MXPA01001984A - Hydroperoxide decomposition process - Google Patents

Abstract

An improved process for decomposing alkyl or aromatic hydroperoxides to form a decomposition reaction mixture containing the corresponding alcohol and ketone is disclosed. The improvement relates to adding water to a starting hydroperoxide containing mixture, then removing the bulk of said water by a means such that water-soluble impurities are removed along with the water, then decomposing the hydroperoxide by contacting the hydroperoxide with a catalytic amount of a heterogeneous catalyst of Au, Ag, Cu or a sol-gel compound containing particular combinations of Cr, Co, Zr, Ta, Si, Mg, Nb, Al and Ti wherein certain of those metals have been combined with an oxide, such as an inorganic matrix of hydroxides or oxides, or combinations thereof. The catalysts may also optionally be supported on a suitable support member.

Description

HIDROPEROXIDE DECOMPOSITION PROCESS FIELD OF THE INVENTION The invention relates generally 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 the decomposition of a hydroperoxide by washing the feed with water to remove acid impurities, removing most of the water from the product flow, then contacting it with a catalytic amount of a heterogeneous catalyst.

BACKGROUND OF THE INVENTION Industrial processes for the production of mixtures of cyclohexanol and cyclohexanone from cyclohexane are currently of commercial significance and are well described in the patent literature. In accordance with typical industrial practice, the cyclohexane is oxidized to form a reaction mixture containing cyclohexyl hydroperoxide (CHHP). The resulting CHHP is decomposed or hydrogenated, optionally in the presence of a catalyst, to form a reaction mixture containing cyclohexanol and cyclohexanone. In the Ref: 127329 industry, such mixture is known as K / A mixture (ketone / alcohol), and can be easily oxidized to produce adipic acid or caprolactam, which are important reagents in processes to prepare certain condensation polymers, notably polyamides. Finally, a high K / A ratio in the reaction mixture is preferred. Due to the large volumes of adipic acid consumed in these and other processes, process improvements can be used to produce adipic acid and its precursors to provide benefits of beneficial costs. Drulinet et al. (WO 98/34894) used a heterogeneous gold catalyst in an improved catalytic process to decompose alkyl or aromatic hydroperoxides to form a mixture containing the corresponding alcohol and ketone. Two common problems in CHHP processes, especially in heterogeneous catalytic processes, are the presence of water and acid by-products in the reaction mixture containing CHHP. Both of these can deactivate the catalyst, resulting in lower conversion speeds and / or lower K / A ratios. One method for removing the acid by-products is by the addition of a neutralizing agent, such as that described in U.S. Patent No. 4,238,415. This, however, results in undesirable salts, which are necessary to remove from the final product. The drying of the reaction mixture in itself to remove the water has been used both in the hydrogenation and decomposition processes (U.S. Patent Nos. 5,550,301 and 3,927,108), but those methods do not remove the acid by-products along with the water. Applicants have discovered that good conversion rates and good K / A ratios can be achieved by the addition of a fixed amount of water to the reaction mixture, and the subsequent removal of the water before the heterogeneous decomposition step removes the impurities acids. Further improvements and options are necessary for the decomposition of the hydroperoxide to K / A mixtures to overcome the de? Ciencies 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 following detailed description.

BRIEF DESCRIPTION OF THE INVENTION An improved process is provided in which a hydroperoxide is decomposed to form a mixture containing a corresponding alcohol and ketone. The improvement comprises the steps of a) adding water in the amount of 0.5-20% to a mixture containing hydroperoxide; b) remove the volume of water by means such that the water-soluble impurities are removed together with the water; c) remove the remaining water by means such that no more than 2% of the water remains in the reaction mixture; and d) decomposing the hydroperoxide by contacting the reaction mixture with a catalytic amount of a heterogeneous catalyst. The heterogeneous catalyst preferably comprises Au (gold). The process of the invention can optionally be carried out using Au in the presence of other metals, preferably Pd. The catalyst may also, optionally, be supported on a suitable support member, such as Si02, A1203, carbon, zirconia, MgO or Ti02. - The hydroperoxide is preferably cyclohexylhydroperoxide, and the decomposition reaction mixture is preferably the result of an oxidation reaction of the cyclohexane. The preferred means for removing the water in step b) is decantation, and the preferred means for removing the water in step c) is evaporation.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES The present invention provides an improved process for conducting a step of decomposing hydroperoxide 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, the cyclohexane can be oxidized to form a mixture containing cyclohexanol (A) and cyclohexanone (K). The industrial process involves two steps: first, the cyclohexane is oxidized, forming a reaction mixture containing CHHP; second, the CHHP is decomposed, forming a mixture of containing K and A. As mentioned above, the processes for the oxidation of cyclohexane are well known in the literature and are available to those skilled in the art. The improved process can also be used for the decomposition of other alkane or aromatic hydroperoxides, for example, t-butyl hydroperoxide, cyclododecylhydroperoxide and eumenohydroperoxide. The advantages of the heterogeneous catalytic process of the present, in relation to the processes employing homogeneous metal catalysts, such as metal salts or metal-ligand mixtures, include longer catalyst life, better yields of useful product and absence of soluble metal. However, the use of a heterogeneous catalyst subjects the process to alkalinity by water and organic impurities from the oxidation reaction, especially acid impurities. Applicants have discovered a multi-step process that overcomes those obstacles: (a) adding water in an amount of approximately 0.5-206 to a mixture containing hydroperoxide; b) remove the volume of water by any means such that the water-soluble impurities are removed together with the water; c) remove the remaining water by any means such that no more than 2% remains in the reaction mixture; and (d) decomposing the hydroperoxide by contacting the catalytic reaction mixture of a heterogeneous catalyst. The first two steps are to wash by adding a certain amount of water to the mixture containing hydroperoxide, and the subsequent removal of the volume of water by any means that removes the impurities from the reaction mixture together with the water, notably acid by-products of the Oxidation process such as organic mono and dibasic acids. The water is added in the amount of 0.5-20 by weight of the mixture containing hydroperoxide. About 4% is preferred. The removal of these impurities prevents catalyst contamination, which lowers the K / A ratio. In general, a high K / A ratio is preferred. Methods for removing water that will also remove impurities from the reaction mixture along with water include, but are not limited to, decanting and extraction. Decanting is a preferred method. The water is preferably removed at levels of less than about 5%. The hydroperoxide is preferably cyclohexylhydroperoxide, and the hydroperoxide-containing mixture is preferably the result of an oxidation reaction of the cyclohexane. Any oxidation process can be used, but one typical of those used in the industry is that described in Druliner et al., US Patent No. 4,326,084. Then, the remaining water is removed in any way, going down to levels of less than about 2%, preferably less than 0.5%, to eliminate deactivation of the catalyst by water, which would decrease the conversion rate. Methods to accomplish this include, but are not limited to, evaporation, distillation and contact with drying agents. A preferred method is evaporation. The process can be continuous or in batches. After removal of the remaining or remaining water, the dry decomposition reaction mixture containing hydroperoxide is then contacted with a catalytic amount of a heterogeneous catalyst. This decomposition process can be carried out under a wide variety of conditions and in a wide variety of solvents, including the initial alkane that is oxidized to the hydroperoxide. Since CHHP, typically produced industrially as a solution in cyclohexane from the catalytic oxidation of cyclohexane, a convenient and preferred solvent for the decomposition process of the invention is cyclohexane. Such a mixture may be used as received from the first step of the oxidation process of the cyclohexane 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 reaction mixture can range from about 0.5 wt% to 100% (ie, pure). In the industrially practiced route, the preferred range is approximately 0. 5% to about 3% by weight. Suitable reaction temperatures for the processes of the invention range from about 80 ° C to about 170 ° C. Temperatures of about 110 ° C to about 160 A are typically preferred. The reaction pressures may preferably range from pressures of about 69 kPa to about 2760 kPa (10-400 psi), and pressures of about 276 kPa to about 1380 kPa (40-200 psi) are most preferred. The reaction time varies inversely with the reaction temperature, and typically ranges from about 1 to about 30 minutes. As noted above, the heterogeneous catalysts of the invention comprise Au and Au compounds, preferably applied to suitable solid supports. The process of the invention can also be carried out using Au in the presence of other metals, preferably Pd. The percentage of the metal of the support can vary from about 0.01 to about 50% by weight, and is preferably from about 0.1 to 10% by weight. Suitable and currently preferred supports include Si02 (silica), A120 (alumina), C (carbon), Ti02 (titanium), MgO (magnesia) or 'Zr02 (zirconia). Zirconia is a particularly preferred support, and Au supported on alumina is a particularly preferred catalyst of the invention. A preferred catalyst is 0.1-10% C.I Au / 0.05-2% Pd on α-alumina, preferably 1% of Au / 0.1% of Pb on α-alumina. Some of the heterogeneous catalysts can be obtained already prepared from manufacturers, or they can be prepared from suitable starting materials using methods known in the art. The supported gold catalysts can be prepared by any known standard gold-in-disperse process, such as sol-gel techniques, evaporative techniques or colloidal dispersion coatings. In particular, gold with an ultrafine particle size is preferred. Such small particle gold (often less than 10 nm) can be prepared according to Haruta, M., "Size and Support Dependence on Gold Catalysis," Catalysis Today 36 (1997) 153-166, and Tsubota et al., Preparation of Catalyst V, pp. 695-704 (1991). Such gold preparations produce samples that are purple-pink in place of the typical bronze color associated with gold and result in highly dispersed gold catalysts when placed on the suitable support member. These highly dispersed gold particles are typically from about .3 nm to about 15 nm in diameter. The solid support of the catalyst, including Si02, Al203, carbon, MgO, zirconia or Ti02, can be amorphous or crystalline, or a mixture of the amorphous and crystalline forms. The selection of the optimum average particle size for the catalyst supports will depend on process parameters such as the residence time of the reactor and the desired reactor flow rates. Generally, the average particle size selected will vary from about 0.005 mm to about 5 mm. Catalysts having a surface area greater than 10 m2 / g are preferred, since the increase in surface area of the catalyst has a direct correlation with the increase in decomposition rates in batch experiments. Substrates having much larger surface areas can also be employed, but the inherent fragility of the high surface area catalysts, and the concomitant problems in maintaining an acceptable particle size distribution, will establish a practical upper limit on the surface area of the support. of the catalyst. A "sol-gel technique" is a process where a free flowing fluid solution, "sol", is prepared by first dissolving suitable precursor materials such as colloids, alkoxides or metal salts in a solvent. The "sol" is then dosed with a reagent to initiate the reactive polymerization of the precursor. A typical example is tetraethoxyorthosilicate (TEOS) dissolved in ethanol. Water is added, with traces of acid or base as catalyst to initiate hydrolysis. As the polymerization and crosslinking proceed, the viscosity of the free flowing "sol" is increased and eventually a "rigid" gel can result. The "gel" consists of a reticulated network of the desired material, which encapsulates the original solvent within its open porous structure. The "gel" can then be dried, typically by simple heating in a flow of dry air to produce a xerogel or the trapped solvent can be removed by displacement with a supercritical fluid such as liquid C0 to produce an airgel. These aerogels and xerogels can be optionally calcined at elevated temperatures (>; 200 ° C) which results in products which typically have very porous structures and concomitantly high surface areas. In the practice of the invention, the catalyst can be brought into contact with CHHP by formulation in a catalyst bed, which is arranged to provide intimate contact between the catalyst and the reagents. Alternatively, the catalysts can be suspended with the reaction mixtures using techniques known in the art. The process of the invention is suitable for batch or continuous CHHP decomposition processes. These processes can be carried out under a wide variety of conditions. The addition of air or a mixture of air and inert gases to the decomposition mixtures of CHHP provides higher conversions of the process reagents to K and A, since some of the cyclohexane is directly oxidized to K and A, in addition to K and A that has been formed by the decomposition of CHHP. This auxiliary process is known as "cyclohexane participation" and is described in detail in Druliner et al., U.S. Patent No. 4,236,084, all the contents of which are incorporated herein by reference. Moderate increases in conversion can be obtained by adding hydrogen to the reaction, which also results in an increase in the ratio of K to A produced. A preferred process of the invention would comprise the steps of: a) removing impurities from the hydroperoxide mixture by adding 4% water; b) removing the water at a level of less than 5% by decanting from about 90 to about 160 ° C and from about 1 to about 300 psi (0.006 to 2.07 MPa gauge); c) removing the remaining water at a level of less than about 0.5% by evaporation of about 70 to about 250 ° C, and d) decomposing the cyclohexylhydroperoxide by contacting the reaction mixture with a catalytic amount of an Au catalyst, the catalyst understands 1% Au and 0.1% Pd supported on a suitable support on alumina. The process of the present invention is further illustrated by the following non-limiting examples. In the examples, all temperatures are in degrees Celsius and all percentages are by weight unless otherwise indicated.

METHODS AND MATERIALS The catalysts used in the following Examples were prepared according to that described in Druliner et al., WO 98/34894, all the contents of which are incorporated herein by reference. The abbreviations used hereinafter are listed and defined below as follows: CHHP: Cyclohexylhydroperoxide K: Cyclohexanone A: Cyclohexanol All percentages are expressed as weight percent, unless otherwise specified. The catalyst used for all the Examples was lOg of 1% Au / 0.1% Pd supported on α-alumina. The reactor was a 30-inch (76 cm) full-piston fluid flow reactor with a diameter of 1/4 inch (0.64 cm). The inlet and outlet pressure was 150 psig (1.03 MPa gauge) controlled with a back pressure regulator. The feed consisted of 1.6% CHHP in cyclohexanone, approximately 1% K and 2% A, and varying amounts of water and acid impurities. The acid impurities referred to in the Examples consisted of monobasic and dibasic acids which would be typical of those produced in the oxidation of cyclohexane such as adipic acid, succinic acid, formic acid and hydroxycaproic acid, in approximately equal amounts. Analyzes were carried out on CHHP, K and A by gas chromatography. Cyclohexane, CHHP, K and A were obtained from E.l. du Pont de Nemours and Company, Wilmington, DE. The ratio of K / A obtained after conversion of the cyclohexylhydroperoxide to the catalyst was calculated using the equation: (g of K in the product) - (g of K in food) (g of A in the product) - (g of A in food) To illustrate the dependence of water and acid impurities in the feed for the decomposition reaction of CHHP, the feed containing cyclohexylhydroperoxide was fed onto the catalyst with varying amounts of pure water, and containing 10% water. As shown in Examples 2, 3, 5, and 6, the presence of water above 0.1% results in deactivation of the catalyst, giving a lower CHHP conversion and a lower K / A ratio. As shown in Example 4 the presence of acidic impurities regardless of the amount of water present also results in deactivation of the catalyst, giving a lower conversion of CHHP and a lower K / A ratio.

EXAMPLE 1 10 g of the catalyst of 1% Au-0.1% Pd was used to decompose a feed mixture containing 1.6% CHHP, 0.9% K, 1.9% A, 0.1% water, and 0.3% acids with the rest of the mixture being cyclohexane. That mixture was fed over the catalyst at 8 ml / min at 150 ° C, and 150 psig (1.03 MPa gauge). The results are presented below in Table I: Table I EXAMPLE 2 This Example illustrates the effect of pure water. The increase in water has only a small effect on conversion speeds, but it greatly decreases the K / A ratio. The catalyst and the reaction conditions were the same as described in Example 1. To the feed, varying levels of pure water were added. The results are presented below in Table II: Table II EXAMPLE 3 This Example illustrates the effect of water containing low amounts of acids. The increase in the water / acid mixture has a significant effect on the conversion rates and the K / A ratio. The catalyst and the reaction conditions were the same as described in Example 1. Variable levels of water containing 10% acids were added to the feed. The% acid indicates the percentage of acid in the added water, not the percentage in the total feed mixture. The results are presented below in Table III: Table III Table III (continued) EXAMPLE 4 This example illustrates the effect of water containing higher amounts of acid. The greater presence of acid greatly increases the effect of added water on the conversion rate and the K / A ratio. The catalyst and the reaction conditions were the same as described in Example 1. The feed in this example contains 1.9% CHHP, 0.5% K, 2.0% A, 0.1% water, and 1% acids, where the percentage indicates the amount of acid present in the total diet. The results are shown below in Table IV: Table IV EXAMPLE 5 The Example illustrates the effect of temperature on the decomposition reaction of CHHP. The catalyst and the reaction conditions were the same as described in Example 1, except for the variation in temperature. 0.2% water containing 10% acids was added to the feed. The results are shown in Table V: Table V EXAMPLE 6 The Example illustrates the effect of pressure on the decomposition reaction of CHHP. The catalyst and the reaction conditions were the same as described in Example 1, except for the variation in temperature. 0.2% water containing 10% acids was added to the feed. The results are shown in Table VI: Table VI It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (20)

1. CLAIMS Having described the invention as above, the content of the following claims is claimed as property: 1. An improved process for decomposing a hydroperoxide, to form a mixture containing a corresponding alcohol and ketone, the improvement is characterized in that it comprises the steps of : a) add water in the amount of 0.5-20% to a mixture containing hydroperoxide; b) remove the volume of the water by means such that the water-soluble impurities are removed together with the water; c) remove the remaining water by means such that no more than 2% of water remains in the reaction mixture; and d) decomposing the hydroperoxide by contacting the reaction mixture with a catalytic amount of a heterogeneous catalyst, wherein the catalyst is comprised of gold.
2. 2. The process in accordance with the claim 1, characterized in that the heterogeneous catalyst is supported on a catalyst support member.
3. 3. The process in accordance with the claim 2, characterized in that the catalyst support member is selected from the group consisting of SiO2, A1203, carbon, TiO, MgO and zirconium.
4. 4. The process according to claim 1, characterized in that the hydroperoxide is cyclohexylhydroperoxide.
5. 5. The process according to claim 1, characterized in that the temperature of the decomposition reaction is from 80 ° C to 170 ° C, and the pressure of the decomposition reaction is from 69 kPa to 2760 kPa.
6. 6. The process according to claim 5, characterized in that the pressure of the reaction is from 276 kPa to 1380 kPa.
7. 7. The process according to claim 1, characterized in that the reaction mixture contains from 0.5 to 100 weight percent of cyclohexyl hydroperoxide.
8. 8. The process in accordance with the claim 1, characterized in that the process is carried out in the presence of cyclohexane.
9. 9. The process according to claim 1, characterized in that the process is carried out in the presence of added oxygen.
10. 10. The process according to claim 3, characterized in that the gold is supported on zirconia.
11. 11. The process according to claim 10, characterized in that the gold is 0.1 to 10 weight percent of the catalyst and the support member.
12. 12. The process in accordance with the claim 1, characterized in that a metal is present from 0.05 to 2J by weight of the catalyst and the support member with gold.
13. 13. The process according to claim 12, characterized in that the metal is Pd.
14. 14. The process in accordance with the claim 2, characterized in that gold is present on the support member as well dispersed particles having a diameter of 3 nm to 15 nm.
15. 15. The process in accordance with the claim 13, characterized in that the catalyst is 1.0 percent in Au weight with 0.1 weight percent of Pd supported on alumina.
16. 16. The process according to claim 1, characterized in that the gold catalyst is in the form of a sol-gel compound.
17. 17. The process according to claim 1, characterized in that the process is carried out in the presence of added hydrogen.
18. 18. The process in accordance with the claim 1, characterized in that the means for removing the water in step b) are decanting.
19. 19. The process in accordance with the claim 18, characterized in that the means for removing the water in step c) are evaporation.
20. 20. The process according to claim 1, characterized in that the hydroperoxide-containing mixture results from the oxidation of the cyclohexane. HIDROPEROXIDE DECOMPOSITION PROCESS SUMMARY OF THE INVENTION An improved process for decomposing alkanocarbaceous hydroperoxides is described to form a decomposition reaction mixture containing the alcohol and ketones cerresoondienres. the rr.-; ra laughed I? aG-: OG. adding water to a mixture containing initial hiarcperoxide, then removing the volume of water by means such that the water-soluble impurities are removed with the water, then decomposing the hydroperoxide by contacting the hydroperoxyac. A quantity of the heterogeneous catalyst of Au, Ag, Cu or an oo in scl-gei containing particular combinations of Cr, Co, Zr, 7a, S, Mg, c, Al and Ti, closure of these materials they have been combined with an oxide, ral as an inorganic matrix of hiarcides or oxides, or combinations thereof. The catalaisers can also optionally be supported on a suitable support member.