JP2008511645A5 - - Google Patents

Claims (51)

  Oxidizing the oxidizable compound in the liquid phase of the multiphase reaction medium contained in the reaction zone of the initial oxidation reactor, wherein the total volume of the reaction medium is equal to 2,000 separate volumes. The method of performing the oxidation such that when theoretically divided into horizontal slices, less than 120 of the horizontal slices have a gas holdup of less than 0.3 on a time average and volume average basis. The method of claim 1 wherein the total volume of the reaction medium has a gas holdup of at least 0.4 on a time average and volume average basis.   The method of claim 1, wherein less than 80 of the horizontal slices have a gas holdup of less than 0.3 on a time average and volume average basis. Less than 40 of the horizontal slices have a gas holdup of less than 0.3 on a time average and volume average basis, and the total volume of the reaction medium ranges from 0.6 to 0.9 on a time average and volume average basis The method of claim 1 having a gas holdup of   The method of claim 1, wherein the initial oxidation reactor is a stirred reactor.   The method of claim 1, wherein the initial oxidation reactor is a bubble column reactor. The method produces a substantially degassed slurry containing less than 5% by volume of gas by degassing a portion of the reaction medium in a degassing zone separate from the reaction zone. The method according to claim 6, further comprising the step of causing the degassing mainly by natural buoyancy of the gas phase of the reaction medium in a solid phase and a liquid phase of the reaction medium. The degassing zone is defined between one or more upstanding side walls of a degassing vessel, and the maximum horizontal cross-sectional area of the degassing zone is less than 25% of the maximum horizontal cross-sectional area of the reaction zone. The method described in 1.   The method of claim 8, wherein at least a portion of the degassing zone is disposed in the reactor.   The method of claim 8, wherein all of the degassing zone is located outside the reactor. The process according to claim 6, wherein the reaction medium has a maximum height (H), a maximum width (W) and an H: W ratio of 3: 1 . The method of claim 11 wherein the H: W ratio is in the range of 8: 1 to 20: 1 . The method further comprises introducing a predominantly gas phase oxidant stream comprising molecular oxygen into the reaction zone, wherein the majority of the molecular oxygen is within 0.25 W at the bottom of the reaction zone. The process of claim 11 entering the reaction zone. The method of claim 13, the majority of the molecular oxygen enters said reaction zone at less than 0.2W and 0.02H of the bottom of the reaction zone. When the molecular oxygen theoretically divides the reaction zone into four equal quadrants of equal volume by a pair of tolerance vertical planes, no more than 80% by weight of the molecular oxygen is a single unit of the vertical quadrant. 14. The method of claim 13, wherein the reaction zone is entered in one quadrant. At least a portion of the reaction zone is defined by one or more upstanding sidewalls of the reactor, and at least 25% by weight of the molecular oxygen is spaced at least 0.05D inward from the upstanding sidewalls. 14. The method of claim 13, wherein the reaction zone is entered at one or more disposed locations, the reaction zone having a maximum diameter (D). A first portion of the oxidant stream is introduced into the reaction zone through one or more lower oxidant openings and a second portion of the oxidant stream is introduced into one or more upper oxidations. The method of claim 13, wherein the method is introduced into the reaction zone via an agent opening, and the upper oxidant opening is disposed at least 1 W above the lower oxidant opening. The method of claim 17, wherein the first and second portions of the oxidant stream each comprise less than 50 mol% molecular oxygen. Wherein at least 10 mole% of the total amount of molecular oxygen introduced into the reaction zone is introduced through said for the lower oxidant opening, at least 10 mole% of the total amount of molecular oxygen is introduced into said reaction zone the upper The method according to claim 17, wherein the method is introduced through an opening for an oxidant. The upper oxidant opening is positioned at least 2D above the lower oxidant opening, and the first and second portions of the oxidant stream are each less than 40 mole% molecular oxygen The method of claim 17 comprising:   The method according to claim 1, wherein the oxidizable compound is an aromatic compound.   The method according to claim 1, wherein the oxidizable compound is p-xylene. The method of claim 1, wherein the oxidation forms a solid in at least 10% by weight of the oxidizable compound in the reaction medium.   The process according to claim 1, wherein the oxidation is carried out in the presence of a catalyst system comprising cobalt.   The method of claim 24, wherein the catalyst system further comprises bromine and manganese.   The oxidation in the initial oxidation reactor forms terephthalic acid in the reaction medium, and the method further comprises subjecting at least a portion of the terephthalic acid to oxidation in a secondary oxidation reactor. the method of. 27. The method of claim 26, wherein the oxidation in the secondary oxidation reactor is carried out at an average temperature that is at least 10 [deg.] C higher than the oxidation in the initial oxidation reactor. The oxidation in the secondary oxidation reactor is carried out at an average temperature in the range of 20 to 80 ° C. higher than the average temperature in the initial oxidation reactor, and the oxidation in the initial oxidation reactor is performed at 140 to 180 ° C. 27. The process according to claim 26, wherein the process is carried out at an average temperature in the range and the oxidation in the secondary oxidation reactor is carried out at an average temperature in the range of 180-220 [deg.] C. The oxidation forms crude terephthalic acid particles in the reaction medium, and a representative sample of the crude terephthalic acid particles has the following characteristics:
(I) containing less than 12 ppmw of 4,4-dicarboxystilbene (4,4-DCS),
(Ii) containing less than 800 ppmw isophthalic acid (IPA);
(Iii) comprising less than 100 ppmw 2,6-dicarboxyfluorenone (2,6-DCF);
The method of claim 1, wherein (iv) the percent transmission (% T ₃₄₀ ) at ₃₄₀ nm has one or more of greater than 25 . (A) introducing a feed stream comprising p-xylene into the reaction zone of a bubble column reactor;
(B) An oxidant stream containing molecular oxygen is introduced into the reaction zone (the reaction zone has a maximum diameter (D), most of the molecular oxygen being 0.25D at the bottom of the reaction zone. (C) oxidizing at least a portion of the p-xylene in the liquid phase of the three-phase reaction medium contained in the reaction zone (the oxidation is the p in the reaction medium). -Solid crude terephthalic acid particles are formed in at least 10% by weight of xylene)
A method comprising that. 31. The method of claim 30, wherein the reaction medium has a maximum height (H) and a majority of the molecular oxygen enters the reaction zone within 0.025H at the bottom of the reaction zone. The method of claim 31, the majority of the molecular oxygen enters said reaction zone at less than 0.2D and 0.02H of the bottom of the reaction zone.   32. The method of claim 31, wherein a majority of the molecular oxygen enters the reaction zone within 0.15D and 0.015H at the bottom of the reaction zone. Said method producing a substantially degassed slurry comprising less than 5% by volume of gas by degassing a portion of said reaction medium in a degassing zone separate from said reaction zone. 31. The method of claim 30, further comprising causing the degassing primarily by the natural buoyancy of the gas phase of the three-phase reaction medium in the solid and liquid phases of the three-phase reaction medium. The degassing zone is defined between one or more upstanding sidewalls of a degassing vessel, and the maximum horizontal cross-sectional area of the degassing zone is less than 25% of the maximum horizontal cross-sectional area of the degassing zone. 34. The method according to 34. 31. A process according to claim 30, wherein the reaction medium comprises a solids content in the range of 5 to 40% by weight on a time average and volume average basis.   When the oxidation is theoretically divided into 2,000 separate horizontal slices of equal volume of the reaction medium, less than 120 of the horizontal slices are less than 0.3 on a time average and volume average basis 32. The method of claim 30, wherein the method is carried out to have a gas holdup of   32. The method of claim 30, wherein the method further comprises subjecting at least a portion of the crude terephthalic acid particles to oxidation in a secondary oxidation reactor. A representative sample of the crude terephthalic acid particles has the following characteristics:
(I) containing less than 12 ppmw of 4,4-dicarboxystilbene (4,4-DCS),
(Ii) containing less than 800 ppmw isophthalic acid (IPA);
(Iii) comprising less than 100 ppmw 2,6-dicarboxyfluorenone (2,6-DCF);
32. The method of claim 30, wherein (iv) the percent transmission at 340 nm (% _T340 ) has one or more of greater than 25 . In a bubble column reactor for reacting mainly a liquid phase stream and a mainly gas phase stream, a vessel shell that defines an elongated reaction zone along the central axis (the reaction zones have a maximum axial distance ( L) with a normal (vertical) lower end and a normal (vertical) upper end spaced apart, the reaction zone has a maximum diameter (D), and the reaction zone is at least 6: 1 And one or more gas openings (with a cumulative pore area defined by all of the gas openings) for releasing the gas stream into the reaction zone. A bubble column reactor improved in that it comprises a major portion within 0.25D of the normal bottom of the reaction zone. 41. The bubble column reactor of claim 40, wherein a majority of the cumulative pore area defined by all of the gas openings is located within 0.022L of the normal lower end of the reaction zone. Substantially all of the cumulative open area defined by all of said gas openings, said within the lower end of 0.25D and 0.022L in said normal state of the reaction zone, according to claim 40 to place Bubble column reactor. 41. The bubble column reactor according to claim 40, wherein at least two of the gas openings are arranged at least 1D apart from each other in the axial direction. The bubble column reactor further comprises one or more liquid openings for discharging the liquid phase stream into the reaction zone, the cumulative pore area defined by all of the liquid openings 41. The bubble column reactor according to claim 40, wherein at least 30% is disposed within 1.5D of the oxidant opening closest to the lower end in the normal state. 45. The bubble column reactor of claim 44, wherein the reactor comprises at least two liquid openings that are spaced at least 0.5D from each other. 41. The bubble column reactor according to claim 40, wherein L is in the range of 20 to 75 m , D is in the range of 2 to 10 m , and the L: D ratio is in the range of 8: 1 to 20: 1 . The reactor further includes a degassing vessel defining an inlet and an outlet, wherein the inlet is in fluid communication with the reaction zone, the outlet is normally disposed below the inlet, and the degassing vessel is at least partially the A normal upstanding sidewall extending between the inlet and the outlet and defining a degassing zone, the degassing zone having a maximum horizontal cross-sectional area that is less than 25% of the maximum horizontal cross-sectional area of the reaction zone. 40. A bubble column reactor according to 40.   48. The bubble column reactor of claim 47, wherein at least a portion of the degassing zone is disposed in the vessel shell.   48. The bubble column reactor according to claim 47, wherein the degassing zone is located completely outside the vessel shell. When the gas opening is theoretically divided into four equal quadrants of equal volume by a pair of tolerance vertical surfaces, the cumulative pore area defined by all of the gas openings is 80. 41. The bubble column reactor of claim 40, constructed so that no more than % is placed in a common one of the vertical quadrants. At least a portion of the reaction zone is defined by one or more upstanding sidewalls of the reactor, and at least 25% of the cumulative pore area defined by all of the gas openings is at least 0 inward from the vertical sidewalls. 41. The bubble column reactor of claim 40 with gas openings disposed at a spacing of .05D.