# US 7,608,733 B2 · Optimized liquid-phase oxidation > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,608,733 B2 - Document ID: US7608733B2 - Status: Granted - Kind: B2 - Application number: 11/154,479 - Filed: 2005-06-16 - Published: 2006-03-02 - Granted: 2009-10-27 - Earliest claimed: 2004-09-02 - Assignees: Eastman Chemical Company - Inventors: Alan George Wonders; Howard Wood Jenkins, Jr.; Lee Reynolds Partin; Wayne Scott Strasser; Marcel de Vreede - Web page: https://patentgrep.com/patent/US7608733B2 ## CPC - C07C 51/265: having alkyl side chains which are oxidised to carboxyl groups - C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS ## Abstract Disclosed is an optimized process and apparatus for more efficiently and economically carrying out the liquid-phase oxidation of an oxidizable compound. Such liquid-phase oxidation is carried out in a bubble column reactor that provides for a highly efficient reaction at relatively low temperatures. When the oxidized compound is para-xylene and the product from the oxidation reaction is crude terephthalic acid (CTA), such CTA product can be purified and separated by more economical techniques than could be employed if the CTA were formed by a conventional high-temperature oxidation process. ## Claims ### Claim 1 A process for producing terephthalic acid, said process comprising: oxidizing in a steady state operation para-xylene in a liquid phase of a reaction medium contained within a reaction zone of a bubble column reactor, wherein less than 0.03 volume percent of said reaction medium has a para-xylene concentration greater than 25,000 ppmw on a time-averaged basis, wherein said oxidizing is carried out in a manner such that when said reaction medium is theoretically partitioned into 30 horizontal slices of equal volume, a pX-max horizontal slice has the maximum para-xylene concentration of all of said 30 horizontal slices and a pX-min horizontal slice has the minimum para-xylene concentration of all the horizontal slices located above said pX-max horizontal slice, wherein said para-xylene concentration is measured in a liquid phase of said reaction medium on a time-averaged and volume-averaged weight basis, wherein the ratio of the para-xylene concentration of said pX-max horizontal slice to the para-xylene concentration of said pX-min horizontal slice is at least 5:1. ### Claim 2 (depends on 1) The process of claim 1 wherein less than 0.015 volume percent of said reaction medium has a para-xylene concentration greater than 25,000 ppmw on a time-averaged basis. ### Claim 3 (depends on 1) The process of claim 1 wherein less than 0.007 volume percent of said reaction medium has a para-xylene concentration greater than 25,000 ppmw on a time-averaged basis. ### Claim 4 (depends on 1) The process of claim 1 wherein the ratio of the para-xylene concentration of said pX-max horizontal slice to the para-xylene concentration of said pX-min horizontal slice is at least 20:1. ### Claim 5 (depends on 1) The process of claim 1 wherein the ratio of the para-xylene concentration of said pX-max horizontal slice to the para-xylene concentration of said pX-min horizontal slice is in the range of from 40:1 to 1,000:1. ### Claim 6 (depends on 1) The process of claim 1 wherein said reaction medium has a maximum height (H), a maximum width (W), and an H:W ratio of at least 3:1. ### Claim 7 (depends on 6) The process of claim 6 wherein said H:W ratio is in the range of from about 8:1 to about 20:1. ### Claim 8 (depends on 6) The process of claim 6 wherein said process further comprises introducing a predominately liquid-phase feed stream comprising said para-xylene into said reaction zone. ### Claim 9 (depends on 8) The process of claim 8 wherein at least a portion of said feed stream enters said reaction zone at an inlet superficial velocity of at least 5 meters per second. ### Claim 10 (depends on 8) The process of claim 8 wherein at least 50 weight percent of said feed stream enters said reaction zone at an inlet superficial velocity of at least 6 meters per second. ### Claim 11 (depends on 8) The process of claim 8 wherein said feed stream is introduced into said reaction zone via a plurality of feed openings, wherein at least two of said feed openings are vertically spaced from one another by at least 0.5W. ### Claim 12 (depends on 11) The process of claim 11 wherein at least two of said feed openings are vertically spaced from one another by at least 1.5W. ### Claim 13 (depends on 8) The process of claim 8 wherein said feed stream is introduced into said reaction zone in a manner such that when said reaction zone is theoretically partitioned into 4 vertical quadrants of equal volume by a pair of intersecting vertical planes, not more than 80 weight percent of said para-xylene enters said reaction zone in a single one of said vertical quadrants. ### Claim 14 (depends on 13) The process of claim 13 wherein not more than 60 weight percent of said para-xylene enters said reaction zone in a single one of said vertical quadrants. ### Claim 15 (depends on 8) The process of claim 8 wherein at least a portion of said reaction zone is defined by one or more upright sidewalls of said reactor, wherein at least 25 weight percent of said para-xylene enters said reaction zone at one or more locations spaced inwardly at least 0.05D from said upright sidewalls, wherein said reaction zone has a maximum diameter (D). ### Claim 16 (depends on 15) The process of claim 15 wherein at least 50 weight percent of said para-xylene enters said reaction zone at one or more locations spaced inwardly at least 0.05D from said upright sidewalls. ### Claim 17 (depends on 8) The process of claim 8 wherein said process further comprises introducing a predominately gas-phase oxidant stream comprising molecular oxygen into said reaction zone. ### Claim 18 (depends on 17) The process of claim 17 wherein at least 30 weight percent of said para-xylene enters said reaction zone within about 1.5W of the lowest location where said molecular oxygen enters said reaction zone. ### Claim 19 (depends on 17) The process of claim 17 wherein at least 50 weight percent of said para-xylene enters said reaction zone within about 2.5W of the lowest location where said molecular oxygen enters said reaction zone. ### Claim 20 (depends on 17) The process of claim 17 wherein a majority of said molecular oxygen enters said reaction zone within about 0.25W of the bottom of said reaction zone. ### Claim 21 (depends on 17) The process of claim 17 wherein substantially all of said molecular oxygen enters said reaction zone within about 0.25W and about 0.025H of the bottom of said reaction zone. ### Claim 22 (depends on 1) The process of claim 1 wherein said reaction medium is a three-phase reaction medium. ### Claim 23 (depends on 1) The process of claim 1 wherein said oxidizing causes at least 10 weight percent of said para-xylene to form solids in said reaction medium. ### Claim 24 (depends on 1) The process of claim 1 wherein said reaction medium comprises in the range of from about 5 to about 40 weight percent solids on a time-averaged and volume-averaged basis. ### Claim 25 (depends on 1) The process of claim 1 wherein said oxidizing is carried out in the presence of a catalyst system comprising cobalt. ### Claim 26 (depends on 25) The process of claim 25 wherein said catalyst system further comprises bromine and manganese. ### Claim 27 A process for producing terephthalic acid, said process comprising: oxidizing in a steady state operation para-xylene in a liquid phase of a reaction medium contained in a reaction zone of a bubble column reactor, wherein less than 0.3 volume percent of said reaction medium has a para-xylene concentration greater than 10,000 ppmw on a time-averaged basis, wherein said oxidizing is carried out in a manner such that when said reaction medium is theoretically partitioned into 30 horizontal slices of equal volume, a pX-max horizontal slice has the maximum para-xylene concentration of all of said 30 horizontal slices and a pX-min horizontal slice has the minimum para-xylene concentration of all the horizontal slices located above said pX-max horizontal slice, wherein said para-xylene concentration is measured in a liquid phase of said reaction medium on a time-averaged and volume-averaged weight basis, wherein the ratio of the para-xylene concentration of said pX-max horizontal slice to the para-xylene concentration of said pX-min horizontal slice is at least 5:1. ### Claim 28 (depends on 27) The process of claim 27 wherein less than 0.1 volume percent of said reaction medium has a para-xylene concentration greater than 10,000 ppmw on a time-averaged basis. ### Claim 29 (depends on 27) The process of claim 27 wherein less than 0.03 volume percent of said reaction medium has a para-xylene concentration greater than 10,000 ppmw on a time-averaged basis. ### Claim 30 (depends on 27) The process of claim 27 wherein said reaction medium has a maximum height (H), a maximum width (W), and an H:W ratio of at least 3:1. ### Claim 31 (depends on 30) The process of claim 30 wherein said process further comprises introducing a predominately liquid-phase feed stream comprising said para-xylene into said reaction zone. ### Claim 32 (depends on 31) The process of claim 31 wherein at least a portion of said feed stream enters said reaction zone at an inlet superficial velocity of at least 5 meters per second. ### Claim 33 (depends on 31) The process of claim 31 wherein said feed stream is introduced into said reaction zone via a plurality of feed openings, wherein at least two of said feed openings are vertically spaced from one another by at least 0.5W. ### Claim 34 (depends on 31) The process of claim 31 wherein said feed stream is introduced into said reaction zone in a manner such that when said reaction zone is theoretically partitioned into 4 vertical quadrants of equal volume by a pair of intersecting vertical planes, not more than 80 weight percent of said para-xylene enters said reaction zone in a single one of said vertical quadrants. ### Claim 35 (depends on 31) The process of claim 31 wherein at least a portion of said reaction zone is defined by one or more upright sidewalls of said reactor, wherein at least 25 weight percent of said para-xylene enters said reaction zone at one or more locations spaced inwardly at least 0.05W from said upright sidewalls. ### Claim 36 (depends on 31) The process of claim 31 wherein said process further comprises introducing a predominately gas-phase oxidant stream comprising molecular oxygen into said reaction zone. ### Claim 37 (depends on 36) The process of claim 36 wherein at least 30 weight percent of said para-xylene enters said reaction zone within about 1.5W of the lowest location where said molecular oxygen enters said reaction zone. ### Claim 38 A process for producing terephthalic acid, said process comprising: oxidizing in a steady state operation para-xylene in a liquid phase of a reaction medium contained in a reaction zone of a bubble column reactor, wherein less than 1.5 volume percent of said reaction medium has a para-xylene concentration greater than 2,500 ppmw on a time-averaged basis, wherein said oxidizing is carried out in a manner such that when said reaction medium is theoretically partitioned into 30 horizontal slices of equal volume, a pX-max horizontal slice has the maximum para-xylene concentration of all of said 30 horizontal slices and a pX-min horizontal slice has the minimum para-xylene concentration of all the horizontal slices located above said pX-max horizontal slice, wherein said para-xylene concentration is measured in a liquid phase of said reaction medium on a time-averaged and volume-averaged weight basis, wherein the ratio of the para-xylene concentration of said pX-max horizontal slice to the para-xylene concentration of said pX-min horizontal slice is at least 5:1. ### Claim 39 (depends on 38) The process of claim 38 wherein less than 1 volume percent of said reaction medium has a para-xylene concentration greater than 2,500 ppmw on a time-averaged basis. ### Claim 40 (depends on 38) The process of claim 38 wherein less than 0.5 volume percent of said reaction medium has a para-xylene concentration greater than 2,500 ppmw on a time-averaged basis. ### Claim 41 (depends on 38) The process of claim 38 wherein said reaction medium has a maximum height (H), a maximum width (W), and an H:W ratio of at least 3:1. ### Claim 42 (depends on 41) The process of claim 41 wherein said process further comprises introducing a predominately liquid-phase feed stream comprising said para-xylene into said reaction zone. ### Claim 43 (depends on 42) The process of claim 42 wherein at least a portion of said feed stream enters said reaction zone at a velocity of at least 5 meters per second. ### Claim 44 (depends on 42) The process of claim 42 wherein said feed stream is introduced into said reaction zone via a plurality of feed openings, wherein at least two of said feed openings are vertically spaced from one another by at least 0.5W. ### Claim 45 (depends on 42) The process of claim 42 wherein said feed stream is introduced into said reaction zone in a manner such that when said reaction zone is theoretically partitioned into 4 vertical quadrants of equal volume by a pair of intersecting vertical planes, not more than 80 weight percent of said para-xylene enters said reaction zone in a single one of said vertical quadrants. ### Claim 46 (depends on 42) The process of claim 42 wherein at least a portion of said reaction zone is defined by one or more upright sidewalls of said reactor, wherein at least 25 weight percent of said para-xylene enters said reaction zone at one or more locations spaced inwardly at least 0.05W from said upright sidewalls. ### Claim 47 (depends on 42) The process of claim 42 wherein said process further comprises introducing predominately gas-phase oxidant stream comprising molecular oxygen into said reaction zone. ### Claim 48 (depends on 47) The process of claim 47 wherein at least 30 weight percent of said para-xylene enters said reaction zone within about 1.5W of the lowest location where said molecular oxygen enters said reaction zone. ### Claim 49 A process for producing terephthalic acid, said process comprising: oxidizing in a steady state operation para-xylene in a liquid phase of a reaction medium contained in a reaction zone of a bubble column reactor, wherein less than 9 volume percent of said reaction medium has a para-xylene concentration greater than 1,000 ppmw on a time-averaged basis, wherein said oxidizing is carried out in a manner such that when said reaction medium is theoretically partitioned into 30 horizontal slices of equal volume, a pX-max horizontal slice has the maximum para-xylene concentration of all of said 30 horizontal slices and a pX-min horizontal slice has the minimum para-xylene concentration of all the horizontal slices located above said pX-max horizontal slice, wherein said para-xylene concentration is measured in a liquid phase of said reaction medium on a time-averaged and volume-averaged weight basis, wherein the ratio of the para-xylene concentration of said pX-max horizontal slice to the para-xylene concentration of said pX-min horizontal slice is at least 5:1. ### Claim 50 (depends on 49) The process of claim 49 wherein less than 6 volume percent of said reaction medium has a para-xylene concentration greater than 1,000 ppmw on a time-averaged basis. ### Claim 51 (depends on 49) The process of claim 49 wherein less than 3 volume percent of said reaction medium has a para-xylene concentration greater than 1,000 ppmw on a time-averaged basis. ### Claim 52 (depends on 49) The process of claim 49 wherein said reaction medium has a maximum height (H), a maximum width (W), and an H:W ratio of at least 3:1. ### Claim 53 (depends on 52) The process of claim 52 wherein said process further comprises introducing a predominately liquid-phase feed stream comprising said para-xylene into said reaction zone. ### Claim 54 (depends on 53) The process of claim 53 wherein at least a portion of said feed stream enters said reaction zone at an inlet superficial velocity of at least 5 meters per second. ### Claim 55 (depends on 53) The process of claim 53 wherein said feed stream is introduced into said reaction zone via a plurality of feed openings, wherein at least two of said feed openings are vertically spaced from one another by at least 0.5W. ### Claim 56 (depends on 53) The process of claim 53 wherein said feed stream is introduced into said reaction zone in a manner such that when said reaction zone is theoretically partitioned into 4 vertical quadrants of equal volume by a pair of intersecting vertical planes, not more than 80 weight percent of said para-xylene enters said reaction zone in a single one of said vertical quadrants. ### Claim 57 (depends on 53) The process of claim 53 wherein at least a portion of said reaction zone is defined by one or more upright sidewalls of said reactor, wherein at least 25 weight percent of said para-xylene enters said reaction zone at one or more locations spaced inwardly at least 0.05D from said upright sidewalls. ### Claim 58 (depends on 53) The process of claim 53 wherein said process further comprises introducing a predominately gas-phase oxidant stream comprising molecular oxygen into said reaction zone. ### Claim 59 (depends on 58) The process of claim 58 wherein at least 30 weight percent of said para-xylene enters said reaction zone within about 1.5W of the lowest location where said molecular oxygen enters said reaction zone. ### Claim 60 (depends on 49) The process of claim 49 wherein said reaction medium is a three-phase reaction medium, wherein said oxidizing in said bubble column reactor forms crude terephthalic acid, wherein said process further comprises oxidizing at least a portion of said crude terephthalic acid in a secondary oxidiation reactor to thereby form purer terephthalic acid. ### Claim 61 (depends on 60) The process of claim 60 wherein less than 1.5 volume percent of said reaction medium has a para-xylene concentration greater than 2,500 ppmw on a time-averaged basis. ### Claim 62 (depends on 60) The process of claim 60 wherein less than 0.3 volume percent of said reaction medium has a para-xylene concentration greater than 10,000 ppmw on a time-averaged basis. ### Claim 63 (depends on 60) The process of claim 60 wherein said oxidizing in said secondary oxidation reactor decreases the average concentration of 4-CBA present in said crude terephthalic acid by at least 200 ppmw to thereby form said purer terephthalic acid. ### Claim 64 (depends on 60) The process of claim 60 wherein said crude terephthalic acid has an average 4-CBA concentration of at least 400 ppmw and said purer terephthalic acid has an average 4-CBA concentration of less than 400 ppmw. ### Claim 65 (depends on 60) The process of claim 60 wherein said oxidizing in said secondary oxidation reactor decreases the average concentration of 4-CBA in said crude terephthalic acid by at least 400 ppmw to thereby form said purer terephthalic acid, wherein said crude terephthalic acid has an average 4-CBA concentration of at least 800 ppmw and said purer terephthalic acid has an average 4-CBA concentration of less than 250 ppmw. ### Claim 66 (depends on 60) The process of claim 60 wherein said oxidizing in said secondary oxidation reactor is carried out at an average temperature at least 10° C. greater than the average temperature of said oxidizing in said bubble column reactor. ### Claim 67 (depends on 66) The process of claim 66 wherein said oxidizing in said bubble column reactor is carried out at an average temperature in the range of from about 125 to about 200° C., wherein said oxidizing in said secondary oxidation reactor is carried out at an average temperature in the range of from about 160 to about 240° C. ### Claim 68 (depends on 60) The process of claim 60 wherein said oxidizing in said secondary oxidation reactor is carried out at an average temperature in the range of from about 20 to about 80° C. greater than the average temperature of said oxidizing in said bubble column reactor, wherein said oxidizing in said bubble column reactor is carried out at an average temperature in the range of from about 140 to about 180° C., wherein said oxidizing in said secondary oxidation reactor is carried out at an average temperature in the range of from about 180 to about 220° C. ### Claim 69 (depends on 60) The process of claim 60 wherein a substantial portion of said crude terephthalic acid exists as solid crude terephthalic acid particles having an average BET surface area of at least 0.25 meters squared per gram. ### Claim 70 (depends on 69) The process of claim 69 wherein said solid crude terephthalic acid particles have an average particle size in the range of from about 20 to about 150 microns. ### Claim 71 (depends on 70) The process of claim 70 wherein a substantial portion of said solid crude terephthalic acid particles are formed of a plurality of agglomerated sub-particles having an average particle size in the range of from about 0.5 to about 30 microns. ### Claim 72 (depends on 71) The process of claim 71 wherein said solid crude terephthalic acid particles have an average particle size in the range of from about 30 to about 120 microns, wherein said sub-particles have an average particle size in the range of from about 1 to about 15 microns. ### Claim 73 (depends on 60) The process of claim 60 wherein said process further comprises recovering an initial slurry comprising a mother liquor and said crude terephthalic acid from said bubble column reactor, wherein said process further comprises replacing at least 50 weight percent of said mother liquor in said initial slurry with a replacement solvent to thereby provide a solvent-exchanged slurry comprising said replacement solvent and said crude terephthalic acid, wherein said process further comprises introducing said solvent-exchanged slurry into said secondary oxidation reactor.