# US 7,612,232 B2 · Purification of acetic acid from wood acetylation process > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,612,232 B2 - Document ID: US7612232B2 - Status: Granted - Kind: B2 - Application number: 12/079,452 - Filed: 2008-03-27 - Published: 2009-10-01 - Granted: 2009-11-03 - Earliest claimed: 2008-03-27 - Assignees: Celanese International Corporation - Inventors: R. Jay Warner; Melchior A. Meilchen; Michael O. Streb; Nathan K. Powell; Rolf Soellner - Web page: https://patentgrep.com/patent/US7612232B2 ## CPC - C07C 51/46: by azeotropic distillation - C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS ## Abstract A method of purifying acetic acid containing terpene and terpenoid impurities, includes: (a) supplying acetic acid containing terpene or terpenoid impurities and water to a distillation column; (b) azeotropically removing terpene or terpenoid impurities from the mixture of acetic acid and water supplied to the column as distillate; and (c) withdrawing a product stream from the column comprising acetic acid purified of terpene or terpenoid impurities. The method is particularly effective for purifying acetic acid recovered from a wood purification process. ## Claims ### Claim 1 A method of purifying acetic acid containing terpene and terpenoid impurities, comprising: (a) supplying acetic acid containing terpene or terpenoid impurities and water to a distillation column; (b) azeotropically removing terpene or terpenoid impurities as low boiling point water azeotropes in distillate from the mixture of acetic acid and water supplied to the column; and (c) withdrawing a product stream from the column comprising acetic acid purified of terpene or terpenoid impurities. ### Claim 2 (depends on 1) The method of purifying acetic acid containing terpene and terpenoid impurities according to claim 1, wherein the product stream withdrawn from the column is a liquid. ### Claim 3 (depends on 2) The method of purifying acetic acid containing terpene and terpenoid impurities according to claim 2, further comprising drying the liquid product stream. ### Claim 4 (depends on 1) The method of purifying acetic acid containing terpene and terpenoid impurities according to claim 1, wherein the acetic acid:water feed ratio is at least 2:1 and up to 50:1. ### Claim 5 (depends on 1) The method of purifying acetic acid containing terpene and terpenoid impurities according to claim 1, wherein the acetic acid:water feed ratio is at least 4:1. ### Claim 6 (depends on 1) The method of purifying acetic acid containing terpene and terpenoid impurities according to claim 1, wherein the acetic acid:water feed ratio is at least 7:1 and up to about 15:1. ### Claim 7 (depends on 1) The method of purifying acetic acid containing terpene and terpenoid impurities according to claim 1, wherein the method provides removal of 70% by weight or more of the total terpene and terpenoid impurities. ### Claim 8 (depends on 1) The method of purifying acetic acid containing terpene and terpenoid impurities according to claim 1, wherein the method provides removal of 80% by weight or more of the total terpene and terpenoid impurities. ### Claim 9 (depends on 1) The method of purifying acetic acid containing terpene and terpenoid impurities according to claim 1, wherein the method provides removal of 85% by weight or more of the total terpene and terpenoid impurities. ### Claim 10 (depends on 1) The method of purifying acetic acid containing terpene and terpenoid impurities according to claim 1, wherein the amount of water in the product stream is 25% or less. ### Claim 11 (depends on 1) The method of purifying acetic acid containing terpene and terpenoid impurities according to claim 1, wherein the amount of water in the product stream is 15% or less. ### Claim 12 (depends on 1) The method of purifying acetic acid containing terpene and terpenoid impurities according to claim 1, wherein the amount of water in the product stream is 5% or less. ### Claim 13 (depends on 1) The method of purifying acetic acid containing terpene and terpenoid impurities according to claim 1, wherein the amount of water in the product stream is 2% or less. ### Claim 14 (depends on 1) The method of purifying acetic acid containing terpene and terpenoid impurities according to claim 1, wherein the amount of water in the product stream is 1% or less. ### Claim 15 (depends on 1) The method of purifying acetic acid containing terpene and terpenoid impurities according to claim 1, wherein the amount of water in the product stream is 0.2% or less. ### Claim 16 (depends on 1) The method of purifying acetic acid containing terpene and terpenoid impurities according to claim 1, effective to remove at least 80% of one or more of the following: terpinenes; terpinolenes; α-terpineol acetate; pinenes; α-fenchene; camphene; p-methyl isopropyl benzene (p-cymene); limonenes; α-fenchyl acetate; isobornyl acetate; and mixtures thereof. ### Claim 17 A method of purifying acetic acid containing terpene and terpenoid impurities, comprising: (a) recovering dry acetic acid from a wood acetylation process; (b) supplying the acetic acid and water to a distillation column; (c) azeotropically removing terpene or terpenoid impurities as low boiling point water azeotropes in distillate from the mixture of acetic acid and water supplied to the column; (d) withdrawing a product stream from the column comprising acetic acid purified of terpene or terpenoid impurities; and (e) drying the product stream. ### Claim 18 (depends on 17) The method of purifying acetic acid containing terpene and terpenoid impurities according to claim 17, wherein the method further comprises maintaining a water concentration in the tower above a point at which the product stream is withdrawn of at least 10%. ### Claim 19 (depends on 17) The method of purifying acetic acid containing terpene and terpenoid impurities according to claim 17, wherein the method further comprises maintaining a water concentration in the tower above a point at which the product stream is withdrawn of at least 20%. ### Claim 20 (depends on 17) The method of purifying acetic acid containing terpene and terpenoid impurities according to claim 17, wherein the method further comprises maintaining a water concentration in the tower above a point at which the product stream is withdrawn of at least 30%. ### Claim 21 (depends on 17) The method of purifying acetic acid containing terpene and terpenoid impurities according to claim 17, wherein the method further comprises maintaining a water concentration in the tower above a point at which the product stream is withdrawn of at least 40%. ### Claim 22 A method of purifying acetic acid containing terpene and terpenoid impurities, comprising: (a) supplying acetic acid containing terpene or terpenoid impurities to a distillation column; (b) feeding water to the distillation column at a location above the location where acetic acid is supplied; (c) azeotropically removing terpene or terpenoid impurities as low boiling point water azeotropes in distillate from the mixture of acetic acid and water supplied to the column by way of withdrawing overhead vapor from the distillation column; (d) condensing the overhead vapor; (e) refluxing a portion of the condensed distillate withdrawn from the distillation column; and (f) withdrawing a product stream from the column comprising acetic acid purified of terpene or terpenoid impurities. ### Claim 23 (depends on 22) The method of purifying acetic acid containing terpene and terpenoid impurities according to claim 22, wherein the water feed:distillate ratio is not higher than 5:1. ### Claim 24 (depends on 22) The method of purifying acetic acid containing terpene and terpenoid impurities according to claim 22, wherein the water feed:distillate ratio is not more than 2:1. ### Claim 25 (depends on 22) The method of purifying acetic acid containing terpene and terpenoid impurities according to claim 22, wherein the water feed:distillate ratio is at least 1:1 and not more than 2:1. ### Claim 26 (depends on 22) The method of purifying acetic acid containing terpene and terpenoid impurities according to claim 22, wherein the reflux:distillate ratio is at least 1:1. ### Claim 27 (depends on 22) The method of purifying acetic acid containing terpene and terpenoid impurities according to claim 22, wherein the reflux:distillate ratio is at least 3:1. ### Claim 28 (depends on 22) The method of purifying acetic acid containing terpene and terpenoid impurities according to claim 22, wherein the reflux:distillate ratio is at least 10:1. ### Claim 29 (depends on 22) The method of purifying acetic acid containing terpene and terpenoid impurities according to claim 22, wherein the reflux:distillate ratio is at least 10:1 and not more than 25:1.