich in aromatics. Typically the dehydrogenation of naphthenes approaches 100%. From 0% to 70% of the paraffins are dehydrocyclized. The liquid product from the separator goes to a stabilizer where light hydrocarbons are removed and sent to a debutanizer. The debutanized platformate is then sent to a splitter where Cg and C9 aromatics are removed. The platformate splitter overhead, consisting of benzene, toluene, and nonaromatics, is then solvent extracted (46). 

The sour oil from each three-phase separator is metered and commingled, and flows to a stabilizer where the hydrogen sulfide and light hydrocarbons are removed. The crude product to storage is controlled at 10-psi Reid vapor pressure and less than 50-ppm hydrogen sulfide. 

Heat exchangers are employed to cool the reactor effluent and the desulfurized liquid product is separated from the recycle gas at a pressure somewhat lower than that of the reactor section. Hydrogen sulfide and any light hydrocarbon gases are removed from the recycle gas which is then mixed with fresh (makeup) hydrogen, compressed, and mixed with further hydrocarbon feedstock. 

The product gases are cooled and compressed (4) to facilitate separation of products and by-products. The suction-side of the compressor ensures that upstream units operate at a low pressure. The product gases are first dried (5) and the cooled product passed to a cryogenic separator (6) which removes hydrogen from the system. Some is recycled with the other portion passed-on for other uses. A selective hydrogenation unit (7) removes dienes and acetylenes. A final distillation train removes light hydrocarbon (C2-), propylene product, propane, which is recycled, and a C4 by-product. 

The products from these hydrogenations were separated into gases (analyzed by G.C.), water (analysed by azeotropic distillation), insolubles (CH2CI2 insolubles), asphaltene (CH2CI2 soluble/X4 insoluble) (Shell X4 40-60 C b.p. light petroleum), oils (CH2CI2 soluble/X4 soluble). Hydrogen transferred from the donor solvent was determined by G.L.C. analysis of the ratio of tetralin to naphthalene in the total hydrocarbon liquid product. 

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