TW200831456A - Oxidation reaction for producing aromatic carboxylic acids - Google Patents

Abstract

A method of minimising or preventing catalyst loss and/or the precipitation of metal oxide in a process for the production of an aromatic carboxylic acid, said process comprising contacting in the presence of a catalyst comprising a metal salt within a reactor, one or more precursors of the aromatic carboxylic acid with an oxidant, such contact being effected with said precursor(s) and the oxidant in an aqueous solvent comprising water under supercritical conditions or near supercritical conditions, wherein (i) said method comprises the step of adding an acidic component comprising one or more acid(s) into the oxidation reaction zone; (ii) contact of at least part of said catalyst with said oxidant is in the presence of said acidic component; and (iii) said acidic component comprises one or more organic acid(s).

Description

200831456 IX. INSTRUCTIONS: TECHNICAL FIELD OF THE INVENTION The present invention relates to the field of catalytic oxidation and oxidation of metal salts in supercritical water, and in particular to the oxidation of alkyl-substituted aromatic hydrocarbons to the corresponding aromatic acids. In particular, the present invention relates to catalyst stability in such systems, and in particular to maintaining catalyst activity and/or efficiency, and to avoid reactor fouling. [Prior Art] When the water approaches its critical point (374 ° C and 220·9 bar), its dielectric constant is significantly reduced from a room temperature value of about 80 C 2 /Nm 2 to a value of 5 c 2 /Nm 2 to make it soluble. Organic molecules. As a result, water thus behaves similarly to an organic solvent in that a hydrocarbon such as toluene is completely miscible with water under supercritical conditions or near supercritical conditions. For example, terephthalic acid is hardly soluble in water below about 200 C. Molecular oxygen is also very soluble in subcritical and supercritical water.

Holliday RL et al. (J. Supercritical Fluids 12, 1998, 255-260) describe the synthesis of (in particular) from alkylaromatic compounds in a reaction medium of subcritical water using molecular oxygen as an oxidant in a sealed autoclave. Batch method of private carboxylic acid. However, the use of supercritical water as a medium for the manufacture of aromatic carboxylic acids in a continuous flow reactor presents a serious problem. WO-02/06201-A discloses a process for the manufacture of an aromatic carboxylic acid comprising contacting one or more precursors of the aromatic carboxylic acid with an oxidant in the presence of a catalyst in a continuous flow reactor, The contact system is implemented by the (or) precursor and the oxidizing agent in a supercritical or near supercritical condition close to a supercritical point in an aqueous solvent comprising water such that the precursor or the oxidizing agent and the aqueous solvent are in the The reaction zone constitutes a substantially single 126161.doc 200831456 phase. In the method described in WO-02/06201-A, at least a portion of the contact with the oxidant and the contact of the catalyst with at least a portion of the oxidant occur simultaneously. The continuous process of WO-02/0620 1-A is carried out by the formation of a reactant and a solvent which form a substantially homogeneous homogeneous fluid phase wherein the components are mixed at a molecular level. The concentration of molecular oxygen in water close to and beyond the supercritical point is significantly increased, which helps to improve the reaction kinetics. The reaction kinetics are further enhanced by the high temperatures present when the aqueous solvent is under supercritical or near supercritical conditions. The combination of temperature, high concentration and homogeneity means that compared to the residence time used in the manufacture of aromatic carboxylic acids (such as terephthalic acid) by conventional techniques using a gas crystal two-phase oxidation reactor The conversion of precursors to aromatic tetamine can occur extremely rapidly. Under these conditions, the intermediate aldehyde (for example, carboxybenzaldehyde (4-CbA) in the case of terephthalic acid) is easily oxidized to the desired aromatic carboxylic acid, which is soluble in supercritical or near-super In the critical fluid, the contamination of the recovered aromatic carboxylic acid product with the aldehyde intermediate is further reduced. The process conditions of WO-02/06201-A substantially reduce or avoid the autocatalytic destructive reaction between the precursor and the oxidant and the consumption of the catalyst. The continuous process involves short residence times and exhibits high yields and good selectivity for product formation. Preferably, the catalyst comprises a salt (especially MnBr2) in a supercritical oxidation reaction for the production of an aromatic carboxylic acid, but it has been observed that the salt is irreversibly oxidized to manganese oxide during strong oxidative reaction conditions (including Μη〇2). , Μη2〇3 and ΜηΟ(〇Η)2). The (equal) via oxide forms an insoluble precipitate that adheres to the inner wall 126161.doc 200831456 after initial contact of the catalyst with the oxidant (typically molecular oxygen), resulting in progressive fouling of the reactor and/or in a pressure reduction device. Blocked. Metal salts are known to oxidize in aqueous supercritical oxidation processes, and this is specifically used to make nanoparticles, such as by, for example, Viswanathan et al. (J.

Supercritical Fluids, 2003, 27(2), pp. 187-193). Under certain conditions it is possible to separate the metal oxide by reducing it to a more soluble lower oxidation state, and US-4645650 teaches that at least atmospheric mass and relatively low temperature can be used to account for the mass of the metal oxide. 50% of the coal or other reducing carbonaceous material and this reduction is achieved in the presence of a mineral acid. However, it is also known that some metal oxides are stable under supercritical water oxidation conditions, which have been developed as catalysts under extreme oxidative conditions to enhance the complete oxidation of certain organic materials, for example by Kranjnc et al. (Applied)

Catalysis, B: Environmental (1997), 13(2), 93-103). In supercritical oxidation reactions for the manufacture of aromatic carboxylic acids, the oxidative precipitation reduces or prevents the opportunity to recycle the catalyst for efficient operation, and this catalyst depletion is economically undesirable. In addition, the sinking hall reduces or prevents flow in the tubular reactants' and the passages in the device need to be cleaned or dredged to continue operating the reactor, which is uneconomical and inefficient. The hybrid configuration described in the silo tube WO-02/06201-A minimizes catalyst oxidation compared to other configurations, but further improvements are still required. SUMMARY OF THE INVENTION One object of the present invention is to reduce or avoid one or more of the above problems. In particular, the present invention is directed to reducing the amount of metal oxide precipitation and/or reducing the loss of catalyst during the supercritical (or near supercritical) aqueous synthesis oxidation process using a metal salt as a catalyst. Accordingly, one of the present inventions 126161.doc 200831456 is directed to improving catalyst stability in such systems, particularly to maintain catalyst activity and/or efficiency, and to avoid reactor fouling. Another object is to provide an improved process for the production of aromatic carboxylic acids via catalytic oxidation of a precursor in supercritical water, in particular a continuous process in which the amount of metal oxide killing is reduced and/or the loss of catalyst is reduced. In particular, this method has good selectivity for aromatic carboxylic acids and obtains a high yield of aromatic carboxylic acid. According to a first aspect of the invention, there is provided the use of an acidic component comprising one or more acids for minimizing or preventing catalyst loss and/or precipitation of metal oxides in a process for the manufacture of aromatic carboxylic acids, The method comprises contacting one or more precursors of the aromatic carboxylic acid with an oxidant in the presence of a catalyst comprising a metal salt, preferably a transition metal salt, in the reaction, the contact being from the precursor And the oxidizing agent is carried out in an aqueous solvent comprising water under supercritical conditions or near supercritical conditions, usually such that the or the precursors, oxidizing agents and aqueous solvent form a single homogeneous phase in the reaction zone, wherein: And adding the acidic component to the reaction zone; (ϋ) at least a portion of the catalyst is contacted with the oxidant in the presence of the acidic component; and (out) the acidic component comprises one or more organic acids. According to a second aspect of the present invention, there is provided a method for minimizing or preventing catalyst loss and/or sinking of metal oxides in a method for producing aromatic formic acid in a material. The method is included in the reactor. In the case of a catalyst comprising a metal salt (compared to a transition metal salt), one or more precursors of the aromatic carboxylic acid are contacted with an oxidizing agent from the (or) precursor and the 126161.doc 200831456 oxidizing agent In an aqueous solvent comprising water, under supercritical conditions or near supercritical conditions, 'usually such that the or the precursors, oxidizing agents and aqueous solvent form a single homogeneous phase in the reaction zone, wherein: (1) method a step of adding an acidic component comprising one or more acids to the reaction zone; (Π) at least a portion of the catalyst is contacted with the oxidant in the presence of the acidic component; and (111) the acidic component comprises One or more organic acids. According to a third aspect of the present invention, there is provided an oxidation process for producing an aromatic tannic acid, the method comprising: comprising a catalyst comprising a metal salt, preferably a transition metal salt, in a reactor One or more precursors of the aromatic carboxylic acid are contacted with an oxidizing agent, the contacting being carried out by the (or) precursor and the oxidizing agent in an aqueous solvent comprising water under supercritical conditions or near supercritical conditions, usually such that Or the precursor, the oxidizing agent and the aqueous solvent form a single homogeneous phase in the 5 hr reaction zone, wherein: (i) an acidic component comprising one or more acids is added to the reaction zone; (ii) at least a portion The catalyst is contacted with the oxidant in the presence of the acidic component; and (Hi) the acidic component comprises one or more organic acids. Preferably, the addition of an acidic component comprising one or more acids is achieved such that the acid is present at any point in contact with the oxidizing agent of the oxidizing process. Thus, at least a portion, and preferably substantially all, of the contact of the metal salt with the oxidant is effected in the presence of an acidic component, and preferably occurs after the metal salt is contacted with the acidic component (ie, the metal salt and the acidic group) The fraction is mixed prior to contact with the oxidizing agent at 126161.doc -10- 200831456 such that the acidic component already exists as described herein when the catalyst is first contacted with the oxidizing agent, and the inert component is preferably a single unit in the reaction zone In the homogeneous phase.

The use of an acid under supercritical or near supercritical conditions in an aqueous solvent comprising water in an oxidizing process according to the invention may minimize or avoid the oxidative side reaction associated with the metal salt becoming a metal oxide in the oxidation process. problem. Although the inventors do not wish to be bound by theory, the presence of salty acid can minimize or prevent the oxidation of the metal salt to a metal oxide under the #supercritical or near supercritical conditions. Because, according to the present invention, since the formation of the metal oxide and/or the destruction of the metal salt is minimized or prevented, precipitation of the metal oxide from the metal salt is avoided, and thus the stability of the metal salt is improved, and further Maintain catalyst activity and efficiency, reduce reactor name and improve process economy and efficiency. Surprisingly, the acid can reach this result because the metal salt plays a role in the supercritical oxidation process and its associated reaction, and the path is not only improperly oxidized with the metal salt to become a metal oxide. Sexual transformation-related reaction pathways compete and compete with reaction pathways associated with the interaction of acids with metal salts. Thus, the presence of acid surprisingly minimizes the production of undesirable metal oxides and solves the problems raised by the present invention. Compared to the continuous process of W〇-〇2/06201_A, the process according to the invention provides an unexpected improvement in reducing the oxidative side reaction of the metal salt to the metal oxide in this oxidation process, and a larger proportion of the catalyst is maintained It can be recovered from the system and/or can be recovered from the system. Although the 126161.doc 11 200831456 production described in |〇_〇2/〇62〇1_eight itself presents an unexpected improvement over other potential configurations in this respect, there is still catalyst loss. The present invention demonstrates that the addition of an acid improves catalyst stability and/or recovery. This effect is completely different from any observed increase in the yield and/or selectivity of the target molecule caused by the optional addition of an oxidation promoter such as a desertification.

The inventors of the present invention have found that the addition of acid (i.e., [H+]) has an effect of improving the recovery of the catalyst by the amount of metal oxide precipitated therefrom. Increasing the amount of acid in the reaction mixture increases the recovery of the catalyst until it reaches the saturation point, i.e., the catalyst recovery effect reaches the plateau and the addition of more acid has no further significant effect on the catalyst recovery. Thus, in one embodiment, the amount of acid added to the reaction mixture should be sufficient to achieve at least 60%, preferably at least 7%, preferably at least 8%, more preferably > 90 / 〇, and in one embodiment, the amount of acid added to the reaction mixture should be sufficient to achieve saturation of the catalyst recovery effect. The organic acid is preferably such that the molar ratio of the added organic acid to M (wherein the ruthenium is the metal of the metal salt present during the oxidation reaction) is at least 0.5:1, preferably at least 〇75: Ip, preferably at least 丨〇: 1, preferably at least 1·3:1 and usually not more than about 3 〇: 1, usually not more than about η", usually not more than 10:1, usually not more than 5·0:1 Typically, it is added to the reaction zone in an amount of no greater than about 3 Torr:1 and more typically no greater than about 2:6:1.

As used herein, the term "acid" means any proton-donating material that is less than the pKa of water at ambient temperature and pressure. According to the Bronsted theory 〇f acidity (see, for example, Michael B)

Smith, Jerry March; March's Advanced Organic Chemistry, 126161.doc -12- 200831456 5th edition, Chapter 8), at ambient temperature and pressure, the acidity of the proton donor is measured by the following range of pKa values: from about -12 (for very strong acids) to 1 5 · 7 4 (for water and s) and up to about 5 〇 (for very weak acids). The acid selected for the acid component should be based on the stability of the acid under supercritical conditions. The acid is preferably substantially oxidatively stable under supercritical conditions or near supercritical conditions. The acidic component according to the invention comprises one or more organic acids. If more than one acid is used in the acidic component, at least one of the acids should be an organic acid. Reference herein to an organic acid is an acid of the formula R(C00H)n wherein 11 is 1 or more (generally n = 1 or 2, and in one embodiment, n = 1) and wherein the organic is organic Part, such as a non-aromatic hydrocarbon group (usually a Ci to C6 hydrocarbon group; usually a saturated hydrocarbon group, usually a linear hydrocarbon group; optionally substituted), or preferably an aromatic group (taken or unsubstituted) . Purely an aromatic group, the aromatic diruthenium 3 single aromatic ring or may contain two or more aromatic rings (eg two or more fused aromatic rings), the ring or Each ring typically has 5, 1, 7 = 8 ring atoms, more typically 6 ring atoms. The aromatic group is usually a single: A: the private group may be a ruthenium aromatic group or it may contain one or more heterocyclic aromatic groups (for example, ^? right, .4, ., 2 Or 3 heteroatoms selected from N, 0 and S, usually N (only one hetero atom is hanged). The group is a phenyl group. In another embodiment, in the case of an aromatic force, aromatic The group is a pyridyl group. If R is a substituted aromatic group, one or more substituents are present, and the substituent or each substituent is usually a gas group selected, especially selected from the group consisting of. a 14-diol group, an alkoxy group or a benzyl group, and especially a "4 alcohol group, (Cl_4 alkoxy group ... is a methyl group W is a non-aromatic selected from: (10), a suitable substituent of the diyl group Usually selected from the group consisting of alcohol groups, 126161.doc •13- 200831456 alkoxyalkyl and a base group, especially a Cl·4 alcohol group, a (Ci·4 alkoxyalkyl group and a C. 4 aldehyde group). The organic acid in the mixture is usually an acid different from the target aromatic acid of the oxidation reaction. If more than one organic acid is added to the reaction mixture, at least one of the organic acids is usually different from the oxidation The target aromatic carboxylic acid. The target aromatic carboxylic acid of the oxidation process generally has the formula Ar(c〇2H)x, wherein Ar is an aromatic group (preferably phenyl) as defined below and At least 2. In one embodiment, the acidic component comprises an organic acid added to the reaction mixture having the formula Ar(c〇2H)y. In another embodiment, the acidic component package S has the formula added thereto An organic acid in the reaction mixture wherein the R1 or each R1 is generally selected from the group consisting of an alkyl group, an alcohol group, an alkoxyalkyl group or an aldehyde group, especially selected from the group consisting of a C4 alkyl group, a Ci4 alcohol group, (Ci4 alkane) a oxy-PCw alkyl group or a Cl_4 aldehyde group and especially selected from the group consisting of alkyl (especially Ci 4 alkyl, and especially methyl) substituents. Preferably y < X, and preferably y^(x-1), And 苇 y 1. Preferably z < x, and preferably zS (x-1), and usually z = 1. In an embodiment, y = 1. In an embodiment, Z = 1. In a preferred embodiment, Ar is a phenyl group. In another embodiment, the method of producing an aromatic carboxylic acid of the formula Ar(c〇2H)x may comprise the addition of Ar(C02H)^/, wherein the value y Or ζ no limitation, and wherein, for example, a carboxylic acid group Occupy any, some or all of the substituent positions on the aromatic ring. In a preferred embodiment, the organic acid is benzoic acid, especially wherein the target aromatic carboxylic acid of the oxidation process claimed herein is of formula C6h4 (c〇 2h) 2 bis, 'that is, terephthalic acid or phthalic acid, and especially terephthalic acid. In another embodiment, the organic acid is toluic acid (eg p-toluene 126161.doc -14) - 200831456 owe, especially the target aromatic carboxylic acid of the oxidizing method advocated in this article is a C6H4(C〇2H)2 diacid, ie terephthalic acid or phthalic acid, and especially Phthalic acid. In another embodiment, the acidic component comprises benzoic acid or toluic acid or a mixture thereof. In a preferred embodiment, the organic acid added to the reactor is the W product of the oxidation reaction, and this embodiment is an oxidation method for the preparation of the Argonine carboxy oxime of the formula Ar(c〇2H)x. Especially important, as described above, wherein the organic acid added to the reaction mixture has the formula Ar(c02H)y or

Ar(C〇2H)y(Rl)z. Thus, in a preferred embodiment of the invention for the manufacture of a diacid of formula c6h4(co2h)2, the supply of an organic acid (e.g., benzoic acid) to the reactor is by any other undesirable side of the synthetic oxidation reaction. The product is recycled back to the oxidation reactor to achieve. An advantage of using this other undesirable by-product in a process in which the acidic component comprises a rosacea (such as HBr) is that the use of a second acid means that the amount of enthalpy entering the system can be reduced. A mixture of acids can be used to provide an acidic component. In particular, a mineral acid, preferably a ruthenium (wherein X is preferably a halide ion, preferably a desert ion or a chloride ion, more preferably a bromide ion) can be used in combination with an organic acid. In a preferred embodiment, the acidic component comprises a mixture of an organic acid (especially benzoic acid) and _ or a plurality of inorganic acids (especially hydrogen halides and especially HBr) and usually only one inorganic acid. The inorganic acid can be formed in situ; thus, for example, hydrogenated hydrogen can be formed in situ by adding a proton source and a halide source to the reaction mixture. Accordingly, in a fourth aspect of the invention, there is provided an oxidation process for the manufacture of an aromatic acid retardation comprising the inclusion of a metal 126161.doc -15-200831456 salt (preferably a transition metal) in a reactor In the case of a catalyst of a salt), one or more precursors of the aromatic citric acid are contacted with an oxidizing agent, and the contact is caused by the (or) precursor and the oxidizing agent in an aqueous solution containing water in a supercritical condition or near super Realizing under critical conditions, such that the precursor or oxidant and aqueous solvent form a single homogeneous phase in the reaction zone, wherein (i) an acidic component comprising one or more acids is added to the reaction zone (u) at least a portion of the catalyst is contacted with the oxidant in the presence of the acidic component; (a) an acidic component comprising one or more organic acids, and (d) the acidic component further comprises _ or a plurality of inorganic acids, preferably a functional hydrogen, preferably HBr. The amount of the inorganic acid added (preferably hydrogenated hydrogen) is preferably such that all of the anion X (preferably a halide ion) and the metal ion of the catalyst ( M) ([Χ]··[Μ]) is at least 1〇:1, preferably at least 丨5丨, preferably at least 2, preferably at least 2.05:1, preferably at least 2·1:1, preferably at least 2· 2: i, preferably at least 2.3:1, and usually no more than about 12 〇: 1, more usually no more than about 7 〇: b is usually no more than about 6. 〇: 1, more usually no more than about 5 Q: 1 More typically no greater than 4.5:1, more typically no greater than about 4:1, more typically no greater than about 纟: 丨 and more typically no greater than about 3.8: 1. In a preferred embodiment, [χ ]: [Μ] ratio is in the range of 1.5:1 to 5.0:1, preferably 2 〇:1 to 3 5:1 and preferably 2 2:1 to 3. In a preferred embodiment, the metal catalyst Manganese is included, and the inorganic acid is preferably hydrogen halide (ΗΧ) and preferably fjBr. In a preferred embodiment, the metal catalyst comprises bromine, ruthenium, and 126161.doc -16 - 200831456 kg: force e5 hydrogen Preferably, the molar ratio [Χ]:[Μη] of all halide ions (猛) and 猛 (Mn) is greater than 2.0:1 and usually not greater than about 12 〇:1. [ΧΗΜη] is preferably at least 2 〇5:1, preferably at least 2ι:ι, preferably at least 2.2.1, preferably at least 2.3:1 'and usually no more than about 12 〇: 1, more Typically no greater than about 7.0:1, more typically no greater than about 6 〇: 1, more typically no greater than about =1, more typically no greater than 4.5:1, more typically no greater than about 4 〇: 1, more generally less than about 3.5:1 and more usually no more than about 3(): 1. The inventors have found that the effect of the chemokine is 2:1 in the Br:Mn molar ratio (i.e., using Μ n in the absence of HBr). The rate of catalyst recovery was observed when B r2 was used as the ratio of the catalyst and was saturated until acid was also added. In another embodiment, Example B, the metal catalyst comprises manganese acetate Mn(OAc)2, which is used in a conventional system (i.e., a non-scw system) with the ηΒγ group to form the catalyst ΜηΒΓ2 in situ. In this embodiment, the versatile and preferred molar ratios of all halide ions (X) and manganese (Mn) are: [ΜηΗ is as described above for the general metal ruthenium, that is, at least 1 〇: 1 and usually not more than about 12·0·1. The inventors have found that the oxidation promoter effect is saturated at a molar ratio of 1.5:1 for the molar ratio, and the catalyst recovery effect is saturated until the molar ratio is greater than 2:1. For the avoidance of doubt, the term "transition metal" as used herein is defined as the following: accepting or providing electronic access to 4 or [expressing and exhibiting a plurality of oxidative metals, including transition metals and锕系. The pressure and temperature of the method are chosen to ensure supercritical or near supercritical conditions. In one embodiment, the term, near supercritical condition, means that the solvent is at least not less than 100 ° C, preferably not less than 126161.doc -17 · 200831456 5 ° ° than the critical temperature of water at 220·9 bar. C, preferably not less than 35t:, more preferably not less than 2 〇 at its temperature. Thus the operating temperature is typically in the range of from 300 ° C to 480 ° C, more preferably from 330 ° C to 450 ° C, usually from a lower limit of from about 350 ° C to 370 ° C to from about 370 ° C to about 42 (the upper limit of rc) The operating pressure is typically in the range of from about 4 Torr to 35 mbar, preferably from 6 mbar to 300 bar, more preferably from 220 to 280 bar, and in one embodiment from 250 to 270 bar. In one embodiment, the operating pressure is in the range of 23 mbar to 25 mbar. f - Synthetic oxidation reaction " or "synthetic oxidation method" means partial oxidation by one or more oxidizable precursors The (etc.) precursor produces one or more of the target compounds. The term "partial oxidation" means consisting of less than the degree of oxidation (or absorption of oxygen) required for complete oxidation of the precursor to carbon oxides. Oxidation reaction; 1H and other reaction systems are related to the following factors: controlled oxidant/precursorization to a ten mile, while the selectivity of the selective synthesis of a few compounds and the retention of the chemical structure of the precursor without the group. Complete oxidation " means the oxidation of a compound to a carbon oxide (usually carbon dioxide), That is, destructive oxygen~ In the case of the cockroach, the term "near supercritical conditions" means that the reactants and the solvent form a single-homogeneous phase. In fact, this can be below the critical temperature of water: The term "single homogeneous" as used herein means at least (9) wt%, typically at least 90 wt%, typically at least 95 wt%, more typically at least 98 wt% and most typically effective for all precursors. The oxidizing agent, the 2 solvent, the acidic component, the catalyst and the reaction product and, if present, each of the 2 acid precursors P0A (as described hereinafter) are in the same single homogeneous phase in the reaction zone. .doc -18- 200831456 The term "aromatic carboxylic acid, as used herein, means an aromatic compound in which a carboxy group (-C〇2H) is directly attached to an aromatic group (f). The aryl (tetra) acid may contain one or more a rebel group directly attached to an aromatic group, and the present invention is particularly directed to an aromatic acid retardation containing at least 2 and especially only 2 (c) 2H directly bonded to an aromatic group. Group (Ar) may comprise a single aromatic ring or may comprise two- or two The above aromatic ring (for example, two or more fused aromatic rings), the ring or each ring usually has 5, 6, 7 or 8 ring atoms, more usually 6 rings (, ten + aryl-free groups) The group is usually a monocyclic ring. The aromatic group may be a carbocyclic aromatic group 4 which may contain - or a plurality of heterocyclic aromatic rings (for example containing i, 2 or 3 selected from the group consisting of ^, 〇 and S, usually % of the heteroatoms (usually only one heteroatom) %) - In one embodiment, the aromatic group is a phenyl group. In another embodiment, the aromatic group is a D to a bite group. Typical aromatic acid retardants synthesized by the present invention include terephthalic acid, isophthalic acid, phthalic acid, naphthalene dicarboxylic acid and acid testing. The term "aromatic carboxylic acid precursor" as used herein means a compound that can be oxidized by an oxidizing agent to a target aromatic traconic acid under supercritical C= or near supercritical conditions. Precursor selection a compound derived from a substituent having at least one substituent attached to an aromatic group as defined above and oxidizable to a carboxylic acid moiety. Suitable substituents are usually selected from the group consisting of a county, an alcohol group, an alkoxy group, and The base 'is especially selected from the group consisting of a top group, an alcohol group and a methoxy group, and the (4) is selected from an alkyl group. The alkyl group is especially selected from a 4-alkyl group, preferably a methyl group. The group is especially selected from CM alcohols. The oxyalkyl group is especially selected from the group consisting of Cm alkyl groups. The aldehyde groups are especially selected from the group consisting of Cw aldehyde groups. If two or more substituents are present, the substituents may be the same or Different, and the same in a comparison of 126161.doc -19·200831456, j. For example, the terephthalic acid precursor can be selected from the group consisting of a pair of w #一甲本, 4-methylbenzaldehyde and 4-toluic acid, and the second precursor is a preferred precursor of nicotinic acid (for example) ) 3-methylpyridine. Unless otherwise stated, J herein and the term "precursor" refers to the aromatic acid retardant precursor as the target of the oxidation reaction of the main a herein. σ human does not exclude the generation of at least a portion via in situ. The possibility of adding at least a portion of the organic acid to the reaction zone, V to the agglomerated component, and usually by introducing an oxidizable or hydrolyzable precursor of the organic acid (for avoidance and as claimed herein) The aromatic carboxylic acid precursor is the target of the synthetic oxidation reaction, which is referred to herein as the precursor p〇A), which is oxidized in the reaction zone or in the reaction zone (or before) Hydrolyzed to the desired organic acid. As used herein, the term 'acid' is added to the reaction mixture, and the damage is not only the acidic component itself is added to the reaction mixture, but also covers the acidic component in the reaction zone. Bit generation. Thus, in one embodiment, at least a portion of the (or other) organic acid added to the reaction zone is in situ by the addition of the oxidizable precursor of the organic acid. Producing, wherein the oxidizable precursor p〇A is different from the aromatic carboxylic acid precursor which is the target of the synthetic oxidation reaction claimed herein. The organic acid system generated in situ is different from the target aromatic acid . Typically, the acidic component comprises only one organic acid and in this embodiment at least a portion of the organic acid is produced in situ. The term "organic acid emulsifiable precursor P0A" as used herein means a compound which can be oxidized to an organic acid R(COOH)n by an oxidizing agent under supercritical conditions or near supercritical conditions. The oxidizable precursor P°A is selected from the group consisting of the compound R-(Q)n wherein the substituent Q can be oxidized to the carboxylic acid 126161.doc -20-200831456 portion. If R is an aromatic group, suitable substituents are generally selected from the group consisting of alkyl, alcohol, alkoxyalkyl and aldehyde groups, especially Ci-4 alkyl, Ci4 alcohol, (c^ alkoxy hC!.4) An alkyl group and a Cm aldehyde group, and preferably an alkyl group (preferably an alkyl group, preferably a methyl group). If r is a non-aromatic hydrocarbon group, suitable substituents are usually selected from an alcohol group and an alkoxyalkyl group. And aldehyde groups, especially Ci4 alcohol groups, (1) alkoxy groups, and Cl 4 aldehyde groups. If two or more substituents are present, the substituents may be the same or different. In one embodiment, for example, if the organic acid generated in situ is benzoic acid, the oxidizable precursor p〇A may be selected from the group consisting of toluene and benzaldehyde, and toluene is preferred. In another embodiment, the organic acid is used. Produced in situ by the addition of a hydrolyzable precursor, p〇A. In this case, the hydrolyzable precursor is typically selected from the group consisting of the compound RCOOR1, wherein the R is as defined herein and is selected from the group as defined herein. a substituted alkyl group (especially a Cm alkyl group, and including a benzyl group) and an aromatic group (especially a phenyl group). Therefore, the hydrolyzable precursor may be selected from benzene. The alkylate phthalate. The precursor P0A can be added to the reaction zone in a manner similar to that described below with respect to the acidic component. In one embodiment, if the acidic component comprises an organic acid produced in situ with one or more other acids ( For example, a combination of another organic acid and/or a mineral acid, as described below, the organic acid precursor (P〇A) and the other acid or each other acid may be introduced into the reaction zone by the same or different routes. In another embodiment of the method of generating an organic acid in situ, the precursor P〇A can be added to the reaction in a manner similar to that described below for the aromatic carboxylic acid precursor as a target of the synthetic oxidation reaction claimed herein. In the example, the precursor and the precursor P0A are premixed and 126161.doc -21 - 200831456 is added to the reaction zone in a single stream. In the embodiment, The precursor p〇A is premixed with the catalyst. It should be understood that the manner in which the precursor P〇A is added depends mainly on its miscibility with other reactants. For example, if the precursor p〇A is toluene, then Passing the precursor p0A with the target carboxylic acid a combination of a precursor (e.g., para-xylene in the case of the production of para-phenylene I.) If the precursor is miscible with water, it is typically, for example, in a manner similar to that described below for the acidic component. Addition to any of the aqueous streams fed into the reaction zone. The reactor suitable for practicing the invention is preferably a continuous flow reactor. As used herein, a continuous flow reactor, meaning and batch In contrast to the type of reactor, the reactor is introduced in a continuous manner and mixed and simultaneously extracts the product. For example, the reactor can be a tubular flow reactor (with a turbulent or laminar flow) or a continuous stirred tank reactor. (CSTR), but the various aspects of the invention as defined herein are not limited to such particular types of continuous flow reactors. The invention as defined herein is primarily described in terms of a continuous flow reactor, as this is the most likely commercial and industrial embodiment, but the invention may also be carried out using a batch reactor. By carrying out the process in a continuous flow reactor, it is possible to obtain a reaction residence time which is consistent with the conversion of the precursor to the desired aromatic carboxylic acid without significant degradation products. The residence time of the reaction medium in the reaction zone is usually not more than 10 minutes, preferably not more than 8 minutes, preferably not more than 6 minutes, preferably not more than 5 minutes, preferably not more than 3 minutes, preferably not more than 2 minutes. Preferably it is no more than 1 minute. The residence time can be controlled such that the precursor is efficiently converted to an aromatic carboxylic acid' such that the aromatic carboxylic acid precipitated from the reaction medium after completion of the reaction contains 126161.doc -22-200831456 having no more than about 5000 ppm, An aldehyde which is preferably produced as an intermediate during the reaction, preferably not greater than about 3 ppm, more preferably no greater than about 1500 ppm, more preferably no greater than about 1 Torr, and most preferably no greater than about 500 ppm. In the case of terephthalic acid production, it is 4_CBA). Typically, at least some of the aldehyde will be present after the reaction, and will typically be at least 5 ppm.

In the process of the present invention, the oxidizing agent is preferably molecular oxygen (e.g., air or oxygen-rich air), but preferably contains a gas containing oxygen as a main component, more preferably pure oxygen or oxygen dissolved in a liquid. The air is not advantageous because it will have a large compression cost and may require an exhaust gas treatment device to treat a large amount of exhaust gas due to the high nitrogen content of the air, but it is not excluded from the material of the present invention. On the other hand, pure oxygen or oxygen enrichment requires the use of smaller pressure, shrinkage and smaller exhaust gas treatment equipment. Molecular oxygen is used as an oxidizing agent in the process of the present invention, especially because it is dissolved in water in the (qua) or near supercritical conditions. (d) At a particular point, the oxygen/water system will become a single homogeneous phase. The oxidizing agent may comprise atomic oxygen derived from a compound having one or more oxygen atoms per molecule (e.g., a room temperature liquid phase compound) in place of the molecular oxygen. For example, one such compound is hydrogen peroxide which acts as a source of oxygen by reaction or decomposition. The oxidation reaction, particularly for the manufacture of aromatic tetamine, in accordance with the present invention is carried out in the presence of a homogeneous oxidation catalyst which is soluble in a reaction medium comprising a solvent and a precursor. As described herein, the catalyst pass t is present in a single homogeneous phase in the reaction zone. The catalyst typically comprises one or more heavy metal compounds (e.g., drilled and/or pulverized compounds), and preferably comprises a tumbling compound. By way of example, the catalyst may exhibit any of the forms that have been used in the liquid phase oxidation of an aromatic traconic precursor (such as terephthalic acid precursor 126161.doc -23-200831456) in an aliphatic carboxylic acid solvent. By,

For example, the beginning and/or the bell", the acid salt, the acid salt (usually c C sulphonate such as acetate) or the benzoate (or other aromatic acid salt). Compounds of other heavy metals such as hunger, chromium, iron, ruthenium, osmium, iridium, steel elements such as ruthenium and/or nickel may be used in place of cobalt and/or manganese compounds. Advantageously, the catalyst system should comprise desert Mn (ΜηΒΜ. A pre-prepared catalyst can be added or it can be formed in the system by the addition of a reagent which can subsequently be combined to form a catalyst. For example, in the case of ΜηΒι*2 catalyst In the following, it is possible to introduce ΜηΒι*2 itself into the system, or to introduce reagents such as manganese acetate and HBr into the system, which are combined under the reaction conditions to form MnBr2. The reactor system suitable for carrying out the process of the invention is generally Configured as described below. The oxidation reaction is initiated by heating and pressurizing the reactants, followed by mixing the heated and pressurized reactants in the reaction zone. This can be achieved by achieving supercritical or near supercritical conditions. The reaction or both of the reactants before or after mixing with the aqueous solvent are effected in a number of ways in such a way as to keep the reactants separated from each other until they are mixed together in the reaction zone. In the method, at least a portion of the catalyst is contacted with the oxidant in the presence of the acidic component. Generally all of the catalyst is associated with the catalyst Preferably, the oxidizing agent is contacted in the presence of an acidic component. In the continuous process described herein for the manufacture of a carboxylic acid, the reactor system is preferably configured such that the oxidant is at least partially and preferably substantially all of the uranium flooding Contact of the contacting system with the catalyst and at least some, and preferably substantially all, of the 126161.doc -24-200831456 oxidant are carried out at the same point in the reactor system and simultaneously, and such configurations are shown in Figures 1 and 2A. And in Figure 2B. However, other configurations for the manufacture of the carboxylic acid when at least a portion of the precursor is contacted with the oxidant and the catalyst is contacted with at least a portion of the oxidant are not excluded, and such configurations are shown in the figures. 3 in.

t In Example I, the oxidizing agent is mixed with the latter after the aqueous solvent has been heated and pressurized to ensure a supercritical or near supercritical state, while the oxidizing agent is suitably pressurized and (if necessary) heated prior to mixing with the aqueous solvent. . The precursor is subjected to pressurization and, if necessary, heating. The catalyst-containing component is subjected to pressurization and, if necessary, heating. The acid component can be subjected to pressurization and, if necessary, heating. The separate stream comprising the precursor, catalyst, acid and oxidant/solvent mixture can then be contacted simultaneously. In one configuration, the acid is premixed with the catalyst. A schematic flow diagram showing Example I is presented in Figure i. In an embodiment of the invention, the precursor is mixed with the latter after the aqueous solvent has been heated and pressurized to ensure a supercritical or near supercritical state, while the precursor is suitably pressurized prior to mixing with the aqueous solvent (required When the heating catalyst is placed, the homogeneous catalyst component is contacted with the aqueous solvent while being pressurized and, if necessary, heated, followed by contact of the precursor with the aqueous solvent. The acid component may be contacted with the catalyst, the precursor, and the aqueous solvent while being pressurized and (if necessary) heated, or may be premixed with the catalyst. Alternatively, the acid component can be fed directly into the reaction vessel after pressurization and (if necessary) heating (see Figure 2Α and Figure 2Β). After adding and (if necessary) heating the oxidant is in water: solvent = heated and twisted to ensure supercritical or near supercritical state "the latter is snapped, and the oxidant 'aqueous solvent mixture is followed by the inclusion of precursor 126161.doc -25- 200831456 Contact of a mixture of a substance, a catalyst, an acid component and an aqueous solvent. In Example III, the oxidizing agent is mixed with the latter after the aqueous solvent has been heated and pressurized to ensure a supercritical or near supercritical state. The oxidizing agent is suitably pressurized and, if necessary, heated prior to mixing with the aqueous solvent. The catalyst may be mixed with the oxidizing agent while being mixed with the acid component. Alternatively, the acid component may be premixed with the catalyst prior to contact with the oxidizing agent. / or acid, and injury t fork pressure and (if necessary) heating. The precursor is subjected to pressurization and (required

t) heating, and then contacting the mixture containing the oxidizing agent, the catalyst and the acid, and the wound in the reaction zone. A schematic flow diagram showing an embodiment m is presented in FIG. The right acidic component comprises a combination of an organic acid and a mineral acid (for example, a hydrogen halide), and the organic acid and the inorganic acid may be introduced into the reaction zone by the same or different routes. Referring to FIG. 1 to FIG. 3, the organic acid and the inorganic acid may be passed through Any of the paths indicated by the acid are introduced independently. The contacting of the various streams can be accomplished by means of separate feeds to a unit: the feeds are mixed to form a preferred single homogeneous fluid phase to allow the emulsifier to react with the hydrazine. The means for internally mixing the feeds may, for example, have a Υ, Τ, Y + , or octah configuration that allows for independent feed mixing

In the case of a continuous flow reaction I "in the early flow channel or in some cases mixed in a plurality of flow channels constituting two or two, flow reactors. Internal mixed feed << The μ-moving channel may comprise one of the official configurations with or without internal kinesive or static-sense mixing elements t+1. In a preferred implementation, & line or static mixer is advantageously used to ensure rapid mixing And homogenous loose, 'for example, to promote the dissolution of the oxidant in an aqueous solvent and 126161.doc -26 - 200831456 to form a single phase. The oxidant feed and the precursor feed can be mixed at a single position. The contact can be in two or more stages. Achieving such that at least a portion of the feed or the two are progressive with respect to the direction of flow through the reactor (eg, via multiple injections. For example, the feed can be worn along the ":" flow channel The 'other-feeds' are introduced at a plurality of points spaced apart at regular intervals in the direction of the length of the continuous flow channel to allow the reaction to proceed: the feed through the continuous flow channels may comprise an aqueous solvent, For the introduction of the feed at a plurality of locations. Similarly, the addition of the catalyst can be achieved in a progressive manner (e.g., via multiple injection points) relative to the direction of the flow through the anti-reservoir. In the configuration, the oxidant is in two Introduced into the reaction at one or more locations. These locations are conveniently positioned relative to the bulk flow of the solvent and reactants in the gingival zone to eclipse the ρ position. The deuteration agent is introduced into the reaction at an initial position and at least one other position downstream of the initial position. There may be more than one reaction zone in series or in parallel. For example, if multiple reactions in parallel are used Zone, the reactants and solvent can form a separate flow stream through the reaction zone, and the necessary daily flow is determined by the two parties. The product stream of more than 4 reaction zones can be mixed to form a single product; a parent ten m seat. If more than one reaction zone is used on the right, the conditions such as temperature in each reactor may be the same or different. The reactor or each reaction H may be adiabatically or isothermally operated. Defining the whole The isothermal or controlled temperature rise should be maintained by the pre-t temperature profile of the reaction. It can be known from the skilled person and is described, for example, in Le-(10) _ _ 126161.doc -27- 200831456 A The prior art in which the disclosures of such techniques are incorporated herein by reference, removes the heat of reaction from the reaction by heat exchange with a heat receiving fluid. The heat receiving fluid conveniently contains water. After the continuous flow reaction and after the oxidation process is completed, the reaction mixture contains a solution of an aromatic carboxylic acid which needs to be recovered from the reaction medium. At this stage, substantially all of the aromatic carboxylic acid produced in the reaction is produced. It is in solution 7. In the process of the invention, it is usually at least 8 ounces per liter during the reaction, more typically at least 90 weight ❻/. Preferably, at least 95% by weight, more preferably at least 98% by weight and most preferably substantially all of the aromatic carboxylic acid produced in the reaction remains in solution and does not begin to precipitate until the solution leaves the oxidation reaction zone and undergoes cooling. . The solution may also contain a catalyst and a relatively small amount of by-products (such as intermediates (for example, p-toluic acid and 4-CBA in the case of terephthalic acid), decarboxylation products (such as benzoic acid), and degradation products (such as partial benzene). Tricarboxylic acid)) and any excess reactants. The desired product aromatic carboxylic acid (such as terephthalic acid) can be recovered by crystallizing the aromatic acid from the solution with - or a plurality of P white segments, followed by solid-liquid separation in - or multiple stages. The product stream is subjected to solid-liquid separation to recover the aromatic carboxylic acid and the mother liquor, which may, but need not necessarily, contain the dissolved catalyst component, is recycled to the oxidation reaction zone. The mother liquor is heated by heat exchange with the product stream prior to reintroduction into the oxidation reaction zone, thereby cooling the product stream. One or both reactants may be mixed with the mother liquor in a % stream or a separate mother liquor recycle stream prior to re-capping the mother liquor into the human reaction zone and the mother liquor recycle stream (or at least a portion thereof to be combined with the reactants) Heated and pressurized prior to mixing with the reactants or respective reactants to ensure supercritical/near supercritical conditions. 126161.doc -28- 200831456 The right mother liquor is heated by heat exchange with the product stream prior to reintroduction into the oxidation zone, and the reactants may be reacted with the mother liquor stream or separately before or after this heat exchange with the product stream. The mother liquor stream is mixed. The addition of the right as an acidic component to the reactor is achieved by recycling a by-product of the oxidation reaction, such as benzoic acid, to achieve the desired level of organic acid in the reactor, by To near super-burst or supercritical pressure, the stream is heated to near supercritical or supercritical temperatures and the stream is mixed with other catalysts and/or organic acid streams, precursors and oxidants to recycle the mother liquor back to the reactor. Preferably, the temperature rise of the recycle mother liquor stream is effected by heat exchange with the reactor product to thereby cool the product stream from the reactor. As shown in Figures i to 4", the pressurized and heated mother liquor stream containing the catalyst and organic acid can be fed directly into the mixer or reaction zone. The composition of the recycled mother liquor stream in this system is essentially determined by two factors: first, the rate at which by-products are formed, such as benzoic acid in the case of p-xylene to terephthalic acid oxidation. The body is determined by reactor conditions (including pressure, temperature, catalyst concentration, etc.); and secondly, the rate at which (particularly) by-products are removed from the mother liquor recycle stream, and also the extent to which the stream is purified. The purge removes organic acids (such as benzoic acid) resulting from the oxidation of the precursor from the reactor feed, as well as other undesirable by-products and catalysts. Sampling and analysis of the recycle stream enables the amount of other catalysts and/or organic acids required to be recycled to the reaction zone to be estimated and subsequently fed into the reaction zone to control the reaction. At the time of the reaction: for example, in the oxidation of p-xylene to terephthalic acid, a sufficiently high steady state concentration of benzoic acid (ie organic acid) may not be present in the mother liquor recycle 126161.doc -29- 200831456 2 'And it may therefore be necessary to add benzoic acid until the desired steady state concentration is reached. Similarly, it may be necessary to periodically add fresh organic acids (such as benzene) to the reaction zone in addition to the organic acid (such as benzoic acid) produced as a by-product of the oxidation reaction and recirculated to the reaction zone via the recycle mother liquor. Formic acid) achieves the desired concentration of organic acid in the reaction zone. Thus, in the aspect of the invention for providing the addition of an organic acid to the reaction zone by recycling by-products of the oxidation reaction, the process comprises adjusting the degree of purification from the recycle mother liquor stream to control the feed to the reactor. The amount and concentration of the organic acid (such as benzoic acid), and thus in the reaction zone, can effectively achieve the catalyst recovery effect described herein. The invention will now be further described by way of example only with reference to the accompanying drawings. Referring to Fig. 1, after the water has been heated, the pressurized molecular oxygen is mixed with water, and the mixture is pressurized in a preheater crucible and further heated as necessary to reach a supercritical state. The precursor and catalyst are added to the 水" water stream at or just before the beginning of the reactor 2, and the mixture passes through the reactor. The pressurized acid component is added to the ον water stream while the catalyst is being added, or the acid fraction is added to the catalyst stream prior to contact with the oxidant stream. After leaving the reactor, the stream is cooled and depressurized at the back pressure regulator 3. The product is produced in a stream of cooling water. Referring to Figures 2A and 2B, the pressurized precursor and catalyst are added to the water after the water has been pressurized and optionally heated. The acid component can be added to the catalyst before, simultaneously with or after mixing with water. The mixture is further heated in the preheater 1A as appropriate to reach a supercritical state. Alternatively, the acid component, which is well pressurized and optionally heated, can be combined with the catalyst/precursor stream as the catalyst/precursor stream is combined with the oxygen 126161.doc -30-200831456 agent. The pressurized molecular oxygen gas is mixed with water in a supercritical state and further heated in the preheater 1 as appropriate. In Figure 2A, the streams are mixed at or just before the beginning of reactor 2 and the mixture is passed through the reactor. In Figure 2b, the 〇2/water stream is added to the reactor in a progressive manner at multiple injection points. After leaving the reactor, the stream is cooled and depressurized at the back pressure regulator 3. The product is produced in a stream of cooling water. Figure 3 corresponds to Figure 1 in which the catalyst and oxidant are mixed prior to contacting either stream with the precursor. The pressurized molecular oxygen gas is mixed with water in a supercritical state and further heated in a preheater crucible as appropriate. The acid component is mixed with the catalyst before or at the same time as the catalyst is contacted with the oxidant. Referring to Figure 4, a raw material component comprising water, a precursor (e.g., para-xylene in the process for producing terephthalic acid), and molecular oxygen gas is pressurized to operating pressure and via respective sources 1 , 12 and 14 via A preheater 16 is continuously supplied, wherein the components are heated to a temperature of from 300 ° C to 480 ° C, more preferably from 330 ° C to 450 ° C, usually from about 350 ° C to 370 ° C. A temperature of about 37 (rc to about 42 〇t: upper limit, pressure and temperature are selected to ensure supercritical or near supercritical conditions. The portion of the heat used to preheat the feedstock component may be derived from subsequent precursors and oxidants The exotherm generated during the reaction may be in the form of, for example, high pressure steam and/or may be achieved by heating the water stream directly with fire. The fluid may be reacted in any suitable manner, for example by means of a reaction /, heat transfer between heat receiving fluids (such as water) to recover heat of reaction. For example, the heat receiving fluid can be configured to cross-react with the 126161.doc -31 - 200831456 reaction zone in a heat exchange relationship Reactant and solvent flow countercurrently and/or cocurrently The passage of heat # through the reaction zone may be external to the reaction and/or may extend through the interior of the reaction zone. The internal extension flow channel may, for example, typically react with the reactant/solvent. The general direction of the zone extends parallel and/or laterally. In this case, the 't heat receiving fluid can be traversed through the reaction zone through one or more coils located inside the reactor. The reaction enthalpy can be used for recovery via a suitable power. A system (such as a _ thirsty wheel) recovers power; for example, a heat receiving fluid (eg, water) can be used to generate a saturated vapor at a temperature of, for example, about 30 (rc/1 Torr), which in turn can The external heat becomes superheated and feeds into the high-efficiency condensing vapor (4) in time. In this way, the reactor can be maintained at an optimum temperature and effective energy efficiency can be achieved. In another method, the reaction can be in adiabatic conditions. The lower operation can employ a suitable high velocity water flow through the reaction zone to limit the temperature rise of the entire reactor during operation. If necessary, it can be: a combination of the two methods, ie, via a heat receiving fluid recovery reaction, plus a tooth Over Suitable water flow rate of the reaction zone. % After heating the raw material component, the oxygen is mixed with water, because preheating and adding [4 water should be under supercritical or near supercritical conditions and thus capable of dissolving the L', In the embodiment illustrated in Figure 4, the oxygen and water are mixed in a premixer. The precursor is also mixed with water in the premixer 18 。. Of course, the drive may also enter the preheater 16 Pre-mixed with water previously. The pre-locking sigma (or premixer for pre-mixing each reactant with water) can take a variety of forms, such as in Figure 5, Figure 5, Figure 5C, Figure 5D, and Figure 6. Describe the gamma penalty, T _ + m ^ Li or T-type, double τ configuration or static mixer respectively. In 126161.doc -32- 200831456 Figure 5A to 5D and Figure 6 'Reference symbol A indicates the premixer The preheated water supply, B represents the reactant (precursor or oxygen) and p represents the resulting mixed stream. In the dual T configuration of Figure 5D, two mixed streams ^ and ^ are generated. The streams can be passed through separate continuous flow reactors or combined into a single stream and subsequently passed through a single continuous flow reactor. It is also possible to use an X-type configuration known to those skilled in the art. It should also be understood that any suitable mixing device can be used in the present invention. It should be further appreciated that the mixing apparatus mentioned above is used in a continuous process apparatus. In a batch system, there is of course no continuous flow and therefore no specific flow-related mixing requirements. In a continuous vessel reactor, the reactants can also be fed independently into the vessel. It will be appreciated that one or each reactant is not premixed with water prior to introduction into the reaction zone. Instead, the reactants and water can be introduced separately into the reaction zone and in some parts of the reaction zone by means of some form of mixing device (eg static mixing) [mixing] whereby substantially all of the mixing of the components occurs within the reaction zone. The precursor is added to the premixed oxygen/water stream just prior to entering the reactor or at the beginning of the reactor, while a homogeneous catalyst in the form of a solution from source 19 is added to the premixed oxygen/water stream (ie, Shown in Figure 1). In the comparative example, as shown in Figure 4, the acid is included in the catalyst source 19. After preheating and premixing, the raw material components are combined in a reaction zone 2 to form a single homogeneous fluid phase in which the reactants are mixed together. The reaction zone 2 can be composed of a simple mixer configuration in the form of a tubular flow reactor (e.g., a tube) of a length that combines the flow rate of the combined reactants to provide a suitable reaction time to ensure, for example, high conversion efficiency and The low 4-CBA content converts 126161.doc •33 · 200831456 xylene to terephthalic acid. The reactants can be combined in a progressive manner by injecting a reactant into a stream containing the reactants at a plurality of points along the length of the reactor. One way of achieving a multi/shot configuration is shown in the continuous flow reactor of Figure 7, wherein: consists of a tube or vessel P. In an embodiment where a premixed oxygen/water stream is added to the premixed precursor/water stream, is the premixed precursor/supercritical or near supercritical water stream w supplied to the tube or vessel? The upstream end. The water stream ~ also contains a homogeneous catalyst plus acid. The stream passes through the reactor tube or vessel P and is supplied at a predetermined interval along the length of the official or container p, via a plurality of injection channels VIII to E for pre-dissolution in supercritical or near supercritical water. The hot and compressed oxygen produces a product stream s comprising a tickacid product in a supercritical or near supercritical aqueous solution. In this way, progressive injection achieves, for example, the oxygen necessary to completely oxidize p-xylene to terephthalic acid, the purpose of which is to control the oxidation of para-xylene, terephthalic acid or terephthalic acid intermediates and will Its side reactions and possible combustion are minimized. U. Referring now again to Figure 4, after the reaction has reached a desired level, a supercritical or near supercritical fluid is passed through a heat exchanger 22 through which the heat exchange fluid system is circulated via the closed loop 24 to Heat can be recovered for use in the preheater 16. A post-reaction cooling process for a carboxylic acid product solution (not shown) involves the use of a heat exchanger network to cool the stream to, for example, a subcritical temperature of about 3 ° C to maintain the carboxylic acid product in solution. And thereby reducing the fouling of the heat exchange surface, followed by cooling and precipitating the carboxylic acid using a series of flash crystallizers (similar to their flash crystallizers used in conventional terephthalic acid purification by hydrogenation) product. 126161.doc -34- 200831456 The cooling solution is then supplied to a product recovery zone 2 6 where the formic acid product precipitates from the solution. Any suitable method of product recovery known to those skilled in the art can be used. The product recovery zone 26 may comprise one or more cooling or evaporation crystallization stages to crystallize the carboxylic acid product to form a slurry of crystals in the aqueous mother liquor. If the product recovery zone 26 comprises one or more flash crystallizers, the resulting flash stream from the crystallizers can be used to indirectly or via direct injection of flashes into the reactor water via a conventional heat exchanger and/or Or the preheating reaction in the precursor feed is the inlet water and the precursor stream. It is obtained after crystallization, as described in the previously published International Patent Application No. WO-A-93/24440 and the disclosure of WO-A-94/17982, the disclosure of which is incorporated herein by reference. The slurry can be subjected to a solid-liquid separation process (with or without a washing tool) using, for example, a filtration apparatus operating under superatmospheric conditions, atmospheric conditions, or sub-atmospheric conditions. Thus, for example, an integrated solids separation and water scrubbing unit can comprise a belt filter unit, or a rotary cylindrical filter unit operated from a slurry side, or a drum filter unit (eg, a plurality of slurry receiving units) A BHS-Fest pressure filter drum is formed in which the mother liquor is transferred from the filter cake by water under the water pressure supplied to the units. After filtering the slurry, the recovered carboxylic acid product can be used directly to make, for example, a polyester (such as a bottle or fiber) for packaging. It can be similarly dried. If not at atmospheric pressure, the filter cake of the carboxylic acid product can be transferred to a low pressure zone (e.g., atmospheric pressure) via a suitable pressure reducing device (such as a lock hopper configuration, a rotary valve, a piston pump, a screw feed device, or a progressive type). A feed device, such as a screw pump of the type used to pump a high solids cold paste, is dried. The separation temperature and degree of washing required should be based on the amount of impurities produced in the reaction, including the amount of 126161.doc -35- 200831456, the manner in which the product is recovered, and the desired product specifications. In general, 'it may need to be made pure enough to allow a one-step purification (eg, by oxidation and/or hydrogenation of an aqueous solution of terephthalic acid, as the case may be, to convert 4-CBA to terephthalic acid or conversion) It is a slow acid product of p-benzoic acid (such as terephthalic acid), but we do not rule out the possibility of carrying out this purification after supercritical or near supercritical water oxidation. (_,

After recovery of the aromatic carboxylic acid product, at least a portion of the aqueous mother liquor (including the soluble catalyst component) can be recycled for reuse in the oxidation reaction, for example, by mixing with fresh water and/or reactants. However, if the recycle mother liquor contains a catalyst component, it is preferably not added to the 水" water stream prior to the addition of the precursor. The amount of recycle should normally be the majority of the recovered mother liquor, which is purified to reduce the solids of by-products in the process. The purge stream can be treated to recover its catalyst contents (if applicable) and its organic contents. Referring now to Figure 8, in this embodiment, liquid oxygen (line 3 〇), liquid precursor (e.g., paraxylene K line and water (line 34) in the process for producing terephthalic acid are supplied to In the mixing unit, the oxygen and precursor supply is pressurized by the pumps 38, 38A and heated to high temperatures in the heat exchangers 4, 4A, for example by high pressure steam. The mixing unit 36 is shown in Figure 4. The force shown is: configured to mix the reactants with the water supply to produce two streams 42, 44, one stream comprising the water/precursor mixture and the other stream comprising oxygen dissolved in water 'feeding it into - In the continuous flow reactor 46 in the form of a tube, the reaction is started, for example, by mixing the streams in a static mixing configuration in the tube. The rapid mixing is used (for example by using a static mixing 2 or the like) Apparatus) a homogeneous catalyst in the form of a solution in water: acid 12616l.d〇i -36- 200831456 The sap component is just added to the precursor/water stream 42 before entering the reactor' or at the beginning of the reactor Or just in front of it combined with logistics 42 and 44 0 can be more The supply of fresh makeup water to the system is achieved at the point. One of the most convenient points is upstream of the main dust pump 68, for example via a line 丨丨6, which is described in more detail below with respect to Figure 9. The water that is pressurized in the pump 38 (: and heated in the hot parent 40C is fed into the line 74 via the line 35a) or fed into the line 74 before the parent exchanger (50, 70). Alternatively, The water pressurized in the pump 38B and heated in the heat exchanger 4〇B is independently fed into the preheater 36 via the line 35. After the reaction under supercritical or near supercritical conditions, the reaction product (added) The product stream 48 in the form of a solution of less I unreacted reactants, intermediates, etc., is cooled by the dental superheating masters 50 and 52 and may optionally drop to a lower pressure and temperature in the flash vessel 54. The method of accomplishing this step at this time or in the product recovery zone 62 may involve a single or multiple known devices, but it should be organized to avoid solids by means known to those skilled in the art, such as local heating. Deposition. Therefore, when the stream from reactor 46 passes through heat exchange to 50 and 52 Monitoring, and controlling the temperature of the stream so that the product does not sink, should not sink until the flash vessel 54. The solid mass of steam and some gaseous components (such as nitrogen, oxygen, carbon oxides) are supplied via line 56. The recovery system 58 is supplied to the vessel, and the carboxylic acid product solution is supplied via line 6 to a product recovery zone 62. In the product recovery zone, the solution of the citrate product is passed through a multistage crystallization system where pressure is applied. And the temperature is gradually reduced to crystallize the carboxylic acid product in the form of crystal 126161.doc -37-200831456 f. The product of the crystallization process is a slurry of crystals of the carboxylic acid product in the aqueous mother liquor. After the final crystallization stage, the slurry can be At any desired pressure 'eg atmospheric pressure or above atmospheric pressure. The slurry is then subjected to any suitable form of solid-liquid separation to separate the crystals from the mother liquor. Solid-liquid separation can be carried out using any apparatus suitable for this purpose and configured to operate under high pressure conditions or at atmospheric pressure, depending on the pressure after the final crystallization stage. As mentioned previously, an integrated solids separation and water scrubbing unit (such as a belt filter unit, a rotating cylindrical filter unit or a drum filter unit (eg, a BHs_F formed from a plurality of slurry receiving units) may be used. ^t Filter drum in which the mother liquor is transferred from the filter cake by water under the water pressure supplied to the units)) for solid-liquid separation. In Figure 8, the recovered carboxylic acid product crystals are supplied via line to a dryer (not shown) or for direct manufacture of the polyester. If the solid-liquid separation is carried out under high pressure conditions, it is convenient to use a suitable device before being transferred to the drying apparatus (for example, as disclosed in U.S. Patent No. 5,470,473, or U.S. Patent No. 5,470,473). Ground the crystal to atmospheric pressure. The mother (4) of the self-solid separation is re-recovered via line 66, re-pressurized by (iv) and recirculated via heat exchanger 70, line 72, heat exchanger 5, line 74, start/adjust heater 76 and line 34. To the mixer unit %. Thus, under the conditions of the shifting operation, the recycle mother liquor can be used to supply the water source to the reactor 46 as well as to the catalyst and organic acid by-products (such as benzoic acid in the case of p-dimethylene terephthalic acid). The recycle to the process medium 36 is configured such that if the recycle mother liquor can contain a catalyst ', ie, a homogeneous catalyst, then the recycle mother liquor is preferably combined with the precursor stream rather than oxygen 126161.doc -38 - 200831456 The combination of wu(10) is preferred because the addition of the catalyst to the oxidant is carried out simultaneously with the addition of the precursor to the oxidant. Thus, if the recycle mother liquor contains a catalyst, the mixing unit is configured such that the oxidant stream 3〇 can be combined with fresh water from line 4. Similarly, other catalyst 戋 acidic components may be added to the mother liquor in line 34 as needed or added directly to reaction zone 46. Produced during the reaction, so water purification from the system. : can be achieved in a right-handed manner; for example, it may be more advantageous to purify the condensate via line π or from a suitable flash condensate (as will be described below with respect to the energy recovery system), as it will be more than recovered from the pipeline. Mother liquor purification is slightly less contaminated with organic matter. However, the recovered purification can be transferred to an exhaust treatment such as aerobic and/or anaerobic treatment. The temperature of the mother liquor is raised by about 3 Torr in the heat exchange H7G by "steam heat transfer" in the free crystallization stage - or multiple stages (e.g., the first stage high pressure and temperature crystallizer vessel). . To 1〇〇. . . The flash (tank 79) used for this purpose after passing through the heat exchanger can be returned as condensate to the wash water used in the product recovery zone for washing the carboxylic acid product cake produced by solid-liquid separation. In the heat exchanger 5, the mother liquor temperature is further increased (e.g., by about (10) C to 200 ° C) due to heat transfer from the high temperature product stream 48 from the reactor. In this way the product stream is subjected to cooling and the temperature of the mother liquor to the % stream is significantly increased. The adjustment/starter heater 76 is used to increase the temperature of the mother liquor recycle stream, if necessary to ensure supercritical or near supercritical conditions: under steady state process operation, the increase may be optional because of the heat exchange through After H5G, the mother liquor can be in a supercritical or near supercritical state. Thus 126161.doc -39- 200831456 Heater 76 is not necessarily required under steady state conditions and the heater can be configured to be used purely for the initial operation of pressurized water from the source rather than the mother liquor. In the case of mussels, the aqueous solvent is subjected to a supercritical or near supercritical state prior to mixing with one or both of the reactants. However, it should be understood that increasing the temperature to ensure that the required super-boundary or near supercritical conditions can be achieved before, during, and/or after the mixing stage. In the embodiment of Figure 8, the reaction occurs during the reaction of the precursor with oxygen.

The heat system is at least partially removed by heat exchange with a heat receiving fluid (preferably water). The heat is connected to the double flow system by means of a coil 80 or a series of generally parallel tubes (eg, in a shell heat) The tube of the exchanger design or its analog passes through the interior of the reactive body 46. The water used is pressurized and heated to a temperature high enough to allow the water to pass through the outer surface of the conduit 80 of the reactor, which may otherwise cause precipitation of components such as terephthalic acid in the reaction medium. Bureau 4 cold part to avoid. The water system used for this purpose is derived from the energy recovery system 58. Thus, in Figure 8, the water at high pressure and temperature is supplied via line "to the heat exchanger 52, which is used to be worn. The product after passing through the heat exchanger 5G flows into the step-by-step cooling. The water then passes through the line 8 through the line μ, which in turn produces a high-pressure, high-temperature vapor which is fed via line 84 into the energy recovery system 58. - or multiple stages of flashing vapor. This is illustrated by line 88. This vapor can be used, for example, to preheat the water supplied to the heat transfer line 80 via line 82. The vapor feed supplied to the energy recovery system 58 from the process. The resulting dehydrated product can be transferred via line 9 to the product recovery zone for, for example, washing the carboxylic acid product produced in the solidification of the knife. 126161.doc 200831456 cake. If necessary, from line 90 Water purification 92 is carried out which has the following advantages: The purification at this time will be less polluted than the purification from the mother liquor via line 78. In Figure 8, it is shown that the mother liquor has been passed through the product in the heat exchanger 5 Heat exchange After the heat, the reactants are introduced into the recycle mother liquor. In the '-variant', the reactants can be mixed with the parent's liquid recycle stream upstream of the heat exchange with the product stream. If the two reactants and the mother liquor are recycled The flow is so mixed, the latter is divided into separate streams, whereby the reactants are separately mixed to keep the reactants I separated from each other until mixed together for reaction. It should also be understood that the embodiment of Figure 8 can be One or both of the reactants introduced via a plurality of injection points along the flow path of the reaction medium are altered in the manner indicated in Figure 7 such that the reactants or the two reactants are progressively introduced into the reaction. In the energy recovery system 58, various heat recovery processes can be implemented to make the process energy efficient. For example, the high i, 4 gas generated after the water passes through the pipe 8 can be used in a furnace for supplying combustible fuel. The superheated and superheated vapor can then pass through one or more vapor condensing turbine sections to recover power. Part of the high pressure steam can be diverted for preheating the reactants (heat exchangers 4〇, 4〇A and 4〇b) or for pre-heating Hot 7 stream 82, where this It is necessary to achieve a high thermal efficiency system. The condensed water recovered from the turbine section and recovered from the heat exchangers 40, 40A and 40B can then be passed through a series of heating zones to preheat the water recirculated to the reactor via the heat exchanger 52. Thus, a closed loop is formed with the supplementary water added as needed. The cascade of the heating section L3 is replaced by a gradual increase in the return to the reactor 46. In the section, the heating fluid may be composed of flash steam obtained from different stages of the crystallization series at different pressures and temperatures by 126161.doc • 41 - 200831456. In other heating sections, the heating fluid may be used for The combustion gases present in the furnace stack associated with the high pressure steam superheated furnace supplied by the official line 84. The embodiment of Figure 8 uses substantially pure oxygen as the oxidant. Figure 9 illustrates a similar embodiment, but which uses compressed air (which may be enriched in oxygen) as an oxidant. The embodiment of FIG. 9 is generally similar to the embodiment of FIG. 8 and generally functions in the same manner, and the same reference numerals are used in the two figures, and will not be further hereinafter unless the context requires otherwise. As shown in the description, the air supply 100 is supplied via an air compressor 1〇2. Due to the use of air, a substantial amount of nitrogen is introduced into the process and must therefore be properly treated. In this case, after passing through the heat exchangers 5 and 52, the product stream is rapidly reduced to a lower temperature in the flash vessel 103 to condense the water to a greater extent than the embodiment of Figure 8, thereby reducing The water content of the top product. As described with respect to Figure 8, the degree of product flow through heat exchangers 50 and 52 is controlled such that product precipitation occurs only in flash vessel crucible 3. The overhead production stream is supplied to a gas turbine 110 via line 104, heat exchanger 1〇6, and fuel combustion heater 108. The overhead product stream is passed through heat exchanger 1〇6 to transfer heat to the mother liquor recycle stream while further draining water, which may be passed via line 112 to product recovery zone 62 for use as, for example, wash water. In order to be energy efficient, the gaseous overhead product stream needs to be heated to a high temperature prior to introduction into the turbine crucible 1 (), so that more than one gas turbine section may be present for heating the overhead product stream by the heater 108, in which case The lower overhead product stream should be heated to a high temperature upstream of each turbine section. Line 114 represents the overhead product stream exiting turbine 1 10 at low pressures 126161.doc -42 - 200831456 and at low temperatures. If the oxidation process results in the production of undesirable materials (such as carbon monoxide, etc.), for example, for reasons of corrosion and/or environmental reasons, the following precautions can be taken: • Processing the overhead product before or after passing through the turbine 110 and/or discharging Logistics to reduce/eliminate these components. The treatment may comprise subjecting the overhead product stream to catalytic combustion and/or washing with a suitable reagent, such as an alkaline wash. Turbine 110 can be mechanically coupled to an air compressor such that the air compressor is driven by the turbine.

In the embodiment of Figure 9, water exits the system via the overhead product stream. At least a portion of this water may be recovered as needed and recycled for use as, for example, wash water in product recovery zone 62. Additionally or alternatively, make-up water can be supplied to the product recovery zone via line ^^6 to compensate for water lost as a result of the use of compressed air when processing large amounts of helium. The make-up water can be preheated and used as wash water, and the preheating system is achieved, for example, by diverting a portion of the flash stream (shown collectively by reference numeral Μ) to heat exchanger 12〇 via line i 16 and will The water condensed in the flash stream is returned to the product recovery zone 62 as wash water. , k & has been described primarily with respect to p-xylene as a precursor to terephthalic acid, but it should be understood that alternative precursors may be used instead of or in addition to other precursors other than p-toluene. Acid, and the precursors include o-dimethyl strependine, Q-Tian #本一一甲本, 4-toluene furfural, 4-methyl benzoic acid and 3-methyl group. As above - no, the invention is also applicable to the manufacture of other aromatic carboxylic acids (such as meta-benzoic acid, o-stuppy) from the corresponding alkyl aromatic sulfonate (Xingyijia methyl compound) or other precursors. Formic acid, trimellitic acid and naphthalenedicarboxylic acid) The invention is further illustrated by the following non-limiting examples. Example 126161.doc -43- 200831456 Experimental study on a laboratory scale by continuous oxidation of o-xylene from ruthenium 2 in supercritical water with a combined catalyst and acid solution at about 380 ° C and 230 bar to 24 bar . The exotherm is minimized by using a relatively dilute solution (less than 〇·5% organic, weight/weight). The basic configuration of the system is shown in Figure 1. A more detailed description of the systems used for these laboratory scale experiments is shown in Figure 1. The crucible 2 is produced by heating the H2〇2/H2〇 mixture in the preheater 1 52 to over 4 °C. H2〇2 decomposition releases 〇2. The OVHW fluid then passes through a cross member 1 54, wherein the fluid is contacted with a solution of o-diphenylbenzene and acid from the respective pump and the catalyst. The reaction mixture is passed through reactor 156. The other components marked in Figure 10 are as follows: cooling coil 158; 0.5 filter 159; back pressure regulator 160; valves 162 Α to 162C; pressure relief valves 163 persons and 1633; check valves 164 eight to 164 (1; Pressure transducer 165 eight to 165D; thermocouple τ (the aluminum heater block of preheater 152 and reactor 156 also contains a thermocouple, not shown). The pump is Gilson 302, 305, 306 and 3 03; back pressure regulation The system is obtained from Tescom. The maximum corrosion occurs in the area of the cross member 154 where the raw material and the catalyst solution meet, especially when the high temperature gradient coincides with the bromide ion and is introduced into the unheated catalyst feed tube. The alloy (Hastell〇y) is used to catalyze the last part of the WJ feed tube and is used in the reactor, and the 3 16 stainless steel is used for other components. Before each operation, the device is hydrostatically measured while cooling. And after heating, it is heated by pure water flow -1 〇mL/min). Once the operating temperature is reached, the H2〇2/H2〇 is typically fed sequentially and the o-diphenylbenzene and acid/catalyst pump 126161.doc -44-200831456 are activated. The residence time per operation remains constant and typically reaches about 1 minute, but in most cases is about 10-20 seconds. The yield of manganese is calculated by dividing the outflow of Μη by the inflow of Μη (wherein the concentration of manganese is measured by atomic absorption). In these examples, the concentration of the given catalyst and acid is the concentration of the catalyst feed stream. The actual concentration in the reactor corresponds to about one-third of the equivalent because the catalyst feed represents about one-third of the (mass) flow, with the other two-thirds coming primarily from the other streams. Example 1 An oxidation process was carried out using an aqueous MnBr 2 solution (1700 ppm Μη) with and without HBr (1000 ppm Br) and 1500 ppm benzoic acid (i.e., the same concentration as HBr, 0.0124 Μ). Preliminary results indicate that catalyst recovery is almost complete when benzoic acid is used in combination with HBr, indicating that benzoic acid also plays a role in catalyst stabilization. When the o-xylene feed was closed, the benzoic acid containing operation (Operation C) showed a significant improvement in catalyst recovery relative to Operation B without BA. The results are shown in Tables 1 and 2. Table 1 Operation Μη (ppm) HBr (ppm) Benzoic acid (ppm) Μ 回收 recovery with ortho-xylene feed (%) Μ 回收 recovery without o-xylene feed (%) A 1700 0 0 75 15 B 1700 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 63 93 1 0 0.7 0 6 B 1700 1000 0 66 93 0 0 0.8 0 6 C 1700 1000 1500 66 95 ^ 0 0 0.2 0 5 • PHT is phthalic acid; CBA is o-carboxybenzaldehyde; BA is benzoic acid; p D ^ ^ is o-tolualdehyde; TA is o-toluic acid; hydrazine is benzoquinone. (Selectivity (in percent) calculated as the molar concentration of the product relative to the total molar concentration of the products). In the first part of the experiment of each of operations A, B and C, as required by WO-02/06201-A, the o-xylene stream is initially supplied to bring the oxidant/catalyst contact system into contact with the oxidant/precursor At the same time. In operation A, for example, a 75% catalyst recovery is observed, and the remaining 25% is a manganese oxide precipitate (as determined by X-ray diffraction, mainly Mn〇2, but also includes some Mn2〇3& Mn0(0H)2) Form loss. The current drive stream shuts down and the catalyst recovery rate drops significantly, indicating that the MnBr2 catalyst is significantly more stable in the presence of the precursor. The effect of the acid is illustrated by operations B and c, where the initial mixing is simultaneous with operation A, and wherein the catalyst recovery is significantly increased in the presence of the precursor, but also significantly increased after the precursor stream is shut down. Operation c is particularly noteworthy in that it demonstrates that the combination of HBr and benzoic acid provides significantly greater catalyst stability than HBr alone, further demonstrating the surprising effect in the experiments described below. Therefore, operations 8 and c demonstrate that the stability of the catalyst is increased by 126161.doc -46-200831456 in the presence of acid but in the absence of precursor, so that the simultaneous mixing scheme of WO-02/06201-A is desirable, but this is not necessary. Example 2 Example A and C were repeated except that CoBr2 (1842 ppm Co) was used instead of MnBr2. Similar catalyst stabilization and recovery effects were observed. The results are not shown in Table 3. Table 3 Operation Co back to ιΜτ rate PHT Select H%) Team dry (%) a Press dry (%) PHT CBA TA Phth TALD ba CoBr2 47 51 63 10 6 10 0 11 CoBr2/HBr/BA 99 52 68 7 7 7 0 12 ί' a : Example 3 in the presence of a precursor To further investigate the role of benzoic acid in a system using manganese bromide as a catalyst, an experiment similar to that of Example 1 was performed. To dissolve a relatively large amount of benzoic acid in the system, the apparatus of Figure 10 was modified, particularly by employing a hot catalyst feed system. A 1 〇〇W ribbon heater was placed around the catalyst feed tube (1/8 Torr), which was controlled by an autotransformer (Variac) (which required 100 V for 8 〇). Allow hot water (80 ° C) to circulate around the catalyst pump head. The experimental conditions were as follows: Reactor temperature: about 380 ° C; reactor pressure: about 230 bar; acid / catalyst and o-xylene flow rate of 4.084 mL / min; o-xylene flow rate of 0.061 mL / min; oxidant The flow rate (H202 in H2) was 8.1 mL/min. (Provided in 126161.doc -47-200831456 H2〇2 water> The amount of [〇2] in the gluten solution is 〇276 m〇1丄-heart 5 mole equivalent required to completely oxidize the organic precursor to the aromatic acid The stoichiometry, in the case of o-xylene, its molar ratio is 3〇2/organic)). Typically, the experiment is carried out by the following steps: (1) obtaining the SCWO conditions achieved with pure water, and subsequently (u) pumping the catalyst in the absence of oxygen and o-xylene, followed by (in) in the preheater via H2〇2 Decompose to supply oxygen and (iv) open the o-xylene pump. However, initially, in the absence of an ortho-xylene precursor, in the presence of benzoic acid under supercritical conditions, first in the absence of an oxidizing agent (ie, steps (1) and (ii) above) and then in the oxidizing agent In the case (i.e., steps (1) to (iii) above), the stability of ΜηΒΓ2 was tested. The results of operations A through E in this configuration are presented in Table 4 below. At 8 〇. The experiment was carried out using a concentration of 17 〇〇 ppm ΜηΒι*2. The concentration of benzoic acid was changed as shown in Table 4 below.

Table 4 Sample BA (ppm) 〇 2 (Y/N) BA recovery (%) Μ η recovery (%) A 10000 N 98.3 99 B 10000 Y 95.2 90.1 C 5000 N 99.5 98.9 D 5000 Y 98.3 85.3 E 3000 N 99 84 Comparison 1: MnBr2 0 N - 88 Comparison 2 : MnBr2+02 0 Y - 48 Comparison 3 : MnBr2+HBra+02 0 Y - 66 a : The added HBr is 1000 ppm HBr 126161.doc -48- 200831456 Results first show BA is extremely stable in water under supercritical conditions with or without oxygen. Atomic adsorption analysis showed that MnBr2 was extremely stable in the presence of BA under supercritical conditions. At 1 〇〇〇〇 ppm BA, Mn is fully recovered in the absence of oxygen and o-xylene precursors. At a concentration similar to BA, # #丨,氧氧伊当不# is in the o-xylene precursor (when there is no organic matter, 〇2 is a 3-fold excess), and 9〇% Mn is recovered. This is extremely significant and unexpected compared to the results of previous studies using ΜηΒι·2 or MnBWHBr, which yielded about 2% -30% Μ η recovery in the presence of oxidant in the absence of o-xylene precursor. Improvement. These results are also unexpected given the recovery of about 6% of the 得到 obtained at ΒΑΛ 1500 ppm. The results indicate that the use of higher cerium concentrations plays an important role in the stabilization of the catalyst. As a result, it was confirmed that the simultaneous mixing scheme of W〇_〇2/〇62〇1_A is desirable because the stability of the catalyst is increased in the presence of an acid but in the absence of an ortho-xylene precursor, but this is not essential. The experiment continues at the stage (丨v) (ie by opening the o-xylene pump). The results are presented in Table 50 below and show that the use of benzoic acid in the catalyst material yields an almost quantifiable Μ recovery. The ruthenium selectivity was evaluated by considering the BA concentration (which was measured by HPLC) from the catalyst feed. As a result, it was confirmed that BA can be used as an additive in the feed of the MnBgifier to stabilize the catalyst and swell the oxidation; I is again minimized. The results are also indicative of benefits from catalyst recovery effects. The absence of HBr is important because HBr is known to be corrosive to the inner surface of the device. Table 5 also includes the results obtained for the operation of including hydrazine or HBr in the catalyst feed, emphasizing the importance of acid (rather than bromide) for achieving catalyst recovery. 126161.doc -49· 200831456 ,\ Selectivity (%) BA (N vd Q\ inch rn m l> 00 (N TALD o <N 〇〇o (N 〇〇Phth 00 o cn ▼—H (N ( N i—H < N inch CN o 卜 d rn 〇〇cn CBA yn O 00 dqdo cn PHT 92.4 94.0 92.0 91.0 92.2 92.6 PHT yield (%) CN o Μη Recovery (%) 00 Operation MnBr2+10000 ppm BA MnBr2+5000 ppm BA MnBr2+3000 ppm BA MnBr2+1500 ppm BA MnBr2+3000 ppm BA+1000 ppm HBr MnBr2+3000 ppm BA+1000 ppm NaBr 126161.doc -50- 200831456 [Simplified Schematic] Figure 1 is an illustration Schematic flow chart for the basic configuration described above in Example I. The dashed line indicates an alternative path for the acid component. Figures 2A and 2B are schematic flow diagrams illustrating the basic configuration described with respect to Example π above. In Figure 2, the oxidant is introduced along the reaction zone in a progressive manner at multiple injection points. The dashed line represents an alternative pathway for the acid component.

Figure 3 is a schematic flow diagram illustrating the configuration of a precursor (in the above embodiment) when the contact of the precursor with the oxidant is not the same as the contact of the catalyst with the oxidant. Figure 4 is a schematic flow diagram illustrating the configuration of adding a seven-driver to a premixed stream of oxygen and water (i.e., according to the configuration of the method illustrated in Figure 1). Figure 5, Figure 5, Figure 5C, Figure 5D, and Figure 6 illustrate various premixer configurations that can be used to achieve mixing of the reactants with aqueous solvents. Figure 7 is a schematic diagram illustrating multiple injections of oxidant. 8 and 9 are schematic flow diagrams illustrating mother liquor recirculation and heat removal from a reactor for oxidizing a terephthalic acid precursor in supercritical or near supercritical water, generally in the embodiment of FIG. Pure oxygen is used as the oxygen: and in the embodiment of Figure 9, the air is the oxidant. Sheet [Major component symbol description] Figure 10 is a detailed illustration of the apparatus for laboratory scale experiments. 1 Preheater 1 Α Preheater 2 Reactor 3 Back Pressure Regulator 126161.doc -51 - 200831456 10 Water source 12 Precursor source 14 〇 2 source 16 Preheater 18A Premixer 18B Premixer 19 Catalyst source 20 Reaction Zone 22 Heat exchanger 24 Closed circuit 26 Product recovery zone 30 Line 32 Line 34 Line 35 Line 35A Line 36 Mixing unit 38 Pump 38A Pump 38B Fruit 38C Pump 40 Heat exchanger 40A Heat exchanger 40B Heat exchanger 126161.doc -52 - 200831456 40C Heat exchanger 42 Stream 44 Stream 46 Continuous flow reactor 48 Product stream 50 Heat exchanger 52 Heat exchanger 54 Flash vessel 56 Line 58 Energy recovery system 60 Line 62 Product recovery area 64 Line 66 Line 68 Line 70 Heat Exchanger 72 Line 74 Line 76 Start/Adjust Heater 78 Line 79 Line 80 Coil/Pipe 82 Line 83 Line 126161.doc -53- 200831456 84 88 90 92 100 102 103 104 106 108 110 112 114 116 120 152 154 156 158 159 160

162A/162B/162C

163A/163B

164A/164B/164C Pipeline Pipeline Water Purification Air Supply Air Compressor Flash Tank Line Heat Exchanger Fuel Combustion Heater Gas Turbine Line Pipeline Heat Exchanger Preheater Cross Member Reactor Cooling Rotary Filter Back Pressure Regulator Valve pressure relief valve check valve 126161.doc -54- 200831456 165A/165B/165C/165D Pressure transducer A Preheated water supply / Injection channel B Reactant (precursor or oxygen) / Injection channel C Injection channel D Injection Channel E injection channel • P resulting mixed flow/tube or vessel PI mixed flow 'P2 mixed flow s product flow T thermocouple w water flow 126161.doc -55-

Claims (1)

200831456 X. Patent Application Range: 1 · The use of an acidic component comprising one or more acids to prevent catalyst loss and/or metal oxide precipitation or to minimize it in a process for producing an aromatic carboxylic acid, The method comprises contacting one or more precursors of the aromatic carboxylic acid with an oxidant in the presence of a catalyst comprising a metal salt in a reactor, the contact being comprised of the precursor and the oxidant comprising ruthenium X is produced in a supercritical or near supercritical condition, wherein: (0) the acidic component is added to the reaction zone; (11) at least a portion of the catalyst and the oxidant are in the acidic group And (iii) the acidic component comprises one or more organic acids. 2. The use of claim 1, wherein the or the precursor, the oxidizing agent and the aqueous solvent constitute a single homogeneous phase in the reaction zone 3. The use of claim 1 or 2, wherein the organic acid is added in an amount such that the molar ratio of the added organic acid to cerium in the reaction zone is at least 〇5:1, wherein hydrazine is the catalyst Metal. 4. The use of claim 1 or 2, wherein the organic acid is added such that the molar ratio of the added organic acid to the ruthenium in the reaction zone is not more than about υ·Α. 5. The use of claim 1 or 2, wherein the addition of the acidic component is carried out such that the acidic component is present at any position where the metal salt is in contact with the oxidation process or the stone oxidant. The use of claim 1 or 2, wherein the metal salt comprises a transition metal. 126161.doc 200831456 7. The use of claim 2 or 2, wherein the metal salt comprises manganese. 8. The use of claim 1 or 2, wherein The metal salt comprises manganese bromide. 9. The use of claim 1 or 2, wherein the aromatic dicarboxylic acid is selected from the group consisting of terephthalic acid, isophthalic acid, phthalic acid, trimellitic acid, The use of naphthoquinone as described in claim 1 or 2, wherein the aromatic dicarboxylic acid is terephthalic acid. 11 · The use of the precursor or the like, wherein the precursor is selected Free having at least one selected from the group consisting of an alkyl group, an alcohol group, an alkoxyalkyl group, and an aldehyde group The group of aromatic compounds of the group. The use of the item of claim 2 or 2, wherein the precursor is selected from the group consisting of aromatic having at least one substituent selected from the group consisting of an alkyl group, an alcohol group, and an alkoxy group. A group of compounds consisting of 13. The use of claim 2 or 2, wherein the precursor is selected from the group consisting of aromatic compounds having at least one substituent selected from the group consisting of: substituents. The use of 2, wherein the precursor is selected from the group consisting of aromatic compounds having at least one substituent from C 丨 4 alkyl. 15. The use of claim 14, wherein the precursor is para-xylene The use of claim 2, wherein the organic acid has the formula R(c〇〇H)n, wherein η is at least 1 and wherein R is selected from the group consisting of a non-aromatic hydrocarbon group and an aromatic group. The use of claim 1 or 2, wherein the target aromatic acid of the oxidation method has the formula Ar(C〇2H)x, wherein Ar is an aromatic group and X is at least 2, and is added thereto The organic acid in the reaction mixture has the formula Ar(c〇2H)y, where y&lt;x. 126161.doc 200831456 18. The use of claim 1 or 2, wherein the organic acid is benzoic acid. 19. The use of claim M2, wherein the target aromatic retinoic acid of the oxidation process has the formula Ar(C〇2; H)x ' wherein Ar is an aromatic group and the hydrazine is at least 2 and is added to the reaction The organic acid in the mixture has the formula Ar(C〇2H)y(Ri)z, wherein the R1 or each R1 is selected from the group consisting of Ci 4, Ci 4 alcohol, (Cm alkoxy)-Cl·4 alkyl Or a substituent of a Cl. 4 aldehyde group, wherein y &lt; x and wherein z &lt; x. 20. The use of claim 1 or 2, wherein the organic acid is toluic acid. • The use of the claim item wherein the acidic component comprises an organic acid and an inorganic acid HX, wherein X is a halide ion. 22. The use of claim 21, wherein X is a desert ion. 23. The use of claim 1 or 2, wherein the organic acid is a by-product of the oxidation reaction of the aromatic carboxylic acid. 24. The use of claim 1 or 2, wherein the organic brew is additionally added to the reaction via recycle from a waste stream to the reactor. 25. The use of claim 1 or 2, wherein at least the organic acid is used by the Qiu Ba Xi. The addition of the organic acid to the reaction mixture is carried out in situ, wherein the precursor ρ0 Α is different from the precursor of the target aromatic carboxylic acid of the synthetic oxidation reaction. And the organic acid which is generated in situ is different from the target aromatic carboxylic acid. 26. The use of claim 25, wherein the organic acid is mazinic acid and the precursor is fluorene. Blade 27. The use of claim 1 or 2, wherein at least ν π of the organic acid is produced by adding the organic acid to the far-reaction mixture to dihydrate the precursor Ρ〇Α 126161.doc 200831456 . 28. For example. Use of the invention of claim 27 wherein the organic acid is benzoic acid and the hydrolyzable precursor P〇a is selected from the group consisting of alkyl benzoate. 29. For example, in May! Or use of 2, wherein at least a portion of the catalyst and the acidic component are mixed prior to contact with the oxidizing agent. The use of claim 1 or 2, wherein at least a portion of the precursor is contacted with the oxidant simultaneously with the contact of the catalyst with at least a portion of the oxidant. f, ^ 31·If you ask for help! The use of *] wherein at least 5% by weight of the aromatic acid produced is maintained in solution during the reaction. 32. The use of the invention, wherein the aromatic carboxylic acid is precipitated from the reaction medium after the reaction and contains no more than 5 〇〇〇ppm by weight of the intermediate produced during the reaction. aldehyde. The use of the aromatic carboxylic acid solution after the reaction to precipitate the aromatic carboxylic acid and to separate the precipitate from the mother liquor. 34. The use of claim 33, wherein at least a portion of the mother liquor is recycled to the reaction zone. 3. The use of claim 1 or 2, wherein the reactor is a continuous flow reaction. The use of the reaction medium in the reaction zone is no more than 10 minutes. 37. A method for preventing or minimizing catalyst loss and/or metal oxide precipitation in a process for producing an aromatic carboxylic acid, the method comprising the presence of a catalyst comprising a metal salt in 126161.doc 200831456 The aromatic "one or more precursors are contacted with an oxidizing agent, and the contact is carried out by the (4) rigid drive and the oxidizing agent in an aqueous solvent containing water under supercritical conditions or near supercritical conditions, wherein (1) a method comprising the steps of adding an acidic component comprising __ or a plurality of acids to the oxidation reaction zone; (8) contacting at least a portion of the catalyst with the oxidant in the presence of the acidic component; and (out) the acidity The composition comprises one or more organic acids. 38. 39. 40. 41. 42. 43. 44. The method of claim 37, wherein the or the precursor, the oxidizing agent and the aqueous solvent are formed in the reaction zone The method of claim 37 or 38 wherein the organic acid is added in an amount such that the molar ratio of the added organic acid to cerium in the reaction zone is at least 〇5:1, wherein Μ is the catalyst gold The method of claim 37 or 38, wherein the organic acid is added in an amount such that the molar ratio of the added organic acid to cerium in the reaction zone is not more than about 3 〇:1, wherein Μ is the catalyst The method of claim 3, wherein the addition of the acidic component is carried out such that the acidic component is present at any position where the metal salt is in contact with the oxidizing agent of the oxidation process. The method of claim 37, wherein the metal salt comprises a transition metal. The method of claim 37 or 38, wherein the metal salt comprises manganese. The method of claim 37 or 38, wherein the metal salt comprises manganese bromide. The method of claim 37 or 38, wherein the aromatic dicarboxylic acid is selected from the group consisting of p-126161.doc 200831456 monocarboxylic acid, isophthalic acid, phthalic acid, trimellitic acid, naphthalene dicarboxylic acid, and acid. The method of claim 37 or 38, wherein the aromatic dicarboxylic acid is terephthalic acid. The method of claim 37 or 38, wherein the precursor is selected from the group consisting of a substituent of a base, an alcohol group, an alkoxyalkyl group and an aldehyde group The method of claim 3, wherein the precursor is selected from the group consisting of aromatic compounds having a substituent selected from the group consisting of an alkyl group, an alcohol group, and an alkoxyalkyl group. The method of claim 37 or 38, wherein the precursor is selected from the group consisting of aromatic compounds having substituents selected from alkyl groups. 5〇·明明37 or 38 The method, wherein the precursor is selected from the group consisting of aromatic compounds having a substituent selected from the group consisting of Ci. 4 alkyl. The method of claim 50, wherein the precursor is p-xylene. 52. The method of claim 37 or 38, wherein the organic acid has R(CO〇H)n, wherein n is at least! And wherein R is selected from a non-aromatic 1 aromatic group. The method of claim 37 or 38, wherein the target aromatic of the oxidation process, the acid has the formula Ar(C02H)x, wherein Ar is an aromatic group and the oxime is to the illusion and is added to the reaction The organic acid in the mixture has V ', Ar(C〇2H)y, where y&lt;x. The method of claim 37 or 38, wherein the organic acid is benzoic acid 55. The method of claim 37 or 38, wherein the oxidation method 126161.doc 200831456 acid has the formula Ar(C〇2H)x Wherein Ar is an aromatic group and the hydrazine is at least 2, and the organic acid added to the reaction mixture has the formula Ar(C〇2H)y(Rl)z, wherein the Ri or each R! is selected from Ci4 a substituent of an alkyl group, an alcohol group, a (C!.4 alkoxy)-Cu4 alkyl group or a Cw aldehyde group, wherein y&lt;x and wherein z&lt;x. 56. The method of claim 37 or 38, wherein the organic acid is toluic acid. 57. The method of claim 37 or 38, wherein the acidic component comprises an organic acid and a mineral acid HX, wherein X is a halide ion. 5. The method of claim 57, wherein X is a bromide ion. The method of claim 37 or 38, wherein the organic acid is a by-product of the precursor to the oxidation reaction of the aromatic carboxylic acid. 60. The method of claim 37 or 38 wherein the organic acid is added to the reaction via recycle from a waste stream to the reactor. The method of claim 37 or 38 wherein at least a portion of the organic acid is generated in situ by adding an oxidizable precursor of the organic acid to the reaction mixture, wherein the precursor P〇A is different from the application The precursor of the target aromatic amide of the synthetic oxidation reaction' and wherein the organic acid produced in situ is different from the target aromatic carboxylic acid. Wherein the organic acid is benzoic acid and the precursor is 62. The method of claim 61 wherein P〇A is toluene. The method of claim 37 or 38, wherein at least a portion of the organic acid is produced in situ by adding the hydrolyzable precursor of the organic acid to the money mixture. 64. The method of claim 63 wherein the organic acid is dodecanoic acid and the hydrolyzable 126161.doc 200831456 precursor p0A is selected from the group consisting of alkyl benzoate. The method of claim 37 or 38, wherein at least a portion of the catalyst and the acid component are mixed prior to contact with the oxidizing agent. 66. The method of claim 37 or 38, wherein at least a portion of the precursor is contacted with the oxidant and the catalyst is contacted with at least a portion of the oxidant. 67. The method of claim 37 or 38, wherein at least 98% by weight. /. The aromatic carboxylic acid produced is maintained in solution during the reaction. The method of claim 37 or 38, wherein the aromatic carboxylic acid is precipitated from the reaction medium after the reaction and contains no more than 5 paws by weight of the intermediate produced during the reaction. aldehyde. The method of claim 37 or 38, wherein after the reaction, the aromatic carboxylic acid-containing solution is treated to precipitate the aromatic carboxylic acid and separate the sediment from the mother liquor. 7. The method of claim 69, wherein at least a portion of the mother liquor is recycled to the reaction zone. The method of claim 37 or 38, wherein the reactor is a continuous flow reactor. The method of claim 71, wherein the reaction medium has a residence time in the reaction zone of no more than 1 minute. 73. An oxidation process for the manufacture of an aromatic carboxylic acid, the method comprising contacting one or more precursors of the aromatic trestic acid with an oxidant in the presence of a catalyst comprising a metal salt in a reactor, the contacting And the oxidizing agent is reacted with the oxidizing agent in an aqueous solvent containing water under supercritical conditions or under supercritical conditions of 126161.doc 200831456, wherein: (1) an acidic component comprising one or more acids is added to the In the reaction zone; (li) at least a portion of the catalyst is contacted with the oxidant in the presence of the acidic component; and (iii) the acidic component comprises one or more organic acids. The method of claim 73, wherein the or the precursor, the oxidizing agent, and the aqueous solvent form a single homogeneous phase in the reaction zone. The method of claim 73 or 74, wherein the organic acid is added in an amount such that the molar ratio of the added hydrazine and hydrazine in the reaction zone is at least an amount, wherein hydrazine is a metal of the catalyst. The method of claim 73 or 74, wherein the organic acid is added in an amount such that the molar ratio of the added machine I and hydrazine in the reaction zone is not more than about υ, wherein Μ is the metal of the catalyst. 77. The method of claim 73 or 74, wherein the added component of the acidic component is such that the acid is 纟 and 彳8+ &gt;, and the wound is present in the metal salt and the oxidation Method 78. Method 79 of claim 73 or 74, method 80 of claim 73 or 74, method 81 of claim 73 or 74, or any method of contacting the method of claim 73 or 74. The metal salt contains a transition metal. Wherein the metal salt comprises manganese. Wherein the metal salt comprises manganese bromide. One of the aromatic dicarboxylic acids is selected from the group consisting of p-monocarboxylic acid, m-benzoic acid, benzoic acid, and nicotinic acid.丰一甲酉夂奈二 82. If the request is 73 or 74, the acid. The method wherein the aromatic dicarboxylic acid is a paraben 126161.doc 200831456 83. The method of claim 73 or 74, wherein the precursor is selected from the group consisting of: an alkyl group, an alcohol group, and an alkane A group of aromatic compounds consisting of a substituent of an oxyalkyl group and an aldehyde group. The method of claim 73 or 74, wherein the precursor is selected from the group consisting of aromatic compounds having up to a substituent selected from the group consisting of an alkyl group, an alcohol group, and an alkoxy group. , The method of claim 73 or 74, wherein the precursor is selected from the group consisting of aromatic compounds having a substituent derived from an alkyl group. The method of claim 73 or 74, wherein the precursor is selected from the group consisting of aromatic compounds having a substituent selected from the group consisting of Cl. 4 alkyl groups. 87. The method of claim 86, wherein the precursor is para-xylene. The method of claim 73 or 74, wherein the organic acid has the formula R(COOH)n, wherein n is at least i and wherein the group is selected from the group consisting of non-aromatic hydrocarbon aromatic groups. 89. The method of claim 73, wherein the acid of the oxidation method has a MCO muscle of the formula wherein the oxime is an aromatic group and the ruthenium is at least 2 Å and is added to the organic acid Ar in the reaction mixture ( C02H)y, where y&lt;x. The method of claim 73 or 74 wherein the organic acid is benzoic acid. The method of claim 73 or 74, wherein the oxidizing method acid has a muscle of formula A (10), wherein Ar is an aromatic group and hydrazine is to 竣 and L is added to the organic acid Ar (C〇2HMR1) in the reaction mixture. -^-Rl^ an alcohol-based oxime cardinyl group or a substituent of a Ci group, which is 126161.doc -10- 200831456 y&lt;x and wherein ζ&lt;χ. 92. The method of claim 73 or 74, wherein the method of claim 73 or 74, wherein the acidic component package: has: Inorganic acid strontium, in which strontium is painted ions. 3 Organic acid and 94. The method of claim 93, wherein X is a desert ion. 95. The method of claim 73 or 74, wherein the by-product of the oxidation reaction of the aromatic decanoic acid. </ RTI> </ RTI> </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; The method of 74, μ, ^ ^ Α 邛 该 该 该 该 该 该 该 该 该 该 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机 有机The precursor of the target aromatic citric acid of the synthetic oxidation reaction, and wherein the in situ generator acid is different from the target aromatic carboxylic acid. 98. The method of claim 97 wherein the organic acid is benzoic acid and the P〇A is toluene. The method of claim 73 or 74, wherein at least a portion of the organic acid is produced in situ by adding the hydrolyzable precursor p〇A of the organic acid to the hydrazine reaction mixture. The method of claim 99, wherein the (4) is benzoic acid and the hydrolyzable precursor P〇A is selected from the group consisting of alkyl alum. The method of claim 73 or 74, wherein at least a portion of the catalyst and the acid component are mixed prior to contact with the oxidizing agent. 102. The method of claim 73 or 74, wherein at least a portion of the precursor is contacted with the oxygen 126161.doc -11 - 200831456 agent and the catalyst and at least a portion of the oxidant. The method of claim 73 or 74, wherein at least 98% by weight of the aromatic carboxylic acid produced is maintained in solution during the reaction. The method of claim 73 or 74, wherein the aromatic carboxylic acid is precipitated from the reaction medium after the reaction and contains not more than 5 Å by weight of the intermediate aldehyde which is produced during the reaction. 1〇5·(4) The method of claim 73 or 74, wherein the spent carboxylic acid/liquid mixture is treated to reduce the aromatic carboxylic acid and separate the precipitate from the mother liquor. 106. The method of claim 1, wherein the at least a portion of the mother liquor is recycled to the reaction zone. The method of claim 73 or 74, wherein the reactor is a continuous flow reactor. 108. The method of claim 1, wherein the reaction medium has a residence time in the reaction zone of no more than 10 minutes. An aromatic carboxylic acid, which is produced by the method of any one of claims 73 to 1-8. 126161.doc -12-