Process for preparing an organic acid or its derivatives using a homogeneous mc-type catalyst and an o2/co2 mixture

Abstract

The present invention relates to a process for producing an organic acid or its derivatives, which comprises oxidation of a hydrocarbon substrate in the presence of a homogeneous MC-type catalyst and an oxidant. In particular, the present invention relates to a process comprising oxidation of a hydrocarbon substrate in the presence of a homogeneous MC-type catalyst selected from Co/Br, Mn/Br, Co/Mn/Br and Co/Mn/M/Br and an O 2 /CO 2 mixed gas oxidant where the partial pressure of O 2 is controlled to 30-40%, thereby improving the oxidation rate, the conversion, the selectivity and the yield even under milder conditions. Especially, the present invention remarkably reduces down to a negligible level the production of color impurities and other impurities such as 4-CBA and p-toluic acid, which had been conventionally removed by hydrogenation reduction. Further, the loss in acetic acid solvent due to combustion can also be drastically decreased using the method of the present invention.

1 . A process of preparing an organic acid or its derivatives in the presence of a homogeneous MC-type catalyst and an oxidant, comprising oxidizing a hydrocarbon substrate,
 wherein the homogeneous MC-type catalyst is selected from the group consisting of Co/Br, Mn/Br, Co/Mn/Br and Co/Mn/M/Br wherein M is selected from the group consisting of Ni, Fe, Zr, Hf, Zn, Ti, Cu, Cr, Na, K, Rb, Cs, Ta, Nb, Ta, Re, Ce, Pr, Nd, Mo, V and a combination thereof;   the oxidant is an O 2 /CO 2  mixed gas and the O 2  is contained 30-40% of the mixed gas in volume; and   the organic acid or its derivatives is selected from the group consisting of PTA (purified terephthalic acid), IPA (isophthalic acid), TMA (trimellitic anhydride), TME (trimesic acid), PMDA (pyromellitic dianhydride), NDCA (2,6-naphthalene dicarboxylic acid), BPDA (biphenyl dianhydride), adipic acid, p-hydroxylbenzoic acid, hydroxynaphthoic acid, 4,4′-dihydroxybiphenyl, BA (benzoic acid), PNBA (p-nitrobenzoic acid), PHBA (p-hydroxybenzoic acid), PABA (p-acetoxybenzoic acid), ONBA (o-nitrobenzoic acid), TBIA (5-t-butylisophthalic acid), PA (phthalic anhydride), CBP (4,4′-carboxybiphenyl), OBBA (4,4′-oxybisbenzoic acid), SBBA (4,4′-sulfonylbisbenzoic acid), CBBA (4,4′-carboxybisbenzoic acid), BTDA (benzophenone tetracarboxylic anhydride), OPAN (oxybisphthalic anhydride), SPAN (sulfonylbisphthalic anhydride), IPAN (isopropylidene bisphthalic anhydride), CPAN (4,4′-carboxybisphthalic anhydride), 6-FDA (hexafluoroisopropylidene diphthalic anhydride), 1,8-naphthoic anhydride, ANA (acetoxynaphthoic acid), PIDA (trimethylphenylindan dicarboxylic acid), PIDADA (trimethylphenylindan dianhydride), HCB (hexacarboxybenzene), CHDA (1,4-cyclohexane dicarboxylic acid), CHTA (cyclohexane tricarboxylic acid), DDA (2,6-decalin dicarboxylic acid), SDA (4,4′-stilbene dicarboxylic acid), 4-TFMPA (4-trivluoromethylphthalic acid), NA (nicotinic acid=3-carboxypyridine), indole-2-carboxylic acid, quinolinic acid, phthalate ester, diphenyl phthalate, diphenyl isophthalate, diphenyl terephthalate, dibenzyl terephthalate and a mixture thereof.   
     
     
         2 . A process of preparing an organic acid or derivatives thereof in the presence of a homogeneous MC-type catalyst and an oxidant, comprising oxidizing a hydrocarbon substrate;
 wherein the homogeneous MC-type catalyst is selected from the group consisting of Co/Mn/Br and Co/Mn/M/Br (M is selected from the group consisting of K, Ni, Fe, Zr, Hf, Zn, Ti, Cu, Cr, Na, K, Rb, Cs, Ta, Nb, Ta, Re, Ce, Pr, Nd, Mo, V and a combination thereof;   the oxidant is an O 2 /CO 2  mixed gas and the O 2  is contained 30-40% of the mixed gas in volume; and   the organic acid or its derivatives is selected from the group consisting of PTA (purified terephthalic acid), IPA (isophthalic acid), TMA (trimellitic anhydride), TME (trimesic acid), PMDA (pyromellitic dianhydride), NDCA (2,6-naphthalene dicarboxylic acid), BPDA (biphenyl dianhydride), adipic acid and a mixture thereof.   
     
     
         3 . A process of preparing an organic acid or derivatives thereof in the presence of a homogeneous MC-type catalyst and an oxidant, comprising oxidization of a hydrocarbon substrate;
 wherein the homogeneous MC-type catalyst is Co/Mn/Br or Co/Mn/M/Br (M is selected from the group consisting of Ni, Zr, K and a combination thereof; the oxidant is an O 2 /CO 2  mixed gas and the volumetric ratio of O 2  is 30-40%; and   the organic acid or derivatives thereof is selected from the group consisting of PTA (purified terephthalic acid), IPA (isophthalic acid), NDCA (2,6-naphthalene dicarboxylic acid) and a mixture thereof.   
     
     
         4 . The process of  claim 3 , wherein the oxidization is conducted at 120-210° C. 
     
     
         5 . The process of  claim 4 , wherein the oxidization is conducted at 140-170° C. 
     
     
         6 . The process of  claim 3 , wherein the O 2  is contained 60-70% of the mixed gas in volume. 
     
     
         7 . The process of  claim 3 , wherein the O 2 /CO 2  mixed gas comprises 5-50% by volume of helium or argon. 
     
     
         8 . The process of  claim 3 , wherein the O 2 /CO 2  mixed gas comprises less than 20% by volume of nitrogen. 
     
     
         9 . The process of  claim 8 , wherein the O 2 /CO 2  mixed gas comprises less than 5% by volume of nitrogen. 
     
     
         10 . The process of  claim 3 , wherein the oxidization is conducted by using a continuous stirred tank reactor system. 
     
     
         11 . The process of  claim 3 , wherein the 4-CBA and the p-toluic acid are produced in the amounts of less than 25 ppm and less than 200 ppm, respectively, without conducting hydrogenation process. 
     
     
         12 . The process of  claim 9 , wherein the organic acid or its derivatives is light yellow in color before conducting recrystallization or centrifugation, and it turns into white after the recrystallization or centrifugation. 
     
     
         13 . The process of  claim 3 , wherein carbon monoxide produced during the oxidation is transformed into carbon dioxide on an oxidation catalyst and the transformed carbon dioxide and reaction heat are recycled.