Rpc, Inc.

Twenty-First Century Research Corporation

University of Michigan

Ader M Rostami

Eustathios Vassiliou

Mark W Dassel

David C DeCoster

Sharon M Aldrich

Douglas J Dudgeon

This invention relates to methods of controlling the oxidation of cyclohexane to adipic acid in the presence of a monobasic acid solvent, by extracting the catalyst from the reaction mixture, outside the reaction zone. Substantially all the unreacted cyclohexane, the majority of adipic acid, and preferably substantially all the monobasic acid solvent are removed from the reaction product. In the case that substantially all the monobasic acid solvent is removed, protic solvent, is added intermittently or continuously in the reaction mixture during the removal of the monobasic acid solvent, preferably by distillation, thus preventing solids precipitation. Dipolar aprotic solvent is then added in the presence of an adequate amount of the protic solvent (the total of dipolar aprotic solvent and the protic solvent constituting a novel combination solvent) to maintain a single liquid phase, followed by a step of extracting substantially all the catalyst in protic solvent. The catalyst extract is preferably recycled to the reaction zone, where the cyclohexane is oxidized to adipic acid. Thus, the novel combination solvent, which is preferably a combination of cyclohexanone with water, allows the dissolution of the reaction product, preferably after removal of the majority of the adipic acid, followed by a substantially complete extraction of the catalyst in water. No catalyst precipitation takes place, and all disadvantages and costs of solids handling are prevented.

Methods of extracting catalyst from a reaction mixture in the oxidation of cyclohexane to adipic acid

This invention relates to methods of controlling the oxidation of cyclohexane to adipic acid in the presence of a monobasic acid solvent, by separating the catalyst from the reaction mixture, outside the reaction zone. Substantially all the unreacted cyclohexane, the majority of adipic acid, and substantially all the monobasic acid solvent are preferably removed. A protic solvent, may be added intermittently or continuously in the reaction mixture during the removal of the monobasic acid solvent, preferably by distillation, for preventing solids precipitation. A dipolar aprotic solvent is then added in the presence of an adequate amount of the protic solvent to maintain a single liquid phase, followed by a step of formation of two liquid phases, a solids-free protic liquid phase containing substantially all the catalyst, and a solids-free aprotic liquid phase containing at least the majority of ingredients of the reaction mixture. The formation of the two phases is performed by a process selected from a group consisting of lowering the first temperature to a second temperature, adding additional protic solvent, adding an apolar aprotic solvent, and a combination thereof.

Methods of separating catalyst in solution from a reaction mixture produced by oxidation of cyclohexane to adipic acid

This invention relates to methods of replacing water and cyclohexanone with acetic acid in an aqueous solution of catalyst, preferably a cobalt compound. Such an aqueous solution is produced by extracting catalyst with water from a cyclohexanone/water solution of reaction products made by the direct oxidation of cyclohexane to adipic acid. The replacement of both water and cyclohexanone are conducted in a solvent exchange column, wherein acetic acid dissolves the catalyst, while water vapors force the cyclohexanone into a condenser, followed by a decanter wherein two liquid phases may be formed and separated; an upper liquid phase containing a majority of cyclohexanone and a lower liquid phase containing a majority of water. The cyclohexanone may be removed in a pretreatment zone, wherein also part of the water may be removed, before the concentrated catalyst extract enters the solvent exchange column.

Methods and replacing water and cyclohexanone with acetic acid in aqueous solutions of catalyst

Methods and devices for controlling the reaction of a hydrocarbon to an acid by making phase-related adjustments are disclosed. In order to improve reaction rate and reactivity of the oxidation, a single phase at the operating temperature is attained and maintained by adjusting one or more of gaseous oxidant flow rate, pressure in the reaction zone, temperature in the reaction zone, feed rate of hydrocarbon, feed rate of solvent, feed rate of water if water is being fed, feed rate of the catalyst and other parameters. Methods and devices are also disclosed, wherein a hydrocarbon is reacted at a steady state with a gaseous oxidant to form an acid in a liquid mixture. The amount of water is maintained between a maximum level of water, over which maximum level the substantially single liquid phase is transformed to two liquid phases, and a minimum level under which catalyst precipitates. Further, methods are disclosed, wherein the temperature of the mixture is lowered to a point at which solid dibasic acid is precipitated, while maintaining a single liquid phase, and optionally all the catalyst in solution. At least part of the formed acid is then removed. The preferred hydrocarbon is cyclohexane, the preferred acid is adipic acid, the preferred solvent is acetic acid, and the preferred catalyst is cobalt(II) acetate tetrahydrate.

Methods and devices for oxidizing a hydrocarbon to form an acid

This invention relates to monitors used in the oxidation of hydrocarbons to respective acids, which monitors are capable to detect formation of a second liquid phase in the reaction mixture. The reactions are conducted in a single liquid phase, and formation of a second liquid phase is highly undesirable. The information gathered by the detector is provided to a controller, which controller in turn takes measures to re-establish operation of the reaction in a single liquid phase.

Device for detecting formation of a second liquid phase

This invention relates to methods and reactor devices for controlling the oxidation of hydrocarbons to dibasic acids, in the presence of a cobalt catalyst and a monobasic acid, such as acetic acid, by treating the catalyst from the reaction mixture, outside the oxidation zone, after the oxidation has taken place at least partially. In one preferred embodiment, the catalyst is reduced to contain, preferably predominantly and more preferably substantially, cobalt ions in valence II, and at least partially precipitated by de-watering and/or thermal treatment. In a different preferred embodiment, the catalyst in the reaction mixture is first oxidized or maintained, preferably predominantly and more preferably substantially, at valence III, the reaction mixture is de-watered, the catalyst is reduced preferably predominantly and more preferably substantially, to valence II, causing precipitation either spontaneously at a predetermined temperature or after further thermal treatment. The precipitated catalyst is preferably recycled directly or indirectly.

Methods for treating cobalt catalyst in oxidation mixtures resulting from oxidation of hydrocarbons to dibasic acids

This invention relates to oxidative methods for controlling the oxidation of a class of compounds, including hydrocarbons, such as cyclohexane for example, alcohols, such as cyclohexanol for example, ketones, such as cyclohexanone for example, and peroxides, such as cyclohexylhydroperoxide for example, to intermediate oxidation products, such as adipic acid for example, by the removing the catalyst, such as cobalt compounds for example, from the oxidation mixture, outside the oxidation zone, after the oxidation has taken place at least partially. The catalyst is at least partially precipitated by following the steps of changing the temperature to be within a specific range, and sequentially reducing the water level to such a degree that causes the catalyst to precipitate. The precipitated catalyst is thereafter preferably filtered from the oxidation mixture and recycled to the oxidation zone.

Methods for removing catalyst after oxidation of hydrocarbons

Methods and devices for controlling the reaction rate and/or reactivity of a hydrocarbon to an intermediate oxidation product, such as an acid, within predetermined limits, are disclosed. Control of the reaction rate and/or reactivity within predetermined limits is achieved by monitoring and controlling the oxidant consumption rate. According to the present invention, examples of ways to determine the oxidant consumption rate include, but are not limited to, monitoring the flow rates of incoming and outgoing oxidant, monitoring pressure differentials after temporarily ceasing entry and exit of gases, and monitoring the flow rates of incoming and outgoing gases, and monitoring the rates of incoming and outgoing hydrocarbon. The methods and devices of the present invention are particularly advantageous in the case that the hydrocarbon is cyclohexane, the intermediate oxidation product is adipic acid, the solvent is acetic acid, the catalyst is cobalt (II) acetate tetrahydrate, and the initiator or promoter is cyclohexane, or acetaldehyde, or a mixture of thereof.

Methods and devices for controlling the reaction rate and/or reactivity of hydrocarbon to an intermediate oxidation product by adjusting the oxidant consumption rate

Methods for controlling the reaction rate of a hydrocarbon to an acid by making phase-related adjustments are disclosed. In order to improve reaction rate of the oxidation, a single phase at the operating temperature is attained and maintained by adjusting one or more of gaseous oxidant flow rate, pressure in the reaction zone, temperature in the reaction zone, feed rate of hydrocarbon, feed rate of solvent, feed rate of water if water is being fed, feed rate of the catalyst. The preferred hydrocarbon is cyclohexane, the preferred acid is adipic acid, the preferred solvent is acetic acid, and the preferred catalyst is cobalt acetate. Other hydrocarbons include, but are not limited to, methylated benzene, methylated structures involving two benzene rings, and methylated naphthalene.

Methods for controlling the reaction rate of a hydrocarbon to an acid by making phase-related adjustments

This invention relates to methods and reactor devices for controlling the oxidation of hydrocarbons to dibasic acids, in the presence of a cobalt catalyst and a monobasic acid, such as acetic acid, by treating the catalyst from the reaction mixture, outside the oxidation zone, after the oxidation has taken place at least partially. In one preferred embodiment, the catalyst is reduced to contain, preferably predominantly and more preferably substantially, cobalt ions in valence II, and at least partially precipitated by de-watering and/or thermal treatment. In a different preferred embodiment, the catalyst in the reaction mixture is first oxidized or maintained, preferably predominantly and more preferably substantially, at valence III, the reaction mixture is de-watered, the catalyst is reduced, preferably predominantly and more preferably substantially, to valence II, causing precipitation either spontaneously at a predetermined temperature or after further thermal treatment. The precipitated catalyst is preferably recycled directly or indirectly.

This invention relates to methods of controlling the oxidation of cyclohexane to adipic acid in the presence of a monobasic acid solvent, by removing the catalyst from the reaction mixture, outside the reaction zone. Substantially all the unreacted cyclohexane along with at least the majority of the monobasic acid solvent are removed. A substantially non-solvent for the catalyst (first constituent), and water are added into the resulting mixture, in such amounts as to maintain one solids-free single liquid phase. This process is highly facilitated in the presence of considerable amounts of adipic acid. The catalyst may then be extracted with water from the solids-free single liquid phase. A water phase containing dissolved catalyst may also be formed by addition of small amounts of a solvent which is substantially non-solvent for the catalyst and substantially non-solvent for the dibasic acids (second constituent), and/or dropping the temperature. Adipic acid may be precipitated after catalyst removal with further addition of second constituent and/or dropping the temperature.

Methods of recovering catalyst in solution in the oxidation of cyclohexane to adipic acid

Devices for controlling the reaction rate of a hydrocarbon to an acid or other intermediate oxidation product by pressure drop rate adjustments. The devices incorporate a reaction chamber, different means for monitoring miscellaneous parameters, means for feeding ingredients including gases, means for exiting products and gases, means for stopping the feeding and exiting of gases at predetermined time intervals, means for measuring the pressure drop rate during the period that the feeding and exiting of gases takes effect, and a controller, the function of which is to conduct adjustments in one or more of temperature, feeding rates of hydrocarbon, solvent, catalyst, promoter, and the like until the pressure drop rate and the reaction rate fall within desirable predetermined limits.

Devices for controlling the reaction rate of a hydrocarbon to an intermediate oxidation product by pressure drop adjustments

This invention relates to methods and devices for removing acetic acid from cyclohexane in the direct oxidation of cyclohexane to adipic acid, especially after recycling catalyst which is precipitated by introduction of additional cyclohexane. The removal of acetic acid is preferably conducted by use of rather small amounts of wash-water in one to three stage extractors. A two stage reactor is preferable as being more efficient.

Devices for removing acetic acid from cyclohexane in the production of adipic acid

This invention relates to methods of preparing dibasic acids, such as adipic acid for example, by oxidizing a hydrocarbon with a gas containing an oxidant, preferably oxygen. A respective hydrocarbon is reacted with a gaseous oxidant to form dibasic acid in a mixture which preferably contains a solvent, a catalyst, and an initiator. The temperature of the mixture is then lowered to a point at which solid dibasic acid is precipitated, while maintaining a single liquid phase. At least part of the formed acid is then removed. The lowering of the temperature is preferably performed at least partially by an operation selected from a group consisting of (a) evaporating at least part of the hydrocarbon or otherwise adjusting the hydrocarbon content of the mixture (b) lowering the pressure (c) adding matter having a temperature lower than the initial temperature (d) removing heat by external means (e) removing a first amount of heat by any suitable means, and adding a second amount of heat by external means, the first amount of heat being greater than the second amount of heat, and (f) a combination thereof.

Methods for preparing polymers from dibasic acids

This invention relates to methods for controlling the oxidation of hydrocarbons to intermediate oxidation products, such as adipic acid for example, by removing the catalyst from the reaction mixture, outside the reaction zone, after the oxidation has taken place at least partially. The catalyst is at least partially precipitated by reducing the water level in the reaction mixture and subjecting the reaction mixture to a temperature, at which or over which catalyst precipitates.

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Bainbridge Island, WA, United States of America

Ader M Rostami