Patent GB-1010693-A (GB)
Title: Improvements relating to the separation of hydrocarbon mixtures
Inventor: ANSTEY ROGER HILARY
IPC: C10G25/03
Filed: 1963-02-10
Abstract: Straight chain hydrocarbons are separated in the gas phase from a mixture also containing branched and/or cyclic hydrocarbons by diluting the feed with an inert gas or low-boiling n-hydrocarbon (as defined) and contacting it with a 5 A DEG  zeolitic molecular sieve in an absorption stage, the non-absorbed material is then removed from the sieve surface in a purge stage and the n-hydrocarbons are desorped at a pressure below that of the adsorption stage.  The low-boiling hydrocarbons are those of lower b.p. than the lowest boiling hydrocarbon in the feed and of critical temperature lower than the absorption temperature. Suitable diluents are N2 and n-paraffins C1- 8 preferably n-pentane. The feedstock may be C9 and above fractions, e.g. kerosine, whilst the operation which may be isothermal, may be carried out at 300-400 DEG C. with an absorption pressure of 65-263 p.s.i.a. and desorption pressure of 0.01-2.0 p.s.i.a.  The bed may be purged using a purging medium, e.g. the diluent, at the same pressure as the absorption stage but preferably counter-current to the feed direction.  Alternatively, purging may be accomplished by reducing the pressure to a value intermediate of the absorption and desorption pressures, e.g. 1.0-7.5 p.s.i.a.  The pressure is preferably released in a direction counter-current to the feed direction but may be released both co- and counter-current. Desorption may be assisted by a bleed of the diluent, e.g. at a rate of 1-50 v./v./hr., with the desorption pressure preferably at 0.1 to 2.0 p.s.i.a.ALSO:Straight chain hydrocarbons are separated in the gas phase from a mixture also containing branched and/or cyclic hydrocarbons by diluting the feed with an inert gas or low-boiling n-hydrocarbon (as defined) and contacting it with a 5   zeolitic molecular sieve in an absorption stage, the non-absorbed material is then removed from the sieve surface in a purge stage and the n-hydrocarbons are desorped at a pressure below that of the adsorption stage.  The low-boiling hydrocarbons are those of lower b.p. than the lowest boiling hydrocarbon in the feed and of critical temperature lower than the absorption temperature. Suitable diluents are N2 and n-paraffins C1-8 preferably n-pentane.  The feedstock may be C9 and above fractions whilst the operation which may be isothermal, may be carried out at 300-400  DEG C. with an absorption pressure of 65-263 p.s.i.a. and desorption pressure of 0,01-2,0 p.s.i.a.  The bed may be purged using a purging medium e.g. the diluent, at the same pressure as the absorption stage but preferably counter-current to the feed direction.  Alternatively, purging may be accomplished by reducing the pressure to a value intermediate of the absorption and desorption pressures, e.g. 1,0-7,5 p.s.i.a.  The pressure is preferably released in a direction counter-current to the feed direction but may be released both co-and counter-current. Desorption may be assisted by a bleed of the diluent e.g. at a rate of 1-50 v/v/hr., with the desorption pressure preferably at 0,1-2,0 p.s.i.a.