# US 4,393,266 A · Separation of para-xylene > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,393,266 A - Document ID: US4393266A - Status: Granted - Kind: A - Application number: 06/412,448 - Filed: 1982-08-27 - Granted: 1983-07-12 - Earliest claimed: 1980-05-23 - Assignees: Texaco Inc. - Inventors: William Smolin - Web page: https://patentgrep.com/patent/US4393266A ## CPC - C07C 7/13: by molecular-sieve technique - C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS ## Abstract Para-xylene may be separated as front-end product in high purity by contacting charge C-8 aromatic hydrocarbon mixture with certain NaY-type zeolites in the presence of a pyridine. ## Claims ### Claim 1 The process for separating para-xylene from a feed mixture containing C-8 aromatic hydrocarbon including para-xylene which comprises contacting said feed mixture with, as an adsorbent, a pyridine or substituted pyridine-containing sodium Y zeolite, said sodium Y zeolite being characterized by a ratio of silicon to aluminum of 1.5-2.1 and by a pyridine or substituted pyridine content of at least about 3.3 w % based on said zeolite, thereby selectively adsorbing substantially all of said C-8 aromatic hydrocarbon to the substantial exclusion of para-xylene; and recovering said para-xylene. ### Claim 2 (depends on 1) The process as claimed in claim 1 where said feed mixture contains para-xylene, meta-xylene, ortho-xylene, and ethylbenzene. ### Claim 3 (depends on 1) The process as claimed in claim 1 wherein said feed mixture contains para-xylene, meta-xylene and ortho-xylene, said ortho-xylene being contained in amount less than the concentration of either para-xylene or meta-xylene. ### Claim 4 (depends on 1) The process as claimed in claim 1 wherein said feed mixture contains ortho-xylene and has been fractionated to remove therefrom at least a portion of the ortho-xylene. ### Claim 5 (depends on 1) The process as claimed in claim 1 wherein said feed mixture contains ethylbenzene and has been fractionated to remove therefrom at least a portion of the ethylbenzene. ### Claim 6 (depends on 1) The process as claimed in claim 1 wherein said feed mixture contains ethylbenzene and ortho-xylene and has been fractionated to remove therefrom at least a portion of the ethylbenzene and at least a portion of the ortho-xylene. ### Claim 7 (depends on 1) The process as claimed in claim 1 wherein said zeolite contains pyridine or a substituted pyridine selected from the group consisting of 2-picoline, 3-picoline, 4-picoline, 2,4-lutidine, 2,6-lutidine, and 3,4-lutidine. ### Claim 8 (depends on 1) The process as claimed in claim 1 wherein said zeolite contains pyridine. ### Claim 9 (depends on 1) The process as claimed in claim 1 wherein said pyridine or substituted pyridine-containing zeolite contains about 3.3 w %-20 w % of a pyridine or substituted pyridine selected from the group consisting of 2-picoline, 3-picoline, 4-picoline, 2,4-lutidine, 2,6-lutidine, 3,4-lutidine and pyridine. ### Claim 10 (depends on 1) The process as claimed in claim 1 wherein said contacting is carried out in liquid phase at 100.degree. F.-450.degree. F. ### Claim 11 (depends on 1) The process as claimed in claim 1 wherein said contacting is carried out in vapor phase at temperature above the boiling point of the feed mixture. ### Claim 12 (depends on 1) The process as claimed in claim 1 wherein said zeolite, after said contacting step, is contacted with desorbent material to remove the adsorbed isomers. ### Claim 13 (depends on 12) The process as claimed in claim 12 wherein said desorbent material is toluene. ### Claim 14 (depends on 1) The process for separating para-xylene as claimed in claim 1 wherein said zeolite is characterized by a silicon to aluminum ratio of about 1.5-1.8. ### Claim 15 (depends on 1) The process for separating para-xylene as claimed in claim 1 wherein said zeolite is characterized by a pyridine content of about 5-8 wt.%. ### Claim 16 The process for separating para-xylene from a feed mixture containing C-8 aromatic hydrocarbons including para-xylene which comprises contacting said feed mixture with, as an adsorbent, a pyridine or substituted pyridine-containing sodium Y zeolite, said sodium Y zerolite being characterized by a ratio of silicon to aluminum of 1.5-2.1 and by a pyridine or substituted pyridine content of at least about 3.3 w % based on said zerolite, in the presence of desorbent, thereby selectively adsorbing substantially all of said C-8 aromatic hydrocarbon to the substantial exclusion of para-xylene; contacting said adsorbent at desorption conditions with desorbent material having a boiling point substantially different from that of said feed mixture to effect withdrawal of the selectively adsorbed C-8 aromatic hydrocarbon; withdrawing from the adsorbent a raffinate stream containing less selectively adsorbed para-xylene; and withdrawing from said adsorbent an extract stream containing said selectively adsorbed C-8 aromatic hydrocarbon. ### Claim 17 (depends on 16) The process as claimed in claim 16 wherein said pyridine is present in said feed mixture. ### Claim 18 (depends on 16) The process as claimed in claim 16 wherein said pyridine is present in said desorbent. ### Claim 19 (depends on 16) The process as claimed in claim 16 wherein said desorbent is toluene. ### Claim 20 (depends on 16) The process as claimed in claim 16 wherein said separating is carried out in vapor phase cyclic operation. ### Claim 21 (depends on 16) The process as claimed in claim 16 wherein said separating is carried out in liquid phase cyclic operation. ### Claim 22 (depends on 16) The process as claimed in claim 16 wherein said separating is carried out in liquid phase simulated continuous counter-flow operation.