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1. WO2012074194 - METHOD FOR PREPARING ALPHA METHYL STYRENE

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[ EN ]

[CLAIMS]

1. A method of preparing alpha methyl styrene comprising:

(a) oxidizing cumene to prepare a cumene hydroperoxide stream;

(b) separating at least a part of the cumene hydroperoxide stream without concentration and selectively hydrogenating it in the presence of a noble metal catalyst so as to prepare cumyl alcohol; and

(c) concentrating the reactant including the cumyl alcohol and dehydrating it in the presence of an acid catalyst so as to prepare a product including alpha methyl styrene.

2. The method according to claim 1, wherein in the step (b), the cumene hydroperoxide stream is used in the hydrogenation reaction in the concentration of 5 to 25 wt%.

3. The method according to claim 1, wherein in step (b), 5 to 50 wt% of the cumene hydroperoxide stream is separated and used in the hydrogenation reaction.

4. The method according to claim 1 , wherein the noble metal catalyst includes at least one selected from the group consisting of gold, silver, platinum, palladium, iridium, ruthenium, rhenium, rhodium and osmium.

5. The method according to claim 4, wherein the noble metal catalyst further comprises a support selected from the group consisting of alumina, silica, clay, carbon, zirconia, titania, a mseoporous molecular sieve, and a combination thereof.

6. The method according to claim 1, wherein the noble metal catalyst is used in an amount of 1 to 15 parts by weight, based on 100 parts by weight of the cumene hydroperoxide stream.

The method according to claim 1, wherein the hydrogenation reaction is

conducted at a temperature of 40 to 80 °C , at a hydrogen flow rate of 1 :1 to 1 : 10 according to the mole ratio to cumene hydroperoxide (CHP) for 1 to 5 hours.

8. The method according to claim 1, wherein the hydrogen reaction has selectivity of 95% or more.

9. The method according to claim 1, wherein in conversion rate of the cumene hydroperoxide is 95% or more.

10. The method according to claim 1, wherein the cumene hydroperoxide stream further comprises cumyl alcohol.

11. The method according to claim 1 , wherein the acid catalyst is a liquid or solid acid catalyst.

12. The method according to claim 1 1, wherein the liquid acid catalyst is hydrochloric acid, sulfuric acid or nitric acid, and the solid acid catalyst is selected from the group consisting of Group 4 metal oxide modified by Group 6 metal oxide, sulfated transition metal oxide, mixed metal oxide of cerium oxide and Group 4 metal oxide, and a combination thereof.

13. The method according to claim 1, wherein in the step (b), a part of the cumene hydroperoxide stream is subjected to a hydrogenation reaction, and in the step (c), the reactant including the cumyl alcohol further comprises a cumene hydroperoxide stream which is not subjected to a hydrogenation reaction.

14. The method according to claim 1 , wherein in the step (c), the product including alpha methyl styrene further comprises phenol and acetone.

15. The method according to claim 1, wherein the reactant including cumyl

alcohol is concentrated to a concentration of 80 to 82 wt% and used in the dehydration reaction.

16. The method according to claim 1, wherein the method further comprises neutralizing the product including alpha methyl styrene and distilling it, after the (c) step.