Method of hydrodechlorinating nuclear-chlorinated ortho-xylenes

1. A method of hydrodechlorinating nuclear-chlorinated o-xylenes which consists of hydrodechlorinating in a single reactor a starting material comprising a nuclear-chlorinated o-xylene or mixtures of nuclear-chlorinated o-xylenes in the gas phase with a gas stream comprising hydrogen in the presence of a noble-metal-containing catalyst at a temperature in the range from 220 to 360° C. to provide a reactor effluent comprising at least 90%-wt yield of o-xylene and hydrogen chloride, and recovering the o-xylene.

2. The method as claimed in claim 1 , wherein the noble-metal-containing catalyst comprises a noble metal selected from the group consisting of palladium, platinum, and mixtures thereof.

3. The method as claimed in claim 1 , wherein the noble-metal-containing catalyst comprises a noble metal disposed on a support material comprising an oxidic material.

4. The method as claimed in claim 1 , wherein the hydrogen is fed to said single reactor in at least an equimolar equivalent of the molar content of nuclear-chlorinated o-xylene in the starting material.

5. The method as claimed in claim 1 , wherein the nuclear-chlorinated o-xylene is selected from the group consisting of nuclear monochlorinated o-xylene, nuclear polychlorinated o-xylene and mixtures thereof.

6. The method as claimed in claim 1 , wherein the hydrodechlorinating reaction is carried out at atmospheric pressure.

7. The method as claimed in claim 2 , wherein the noble-metal-containing catalyst comprises from 0.01 to 5 percent by weight of said noble metal and a support material.

8. The method as claimed in claim 3 , wherein the noble-metal-containing catalyst comprises a noble metal disposed on a support material selected from the group consisting of aluminum oxide; silicon oxide; carbon, and mixtures thereof.

9. The method as claimed in claim 1 , wherein a molar ratio of the hydrogen to an equivalent molar content of nuclear-chlorinated o-xylene in the starting material ranges from 3 to 30 times said equivalent molar content.

10. The method as claimed in claim 1 , wherein the starting material comprises a mixture of nuclear monochlorinated o-xylene and nuclear polychlorinated o-xylene in a molar ratio of from 5:1 to 1:2.

11. The method of claim 1 , wherein the support material is carbon.

12. A method for the dehydrochlorination of mixed nuclear-chlorinated o-xylenes, said method consisting of:

a) passing a gas stream comprising hydrogen and a starting material comprising the mixed nuclear chlorinated o-xylenes, to a single reactor and therein contacting a noble metal catalyst at a temperature in the range from 220 to 360° C. to dehydrochlorinate the mixed nuclear chlorinated o-xylenes and to provide a reactor discharge comprising at least 90%-wt yield of o-xylene and hydrogen chloride, and

b) recovering the o-xylene from the reactor effluent,

wherein said mixed nuclear chlorinated o-xylenes are selected from the group consisting of nuclear monochlorinated o-xylenes, nuclear polychlorinated o-xylenes and mixtures thereof and wherein the noble metal catalyst comprises a noble metal selected from the group consisting of palladium, platinum, and mixtures thereof.

13. The method of claim 12 , wherein said noble metal catalyst comprises the noble metal disposed on a support material selected from the group consisting of aluminum oxide, silicon oxide, carbon and mixtures thereof.

14. The method of claim 12 , wherein step b) comprises fractionation wherein an o-xylene product is recovered and an unwanted byproduct stream comprising nuclear monochlorinated and nuclear dichlorinated o-xylene is combined with the starting material and returned to the single stage reaction zone.

15. The method of claim 12 , wherein said noble metal catalyst is periodically regenerated with air at said reaction temperature.