Adsorptive separation of olefinic hydrocarbons from paraffins involves the regeneration of molecular sieve guard bed by using an internal stream of desorbents as a flush

摘要

Molecular sieve guard bed useful for adsorptive separation of olefinic hydrocarbons is periodically regenerated by using an internal flush stream of desorbents which is recovered and reused. Separation of a hydrocarbon from a feed stream (1) comprises periodically regenerating a molecular sieve guard bed (2) by purging (1) from (2) using a liquid phase stream (4) of a desorbent (3) and passing the effluent of (2) into a fractionation column used to separate (3) and raffinate compounds. (4) is then continued to pass through (2) and the effluent of (2) is transferred to a desorbent recovery fractionation column. Independent claims are also included for the following: (A) prevention of a poison for the molecular sieve adsorbent used in a continuous adsorptive separation process from entering the process comprises: a)contacting (1) with (2) which adsorbs the poison present in (1); (b) periodically purging (2) by passing (4) containing (3) through (2) and passing the effluent of (2) into a raffinate column to separate raffinate compounds and (3); and (c) regenerating (2) by passing an additional quantity of (4) through (2) and passing the effluent of (2) into a recovery fractionation column to recover (3) from the effluent of (2); and (B) a simulated moving bed process for the separation of linear olefinic hydrocarbon (5) from (1) comprises contacting (1) with (2) to cause the selective retention of (5) on the molecular sieve and the resultant formation of the raffinate stream is passed into the raffinating column. The retained (5) is recovered by periodically regenerating (2) with (4) containing (3) and initially passing the effluents of (2) into a raffinate column and then switching the flow of the effluents to the desorbent recovery column.