GB951260A - Method for regenerating a molecular sieve adsorbent - Google Patents

Abstract

A molecular sieve adsorbent that contains adsorbed material is regenerated by contacting the adsorbent with a condensable desorbing agent vapour, increasing the partial pressure of said desorbing agent in contact with the molecular sieve within the range of 0.01 to 0.98 times the vapour pressure of the desorbing agent at the particular temperature employed to cause condensation of the desorbing agent substantially only within the molecular seive channels under the influence of the capillary condensation effect, and thereafter imposing conditions of temperature and pressure on the molecular sieves to cause revaporization and removal of such condensed desorbing agent. This method can be used in molecular sieve separation of many types of organic mixtures e.g. 2-butene from isoprene. The 2-butene/isoprene mixture is passed in the liquid or vapour phase into a column of molecular sieves e.g. as pellets, usually at atmospheric pressure and ambient temperature. Unadsorbed percolate is collected as one product of the separation until or just before the preferentially adsorbed material begins to appear in the percolate. The occluded material remaining in the column is withdrawn from the bottom and is recycled to the next separation phase. Regeneration of the column is then effected by contacting the sieve with the desorbent vapour n-butane until the pressure in the column is just below the pressure at which the desorbent vapour will condense. After a sufficient quantity has condensed the pressure on the column is reduced causing vaporization of the desorbing agent and removal of adsorbed impurities. The procedure of condensing the desorbing agent and revaporization should be repeated, preferably at least 3 times. The column is then purged with an inert gas, preferably at sub-atmospheric pressure and/or elevated temperature. The preferred desorbing agents are straight chain paraffins; they should be inert, should not polymerize, isomerize or decompose under the conditions used and it should be miscible with the material to be adsorbed. Specification 548,905 is referred to.ALSO:A molecular sieve adsorbent that contains adsorbed material is regenerated by contacting the adsorbent with a condensable desorbing agent vapour, increasing the partial pressure of said desorbing agent in contact with the molecular sieve within the range of 0,01-0,98 times the vapour pressure of the desorbing agent at the particular temperature employed to cause condensation of the desorbing agent substantially only within the molecular sieve channels under the influence of the capillary condensation effect, and thereafter imposing conditions of temperature and pressure on the molecular sieves to cause revaporization and removal of such condensed desorbing agent. This method can be used in molecular sieve separation of many types of organic mixtures, e.g. 2-butene from isoprene. The 2-butene/isoprene mixture is passed in the liquid or vapour phase into a column of molecular sieves, e.g. as pellets, usually at atmospheric pressure and ambient temperature. Unadsorbed percolate is collected as one product of the separation until or just before the preferentially adsorbed material begins to appear in the percolate. The occluded material remaining in the column is withdrawn from the bottom and is recycled to the next separation phase. Regeneration of the column is then effected by contacting the sieve with the desorbent vapour n-butane until the pressure in the column is just below the pressure at which the desorbent vapour will condense. After a sufficient quantity has condensed the pressure on the column is reduced causing vaporization of the desorbing agent and removal of adsorbed impurities. The procedure of condensing the desorbing agent and revaporization should be repeated, preferably at least three times. The column is then purged with an inert gas, preferably at sub-atmospheric pressure and/or elevated temperature. The preferred desorbing agents are straight chain paraffins which should be inert, should not polymerize, isomerize or decompose under the conditions used and should be miscible with the material to be adsorbed. Specification 548,905 is referred to.