Process of regenerating a noble metal catalyst used in the reduction of organic nitro compounds

Claim 2

A process for regenerating the activity of a noble metal catalyst which has become deactivated in the reduction of organic compounds with nitro moieties to the corresponding aminated derivative, comprising the sequential steps of: (a) contacting said deactivated catalyst with a liquid, polar organic solvent having from 1 to 10 carbon atoms; (b) contacting the catalyst with a liquid, aqueous solution of an alkali metal hydroxide at a temperature from about 20° C. to about 150° C.; (c) contacting the catalyst with an oxygen-containing gas at a temperature from about 20° C. to about 150° C. prior to or following Step (b); and (d) contacting said catalyst once again with a liquid, polar organic solvent having from 1 to 10 carbon atoms, so as to effect regeneration of the deactivated catalyst.

Claim 3

The process as defined in claim 1 wherein the catalyst to be regenerated has become deactivated in the reduction of compounds of the formula ##STR2## wherein X and Y are, independently, hydrogen, hydroxyl, nitro, alkyl of 1 to 3 carbon atoms, alkoxyl of 1 to 3 carbon atoms, hydroxyalkyl of 1 to 3 carbon atoms, amino, or hydroxyamino moieties and at least one of the X and Y substituents is located in an ortho or para position relative to the nitro groups.

Claim 4

The process as defined in claim 2 wherein the catalyst to be regenerated is palladium on a carbon support material and the weight concentration of the palladium is from about 0.1 percent to 25 percent.

Claim 5

The process as defined in claim 3 wherein the polar organic solvent in Steps (a) and (d) is independently selected from the group consisting of methanol, ethanol, n-propanol, n-butanol, isopropanol, isobutanol, sec-butanol, tert-butanol, allyl alcohol, crotyl alcohol, formic acid, acetic acid, propionic acid, butyric acid, ethylene glycol, propylene glycol, 1,3-propanediol, 1,2-butanediol, meso-2,3-butanediol, 1,4-butanediol, glycerol, ethyl ether and n-propyl ether.

Claim 6

The process as defined in claim 4 wherein the catalyst in Step (b) is contacted with the aqueous solution of an alkali metal hydroxide under an inert atmosphere at a pressure in the range from about 20 to about 50 psig and at a temperature from about 75° C. to about 125° C.

Claim 7

The process as defined in claim 5 wherein the catalyst after Step (c) is washed with water until the wash water remains substantially neutral during contact with the catalyst.

Claim 8

The process as defined in claim 6 wherein the catalyst after Step (b) and the water wash is contacted in Step (c) with an oxygen-containing gas at a temperature from about 75° C. to about 125° C.

Claim 9

The process as defined in claim 7 wherein the alkali metal hydroxide is sodium hydroxide.

Claim 10

The process as defined in claim 8 wherein the catalyst after Step (a) is washed with water prior to contact with the aqueous sodium hydroxide solution.

Claim 11

A process for regenerating the activity of a palladium catalyst supported on carbon with a concentration from about 0.5 percent to about 2 percent palladium by weight, where said catalyst has become deactivated to a level of activity less than 50 percent of that of a broken in, new catalyst in the reduction of compounds of the formula ##STR3## wherein X and Y are, independently, hydrogen, hydroxyl, nitro, alkyl of 1 to 3 carbon atoms, alkoxyl of 1 to 3 carbon atoms, hydroxyalkyl of 1 to 3 carbon atoms, amino, or hydroxyamino moieties and at least one of the X and Y substituents is located in an ortho or para position relative to the nitro group, said process comprising the sequential steps of: (a) contacting said deactivated catalyst with a liquid, polar organic solvent having from 1 to 10 carbon atoms; (b) contacting the catalyst under a substantially inert atmosphere slightly above atmospheric pressure with a liquid, aqueous solution of sodium hydroxide with a concentration of at least about 0.1 normal and at a temperature from about 50° C. to about 150° C.; (c) washing the hydroxide-treated catalyst with water until the wash water is substantially neutral; (d) contacting the water-washed catalyst with an oxygen-containing gas at a temperature from about 75° C. to about 150° C.; and (e) contacting said oxygen-treated catalyst once again with a liquid, polar organic solvent having from 1 to 10 carbon atoms, so as to effect regeneration of the deactivated catalyst to a level of activity at least 70 percent of the level of activity of a broken in, new catalyst.

Claim 12

A process for regenerating the activity of a palladium catalyst supported on carbon with a concentration from about 0.5 percent to about 2 percent palladium by weight, where said catalyst has become deactivated to a level of activity less than 50 percent of that of a broken in, new catalyst in the reduction of compounds of the formula ##STR3## wherein X and Y are, independently, hydrogen, hydroxyl, nitro, alkyl of 1 to 3 carbon atoms, alkoxyl of 1 to 3 carbon atoms, hydroxyalkyl of 1 to 3 carbon atoms, amino, or hydroxyamino moieties and at least one of the X and Y substituents is located in an ortho or para position relative to the nitro group, said process comprising the sequential steps of: (a) contacting said deactivated catalyst with a liquid, polar organic solvent having from 1 to 10 carbon atoms; (b) contacting the catalyst under a substantially inert atmosphere slightly above atmospheric pressure with a liquid, aqueous solution of sodium hydroxide with a concentration of at least about 0.1 normal and at a temperature from about 50° C. to about 150° C.; (c) washing the hydroxide-treated catalyst with water until the wash water is substantially neutral; (d) contacting the water-washed catalyst with an oxygen-containing gas at a temperature from about 75° C. to about 150° C.; and (e) contacting said oxygen-treated catalyst once again with a liquid, polar organic solvent having from 1 to 10 carbon atoms, so as to effect regeneration of the deactivated catalyst to a level of activity at least 70 percent of the level of activity of a broken in, new catalyst.