METHOD AND CATALYST SYSTEM FOR PRODUCING AROMATIC CARBONATES

Abstract: A method and catalyst system for economically producing aromatic carbonates from aromatic hydroxy compounds is disclosed. In one embodiment, the present invention provides a method of carbonylating aromatic hydroxy compounds by contacting at least one aromatic hydroxy compound with oxygen and carbon monoxide in the presence of a carbonylation catalyst system that includes an effective amount of at least one Group 8, 9, or 10 metal source; an effective amount of at least one onium chloride salt; and an effective amount of a combination of inorganic co-catalysts comprising at least one lead source and at least one other metal source.

Description: METHOD AND CATALYST SYSTEM FOR PRODUCING AROMATIC CARBONATES BACKGROUND OF THE INVENTION The present invention is directed to a method and catalyst system for producing aromatic carbonates and, more specifically, to a method and catalyst system for producing diaryl carbonates through the carbonylation of aromatic hydroxy compounds. Aromatic carbonates find utility, inter alia, as intermediates in the preparation of polycarbonates. For example, a popular method of polycarbonate preparation is the melt transesterification of aromatic carbonates with bisphenols. This method has been shown to be environmentally superior to previously used methods which employed phosgene, a toxic gas, as a reagent and chlorinated aliphatic hydrocarbons, such as methylene chloride, as solvents. Various methods for preparing aromatic carbonates have been previously described in the literature and/or utilized by industry. A method that has enjoyed substantial popularity in the literature involves the direct carbonylation of aromatic hydroxy compounds with carbon monoxide and oxygen. In general, practitioners have found that the carbonylation reaction requires a rather complex catalyst system. For example, in U.S. Patent No. 4,187,242, which is assigned to the assignee of the present invention, Chalk reports that a carbonylation catalyst system should contain a Group VIII B metal, such as ruthenium, rhodium, palladium, osmium, iridium, platinum, or a complex thereof. Further refinements to the carbonylation reaction include the identification of organic co-catalysts, such as terpyridines, phenanthrolines, quinolines and isoquinolines in U.S. Patent No. 5,284,964 and the use of a mixture of carbon monoxide and oxygen maintained in a reactor at a substantially constant molar ratio and partial pressure in U.S. Patent No. 5,399,734, both patents also being assigned to the assignee of the present invention. The economics of the carbonylation process is strongly dependent on the number of moles of aromatic carbonate produced per mole of Group 8, 9, or 10 metal utilized (i.e. "catalyst turnover number or "TON""). Consequently, much work has been directed to the identification of efficacious catalyst combinations that increase catalyst turnover. In U.S. Patent No. 5,231 ,210, which is also assigned to the present assignee, Joyce et al. report the use of a cobalt pentadentate complex as an inorganic co-catalyst ("IOCC"). In U.S. Patent No. 5,498,789, Takagi et al. report the use of lead as an IOCC. In U.S. Patent No. 5,543,547, Iwane et al. report the use of trivalent cerium as an IOCC. In U.S. Patent No. 5,726,340, Takagi et al. report the use of lead and cobalt as a binary IOCC system. Carbonylation catalyst literature lauds the effectiveness of bromide compounds as a halide source in the catalyst system. For example, in the aforementioned U.S. Patent No. 5,543,547, Iwane et al. state the traditional understanding that bromide sources are the preferred halide sources and that chloride is known to exhibit low activity. While it is true that bromide has historically exhibited higher activity, there are drawbacks to using bromide in the carbonylation reaction. Initially, it is worth noting that onium bromide compounds are typically expensive compared to, e.g., onium chloride compounds. Furthermore, when used to carbonylate phenol, bromide ion is consumed in the process forming undesirable brominated byproducts, such as 2- and 4- bromophenols and bromo diphenyl carbonate. These byproducts must typically be recovered and recycled, further adding to the investment and operating cost of the process. However, due to their comparatively low activity, onium chloride compounds have not traditionally been considered an economically viable alternative to onium bromide compounds. A catalyst system comprising an onium chloride but requiring a base has been disclosed. Specifically, Application Serial No. 09/495,539 discloses catalyst systems for preparing aromatic carbonates which comprise a Group VIII B metal source; a combination of inorganic co-catalysts including a lead source and at least one of a titanium source or a manganese source; an onium chloride composition; and a base. The literature is virtually silent, however, as to the role of various catalyst system components, such as IOCC's, onium halides and added base, for example, in the carbonylation reaction (i.e., the reaction mechanism). In this regard, periodic table groupings have failed to provide guidance in identifying additional IOCC's. For example, U.S. Patent No. 5,856,554 provides a general listing of possible IOCC candidates, yet further analysis has revealed that many of the members (and combinations of members) of the recited groups (i.e., Groups IV B and V B) do not effectively catalyze the carbonylation reaction. Accordingly, meaningful guidance regarding the identification of additional catalyst systems is cursory at best. It would be desirable to identify catalyst systems that would minimize consumption of costly components (e.g., palladium, IOCC's and onium halides) or perhaps that would omit components such as base. It would also be desirable to minimize the aforementioned consumption of costly components while increasing selectivity toward desirable products and minimizing formation of undesirable byproducts (e.g., halogenated products such as 2- and 4-bromophenols). Unfortunately, due to the lack of guidance in the literature, the identification of effective carbonylation catalyst systems has become a serendipitous exercise. As the demand for high performance plastics has continued to grow, new and improved methods of providing product more economically are needed to supply the market. In this context, various processes and catalyst systems are constantly being evaluated; however, the identities of improved and/or additional effective catalyst systems for these processes continue to elude the industry. Consequently, a long felt, yet unsatisfied need exists for new and improved methods and catalyst systems for producing aromatic carbonates and the like. SUMMARY OF THE INVENTION Accordingly, the present invention is directed to a method and catalyst system for producing aromatic carbonates. In one embodiment, the present invention provides a method for carbonylating aromatic hydroxy compounds, said method comprising the step of: contacting at least one aromatic hydroxy compound with oxygen and carbon monoxide in the presence of a carbonylation catalyst system comprising an effective amount of at least one Group 8, 9, or 10 metal source; an effective amount of at least one onium chloride salt; and an effective amount of a combination of inorganic co- catalysts comprising at least one lead source and at least one other metal source. In another embodiment, the present invention provides a carbonylation catalyst system comprising an effective amount of at least one Group 8, 9, or 10 metal source; an effective amount of at least one onium chloride salt; and an effective amount of a combination of inorganic co-catalysts comprising at least one lead source and at least one other metal source. One particular advantage of the present method and catalyst composition is that a base need not be added to the reaction mixture and is not required to achieve efficient reaction. Another particular advantage is that halogenated byproducts such as chlorinated phenols and chlorinated aromatic carbonates are not produced. Various other features, aspects, and advantages of the present invention will become more apparent with reference to the following description and appended claims. BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a graph of palladium turn-over number (TON) versus time for a reaction mixture using a catalyst system comprising palladium-lead-cerium and an onium chloride. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The present invention is directed to a method and catalyst system for producing aromatic carbonates. In one embodiment, the method includes the step of contacting at least one aromatic hydroxy compound with oxygen and carbon monoxide in the presence of a carbonylation catalyst system that comprises an effective amount of at least one Group 8, 9, or 10 metal source; an effective amount of at least one onium chloride salt; and an effective amount of a combination of inorganic co-catalysts comprising at least one lead source and at least one other metal source. Unless otherwise noted, the term "effective amount," as used herein, includes that amount of a substance capable of either increasing (directly or indirectly) the yield of the carbonylation product or increasing selectivity toward an aromatic carbonate. Optimum amounts of a given substance can vary based on reaction conditions and the identity of other constituents yet can be readily determined in light of the discrete circumstances of a given application. Any aromatic hydroxy compound convertible to a carbonate ester may be employed in the present invention. Suitable aromatic hydroxy compounds include monocyclic, polycyclic or fused polycyclic aromatic monohydroxy or polyhydroxy compounds having from 6 to 30, and preferably from 6 to 15 carbon atoms. Illustrative examples include mono- and poly-hydroxy compounds such as phenol, alkylphenols, o-, m- or p-cresol, o-, m- or p-chlorophenol, o-, m- or p-ethylphenol, o-, m- or p-propylphenol, o-, m- or p-methoxyphenol, methyl salicylate, 2,6-dimethylphenol, 2,4- dimethylphenol, 3,4-dimethylphenol, 1-naphthol and 2-naphthol, xylenol, resorcinol, hydroquinone, catechol, cumenol, the various iso ers of dihydroxynaphthalene, bis(4-hydroxyphenyl)propane-2,2,α,α , -bis(4-hydroxyphenyl)-p-diisopropylbenzene, and bisphenol A. Aromatic mono-hydroxy compounds are particularly preferred with phenol being the most preferred. In the case of substituents on the aromatic hydroxy compound, the substituents are generally 1 or 2 substituents and are preferably from C-l to C-4 alkyl, C-l to C-4 alkoxy, fluorine, chlorine or bromine. When an aromatic hydroxy compound as a raw material is used as a reaction solvent, then another solvent need not be used. However, the reaction mixture may also optionally contain at least one relatively inert solvent, that is a solvent whose presence does not substantially improve the yield of or selectivity toward the aromatic carbonate. Illustrative inert solvents include, but are not limited to, an aliphatic hydrocarbon, such as hexane, heptane, or cyclohexane; a chlorinated hydrocarbon such as methylene chloride or chloroform; or an aromatic solvent such as toluene or xylene. In various preferred embodiments, the carbonylation catalyst system contains at least one constituent from the Group 8, 9, or 10 metals or a compound thereof. A preferred Group 8, 9, or 10 constituent is an effective amount of a palladium source. In various embodiments, the palladium source may be in elemental form, or it may be employed as a palladium compound. The palladium material can be employed in a form that is substantially soluble in the reaction media or in a form which is substantially insoluble in the reaction media, such as a supported- or polymer-bound palladium species. Accordingly, palladium black or palladium deposited on carbon, palladium deposited on alumina or palladium deposited on silica may be used as well as palladium halides, palladium chloride, palladium bromide, palladium iodide; palladium sulfate; palladium nitrate, palladium carboxylates, palladium oxides, palladium acetate and palladium 2,4-pentanedionate; and palladium complexes containing carbon monoxide, amines, nitrites, nitriles, phosphines or olefϊns. As used herein, the term "complexes" includes coordination or complex compounds containing a central ion or atom. The complexes may be nonionic, cationic, or anionic, depending on the charges carried by the central atom and the coordinated groups. Other common names for these complexes include complex ions (if electrically charged), Werner complexes, and coordination complexes. In various applications, it may be preferable to utilize palladium(II) salts of organic acids, including carboxylates with C 2 . 6 aliphatic carboxylic acids and palladium(II) salts of β-diketones. Palladium(II) acetate and palladium(II) 2,4-pentanedionate (also know as palladium(II) acetylacetonate) are generally most preferred. Mixtures of palladium materials are also contemplated. The quantity of the at least one Group 8, 9, or 10 metal catalyst is not particularly limited in the process of the present invention. Preferably, the amount of Group 8, 9, or 10 metal source employed should be sufficient to provide about 1 mole of metal per 800-1,000,000 moles of aromatic hydroxy compound, more preferably per 4000- 1 ,000,000 moles of aromatic hydroxy compound, still more preferably per 40,000- 200,000 moles of aromatic hydroxy compound, and yet still more preferably per 65,000-100,000 moles of aromatic hydroxy compound. The carbonylation catalyst system further contains an effective amount of at least one onium chloride salt that is substituted with organic residues. Preferably, the onium chloride salt is a sulfonium or quaternary ammonium or quaternary phosphonium chloride. Organic residues on sulfonium or quaternary ammonium or quaternary phosphonium chlorides typically include C 6 . JO aryl, C .j 2 aralkyl, or Cj. 2 o alkyl, or combinations thereof. Illustrative examples include, but are not limited to, tetraalkyl ammonium or tetraalkylphosphonium chlorides. Preferred onium salts are alkylammonium chlorides containing primary and/or secondary alkyl groups containing about 1 -8 carbon atoms. Particularly preferred onium chloride salts include tributylmethyl ammonium chloride, tetramethylammonium chloride, tetrabutylammoniu chloride and tetraethylammonium chloride. In preferred embodiments, the carbonylation catalyst system can contain between about 1 and about 2000 moles of chloride preferably, preferably between about 2 and about 1500 moles of chloride, and more preferably between about 5 and about 1000 moles of chloride, and still more preferably between about 100 and about 600 moles of chloride per mole of Group 8, 9, or 10 metal employed. In especially preferred embodiments, about 400-600 moles of chloride are used per mole of Group 8, 9, or 10 metal employed. The carbonylation catalyst system includes an effective amount of a combination of inorganic co-catalysts (IOCC's) comprising at least one lead source and at least one other metal source. Preferably, the at least one other metal source is selected from the group consisting of manganese, titanium, and a lanthanide metal. Additional IOCC's may be used in the carbonylation catalyst system provided an additional IOCC does not deactivate (i.e. "poison") the original IOCC combination, such that it loses its effectiveness. A non-exclusive listing of additional IOCC's includes iron, zinc, bismuth, nickel, cobalt, copper, zirconium, iridium, rhodium, ruthenium, and chromium. Suitable IOCC's include elemental metals, metal compounds, and precursors thereof which may form catalytically active metal species under the reaction conditions, it being possible for use to be made of the metal in various degrees of oxidation. IOCC's may be initially soluble in the reaction mixture or initially insoluble as in supported- or polymer-bound IOCC species. Alternatively, IOCC's may be initially insoluble in the reaction mixture and form soluble IOCC species during the course of the reaction. An IOCC can be introduced to the carbonylation reaction in various forms, including salts and complexes, such as tetradentate, pentadentate, hexadentate, heptadentate, octadentate, or nonadentate complexes. Illustrative forms may include oxides, halides, carboxylates, diketones (including beta-diketones), nitrates, complexes containing carbon monoxide or olefins, and the like. Suitable beta-diketones include those known in the art as ligands for the IOCC metals of the present invention. Examples include, but are not limited to, acetyl acetone, benzoylacetone, dibenzoylmethane, diisobutyrylmethane, 2,2-dimethylheptane-3,5-dione, 2,2,6- trimethylheptane-3,5-dione, dipivaloylmethane, and tetramethylheptanedione. The quantity of ligand is preferably not such that it interferes with the carbonylation reaction itself, with the isolation or purification of the product mixture, or with the recovery and reuse of catalyst components (such as palladium). An IOCC may be used in its elemental form if sufficient reactive surface area can be provided. In embodiments employing supported palladium, it is noted that the IOCC provides a discrete, catalytic source of metal in a form favorable for such catalysis. At least one lead source (sometimes referred to hereinafter as lead compound) is present in the catalyst compositions of the present invention. A lead compound is preferably at least partially soluble in a liquid phase under the reaction conditions. Examples of such lead compounds include, but are not limited to, lead oxides, for example PbO, Pb 3 O 4 , and PbO 2 ; lead carboxylates, for example lead (II) acetate and lead (II) propionate; inorganic lead salts such as lead (II) nitrate and lead (II) sulfate; alkoxy and aryloxy lead compounds such as lead (II) methoxide, and lead (II) phenoxide; lead complexes such as lead (II) acetylacetonate and phthalocyanine lead, and organolead compounds (that is lead compounds having at least one lead-carbon bond) such as tetraethyl lead. Of these compounds, lead oxides and lead compounds represented by the formula Pb(OR) 2 wherein R is an aryl group having a carbon number from 6 to 10 are preferred. Mixtures of the aforementioned lead compounds are also contemplated. Examples of titanium sources are inorganic titanium salts such as titanium(IV) bromide, titanium (IV) chloride; titanium alkoxides and aryloxides such as titanium (IV) methoxide, titanium (IV) ethoxide, titanium (IV) isopropoxide, titanium (IV) 2- ethylhexoxide, titanium(IV) butoxide, titanium (IV) 2-ethyl-l,3-hexanediolate, titanium (IV) (triethanolaminato)isopropoxide and titanium(IV) phenoxide; and titanium salts of β-diketones or β-ketoesters such as titanium (IV) diisopropoxide bis(acetylacetonate), titanium (IV) bis(ethyl acetoacetato)diisopropoxide, titanium(IV) oxide bis(2,4-pentanedionate) (or titanium (IV) oxide acetylacetonate). Mixtures of titanium compounds may also be employed. The preferred titanium sources are titanium(IV) alkoxides and aryloxides such as titanium (IV) butoxide and titanium (IV) phenoxide; and salts of β-diketones or β-ketoesters such as titanium (IV) oxide acetylacetonate and titanium (IV) bis(ethyl acetoacetato)diisopropoxide. Examples of manganese sources (sometimes referred to hereinafter as manganese compound) include manganese halides, manganese chloride, manganese bromide, manganese nitrate, manganese carboxylates such as manganese (II) acetate, and manganese salts of β-diketones such as manganese (III) 2,4-pentanedionate and manganese (II) 2,4-pentanedionate (manganese (II) acetylacetonate). Mixtures of manganese compounds may also be employed. The preferred manganese compounds are manganese 2,4-pentanedionates. Lanthanide metals include cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. Examples of lanthanide sources (sometimes referred to hereinafter as lanthanide compounds) include lanthanide carboxylates such as cerium acetate, and lanthanide salts of β-diketones such as lanthanide 2,4-pentanedionates (lanthanide acetylacetonates) or lanthanide hexafluoroacetylacetonates. Mixtures of lanthanide compounds may also be employed. In one embodiment preferred lanthanide compounds are cerium compounds including cerium carboxylates such as cerium acetate, and cerium salts of β-diketones such as cerium (III) 2,4- pentanedionate (cerium (III) acetylacetonate). Mixtures of cerium compounds may also be employed. The preferred cerium compounds are cerium 2,4-pentanedionates. IOCC's are included in the carbonylation catalyst system in effective amounts. In this context an "effective amount" is an amount of IOCC (or combination of IOCC's) that increases the number of moles of aromatic carbonate produced per mole of Group 8, 9, or 10 metal utilized; increases the number of moles of aromatic carbonate produced per mole of chloride utilized; or increases selectivity toward aromatic carbonate production beyond that obtained in the absence of the IOCC (or combination of IOCC's). Optimum amounts of an IOCC in a given application will depend on various factors, such as the identity of reactants and reaction conditions. Typically, at least one IOCC is present in the amount of about 0.2-200 gram-atoms of metal, preferably about 1 -150 gram-atoms of metal, and more preferably about 2-100 gram-atoms of metal per gram-atom of the Group 8, 9, or 10 metal. For example, when palladium is included in the reaction, the molar ratio of lead relative to palladium at the initiation of the reaction is preferably between about 0.1 and about 150, more preferably between about 1 and about 100, still more preferably between about 5 and about 100, still more preferably between about 25 and about 100, and yet still more preferably between about 50 and about 70. In especially preferred embodiments the molar ratio of lead relative to palladium at the initiation of the reaction is preferably greater than about 17. The molar ratio of the at least one other metal source IOCC relative to palladium at the initiation of the reaction is typically between about 0.1 and about 25, preferably between about 5 and about 20 moles, and more preferably between about 5 and about 15. The carbonylation reaction can be carried out in a batch reactor or a continuous or semi-continuous reactor system comprising one or more reaction vessels. Reaction vessels suitable for use in the process according to the invention with either homogeneous or heterogeneous catalysts include stirrer vessels, autoclaves and bubble columns, it being possible for these to be employed as individual reactors or as a cascade. In a cascade 2 to 15, preferably 2 to 10, and particularly preferably 2 to 5, reactors may be connected in series. Due in part to the low solubility of carbon monoxide in organic hydroxy compounds, such as phenol, it is preferable that a reactor vessel be pressurized. The composition of the reaction gases carbon monoxide and oxygen can be varied in broad concentration ranges. Preferably a carbon monoxide : oxygen molar ratio (normalized on carbon monoxide) of 1 :(0.001-1.0) is employed, more preferably 1 :(0.01-0.5), still more preferably l :(0.02-0.3), and yet still more preferably 1 :(0.02-0.1). A total pressure in the range of between about 0.10 - 50.66 megapascals, preferably about 0.34 - 25.33 megapascals, more preferably about 1.0 -17.23 megapascals, and yet still more preferably about 1.0 - 15.20 megapascals is typically used. The reaction gases are not subject to special purity requirements but care must be taken to ensure that no catalyst poisons such as sulfur or compounds thereof are introduced. In a preferred embodiment pure carbon monoxide and pure oxygen are used. Carbon monoxide and oxygen can be introduced as a mixture or in a preferred embodiment, carbon monoxide and oxygen may be added independently of each other. When a reactor cascade is used instead of an individual reactor, the separate oxygen addition preferably proceeds in such a way that the optimal oxygen concentration is ensured in each of the reactors. The carbon monoxide may be high-purity carbon monoxide or carbon monoxide diluted with another gas which has no negative effects on the reaction, such as nitrogen, noble gases, or argon. The oxygen used in the present invention may be high purity oxygen, air, or oxygen diluted with any other gas which has no negative effects on the reaction, such as nitrogen, noble gases, or argon. The concentration of inert gas in the reaction gas may amount to 0 to about 60 volume %, preferably 0 to about 20, and more preferably 0 to about 5 volume %. The concentration of 0 volume % represents the special case of the preferred state which is free of inert gas. Provision may be made for including a drying agent or a drying process step in the reaction. For example, drying agents, typically molecular sieves, may be present in the reaction vessel as described, for example, in U.S. Patent 5,399,734 and in co- pending application Serial No. 09/224,162, filed December 31 , 1999. Preferably, a drying process step in included in the reaction process as disclosed, for example, in U.S. Patents 5,498,472, 5,625,091, and 5,917,078; and in co-pending applications (RD-28,464, RD-28,523, RD-28524, RD-28,525, and RD-28,555), all filed December, 14, 2000, the disclosures of which are incorporated herein by reference. Reaction temperatures in the range of between about 50°C and about 150°C are preferred. Gas sparging or mixing can be used to aid the reaction. The following examples are included to provide additional guidance to those skilled in the art in practicing the claimed invention. While some of the examples are illustrative of various embodiments of the claimed invention, others are comparative. The examples provided are merely representative of the work that contributes to the teaching of the present application. Accordingly, these examples are not intended to limit the invention, as defined in the appended claims, in any manner. As discussed above, the economics of aromatic carbonate production is dependent on the number of moles of aromatic carbonate produced per mole of Group 8, 9, or 10 metal utilized. In the following examples, the aromatic carbonate produced is diphenylcarbonate (DPC) and the Group 8, 9, or 10 metal utilized is palladium. For convenience, the number of moles of DPC produced per mole of palladium charged to a reactor is referred to as the palladium turnover number (Pd TON). Another useful metric was the ratio of DPC (a desired product) to chlorophenols (undesired byproducts). In the present examples chlorophenols were not detected at the sensitivity of the gas chromatographic analytical method (less than 0.05 wt.% based on the weight of the reaction mixture). For comparison, typical bromide-containing reactions may produce around 0.5 wt.% brominated byproducts. EXAMPLES 1-19 Reaction mixtures comprised phenol solutions containing 25 ppm palladium (added as Pd(II) acetylacetonate) under a gas mixture containing 8.3 mole % oxygen in carbon monoxide at a total pressure of 8.27 megapascals. Reaction mixtures were analyzed by gas chromatography (GC) after 3 hours at 100°C. Inorganic co-catalysts comprised a lead source and either cerium (III) acetylacetonate or manganese (III) acetylacetonate. Tetrabutyl ammonium chloride or tetraethyl ammonium bromide was used as halide source. Results are shown in Table I. All reactions were run in duplicate and data are reported as the average. Although in many of the examples the Pd TON is greater for bromide than for chloride, nevertheless, the lower cost of chloride and the absence of halogenated byproducts constitutes an advantage. In Examples 8, 10, and 11 the difference in Pd TON between using chloride and using bromide is within about 20% and is not believed to be statistically significant. In Example 14 the Pd TON using chloride is significantly better than that using bromide. TABLE I EXAMPLES 20-43 Reactions were run as described for Examples 1 -19 except that 12 equivalents (based on palladium) of various trivalent lanthanide metal acetylacetonates were used as co- catalysts, unless noted. Tetrabutyl ammonium chloride (400 equivalents based on palladium) was used as chloride source. The amount of lead source was 50 equivalents based on palladium in each example. Results are shown in Table II. All reactions were run 4 times and data are reported as the average. These examples show that various lanthanide metals may be used as co-catalysts in a reaction mixture containing chloride and either an inorganic or an organic lead source. TABLE II added as hex afluoroacetyl acetonate EXAMPLES 44-55 Reactions were run as described for Examples 1-19 except that reaction mixtures comprised phenol solutions containing 20 ppm palladium (added as Pd(II) acetylacetonate), and various titanium sources were used as co-catalysts. Tetrabuty] ammonium chloride was used as chloride source. The lead source was tetraethyl lead (50 equivalents based on palladium in each example). Results are shown in Table III. All reactions were run 3 times and data are reported as the average. These examples show that a titanium source is a particularly effective co- catalyst in a reaction mixture comprising chloride and a lead source. TABLE III EXAMPLE 56 A reaction was carried out in a batch-batch regime in that no additional gas mixture was supplied. A reaction mixture contained 62.3 grams phenol; palladium acetylacetonate (24 ppm palladium); 51 equivalents lead (II) oxide; 5.9 equivalents cerium (III) acetylacetonate; and 500 equivalents tetraethylammonium chloride under a gas mixture containing 9 mole % oxygen in carbon monoxide at 8.96 megapascals. All amounts in equivalents are versus palladium. The reaction mixture also contained a desiccant (30 grams 1/16 inch 3A molecular sieves) contained in perforated TEFLON basket mounted on the stir shaft. The reaction was stirred at 1600 rpm and heated to 100°C over 10 minutes and stirred 4 hours with periodic sampling. Figure 1 shows a graph of Pd TON as a function of time. The graph shows that excellent Pd TON is obtained in the reaction mixture comprising onium chloride. It will be understood that each of the elements described above, or two or more together, may also find utility in applications differing from the types described herein. While the invention has been illustrated and described as embodied in a method and catalyst system for producing aromatic carbonates, it is not intended to be limited to the details shown, since various modifications and substitutions can be made without departing in any way from the spirit of the present invention. For example, additional effective IOCC compounds can be added to the reaction. As such, further modifications and equivalents of the invention herein disclosed may occur to persons skilled in the art using no more than routine experimentation, and all such modifications and equivalents are believed to be within the spirit and scope of the invention as defined by the following claims.

Claims: WHAT IS CLAIMED IS: 1. A carbonylation catalyst system, comprising an effective amount of at least one Group 8, 9, or 10 metal source; an effective amount of at least one onium chloride salt; and an effective amount of a combination of inorganic co-catalysts comprising at least one lead source and at least one other metal source. 2. The carbonylation catalyst system of claim 1, wherein the Group 8, 9, or 10 metal source is a palladium source. 3. The carbonylation catalyst system of claim 2, wherein the palladium source is a palladium(II) salt or complex. 4. The carbonylation catalyst system of claim 3, wherein the palladium source is palladium acetylacetonate. 5. The carbonylation catalyst system of claim 2, wherein the palladium source is palladium metal supported on an inorganic or organic support. 6. The carbonylation catalyst system of claim 5, wherein the palladium source is palladium on carbon. 7. The carbonylation catalyst system of claim 1, wherein the onium chloride salt is a sulfonium chloride, a quaternary ammonium chloride, or a quaternary phosphonium chloride. 8. The carbonylation catalyst system of claim 1, wherein the onium chloride salt is a tetraalkyl ammonium chloride. 9. The carbonylation catalyst system of claim 1 , wherein the other metal source is at least one member selected from the group consisting of a manganese source, a titanium source, and a lanthanide metal source. 10. The carbonylation catalyst system of claim 2, wherein the molar ratio of lead relative to palladium is between about 0.1 and about 150. 1 1. The carbonylation catalyst system of claim 9, wherein the molar ratio of other metal source relative to palladium is between about 0.1 and about 25. 12. The carbonylation catalyst system of claim 1 wherein the amount of halogenated byproducts produced in the preparation of aromatic carbonate is less than 0.05 wt.% based on the wt. of the reaction mixture. 13. A carbonylation catalyst system, comprising an effective amount of a palladium source; an effective amount of a tetraalkylammonium chloride salt; and an effective amount of a combination of inorganic co-catalysts comprising a lead source and at least one metal source selected from the group consisting of a manganese source, a titanium source, and a lanthanide metal source. 14. The carbonylation catalyst system of claim 13, wherein the tetraalkylammonium chloride salt is methyltributylammonium chloride, tetramethylammonium chloride, tetraethylammonium chloride, or tetrabutylammonium chloride. 15. A carbonylation catalyst system, consisting essentially of an effective amount of a palladium source; an effective amount of a tetraalkylammonium chloride salt; and an effective amount of a combination of inorganic co-catalysts comprising a lead source and at least one metal source selected from the group consisting of a manganese source, a titanium source, and a lanthanide metal source, wherein the amount of halogenated byproducts produced in the preparation of aromatic carbonate is less than 0.05 wt.% based on the wt. of the reaction mixture. 16. The carbonylation catalyst system of claim 15, wherein the tetraalkylammonium chloride salt is methyltributylammonium chloride, tetramethylammonium chloride, tetraethylammonium chloride, or tetrabutylammonium chloride. 17. A method of carbonylating aromatic hydroxy compounds, said method comprising the step of: contacting at least one aromatic hydroxy compound with oxygen and carbon monoxide in the presence of a carbonylation catalyst system comprising an effective amount of at least one Group 8, 9, or 10 metal source; an effective amount of at least one onium chloride salt; and an effective amount of a combination of inorganic co-catalysts comprising at least one lead source and at least one other metal source. 18. The method of claim 17, wherein the Group 8, 9, or 10 metal source is a palladium source. 19. The method of claim 18, wherein the palladium source is a palladium(II) salt or complex. 20. The method of claim 19, wherein the palladium source is palladium acetylacetonate. 21. The method of claim 18, wherein the palladium source is supported palladium. 22. The method of claim 21 , wherein the palladium source is palladium on carbon. 23. The method of claim 17, wherein the onium chloride salt is a sulfonium chloride, a quaternary ammonium chloride, or a quaternary phosphonium chloride. 24. The method of claim 23, wherein the onium chloride salt is a tetraalkylammonium chloride. 25. The method of claim 17, wherein the other metal source is at least one member selected from the group consisting of a manganese source, a titanium source, and a lanthanide metal source. 26. The method of claim 17, wherein the molar ratio of lead relative to palladium is between about 0.1 and about 150. 27. The method of claim 25, wherein the molar ratio of other metal source relative to palladium is between about 0.1 and about 25. 28. The method of claim 25, which further comprises a desiccant or a drying process step. 29. The method of claim 17, wherein the aromatic hydroxy compound is phenol. 30. The method of claim 17 wherein the amount of halogenated byproducts produced in the preparation of aromatic carbonate is less than 0.05 wt.% based on the wt. of the reaction mixture. 31. A method of carbonylating aromatic hydroxy compounds, said method comprising the step of: contacting at least one aromatic hydroxy compound with oxygen and carbon monoxide in the presence of a carbonylation catalyst system, comprising an effective amount of a palladium source; an effective amount of a tetraalkylammonium chloride salt; and an effective amount of a combination of inorganic co-catalysts comprising a lead source and at least one metal source selected from the group consisting of a manganese source, a titanium source, and a lanthanide metal source. 32. The method of claim 31, wherein the tetraalkylammonium chloride salt is methyltributylammonium chloride, tetramethylammonium chloride, tetraethylammonium chloride, or tetrabutylammonium chloride. 33. A method of carbonylating aromatic hydroxy compounds, said method comprising the step of: contacting at least one aromatic hydroxy compound with oxygen and carbon monoxide in the presence of a carbonylation catalyst system, consisting essentially of an effective amount of a palladium source; an effective amount of a tetraalkylammonium chloride salt; and an effective amount of a combination of inorganic co-catalysts comprising a lead source and at least one metal source selected from the group consisting of a manganese source, a titanium source, and a lanthanide metal source, wherein the amount of halogenated byproducts produced in the preparation of aromatic carbonate is less than 0.05 wt.% based on the wt. of the reaction mixture. 34. The method of claim 33, wherein the tetraalkylammonium chloride salt is methyltributylammonium chloride, tetramethylammonium chloride, tetraethylammonium chloride, or tetrabutylammonium chloride.

Inventors: JOHNSON BRUCE FLETCHER, SHALYAEV KIRILL VLADIMIROVICH, WHISENHUNT DONALD WAYNE JR, JOHNSON, BRUCE, FLETCHER, SHALYAEV, KIRILL, VLADIMIROVICH, WHISENHUNT, DONALD, WAYNE, JR.
Applicants: GEN ELECTRIC, GENERAL ELECTRIC COMPANY
Application year: 2001
Main classification: C07C68
IPC codes: B01J31, C07B61, C07C68, C07C69