Hydroperoxide decomposition process

Details Hydroperoxide decomposition process Hydroperoxide decomposition process

2000-02-02

2001-09-04

Vollano, Jean F. (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Oxygen containing

C568S376000, C568S385000

Reexamination Certificate

active

06284927

ABSTRACT:

FIELD OF THE INVENTION
The invention generally relates to an improved catalytic process for decomposing alkyl or aromatic hydroperoxides to form a mixture containing the corresponding alcohol and ketone. In particular, the invention relates to decomposing a hydroperoxide by contacting it with a catalytic amount of a heterogenous catalyst of Au, Ag, Cu or a sol-gel compound containing particular combinations of Fe, Ni, Cr, Co, Zr, Ta, Si, Ti, Nb, Al and Mg, wherein certain of those metals have been combined with an oxide.
BACKGROUND OF THE INVENTION
Industrial processes for the production of mixtures of cyclohexanol and cyclohexanone from cyclohexane are currently of considerable commercial significance and are well described in the patent literature. In accordance with typical industrial practice, cyclohexane is oxidized to form a reaction mixture containing cyclohexyl hydroperoxide (CHHP). The resulting CHHP is decomposed, optionally in the presence of a catalyst, to form a reaction mixture containing cyclohexanol and cyclohexanone. In the industry, such a mixture is known as a K/A (ketone/alcohol) mixture, and can be readily oxidized to produce adipic acid, which is an important reactant in processes for preparing certain condensation polymers, notably polyamides. Due to the large volumes of adipic acid consumed in these and other processes, improvements in processes for producing adipic acid and its precursors can be used to provide beneficial cost advantages.
Druliner et al., U.S. Pat. No. 4,326,084, disclose an improved catalytic process for oxidizing cyclohexane to form a reaction mixture containing CHHP, and for subsequently decomposing the resulting CHHP to form a mixture containing K and A. The improvement involves the use of certain transition metal complexes of 1,3-bis(2-pyridylimino)isoindolines as catalysts for cyclohexane oxidation and CHHP decomposition. According to this patent, these catalysts demonstrate longer catalyst life, higher CHHP conversion to K and A, operability at lower temperatures (80-160° C.), and reduced formation of insoluble metal-containing solids, relative to results obtained with certain cobalt(II) fatty acid salts, e.g., cobalt 2-ethylhexanoate.
Druliner et al., U.S. Pat. No. 4,503,257, disclose another improved catalytic process for oxidizing cyclohexane to form a reaction mixture containing CHHP, and for subsequently decomposing the resulting CHHP to form a mixture containing K and A. This improvement involves the use of Co
3
O
4
, MnO
2
, or Fe
3
O
4
applied to a suitable solid support as catalysts for cyclohexane oxidation and CHHP decomposition at a temperature from about 80° C. to about 130° C., in the presence of molecular oxygen.
Sanderson et al., U.S. Pat. No. 5,414,163, disclose a process for preparing t-butyl alcohol from t-butyl hydroperoxide in the liquid phase over catalytically effective amounts of titania, zirconia, or mixtures thereof.
Sanderson et al., U.S. Pat. Nos. 5,414,141, 5,399,794 and 5,401,889, disclose a process for preparing t-butyl alcohol from t-butyl hydroperoxide in the liquid phase over catalytically effective amounts of palladium with gold as a dispersing agent supported on alumina.
Druliner et al., U.S. provisional application No. 60/025,368 filed Sep. 3, 1996 (now PCT US97/15332 filed Sep. 2, 1997), disclose decomposing a hydroperoxide by contacting it with a catalytic amount of a heterogenous catalyst of Zr, Nb, Hf and Ti hydroxides or oxides. Preferably, the catalyst is supported on SiO
2
, Al
2
O
3
, carbon or TiO
2
.
Further improvements and options are needed for hydroperoxide decomposition to K/A mixtures in order to overcome the deficiencies inherent in the prior art. Other objects and advantages of the present invention will become apparent to those skilled in the art upon reference to the detailed description which hereinafter follows.
SUMMARY OF THE INVENTION
In accordance with the present invention, an improved process is provided in which a hydroperoxide is decomposed to form a decomposition reaction mixture containing a corresponding alcohol and ketone. The improvement comprises decomposing hydroperoxide by contacting a hydroperoxide with a catalytic amount of a heterogenous catalyst selected from the group consisting of (1) Au (gold), (2) Ag (silver), (3) Cu (copper) and (4) sol-gel compounds comprised of (a) one or more members selected from a first group consisting of Cr, Co and Ti and (b) one or more members selected from a second group consisting of Fe, Ni, Zr, Ta, Nb, Si, Al, Mg and Ti, wherein the selected members of (b) are combined with an oxide and wherein members of the first group cannot be the same as members of the second group. Preferably, an inorganic matrix of hydroxides or oxides, or combinations thereof, is used as the oxide. Moreover, the catalysts are optionally supported on a suitable support member, such as SiO
2
, Al
2
O
3
, carbon, zirconia, MgO or TiO
2
. Zirconia and alumina are preferred supports.
Where the catalyst is gold, one or more metals selected from the group consisting of members of Periodic Group VIII may additionally be present. Preferably the metal is Pt or Pd. When one or more additional metals are present, the process may optionally be run in the presence of hydrogen gas.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention provides an improved process for conducting a hydroperoxide decomposition step in an industrial process in which an alkyl or aromatic compound is oxidized to form a mixture of the corresponding alcohol and ketone. In particular, cyclohexane can be oxidized to form a mixture containing cyclohexanol (A) and cyclohexanone (K). The industrial process involves two steps: first, cyclohexane is oxidized, forming a reaction mixture containing CHHP; second, CHHP is decomposed, forming a mixture containing K and A. As previously mentioned, processes for the oxidation of cyclohexane are well known in the literature and available to those skilled in the art.
Advantages of the present heterogenous catalytic process, relative to processes employing homogenous metal catalysts, such as metal salts or metal/ligand mixtures, include longer catalyst life, improved yields of useful products, and the absence of soluble metal compounds.
The improved process can also be used for the decomposition of other alkane or aromatic hydroperoxides, for example, t-butyl hydroperoxide, cyclododecylhydroperoxide and cumene hydroperoxide.
The CHHP decomposition process can be performed under a wide variety of conditions and in a wide variety of solvents, including cyclohexane itself. Since CHHP is typically produced industrially as a solution in cyclohexane from catalytic oxidation of cyclohexane, a convenient and preferred solvent for the decomposition process of the invention is cyclohexane. Such a mixture can be used as received from the first step of the cyclohexane oxidation process or after some of the constituents have been removed by known processes such as distillation or aqueous extraction to remove carboxylic acids and other impurities.
The preferred concentration of CHHP in the CHHP decomposition feed mixture can range from about 0.5% by weight to 100% (i.e., neat). In the industrially practiced route, the preferred range is from about 0.5% to about 3% by weight.
Suitable reaction temperatures for the process of the invention range from about 80° C. to about 170° C. Temperatures from about 110° C. to about 130° C. are typically preferred. Reaction pressures can preferably range from about 69 kPa to about 2760 kPa (10-400 psi) pressure, and pressures from about 276 kPa to about 1380 kPa (40-200 psi) are more preferred. Reaction time varies in inverse relation to reaction temperature, and typically ranges from about 2 to about 30 minutes.
As noted previously, the heterogenous catalysts of the invention include Au, Ag, Cu (including, but not limited to, Au, Ag and Cu sol-gel compounds) and certain non-Au/Ag/Cu sol-gel compounds, preferably applied to suitable solid supports. The inventive process may also be performed using Au, Ag or C

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