| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | May 12, 1992 |
| PATENT TITLE |
Production of polycarboxylic acids with hafnium-activated cobalt catalyst |
| PATENT ABSTRACT |
The addition of hafnium to oxidation catalysts provided by a heavy transition metal-bromine ion catalyst combination containing cobalt-manganese-bromine or manganese-bromine or cobalt-bromine and a soluble source of hafnium uniquely increases catalytic activity of the said catalyst combination for converting methyl groups on the benzene nucleus. The presence of hafnium in the total reactor contents is equal to or less than 250 parts per million by weight of the total reactor mother liquor. The solubility of the hafnium in the reactor solvent is such that reactor product cake contains less than 0.3 ppm by weight. Bromine emissions can be reduced. |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | June 6, 1991 |
| PATENT DESCRIPTION |
What is claimed is: 1. A process for oxidizing polymethylbenzenes with molecular oxygen to benzene polycarboxylic acids in a reaction solvent comprising a C.sub.2 -C.sub.6 aliphatic carboxylic acid or a mixture of a C.sub.2 -C.sub.6 aliphatic carboxylic acid and water under liquid phase conditions at temperatures in the range of 100.degree. to 275.degree. C., which comprises conducting said oxidation in the presence of a catalyst consisting essentially of a source of soluble hafnium and a catalyst system selected from the group consisting of cobalt-manganese-bromine, manganese-bromine, and cobalt-bromine wherein said soluble hafnium is present in an amount equal to or less than 250 parts per million by weight of total mother liquor content and said catalyst system contains for each gram mole of such methylbenzene from 1.0 to 20.0 milligram atoms of the transition metal manganese or cobalt or total of cobalt and manganese and from 0.2 to 10.0 milligram atoms of bromine, and reactor product cake of said process contains less than 0.3 ppmw of said hafnium after an acetic acid wash or a water wash or an acetic acid-water wash. 2. The process of claim 1 wherein acetic acid is used as the reaction solvent and air as a source of molecular oxygen. 3. The process of claim 2 wherein said polymethylbenzene is p-xylene and said p-xylene is oxidized to terephthalic acid. 4. The process of claim 2 wherein said polymethylbenzene is o-xylene and said o-xylene is oxidized to phthalic acid. 5. The process of claim 2 wherein said polymethylbenzene is pseudocumene and said pseudocumene is oxidized to trimellitic acid. 6. The process of claim 1 wherein said polymethylbenzene is durene and said durene is oxidized to pyromellitic acid. 7. The process of claim 1 wherein said polymethylbenzene is m-xylene and said m-xylene is oxidized to isophthalic acid. 8. The process of claim 1 wherein the ratio of bromine to total metals of hafnium, cobalt and manganese is from 0.1:1.0 to 10.0:1.0. 9. The process of claim 1 wherein said soluble hafnium is present in said mother liquor in an amount equal to or less than 250 parts per million, mole ratio of bromine to metals in said catalyst system is less than 1.0:2.13 whereby production of bromine compounds in vent gases from said oxidation is decreased. 10. The process of claim 1 wherein concentration of catalyst metals consisting of cobalt and manganese of said catalyst system is reduced by at least 12 wt % in the presence of at least 30 ppmw of a source of soluble hafnium without loss of catalyst activity. 11. The process of claim 1 wherein said polymethylbenzenes are oxidized to corresponding aromatic acids wherein the mole ratio of said soluble hafnium to said catalyst system consisting of cobalt plus manganese plus bromine is from about 1:20 to about 1:600 and mole ratio of cobalt to manganese is in the range of from about 4:1 to about 0.2:1.0. 12. The process of claim 1 wherein said polymethylbenzenes are oxidized to corresponding aromatic acids wherein the weight ratio of said soluble hafnium to said catalyst system consisting of cobalt plus manganese plus bromine is about 1 part hafnium to about 50 parts total cobalt plus manganese plus bromine, and mole ratio of cobalt to manganese is in the range of from about 4:1 to about 0.2:1.0. 13. A process for oxidizing o-xylene with molecular oxygen to phthalic anhydride in a reaction solvent comprising a C.sub.2 -C.sub.6 aliphatic carboxylic acid or a mixture of a C.sub.2 -C.sub.6 aliphatic carboxylic acid and water under liquid phase conditions at temperatures in the range of 100.degree. to 275.degree. C., which comprises conducting said oxidation in the presence of a catalyst consisting essentially of a source of soluble hafnium and a catalyst system selected from the group consisting of cobalt-manganese-bromine, manganese-bromine, and cobalt-bromine wherein said soluble hafnium is present in an amount equal to or less than 250 parts per million by weight of total mother liquor content and said catalyst system contains for each gram mole of such o-xylene from 1.0 to 20.0 milligram atoms of the transition metal manganese or cobalt or total of cobalt and manganese and from 0.2 to 10.0 milligram atoms of bromine, and reactor product cake of said process contains less than 0.3 ppmw of said hafnium after an acetic acid wash or a water wash or an acetic acid-water wash. 14. A process for oxidizing durene with molecular oxygen to pyromellitic anhydride in a reaction solvent comprising a C.sub.2 -C.sub.6 aliphatic carboxylic acid or a mixture of a C.sub.2 -C.sub.6 aliphatic carboxylic acid and water under liquid phase conditions at temperatures in the range of 100.degree. to 275.degree. C., which comprises conducting said oxidation in the presence of a catalyst consisting essentially of a source of soluble hafnium and a catalyst system selected from the group consisting of cobalt-manganese-bromine, manganese-bromine, and cobalt-bromine wherein said soluble hafnium is present in an amount equal to or less than 250 parts per million by weight of total mother liquor content and said catalyst system contains for each gram mole of such durene from 1.0 to 20.0 milligram atoms of the transition metal manganese or cobalt or total of cobalt and manganese and from 0.2 to 10.0 milligram atoms of bromine, and reactor product cake of said process contains less than 0.3 ppmw of said hafnium after an acetic acid wash or a water wash or an acetic acid-water wash. 15. A process for oxidizing durene with molecular oxygen to pyromellitic dianhydride in a reaction solvent comprising a C.sub.2 -C.sub.6 aliphatic carboxylic acid or a mixture of a C.sub.2 -C.sub.6 aliphatic carboxylic acid and water under liquid phase conditions at temperatures in the range of 100.degree. to 275.degree. C., which comprises conducting said oxidation in the presence of a catalyst consisting essentially of a source of soluble hafnium and a catalyst system selected from the group consisting of cobalt-manganese-bromine, manganese-bromine, and cobalt-bromine wherein said soluble hafnium is present in an amount equal to or less than 250 parts per million by weight of total mother liquor content and said catalyst system contains for each gram mole of such durene from 1.0 to 20.0 milligram atoms of the transition metal manganese or cobalt or total of cobalt and manganese and from 0.2 to 10.0 milligram atoms of bromine, and reactor product cake of said process contains less than 0.3 ppmw of said hafnium after an acetic acid wash or a water wash or an acetic acid-water wash. -------------------------------------------------------------------------------- |
| PATENT EXAMPLES | available on request |
| PATENT PHOTOCOPY | available on request |
|
Want more information ? Interested in the hidden information ? Click here and do your request. |