TH53174A - Processes for preparing phenol - Google Patents

Abstract

DC60 (14/05/44) This invention relates to a procedure for the preparation of cumene by reacting isopropanol or a mixture of isopropanol and propene with benzene in the participation of a beta-zeolite catalyst with a molar ratio of SiO2/Al2O3 greater than 10:1, which can be integrated into a procedure for the preparation of phenol, consisting of the following steps: I. Preparation of cumene as described above; II. Oxidation of cumene to obtain cumene hydroperoxide; III. Acid-catalyzed dissociation of cumene hydroperoxide to obtain phenol with acetone; and IV. Hydrogenation of acetone to obtain isopropanol. In the reaction of isopropanol with benzene, propene is produced by the simultaneous dehydration of isopropanol. In contrast to the alkylation of benzene to obtain cumene, similarly achievable by isopropanol and propene are used. The yield of n-propylbenzene in this process, consistent with the invention, is clearly observed or remains below 150 wppm (parts per million by weight). Beta-zeolite catalysts with a molar SiO2/Al2O3 ratio greater than 10:1 exhibit enhanced alkylation efficiency for benzene and lead to higher selectivity in such alkylation, so that the overall yield in the process for phenol preparation can be improved compared to conventional methods. This invention relates to a process for preparing cumene by reacting isopropanol or a mixture of isopropanol and propene in the participation of a beta-zeolite catalyst with a molar SiO2/Al2O3 ratio greater than 10:1 which can... The process for preparing phenol involves the following steps: I. Preparation of cumene as described above; II. Oxidation of cumene to obtain cumene hydroperoxide; III. Acid-catalyzed dissociation of cumene hydroperoxide to obtain phenol and acetone; and IV. Hydrogenation of acetone to obtain isopropanol. In the reaction of isopropanol with benzene, propene is produced by simultaneous dehydration of isopropanol and alkylation of benzene to obtain cumene. The similar production of isopropanol and propene is used for the alkylation of benzene to obtain cumene. The production of n-propylbenzene in this process, consistent with the invention, is clearly observed or is in the range of less than 150 wppm (parts per million by weight). The catalyst... Beta-zeolites with a SiO2/Al2O3 molar ratio greater than 10:1 exhibit enhanced alkylation efficiency for benzene, leading to higher alkylation selectivity. This, in turn, improves the overall yield of phenol preparation compared to conventional methods.

Claims (28)

1. A procedure for preparing cumene by reaction between isopropanol or a mixture of isopropanol and propene with benzene in the participation of a beta-zeolite catalyst with a molar ratio of SiO2/Al2O3 greater than 10:1. 2. The procedure for claim 1, where the catalyst used is beta-zeolite with a SiO2:Al2O3 ratio ranging from 20:1 to 200:1. 3. The procedure for one of the preceding claims is such that the acidity of the catalyst is adjusted by adding water to the surface. 4. The procedure for any one of the preceding claims is such that the volume of water in the total current fed into the reactor does not exceed 5 percent by weight when compared to the weight of the total current fed into the reactor. 5. The procedure for claim number 4 is that the water content will be in the range of 0.1% to 5% by weight, with the preferred amount typically ranging from 0.5% to 4.5% by weight. 6. The process of any one of the preceding claims where the molar ratio of benzene to isopropanol in the reactor feed current is greater than 1:1. 7. The procedure for claim number 6 is such that the molar ratio of benzene to isopropanol in the feed stream to the reactor for the benzene-isopropanol reaction is between 3:1 and 10:1. 8. The process of any one of the preceding claims, whereby the reaction has taken place at a temperature between 100 and 300 degrees Celsius. 9. The process of any one of the preceding claims, whereby the reaction proceeds to a pressure of 10 to 100 bar, is complete. 10. The procedure for any of the preceding claims shall be carried out in a stirred tank reactor, a slow-flow catalytic layer reactor, or a stationary catalytic layer reactor. 11. A procedure under one of the preceding claims whereby the reaction mixture, after leaving the reactor, is separated into an aqueous phase and an organic phase by liquid/liquid separation. 12. In accordance with claim number 11, a portion of the organic components of the reaction mixture is returned to the reactor. 13. The procedure of claim number 12 is such that the ratio of the organic components of the reaction mixture to the reactants can be between 2:1 and 100:1. 14. A procedure for any of the preceding claims where the reaction mixture contains a concentration of n-propylbenzene less than 300 wppm (parts per million by weight), of which the preferred concentration is typically less than 150 wppm (parts per million by weight). 15. A procedure for the preparation of phenol from benzene, which consists of the following steps: I. Preparation of cumene in accordance with the procedure of any one of the claims in claims 1 through 14; II. Oxidation of cumene to obtain cumene hydroperoxide; III. Acid-catalyzed decomposition of cumene hydroperoxide to obtain phenol and acetone; and IV. Hydrogenation of acetone to obtain isopropanol. 16. The procedure for claim number 15, where the isopropanol used is obtained by hydrogenation of acetone in at least two steps. 17. The procedure for claim number 16 is that the acetone used is crude, impure acetone. 18. A procedure for hydrogenating acetone to obtain isopropanol in at least two reaction steps, using crude, impure acetone. 19. The process of any of the claims in Claims 16 through 18, where hydrogenation is carried out as a liquid-phase hydrogenation at temperatures between 60 and 140 °C and at pressures between 20 and 50 bar. 20. The process of any of the claims in Claims 16 through 19, whereby the raw, impure acetone may contain impurities up to 15% by weight. 21. The process of claim number 20 involves the raw, impure acetone containing impurities ranging from 2.5% to 13% by weight. 22. The process of claim number 20 or 21, where the crude, impure acetone contains up to 5% water by weight. 23. The process of any one of the claims in Claims 20 through 22, where crude, impure acetone contains up to 7.5% cumene by weight. 24. The process of any one of the claims in Claims 20 through 23, where the crude, impure acetone contains up to 3000 wppm (parts per million by weight) of acetaldehyde. 25. The process of any one of the claims in Claims 16 through 24 shall allow for the conversion of acetone to hydrogenation by at least 99 percent. 26. The procedure for any of the claims in Claims 16 through 25 shall be such that the catalyst used for hydrogenation shall consist of Ni, Cu, Ru and/or Cr placed on a neutral support. 27. The procedure of claim 26 is performed using a nickel-containing catalyst mounted on an alpha-Al2-O3 support. 28. Using a beta-zeolite catalyst with a normal SiO2/Al2O3 ratio greater than 10:1 for the alkylation of benzene with isopropanol or a mixture of isopropanol with propene.