GB826449A - A process for separating a mixture into components by means of a zeolitic molecular sieve sorbent - Google Patents

Abstract

<PICT:0826449/IV (b)/1> A hydrocarbon which can be adsorbed on a zeolitic molecular sieve is separated from a hydrocarbon not so adsorbed by contacting a mixture thereof with a composite of a zeolitic molecular sieve with a binder at a superatmospheric pressure which is from 1.5 to 20 times the desorption pressure, which is at least 1 atmosphere absolute, the temperature during adsorption and desorption being at least 200 DEG C. The process is preferably applied to the separation of normal from non-normal hydrocarbons, e.g. branched chain and cyclic hydrocarbons, in which case a 5 sieve is used. Adsorption may be effected at 1.5-100 atmospheres absolute and desorption at 1-20 atmospheres absolute. The sieve binder may be a clay or alumina; the adsorbent may be used in a fixed, fluidized or moving bed. In a preferred embodiment the mixture is fed by line 211 to adsorber 201 which contains a fluidized bed of a zeolitic composite fluidized by an inert gas introduced by lines 212 and 215. Suitable inert gases include helium, hydrogen, nitrogen, methane, argon, flue gas (scrubbed to remove reactive impurities), ethane and propane and may contain a small amount of adsorbed hydrocarbons. The zone 202 prevents the hydrocarbons filtering back and escaping with solids. The gases leave by cyclone 204 and non-normal, unadsorbed hydrocarbons are recovered, e.g. by absorption in absorber oil, by adsorption on activated charcoal or by condensation, and the inert gas recycled by line 215. Solids are removed by passage 216 into riser 210 and carried upwards by gas escaping into riser 210 or injected gas or other mechanical means to stripper 205 fed with inert gas by line 219. Gases leave by line 220 and cyclone 206 for recovery of desorbed hydrocarbons by condensation in condenser 224 and separator 225, inert gas being recycled. Solids are returned to the adsorption zone in batches by way of repressurizing chamber 209. Adsorption and desorption may be carried out at temperatures within 50 DEG C. of each other and preferably at the same temperatures to avoid heating and cooling of the sieve.