Two-stage process for separating mixed fatty-acid esters

A process for separating an ester of a polyethanoid fatty acid and an ester from a monoethanoid fatty acid from a first mixture comprising an ester of a polyethanoid fatty acid, an ester of a monoethanoid fatty acid and an ester of a saturated fatty acid which process comprises the steps of:

• a. contacting said first mixture at a temperature within the range of from about 20.degree. to about 250.degree. C. and a pressure from about atmospheric to about 500 psig. with a first adsorbent comprising a X or a Y zeolite containing at the exchangeable cationic sites at least one cation selected from the group consisting of cations of metals of Group IA of the Periodic Table of Elements and combinations thereof thereby selectively adsorbing said ester of a polyethanoid fatty acid;
• b. removing from said first adsorbent a first raffinate output stream comprising said ester of a monoethanoid fatty acid and said ester of a saturated fatty acid;
• c. contacting said first adsorbent at a temperature within the range of from about 20.degree. to about 250.degree. C. and a pressure from about atmospheric to about 500 psig. with a first desorbent material comprising a monocyclic aromatic hydrocarbon to effect the desorption of said ester of a polyethanoid fatty acid from said first adsorbent;
• d. removing from said first adsorbent a first extract output stream comprising said ester of a polyethanoid fatty acid;
• e. contacting a second mixture comprising said first raffinate output stream at a temperature within the range of from about 20.degree. to about 250.degree. C. and a pressure from about atmospheric to about 500 psig. with a second adsorbent comprising a X or a Y zeolite essentially completely exchanged with potassium and copper cations thereby selectively adsorbing said ester of a monoethanoid fatty acid;
• f. removing from said second adsorbent a second raffinate output stream comprising said ester of a saturated fatty acid;
• g. contacting said second adsorbent at a temperature within the range of from about 20.degree. to about 250.degree. C. and a pressure from about atmospheric to about 500 psig. with a second desorbent material comprising a monocyclic aromatic hydrocarbon to effect the desorption of said ester of a monoethanoid fatty acid from said second adsorbent;
• and,
• h. removing from said second adsorbent a second extract output stream comprising said ester of a monoethanoid fatty acid.

A process for separating an ester of a polyethanoid fatty acid and an ester of a monoethanoid fatty acid from a first mixture comprising an ester of a polyethanoid fatty acid, an ester of a monoethanoid fatty acid and and ester of a saturated fatty acid which process employs a first adsorbent comprising a X or a Y zeolite essentially completely exchanged with a cation selected from the group consisting of cations of metals of Group IA of the Periodic Table of Elements and combinations thereof and a second adsorbent comprising a X or a Y zeolite essentially completely exchanged with potassium and copper cations which process comprises the steps of:

• a. maintaining net fluid flow through a first column of said first adsorbent in a single direction, which first column contains at least three zones having separate operational functions occurring therein and being serially interconnected with the terminal zones of said first column connected to provide a continuous connection of said zones;
• b. maintaining a first adsorption zone in said first column, said first adsorption zone defined by the first adsorbent located between a first feed input stream at an upstream boundary of said zone and a first raffinate output stream at a downstream boundary of said zone;
• c. maintaining a first purification zone immediately upstream from said first adsorption zone, said first purification zone defined by the first adsorbent located between a first extract output stream at an upstream boundary of said first purification zone and said first feed input stream at a downstream boundary of said first purification zone;
• d. maintaining a first desorption zone immediately upstream from said first purification zone, said first desorption zone defined by the first adsorbent located between a first desorbent input stream at an upstream boundary of said zone and said first extract output stream at a downstream boundary of said zone;
• e. passing said first feed mixture into said first adsorption zone at a temperature within the range of from about 20.degree. to about 250.degree. C. and a pressure within the range of from about atmospheric to about 500 psig. to effect the selective adsorption of said ester of a polyethanoid fatty acid by said first adsorbent in said first adsorption zone and withdrawing a first raffinate output stream comprising an ester of a monoethanoid fatty acid, an ester of a saturated fatty acid and first desorbent material from said first adsorption zone;
• f. passing a first desorbent material comprising a monocyclic aromatic hydrocarbon into said first desorption zone at a temperature within the range of from about 20.degree. to about 250.degree. C. and a pressure within the range of from about atmospheric to about 500 psig. to effect the displacement of said ester of a polyethanoid fatty acid from said first adsorbent in said first desorption zone;
• g. withdrawing a first extract output stream comprising said ester of a polyethanoid fatty acid and first desorbent material from said first desorption zone;
• h. passing at least a portion of said first extract output stream to a first separation means and therein separating at first separation conditions at least a portion of said first desorbent material thereby producing a first extract product comprising an ester of a polyethanoid fatty acid;
• i. periodically advancing through said first column of first adsorbent in a downstream direction with respect to fluid flow in said first adsorption zone the first feed input stream, first raffinate output stream, first desorbent input stream, and first extract output stream to effect the shifting of zones through said first adsorbent and the production of said first extract output stream and said first raffinate output stream;
• j. maintaining net fluid flow through a second column of said second adsorbent in a single direction, which second column contains at least three zones having separate operational functions occurring therein and being serially interconnected with the terminal zones of said second column connected to provide a continuous connection of said zones;
• k. maintaining a second adsorption zone in said second column, said second adsorption zone defined by the second adsorbent located between a second feed input stream at an upstream boundary of said zone and a second raffinate output stream at a downstream boundary of said zone;
• l. maintaining a second purification zone immediately upstream from said second adsorption zone, said second purification zone defined by the second adsorbent located between a second extract output stream at an upstream boundary of said second purification zone and said second feed input stream at a downstream boundary of said second purification zone;
• m. maintaining a second desorption zone immediately upstream from said second purification zone, said second desorption zone defined by the second adsorbent located between a second desorbent input stream at an upstream boundary of said zone and said second extract output stream at a downstream boundary of said zone;
• n. passing said first raffinate output stream from step (e) above into said second adsorption zone at a temperature within the range of from about 20.degree. to about 250.degree. C. and a pressure within the range of from about atmospheric to about 500 psig. to effect the selective adsorption of said ester of a monoethanoid fatty acid by said second adsorbent in said second adsorption zone and withdrawing a second raffinate output stream comprising an ester of a saturated fatty acid and second desorbent material from said second adsorption zone;
• o. passing a second desorbent material comprising a monocyclic aromatic hydrocarbon into said second desorption zone at a temperature within the range of from about 20.degree. to about 250.degree. C. and a pressure within the range of from about atmospheric to about 500 psig. to effect the displacement of said ester of a monoethanoid fatty acid from said second adsorbent in said second desorption zone;
• p. withdrawing a second extract output stream comprising said ester of a monoethanoid fatty acid and second desorbent material from said second desorption zone;
• q. passing at least a portion of said second extract output stream to a second separation means and therein separating at second separation conditions at least a portion of said second desorbent material thereby producing a second extract product comprising an ester of a monoethanoid fatty acid;
• and,
• r. periodically advancing through said second column of second adsorbent in a downstream direction with respect to fluid flow in said second adsorption zone the second fee input stream, second raffinate output stream, second desorbent input stream, and second extract output stream to effect the shifting of zones through said second adsorbent and the production of said second extract output stream and said second raffinate output stream.