ES2848325B2 - METHOD OF PRODUCTION OF DICARBOXYLIC ACID USING CERIUM COCATALYST - Google Patents

Description

DESCRIPTION

METHOD OF PRODUCTION OF DICARBOXYLIC ACID USING

CERIUM COCATALYST

CROSS REFERENCE TO RELATED APPLICATION

The present international application claims priority to US Provisional Application No. 62/789,583, filed on January 8, 2019, which is incorporated herein by reference.

BACKGROUND

Aromatic dicarboxylic acids (e.g., terephthalic acid) can be produced by oxidation of dimethyl aromatic compounds (e.g., para-xylene) in the presence of a catalyst. The reaction is normally carried out in the presence of a solvent, for example acetic acid. The oxidation of dimethyl aromatics to the corresponding dicarboxylic acids proceeds through several intermediate steps. The inefficient catalyst and/or oxidation process leads to the formation of intermediate products such as impurities in the product. Furthermore, the oxidation process carried out at high pressures and temperatures leads to the formation of COx due to excessive oxidation of the final products (i.e. aromatic dicarboxylic acid) and also to the combustion of the solvent, e.g. acetic acid. . As a result of by-product formation and/or excessive oxidation, the consumption of dimethyl aromatic compounds and solvent increases undesirably.

U.S. Patent No. 5,453,538 discloses a process for the manufacture of aromatic dicarboxylic acids that uses a low ratio of bromine to metals facilitated by the use of cerium along with the catalyst. cobalt and manganese.

BRIEF DESCRIPTION OF THE DRAWINGS

The following figures are exemplary embodiments wherein similar elements are similarly numbered.

FIG. 1 is a process flow diagram of one embodiment of a para-xylene oxidation method to obtain terephthalic acid.

FIG. 2A is a graphical illustration of the mole percentage of carbon monoxide and carbon dioxide (collectively “COx”) formed as byproducts, based on the total moles of reaction product, in Comparative Example A and Example 1; and the percentage reduction in moles of COx in Example 1 compared to Comparative Example A.

FIG. 2B is a graphical illustration of the mole percentage of COx formed as byproducts, based on the total moles of reaction product, in Comparative Example B and Example 2; and the percentage reduction in moles of COx in Example 2 compared to Comparative Example B.

FIG. 3 is a graphical illustration of the weight percentage of C10+ hydrocarbons formed as byproducts, based on the total weight of reaction product, in Comparative Examples A-B and Examples 1-2; and the percentage reduction in the amount of C10+ hydrocarbons in Comparative Examples B and Examples 1-2 compared to Comparative Example A.

The above described features and other features are exemplified by the following detailed description, examples and claims.

DETAILED DESCRIPTION

It would be desirable to provide improved methods of oxidation of dimethyl aromatic compounds that selectively produce aromatic dicarboxylic acids, particularly methods that mitigate the aforementioned disadvantages. Accordingly, methods of oxidation of dimethyl aromatic compounds to obtain aromatic dicarboxylic acids are disclosed herein. Desirably, the methods reduce undesirable side reactions that consume the dimethyl aromatics and solvent to form byproducts by oxidizing the dimethyl aromatics in the presence of a catalyst that includes cobalt and manganese in a weight ratio equal to or greater than 1:1 and a cocatalyst that includes cerium. Previous methods of oxidation of dimethyl aromatics suffered from side reactions, such as oxidation of solvents or excessive oxidation of dimethyl aromatics to form byproducts, such as carbon monoxide, carbon dioxide or C10+ hydrocarbons (e.g. , intermediate or "heavy" products). These side reactions produced a high consumption of the dimethyl aromatics and the solvent. For example, previous methods can consume approximately 0.010 mol% more dimethyl aromatics and approximately 0.016 % mole more solvent compared to the methods of the present disclosure.

As used herein, the term "excessive oxidation" refers to the oxidation of terephthalic acid and acetic acid to COx.

In the methods of the present disclosure, dimethyl aromatic compounds are oxidized in the presence of a catalyst that includes cobalt and manganese in a weight ratio equal to or greater than 1:1, or equal to or greater than 2:1, preferably equal to or greater than 3:1, and a cocatalyst that includes cerium. Surprisingly, it was found that said catalyst and cocatalyst reduce the loss of reactant and solvent, increase the selectivity for aromatic dicarboxylic acids, reduce the amount of at least one of carbon monoxide, carbon dioxide and C10+ hydrocarbons in the reaction product and increases the purity of aromatic dicarboxylic acids compared to previous methods of oxidation of dimethyl aromatics without the presence of said catalyst and cocatalyst (for example, including a weight ratio between cobalt and manganese less than 1:1 and without cocatalyst of cerium).

For example, the methods of the present disclosure can achieve at least one of: (i) a reduction in the total moles of carbon dioxide and carbon monoxide formed equal to or greater than 5 mol % , or equal to or greater than 10%. in moles, preferably equal to or greater than 15 mol%, compared to the total moles of carbon monoxide and carbon dioxide present in a reaction product obtained from a method of oxidation of a dimethyl aromatic compound without the presence of said catalyst and cocatalyst; (ii) a reduction in the amount of C10+ hydrocarbons formed equal to or greater than 10 percent by weight (wt%), or equal to or greater than 20% by weight, preferably equal to or greater than 30% by weight, compared to the total amount of C10+ hydrocarbons present in a reaction product obtained from a method of oxidation of a dimethyl aromatic compound without the presence of said catalyst and cocatalyst; and (iii) an increase in moles of aromatic dicarboxylic acid produced equal to or greater than 0.5 mol % , or equal to or greater than 1.0 mol % , preferably equal to or greater than 1.5 mol%, compared to the moles of aromatic dicarboxylic acid present in a product of reaction obtained from previous oxidation methods of dimethyl aromatic compounds without the presence of said catalyst and cocatalyst.

Furthermore, it was surprisingly found that the amount of catalyst could be reduced compared to previous methods that do not use the catalyst and cocatalyst as described in the present disclosure. For example, the present methods allow the use of smaller amounts of at least one of manganese and bromine in the catalyst, while maintaining the moles of aromatic dicarboxylic acid produced per milligram of catalyst. A reduction in the amount of manganese present may be equal to or greater than 25% by weight, or equal to or greater than 50% by weight, or equal to or greater than 75% by weight, compared to the moles of manganese present in the methods prior oxidation of dimethyl aromatic compounds without the presence of said catalyst and cocatalyst. Desirably, a reduction in the amount of bromine present can reduce, mitigate or prevent corrosion of the equipment used for oxidation or allow the use of different materials of construction for the equipment. A reduction in the amount of bromine present may be equal to or greater than 25% by weight, or equal to or greater than 50% by weight, or equal to or greater than 75% by weight, compared to the moles of bromine present in the methods. prior oxidation of dimethyl aromatic compounds without the presence of said catalyst and cocatalyst.

As noted above, a method of oxidation of a dimethyl aromatic compound may include reacting the compound dimethyl aromatic and an oxidant in the presence of a catalyst and a cocatalyst in a solvent to produce a reaction product comprising an aromatic dicarboxylic acid.

The dimethyl aromatic compound may include at least one of xylene (for example, at least one of para-xylene, meta-xylene and or to-xylene) and 2,6-dimethylnaphthalene; preferably para-xylene.

To catalyze the oxidation of the dimethyl aromatic compound, a catalyst is used. The catalyst may include cobalt, manganese and bromine. The catalyst may be unsupported and sources of cobalt, manganese and bromine may be combined to form the catalyst as a mixture of catalysts. Sources of cobalt and manganese used for the catalyst may include salts of cobalt (e.g., cobalt(II) acetate tetrahydrate) and manganese (e.g., manganese(II) acetate tetrahydrate), respectively. A source of bromine may be hydrobromic acid, sodium bromide, ammonium bromide, tetrabromoethane, or a combination comprising at least one of the above. Other catalyst sources may include metal bromides (e.g., MnBr ² , CoBr ² , etc.) and metal nitrate salts. Desirably, the bromine may be at least one of a solid or dissolved in the solvent.

Desirably, the catalyst may include a weight ratio between cobalt and manganese equal to or greater than 1:1, or equal to or greater than 2:1, preferably equal to or greater than 3:1. A total amount of cobalt and manganese may be equal to or less than 1,000 parts per million by weight (ppm), or equal to or less than 900 ppm, preferably equal to or less than 800 ppm, based on the total weight of the mixture of reactants that includes aromatics dimethyl, acetic acid and water.

Bromine may be present in an amount equal to or less than 800 ppm, or equal to or less than 400 ppm, preferably equal to or less than 200 ppm, based on the total weight of the reactant mixture that includes dimethyl aromatics, acetic acid and water. The catalyst may include a molar ratio between bromine and (cobalt and manganese) in a range of 0.3:1 to 3:1, or 0.3:1 to 2:1, preferably 0.3:1 to 1:1 .

Desirably, in various embodiments, during the reaction, a reaction mixture (for example, comprising the dimethyl aromatic compound, the oxidant, the catalyst, the cocatalyst and the solvent) is substantially free of ammonium acetate, meta-xylene and ionic liquid comprising at least one of a bromide anion or an iodide anion; substantially free of ammonium acetate, meta-xylene and ionic liquid comprising a bromide anion. As used herein, the term "substantially free of" allows for the presence of impurities in the dimethyl aromatic compound, the oxidant, the catalyst, the cocatalyst and the solvent. In other words, during the reaction, neither ammonium acetate, meta -xylene, nor ionic liquid that includes at least one of a bromide anion and an iodide anion, in addition to trace impurities, is present. They are not deliberately added compounds.

In addition to the catalyst, the method uses a cocatalyst. Desirably, the cocatalyst includes cerium. Cerium may be present in an amount ranging from 10 ppm to 200 ppm, or 20 ppm to 190 ppm, preferably 30 ppm to 180 ppm, based on the total weight of dimethyl aromatic compound and solvent.

The solvent may include at least one of: water, a C1-C7 aliphatic carboxylic acid, an aromatic acid and supercritical CO ₂ , preferably acetic acid. The solvent may be an aqueous solution. Desirably, a weight ratio between solvent and dimethyl aromatic compound may be in a range of 15:1 to 1:1, or 10:1 to 1:1, preferably 5:1 to 1:1.

To oxidize the dimethyl aromatic compound, the method uses an oxidant. The oxidant may include hydrogen peroxide, dioxygen, ozone, an anthraquinone, a C ₂ -32 alkyl peroxide, a C ₂ -32 alkyl hydroperoxide, a C ₂ -32 ketone peroxide, a C ₂ -32 diacyl peroxide , a C3-22 diperoxy, a ketal, a C ₂ -32 peroxyester, a C ₂ -32 peroxydicarbonate, a C ₂ -32 peroxyacid, a C6-32 perbenzoic acid, a C ₂ -32 peracid, a periodinane, a periodate , or a combination comprising at least one of the above, preferably dioxygen (for example, in air).

Desirably, the reaction of the dimethyl aromatic compound and the oxidant may be at a temperature in a range of 170°C to 200°C, or 180°C to 200°C, or 190°C to 200°C.

The reaction of the dimethyl aromatic compound and the oxidant may be at a pressure in a range of 1 MegaPascal (mPa) to 1.8 mPa, or 1 mPa to 1.7 mPa, preferably 1 mPa to 1.6 mPa.

A residence time of the reaction of the dimethyl aromatic compound and the oxidant in a reactor may be in a range of 20 minutes to 200 minutes, or 40 minutes to 150 minutes, preferably 60 minutes to 100 minutes.

The reaction of the dimethyl aromatic compound can be carried out in any reactor capable of operating under the conditions described in the present disclosure, such as a batch reactor, a continuous reactor, or semi-continuous. The reactor may include an inlet for feeding at least one of the dimethyl aromatic compound, the solvent, the catalyst and the cocatalyst continuously over a period of time and an outlet for removing the reaction product continuously over a period of time or at specific time(s). Desirably, the reaction of the dimethyl aromatic compound and the oxidant may be in a continuous stirred tank reactor.

The aromatic dicarboxylic acid may be present in the reaction product in an amount equal to or greater than 70 % by weight, or equal to or greater than 90% by weight, preferably equal to or greater than 92% by weight, more preferably equal to or greater than 94% by weight, based on the total weight of solids in the reaction product, for example, measured by high pressure liquid chromatography (HPLC) at room temperature.

Desirably, the present methods result in C ¹⁰ + hydrocarbons that are present in the reaction product in an amount equal to or less than 1.5% by weight, or equal to or less than 1.0% by weight, preferably equal to or less at 0.5% by weight, based on the total weight of solids in the reaction product, for example, measured by HPLC at room temperature. The catalyst and cocatalyst as described in the present disclosure can contribute to preventing the formation of C ¹⁰ + hydrocarbons. As used herein, “C ¹⁰ + hydrocarbon” refers to a hydrocarbon that includes 10 or more carbon atoms. Any number of C ¹⁰ + hydrocarbons may be present in a reaction product, such as at least five hydrocarbons. C ¹⁰ + different, or at least fifteen different C10+ hydrocarbons, or at least twenty different C10+ hydrocarbons.

The method may further include separating the solvent, catalyst and cocatalyst from the reaction product, and recycling the solvent, catalyst and cocatalyst to the dimethyl aromatic compound reaction step. For example, the separation step may include crystallization of the aromatic dicarboxylic acid to obtain an aromatic dicarboxylic acid crystal. The aromatic dicarboxylic acid crystal can then be separated from the solvent, catalyst and cocatalyst. For example, the catalyst and cocatalyst may be in solution in the solvent and the separation may be by filtration or any other solid-liquid separation method. The crystallization step of the aromatic dicarboxylic acid may be in at least one step, or at least two steps, preferably at least three steps.

The method may further include reacting the reaction product and hydrogen in the presence of a hydrogenation catalyst. For example, the method may include reacting the aromatic dicarboxylic acid crystals and hydrogen in the presence of a hydrogenation catalyst to purify the aromatic dicarboxylic acid crystals. The hydrogenation catalyst may include palladium, ruthenium, rhodium, osmium, iridium, platinum, or a combination comprising at least one of the above. The hydrogenation catalyst may be on a support, such as silicon dioxide, diatomaceous earth, titanium dioxide, carbon, thorium oxide, zirconium oxide, silicic carbide, aluminum oxides, or a combination comprising at least one of the previous ones. Desirably, the hydrogenation catalyst It can be palladium on a carbon support. Thus, the purity of aromatic dicarboxylic acid crystals and the yield of aromatic dicarboxylic acid can be improved.

A reaction mixture for the oxidation of a dimethyl aromatic compound by the methods described above may include the dimethyl aromatic compound, the oxidant, the catalyst, the cocatalyst, water and the solvent.

A reaction product can be produced by the methods described above, or using the reaction mixture described above.

A more complete understanding of the components, processes and apparatus disclosed herein can be obtained by reference to the accompanying drawings. These figures (also referred to herein as “FIG.”) are merely schematic representations based on the convenience and ease of demonstrating the present disclosure and, therefore, are not intended to indicate relative size or dimensions of the devices or components of the themselves and/or define or limit the scope of the exemplary embodiments. Although specific terms are used in the following description for the sake of clarity, these terms are only intended to refer to the particular structure of the embodiments selected for illustration in the drawings, and are not intended to define or limit the scope of the disclosure. In the drawings and the following description below, it should be understood that similar numerical designations refer to components of similar function.

As illustrated in FIG. 1, a terephthalic acid production facility may include a reactor 10. The reaction mixture 6 including para-xylene, solvent, catalyst and cocatalyst can be fed into the reactor 10. An oxidant 8 can also be fed into the reactor 10. After the reaction of the para-xylene and the oxidant 8, the product of para-xylene can be removed from the reactor 10. reaction 12 that includes terephthalic acid. The reaction product 12 can be fed into the first crystallizer 20 to produce the first crystallized stream 22. The first crystallized stream 22 can be fed into the second crystallizer 30 to produce the second crystallized stream 32. The second crystallized stream 32 can be fed feed into the third crystallizer 40 to produce the third crystallized stream 42 that includes crystallized terephthalic acid. The solvent, catalyst and cocatalyst stream 44 can be separated from the third crystallized stream 42 and recirculated to the reaction mixture 6.

The present disclosure is further illustrated by the following examples, which are not limiting.

EXAMPLES

The following components listed in Table 1 were used in the examples. Unless specifically indicated otherwise, the amount of each component is in percent by weight in the following examples, based on l l l m i i n.

Examples 1-2 and Comparative Examples A-B

In Examples 1-2 and Comparative Examples A-B, para-xylene was oxidized in the presence of different catalyst and cocatalyst compositions in acetic acid. The oxidation reactions were carried out in a semicontinuous flow stirred tank reactor in the presence of air. In Examples 1-2, cerium was used in an amount of 50 ppm, based on the total weight of para-xylene, water and acetic acid. In Comparative Examples A-B no cerium cocatalyst was used. A smaller amount of catalyst was included in Example 2 and Comparative Example B than in Example 1 and Comparative Example A. The amounts of catalyst, cocatalyst and solvent used, the weight ratio between solvent and para-xylene and the reaction conditions in the examples and m l m r iv.

As shown in FIG. 2A, a reduction in the total amount of carbon monoxide and carbon dioxide (COx) produced of approximately 10 mol% was observed in Example 1 compared to Comparative Example A. As shown in FIG. 2B, a reduction in the total amount of carbon monoxide and carbon dioxide (COx) produced of approximately 8 mol % was observed in Example 2 compared to Comparative Example B. Thus, the catalyst and cerium reduced the oxidation of the solvent and the product terephthalic acid into carbon monoxide and carbon dioxide. Therefore, the presence of the catalyst and cerium during the oxidation reaction did not significantly affect the selectivity for terephthalic acid, which can be measured by high-pressure liquid chromatography (HPLC) and is calculated based only on the solid products, i.e. , non-gaseous products. For example, the methods of the present disclosure can achieve a terephthalic acid purity of approximately 96.5% by weight.

As shown in Fig. 3, a reduction in the amount of catalyst and the use of cocatalyst reduced the formation of C ¹⁰ + hydrocarbons. This decrease in the production of C ¹⁰ + hydrocarbons reduces the specific consumption of para-xylene.

In Examples 3-27, para-xylene was oxidized in the presence of different catalyst and cocatalyst compositions in acetic acid. The oxidation reactions were carried out in a semicontinuous flow stirred tank reactor in the presence of air. The amounts of the metals in the catalyst were based on the total weight of para-xylene, water, and acetic acid. The reaction for Examples 3-10 was carried out at a temperature of 170 ° C, and for Examples 11-26 it was carried out at 190 ° C. All examples were carried out at a pressure of 1.3 mPa.

The composition of Co and Mn was tested at two levels Co:Mn of 400:400 and Co:Mn of 300:100, but Br varied from 166 to 730 ppm. The results show the yield of the cocatalyst compared to the yield of the reaction without a cocatalyst (nothing).

Initial experiments are carried out at the temperature of 170 °C using 50 ppm each of Zr, Pd, Mo, Ce or Ag as cocatalyst in the p-xylene oxidation process. The results showed a decrease in the amount of COx formation with the use of Ce as a cocatalyst. Among all metals, Zr presented the lowest amount of 4-CBA, but it has presented the highest amount of COx. 4-CBA, which is an unwanted impurity, is approximately 4 wt% for reactions performed at 170 °C. It was found that a lower amount of 4-CBA was produced for the reactions performed at 190 °C. Therefore, higher reaction temperatures are beneficial in reducing the production of 4-CBA.

As reported in Table 3, 50 ppm of Fe, Ag, Ce, and Cu were tested as co-metals along with C _0- Mn-Br at 190 °C. Among the different metals studied, the experiment carried out using copper as a cocatalyst showed incomplete oxidation, that is, the product distribution analysis demonstrates more intermediate products, such as p-toluic acid and 4-CBA, than the desired final product, terephthalic acid (TPA).

Fe and Ce are found to be promising candidates as cocatalyst for the oxidation of p-xylene in terms of lower COx formation, particularly at a reaction temperature of 190 °C. When They use these materials as cocatalyst:

• Fe presented reduced formation of COx and heavy metals, but the formation of 4-CBA is higher.

• Ce presented reduced formation of COx and 4-CBA, but the formation of heavy ones is higher.

The function of the cocatalyst was evaluated at reduced amounts of Co, Mn and Br using Fe, Ce, Zr and Ru. The combination of Fe+Ce and Fe+Zr in the distribution of p-xylene oxidation products was also studied, in reduced amounts of Co-Mn-Br of 300-100-332, respectively. All the results showed that the presence of Fe and Ce was capable of reducing the formation of COx and heavy metals. The formation of 4-CBA is reduced with the use of Zr as a cocatalyst, but the formation of COx and heavy was higher.

Therefore, the presence of small amounts of cocatalysts in the C _0- Mn-Br catalyst presented wide performance ranges. The improvement in specific consumption and the reduction of impurities is clearly shown by the incorporation of the cocatalyst in the C _0- Mn-Br catalytic system for the oxidation of para-xylene. This study also shows that the reaction temperature has more influence on the quality of TPA and the formation of heavy metals. Cu as a cocatalyst showed an inhibitory function in the para-xylene formation process. Among the various cocatalysts tested, Fe and Ce showed promising performance, increasing product quality.

As shown in the examples, the present methods using a catalyst that includes cobalt and manganese in a weight ratio equal to or greater than 1:1, or equal to or greater than 2:1, preferably equal to or greater than 3:1, and a cocatalyst that includes cerium can reduce the amount of reactant and solvent used, increase the selectivity for aromatic dicarboxylic acids, reduce the amount of at least one of carbon monoxide, carbon dioxide and C10+ hydrocarbons in the reaction product and increase the purity of aromatic dicarboxylic acids compared to previous methods of oxidation of dimethyl aromatic compounds without the presence of said catalyst and cocatalyst. Furthermore, the amount of catalyst, preferably the amount of bromine, can be reduced compared to said previous methods.

This disclosure also encompasses the following aspects.

Aspect 1. A method of oxidation of a dimethyl aromatic compound comprising: reacting the dimethyl aromatic compound and an oxidant in the presence of a catalyst and a cocatalyst in a solvent to produce a reaction product comprising an aromatic dicarboxylic acid, wherein the catalyst comprises cobalt, manganese and bromine, and wherein a weight ratio between cobalt and manganese is equal or greater than 1:1, or equal to or greater than 2:1, preferably equal to or greater than 3:1, and wherein the cocatalyst comprises at least one of cerium or iron, preferably it comprises cerium, and wherein the cocatalyst is present in an amount in a range of 10 ppm to 200 ppm, or 20 ppm to 190 ppm, preferably 30 ppm to 180 ppm, based on the total weight of dimethyl aromatic compound and solvent, and wherein the aromatic dicarboxylic acid is present in the reaction product in an amount equal to or greater than 70 % by weight, or equal to or greater than 90 % by weight, preferably equal to or greater than 92% by weight, more preferably equal to or greater than 94% by weight, based on the total weight of solids in the reaction product.

Aspect 2. The method of aspect 1, wherein the dimethyl aromatic compound comprises para-xylene, meta-xylene, ortho-xylene, 2,6-dimethylnaphthalene, or a combination comprising at least one of the above, preferably para- xylene.

Aspect 3. The method of any one or more of the preceding aspects, wherein a total amount of cobalt and manganese is equal to or less than 1,000 ppm, or equal to or less than 900 ppm, preferably equal to or less than 800 ppm, based on the total weight of dimethyl aromatic compound and solvent.

Aspect 4. The method of any one or more of the preceding aspects, wherein bromine is present in an equal or lesser amount at 800 ppm, or equal to or less than 600 ppm, preferably equal to or less than 400 ppm, based on the total weight of dimethyl aromatic compound and solvent.

Aspect 5. The method of any one or more of the preceding aspects, wherein the bromine comprises hydrobromic acid.

Aspect 6. The method of any one or more of the preceding aspects, wherein the total moles of carbon monoxide and carbon dioxide present in the reaction product are reduced by equal to or greater than 5 mol%, or equal to or greater 10 mol%, preferably equal to or greater than 15 mol % , compared to the total moles of carbon monoxide and carbon dioxide present in a reaction product obtained from a method of oxidation of a dimethyl aromatic compound without the presence of the catalyst and the cocatalyst.

Aspect 7. The method of any one or more of the preceding aspects, wherein C10+ hydrocarbons are present in the reaction product in an amount equal to or less than 1.5% by weight, or equal to or less than 1.0% by weight. weight, preferably equal to or less than 0.5% by weight, based on the total weight of solids in the reaction product.

Aspect 8. The method of any one or more of the preceding aspects, wherein the oxidant comprises air.

Aspect 9. The method of any one or more of the preceding aspects, wherein the solvent comprises at least one of water and a C1-C7 aliphatic carboxylic acid, preferably acetic acid.

Aspect 10. The method of any one or more of the preceding aspects, wherein the weight ratio between solvent and compound dimethyl aromatic is in a range of 15:1 to 1:1, or 10:1 to 1:1, preferably 5:1 to 1:1.

Aspect 11. The method of any one or more of the preceding aspects, wherein a molar ratio between bromine and cobalt and manganese is in a range of 0.3:1 to 3:1, or 0.3:1 to 2: 1, preferably 0.3:1 to 1:1.

Aspect 12. The method of any one or more of the preceding aspects, wherein the reaction is at a temperature in a range of 170 ° C to 200 ° C, or 180 ° C to 200 ° C, preferably 190 ° C to 200 °C.

Aspect 13. The method of any one or more of the preceding aspects, wherein the reaction is at a pressure in a range of 1 MegaPascal to 1.8 MegaPascals, or 1 MegaPascal to 1.7 MegaPascals, preferably 1 MegaPascal to 1, 6 MegaPascals.

Aspect 14. The method of any one or more of the preceding aspects, wherein the reaction is a continuous stirred tank reactor and a residence time is in a range of 20 minutes to 200 minutes, or 40 minutes to 150 minutes, preferably 60 minutes to 100 minutes.

Aspect 15. The method of any one or more of the preceding aspects, wherein during the reaction, a reaction mixture comprising the dimethyl aromatic compound, the oxidant, the catalyst, the cocatalyst and the solvent is substantially free of ammonium, meta-xylene and ionic liquid comprising at least one of a bromide anion or an iodide anion; preferably the reaction mixture is substantially free of ammonium acetate, meta-xylene and ionic liquid comprising a bromide anion; more preferably, without ammonium acetate, meta-xylene and ionic liquid comprising a bromide anion.

Aspect 16. The method of any one or more of the preceding aspects, further comprising crystallization of the reaction product.

Aspect 17. The method of any one or more of the preceding aspects, further comprising separating the solvent, catalyst and cocatalyst from the reaction product, and recycling the solvent, catalyst and cocatalyst to the reaction step.

Aspect 18. The method of any one or more of the preceding aspects, further comprising the reaction of the dimethyl aromatic compound and hydrogen in the presence of a hydrogenation catalyst.

Aspect 19. The method of any one or more of the preceding aspects, wherein the reaction mixture (comprising the dimethyl aromatic compound, the oxidant, the catalyst, the cocatalyst and the solvent) comprises a total amount of cobalt and manganese equal to or less than 1,000 ppm, preferably equal to or less than 900 ppm, more preferably equal to or less than 800 ppm, based on the total weight of the reactant mixture.

Aspect 20. The method of any one or more of the preceding aspects, wherein the catalyst comprises a molar ratio between bromine and (cobalt and manganese) in a range of 0.3:1 to 3:1, preferably 0.3: 1 to 2:1, more preferably 0.3:1 to 1:1.

Aspect 21. The method of any one or more of the preceding aspects, wherein the catalyst is free of Cu.

Aspect 22. A reaction mixture for the oxidation of dimethyl aromatic compound by the method of any one or more of the preceding aspects, wherein the reaction mixture comprises: the compound dimethyl aromatic; the oxidant; the catalyst; the cocatalyst; and the solvent.

Aspect 23. A reaction product produced by the method of any one or more of aspects 1-21, or using the reaction mixture of aspect 22.

Aspect 24. A catalyst system for the oxidation of a dimethyl aromatic compound, the catalyst system comprising: a catalyst comprising cobalt, manganese and bromine, wherein a weight ratio between cobalt and manganese is equal to or greater than 1:1 , or equal to or greater than 2:1, preferably equal to or greater than 3:1; and a cocatalyst comprising at least one of cerium or iron, preferably comprising cerium.

Aspect 25. A reaction mixture for the oxidation of a dimethyl aromatic compound, the reaction mixture comprising: the catalyst system of aspect 24; the dimethyl aromatic compound; an oxidizer; and a solvent, wherein the cocatalyst is present in an amount in a range of 10 ppm to 200 ppm, or 20 ppm to 190 ppm, preferably 30 ppm to 180 ppm, based on the total weight of dimethyl aromatic compound and solvent, wherein a total amount of cobalt and manganese is equal to or less than 1,000 ppm, or equal to or less than 900 ppm, preferably equal to or less than 800 ppm, based on the total weight of dimethyl aromatic compound and solvent, wherein bromine is present in an amount equal to or less than 800 ppm, or equal to or less than 600 ppm, preferably equal to or less than 400 ppm, based on the total weight of dimethyl aromatic compound and solvent, and wherein a molar ratio between bromine and cobalt and manganese is in a range of 0.3:1 to 3:1, or 0.3:1 to 2:1, preferably 0.3:1 to 1:1.

The compositions, methods and articles may alternatively comprise, consist of, or consist essentially of any appropriate step or component disclosed herein. The compositions, methods and articles may be additionally, or alternatively, formulated so as to be devoid of, or substantially free of, any steps, components, materials, ingredients, adjuvants or species that are not otherwise necessary for the achievement of the function or objectives of the compositions, methods and articles.

The singular forms "a", "an", "the" and "the" include plural referents, unless the context clearly indicates otherwise. “Or” means “and/or” unless the context clearly indicates otherwise. The terms "first", "second" and the like, "primary", "secondary" and the like, as used herein, do not indicate any order, quantity or importance, but are used to distinguish one element from another.

The endpoints of all ranges referring to the same component or property are inclusive and independently combinable (for example, ranges of "less than or equal to 25 % by weight, or 5 % by weight to 20% by weight", include the endpoints and all intermediate values in the ranges "5 wt. % to 25 wt. %," etc.). Disclosure of a narrower range or more specific group, in addition to a broader range, is not a waiver of the broader range or larger group.

The suffix "(s)” is intended to include both the singular and plural of the term it modifies, thus including at least one of that term (for example, the colorant(s) include at least one colorant). "Optional ” or “optionally” means that the event or circumstance subsequently described may or may cannot occur, and that the description includes cases where the event occurs and cases where it does not. Unless otherwise defined, technical and scientific terms used herein have the same meaning as is commonly understood by one skilled in the art to which the present disclosure pertains. A "combination" includes mixtures, alloys, reaction products and the like.

Although typical embodiments have been set forth for the purpose of illustration, the foregoing descriptions should not be considered a limitation of the scope herein. Accordingly, various modifications, adaptations and alternatives may occur to one skilled in the art without departing from the spirit and scope herein.

Claims (21)

1. A method of oxidation of a dimethyl aromatic compound comprising: reacting the dimethyl aromatic compound and an oxidant in the presence of a catalyst and a cocatalyst in a solvent to produce a reaction product comprising an aromatic dicarboxylic acid, wherein the catalyst comprises cobalt, manganese and bromine, wherein a weight ratio between cobalt and manganese is equal to or greater than 3:1, where the molar ratio between bromine and cobalt and manganese is in a range of 0.3:1 to 1:1, wherein a total amount of cobalt and manganese is equal to or less than 800 ppm, based on the total weight of dimethyl aromatic compound and solvent, wherein the bromine is present in an amount equal to or less than 400 ppm, based on the total weight of the dimethyl aromatic compound and solvent, wherein the cocatalyst comprises cerium, wherein the cocatalyst is present in an amount in a range of 30 ppm to 180 ppm, based on the total weight of dimethyl aromatic compound and solvent, and wherein the aromatic dicarboxylic acid is present in the reaction product in an amount equal to or greater than 70 % by weight, based on the total weight of solids in the reaction product, and/or C ¹⁰ + hydrocarbons are present in the product reaction in an amount equal to or less than 1.5% in weight, based on the total weight of solids in the reaction product. 2. The method of claim 1, wherein the aromatic dicarboxylic acid is present in the reaction product in an amount equal to or greater than 70 % by weight, based on the total weight of solids in the reaction product. 3. The method of claim 1, wherein the aromatic dicarboxylic acid is present in the reaction product in an amount equal to or greater than 90% by weight, based on the total weight of solids in the reaction product. 4. The method of claim 1, wherein the aromatic dicarboxylic acid is present in the reaction product in an amount equal to or greater than 92% by weight, based on the total weight of solids in the reaction product. 5. The method of claim 1, wherein the aromatic dicarboxylic acid is present in the reaction product in an amount equal to or greater than 94% by weight, based on the total weight of solids in the reaction product. 6. The method of any one or more of the preceding claims, wherein the dimethyl aromatic compound comprises para-xylene, meta- xylene, o/t-xylene, 2,6-dimethylnaphthalene, or a combination comprising least one of the above, preferably para-xylene. 7. The method of any one or more of the preceding claims, wherein the cocatalyst is cerium. 8. The method of any one or more of the preceding claims, wherein the bromine comprises hydrobromic acid. 9. The method of any one or more of the preceding claims, wherein the C ¹⁰ + hydrocarbons are present in the reaction product in an amount equal to or less than 1.5% by weight, based on the total weight of solids in the reaction product. 10. The method of any one or more of the preceding claims, wherein the C ¹⁰ + hydrocarbons are present in the reaction product in an amount equal to or less than 1.0 % by weight, based on the total weight of solids in the reaction product. 11. The method of any one or more of the preceding claims, wherein the C ¹⁰ + hydrocarbons are present in the reaction product in an amount equal to or less than 0.5% by weight, based on the total weight of solids in the reaction product. 12. The method of any one or more of the preceding claims, wherein the catalyst is free of copper. 13. The method of any one or more of the preceding claims, wherein the solvent comprises at least one of water and a C ¹ -C ⁷ aliphatic carboxylic acid, preferably acetic acid. 14. The method of any one or more of the preceding claims, wherein the weight ratio between solvent and dimethyl aromatic compound is in a range of 15:1 to 1:1, or 10:1 to 1:1, preferably 5 :1 to 1:1. 15. The method of any one or more of the preceding claims, wherein the reaction is at a temperature in a range of 170°C to 200°C, or 180°C to 200°C, preferably 190°C to 200°C. c. 16. The method of any one or more of the preceding claims, wherein the reaction is at a pressure in a range of 1 MegaPascal to 1.8 MegaPascals, or 1 MegaPascal to 1.7 MegaPascals, preferably 1 MegaPascal to 1.6 MegaPascals. 17. The method of any one or more of the preceding claims, wherein the reaction is in a continuous stirred tank reactor and a residence time is in a range of 20 minutes to 200 minutes, or 40 minutes to 150 minutes, preferably 60 minutes to 100 minutes. 18. The method of any one or more of the preceding claims, wherein during the reaction, a reaction mixture comprising the dimethyl aromatic compound, the oxidant, the catalyst, the cocatalyst and the solvent is substantially free of ammonium acetate, meta-xylene and ionic liquid comprising a bromide anion and a iodide anion. 19. The method of any one or more of the preceding claims, further comprising crystallization of the reaction product. 20. The method of any one or more of the preceding claims, further comprising separating the solvent, catalyst and cocatalyst from the reaction product, and recycling the solvent, catalyst and cocatalyst to the reaction step. 21. The method of any one or more of the preceding claims, further comprising reacting the reaction product and hydrogen in the presence of a hydrogenation catalyst.