EP1196367A1 - Procede de preparation d'acide adipique - Google Patents

Procede de preparation d'acide adipique

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Publication number
EP1196367A1
EP1196367A1 EP99935040A EP99935040A EP1196367A1 EP 1196367 A1 EP1196367 A1 EP 1196367A1 EP 99935040 A EP99935040 A EP 99935040A EP 99935040 A EP99935040 A EP 99935040A EP 1196367 A1 EP1196367 A1 EP 1196367A1
Authority
EP
European Patent Office
Prior art keywords
cyclohexane
adipic acid
catalyst
reaction mixture
oxygen
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP99935040A
Other languages
German (de)
English (en)
Inventor
Sanjeev Futurica Petrochemicals MALL (P) Ltd
SREERAMAGIRI SIVA Futurica Petroch.(P) Ltd KUMAR
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Chemintel India Pvt Ltd
Original Assignee
Chemintel India Pvt Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Chemintel India Pvt Ltd filed Critical Chemintel India Pvt Ltd
Publication of EP1196367A1 publication Critical patent/EP1196367A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/16—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation
    • C07C51/31—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation of cyclic compounds with ring-splitting
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/16—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation
    • C07C51/31—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation of cyclic compounds with ring-splitting
    • C07C51/313—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation of cyclic compounds with ring-splitting with molecular oxygen

Definitions

  • the present invention relates to process for the formation of adipic acid from cyclohexane and the adipic acid thus formed.
  • the invention resides in the use of pure molecular oxygen as an oxidant which results in providing higher selectivity towards the formation of adipic acid.
  • the object of the invention is to increase the selectivity and the yield of adipic acid from cyclohexane.
  • the product selectivities using the process of the present invention have been found to be at least 5% higher than the maximum attainable using the hitherto known conventional processes.
  • the process of the present invention employs use of preactivated catalyst in the reactor for carrying out the reaction.
  • Adipic acid is widely used in the manufacture of polyesters, polyamides, plasticizers and the like.
  • Conventionally adipic acid is known to be produced by two step oxidation of cyclohexane.
  • KA oil is produced from cyclohexane by air oxidation which is then oxidized by nitric acid to dicarboxylic acids such as adipic acid, glutaric acid and succinic acid.
  • This process suffers from various disadvantages, especially relating to low conversion per pass of the hydrocarbon in the first step (3-8%), leading to large recycle; use of nitric acid in the second step leading to NOx pollution; and formation of byproducts like lactones which pose difficulties in the downstream use of adipic acid.
  • one step oxidation of cyclohexane has been tried over the years.
  • Air is used as an oxidant in one step oxidation of cyclohexane.
  • the catalysts mostly used in the oxidation of cyclohexane are cobalt and its mixture with other metals like iron.
  • in-situ activation of the catalyst from cobaltous to cobaltic state is carried out with the help of activators like aldehydes and ketones.
  • U.S. Pat. No. 2,589,648 describes a single-step oxidation process wherein acetone is used in the place of acetic acid as solvent.
  • U.S. Pat. No. 3,231 ,608 describes a similar process, suggesting that molar ratios of solvent to saturated cyclic hydrocarbon in the range of 1 :5: 1 to 7:1 (or more) are suitable but that molar ratios below or above this range give unsatisfactory results.
  • U.S. Pat No. 4,032,569 teaches a process for converting cyclohexane to adipic acid which involves oxidizing cyclohexane with molecular oxygen in the presence of critical amounts of cobaltic ions, which is mentioned to be in the range of 25 to 150 millimols per mole of cyclohexane charged. Catalyst activation is in situ during the initial induction period.
  • U.S. Pat. No. 4,902,827 discloses a process for the production of adipic acid from cyclohexane in the presence of cobalt and zirconium and/or hafnium catalyst using air.
  • U.S. Pat. No. 5,221 ,800 also discloses a process for producing adipic acid from cyclohexane but with intermittent addition of water. It is claimed that water, if present during the induction period, depletes the concentration of free radicals which are so essential for catalyst activation. It is shown that water addition after the induction period is more advantageous and results in a selectivity of about 88%. However this selectivity calculation is based only on the identifiable compounds. The true selectivity with all other compounds considered is not given.
  • U.S. Pat. No. 5,321,157 revisits the cobalt catalysed oxidation.
  • Patent Application WO-A-94/07834 and U.S. Pat. No. 5,463,1 19 disclose a process which develops the stage for the purification of the final mixture. This treatment consists in separating the diacid formed, by cooling the mixture in order to bring about precipitation of the diacid, and in separating by filtration the diacid from two liquid phases, a non-polar one which is recycled, and a polar one which is also recycled after an optional hydrolysis and a separation of an additional amount of diacid.
  • U.S. Pat. No. 5,756,837 is similar to this patent but discloses a process for recycling a catalyst containing cobalt including treating a reaction mixture obtained during the direct oxidation of cyclohexane to adipic acid by extracting at least some of the glutaric acid and succinic acid which are formed in the reaction.
  • U.S. Pat. No. 5,547,905 a patent by the same applicant as of the present invention, describes a process for adipic acid production by one-step oxidation in the presence of a novel Co-Fe catalyst. In this patent, a new catalyst activation step is disclosed and use of pure oxygen as oxidant is mentioned. In this work conversion of cyclohexane is taken upto 70% in about 4 to 6 hours.
  • Average selectivity to adipic acid is about 75%>.
  • This patent also shows that the Co-Fe catalyst can be used successfully for the oxidation of other hydrocarbon like xylenes, toluenes and cyclopentane to their corresponding dicarboxylic acid.
  • the present invention relates to one-step oxidation of cyclohexane to adipic acid, using molecular oxygen, in liquid phase and in the presence of a catalyst, containing either cobalt or cobalt and iron.
  • a catalyst containing either cobalt or cobalt and iron.
  • the process of the present invention highlights that the use of any dilute oxygen results in lower production rates and over-oxidation of cyclohexane thereby reducing the economics of the process.
  • Figure 1 presents a graph highlighting the effect of source of oxygen on selectivity at different conversions.
  • Figure 2 depicts a graph highlighting the effect of temperature and source of oxygen on unrecoverable CH.
  • the present invention relates to a process for the preparation of adipic acid by one step oxidation of cyclohexane.
  • the main embodiment of the present invention resides in the enhanced selectivity towards adipic acid as a result of the process employed for the conversion of cyclohexane.
  • the present invention relates to a process for producing adipic acid from cyclohexane using pre-activated catalyst system and molecular oxygen for oxidation which results in an increase in the production rate as the induction period is eliminated. Further, in an another embodiment of the present invention, the activation of the catalyst is carried out at atmospheric pressure outside the reactor which reduces the capital cost. In yet another embodiment of the present invention selectivity to adipic acid is greatly enhanced by restricting the conversion of cyclohexane to below 30%.
  • the intermediate formation as well as by product formation is greatly reduced by the process of the present invention, i.e., the concentration of intermediates like cyclohexanol is insignificant, at the same time the formation of the side products like succinic acid is also very less when molecular oxygen is used instead of any oxygen containing gas like air.
  • the process of the present invention uses molecular oxygen instead of air or dilute oxygen showing a profound beneficial effect on selectivity, restricts the conversion to below 30%) so that formation of succinic acid and glutaric acid is reduced and uses pro- activated Co or Co-Fe catalyst.
  • the oxidation reaction for the process of the present invention is carried out in a gas-liquid stirred reactor.
  • the reaction mixture is in liquid phase through which the gases arc bubbled at space velocities in the range of 15 to 50 hr ' 1 .
  • the liquid is well stirred so as to ensure that the liquid phase is homogeneous and also that above 90% of the oxygen sent in is consumed in the reactor by recirculating the gas bubbles several times in the reactor.
  • the oxygen gas coming out of the liquid is diluted with nitrogen gas such that the gas phase concentration of oxygen is less than 5%.
  • the out going gases are cooled to condense the organic compounds being carried away.
  • the condensed organics are returned to the reactor.
  • the gas is vented out after measuring the oxygen and carbon dioxide concentrations.
  • the reactor is provided with external heating coil for heating the reaction liquid and internal cooling coils to maintain the liquid temperature at the desired level.
  • the reaction can be carried out in batch mode or continuous mode in this reactor.
  • the process of the present invention employs use of salts of Co or Co-Fe as a catalyst where the acid part of the catalyst is selected from the group consisting of acetate, propionate, naphthenate, adipate and phthalate.
  • the catalyst Prior to use in the process for the oxidation of cyclohexane to adipic acid, the catalyst, with desired amounts of iron is activated to cobaltic-ferric form by bubbling oxygen through a solution of cobaltous-iron acetate in acetic acid, in the presence of ketones such as methyl ethyl ketone or cyclohexanone or aldehydes like acetaldehyde as promoters, at temperature in the range between 90-1 30°C and at atmospheric pressure.
  • ketones such as methyl ethyl ketone or cyclohexanone or aldehydes like acetaldehyde as promoters
  • the catalyst should be present in the ratio of 0.01 to 0.1 (mole ratio) to cyclohexane for the reaction to proceed optimally.
  • the activated catalyst is thereafter stored at room temperature.
  • the process of the present invention employs use of solvent and cyclohexane in the ratio of 1 .5: 1 to 6.5: 1 by weight.
  • the catalyst concentration is varied in the range from 0.01 to 0.1 molar ratio with cyclohexane.
  • Activator is ranging from 0.5 to 1.0 molar ratio with catalyst.
  • Oxygen flow rate is such that at least 90% oxygen is consumed in the reaction system. For the range of parameters studied this translates to a space velocity of 15 to 50hr " ' .
  • Temperature is varied in the range of 90 to 1 10°C. Pressure of the system is maintained in the range of 15 to 35 kg/cm 2 or 200 to 500 lb. per sq. inch.
  • the oxidation of cyclohexane is carried out at desired temperature and pressure, in the presence of an activated catalyst.
  • the activated catalyst in acetic acid and cyclohexane is prepared earlier and transferred to the reactor.
  • the reactor is pressurized to desired pressure using nitrogen.
  • the temperature of the reaction mixture is gradually raised to the desired temperature and maintained constant. Oxygen is bubbled through the reaction mixture during the entire reaction process.
  • the oxidation reaction time is measured from the moment the liquid temperature reaches the desired value.
  • the reaction mixture at the end of the oxidation contains, among others, acetic acid, cyclohexane, water, cobalt catalyst and all the oxidation products such as adipic acid, glutaric acid, succinic acid reaction intermediates and esters of diacids.
  • the oxidation products are separated from acetic acid the solvent, cyclohexane, water and catalyst. This is achieved by first distilling off the volatiles from the reaction mixture. After all the acetic acid is removed, the residue is a mixture of oxidation products and catalyst Co-Fe acetate. The separation of these two is achieved by extracting the oxidation products with a suitable solvent like acetone or methyl ethyl ketone.
  • the catalyst is filtered off and dried to be reused.
  • the oxidation products are recovered from acetone by evaporating acetone and drying.
  • This product mixture contains adipic acid and other organic compounds. These arc analyzed by Gas chromatography and the selectivity of cyclohexane converted to adipic acid is measured. Pure adipic acid is obtained from the mixture in the purification section in repeated crystallizations from solvents like water, acetic acid, methanol and the like.
  • Acetic acid recovered from the reaction section contains water produced during the oxidation reaction. The water is removed by distillation and the pure acetic acid is recycled to the reactor.
  • the oxidation products are in solid state when recovered by the above said procedure. These are derivated and analysed in gas chromatography as liquid samples to obtain the product distribution. This is achieved by forming methyl esters of the products and dissolving them in ether. This liquid solution is injected in gas chromatography with FID detector.
  • a product like monocyclohexyl adipate a stable compound formed during the oxidation by the reaction of cyclohexanol (an intermediate) and adipic acid, is converted to di-methyl adipate which is same as that formed by methylation of free adipic acid formed in the reaction.
  • both these different compounds give a peak at the same retention time and appear as same compound in the gas chromatogram. Therefore, the product distribution is not correctly obtained by this method leading to an erroneous over-estimate of the selectivity to adipic acid.
  • the other method is the diazo method which ensures that the esterification is complete. There are no strong acid catalysts and this reaction is essentially irreversible.
  • esters, of the di-acids with reaction intermediates like cyclohexanol remain unaltered. These are not converted to di-methyl esters of adipic acid and thus appear as separate peaks in the gas chromatogram.
  • a comparative analysis of results from diazo method and methanol method is clearly brought out in the following table which shows the weight percentage of various components in the oxidation product in a typical run.
  • the ester of adipic acid and alcohol intermediates is separately estimated in the diazo method where as by the methanol method they are all clubbed in adipic acid peak.
  • the diazo method estimates the adipic acid weight fraction as 75% while the methanol method estimates 92%).
  • the prior art is known to have used the methanol method and reports selectivity in the range of 80 to 88%>. But as illustrated here the actual product distribution is likely to be very different.
  • the diazo method has been used to analyse the products of the present invention.
  • the process of the present invention provides higher selectivity towards oxidation.
  • the percentage of glutaric acid and succinic acid formed in the present work is much less than the values hitherto reported by the conventional processes.
  • the intermediates like cyclohexanone and cyclohexanol are not present in the subject product mixture. It means that the process of the present invention provides a faster rate of conversion of compounds which are precursors to adipic acid but slower rate of oxidation of cyclohexane to acids which form after adipic acid, thereby maximizing the conversion to adipic acid.
  • the present invention relates to a process for preparation of adipic acid from cyclohexane comprising forming a reaction mixture in liquid phase of cyclohexane and preactivated catalyst in a gas liquid stirred reactor; bubbling pure molecular oxygen in the said liquid phase reaction mixture at a space velocity of 15-50 hr " ', at a temperature in the range of 90-1 10°C and a pressure in the range of 15-35 Kg/cm while stirring the said reaction mixture so as to ensure that the said liquid phase reaction mixture is homogenous and also that above 90% > of the pure oxygen is consumed in the reactor by recirculating the gas bubbles several times in the said reactor thereby forming a reaction mixture including oxidation products, cyclohexane, water and catalyst; diluting the unreacted oxygen gas coming out of the said homogenous liquid with nitrogen
  • the present invention relates to a process for preparation of adipic acid from cyclohexane comprising forming a reaction mixture in liquid phase of cyclohexane and preactivated catalyst in a gas liquid stirred reactor; bubbling pure molecular oxygen in the said liquid phase reaction mixture at a space velocity of 15-50 hr '1 , at a temperature in the range of 90-1 10°C and a pressure in the range of 15-35 Kg/cm 2 while stirring the said reaction mixture so as to ensure that the said liquid phase reaction mixture is homogenous and also that above 90% of the pure oxygen is consumed in the reactor by recirculating the gas bubbles several times in the said reactor thereby forming a reaction mixture including oxidation products, cyclohexane, water and catalyst; diluting the unreacted oxygen gas coming out of the said homogenous liquid with nitrogen such that the gas phase concentration of oxygen is less than 5%o followed by cooling to condense the organic compounds being carried away along with the unreacted oxygen gas, and,
  • Conversion is the percentage of cyclohexane from that charged converted to products.
  • Selectivity is the ratio of moles of cyclohexane going towards forming the desired product divided by the total moles of cyclohexane reacted.
  • 63g cobalt acetate and 3 g iron acetate are dissolved in 2060 g acetic acid and activated in the presence of cyclohexanone of about 15 g.
  • the activated catalyst along with acetic acid is mixed with 480 g cyclohexane and charged to the gas-liquid stirred reactor.
  • the reaction mixture is pressurized to 20 kg/cm total pressure using nitrogen and heated to 100°C. Air is bubbled through the agitated liquid at an hourly space velocity of 35 hr. "1 .
  • the reaction is carried out for 500 minutes.
  • the reaction mixture is cooled and products recovered. Total weight of product recovered is 289g. Conversion of cyclohexane is 43%.
  • 63g cobalt acetate and 3 g iron acetate are dissolved in 2060 g acetic acid and activated in the presence of cyclohexanone of about 15 g.
  • the activated catalyst along with acetic acid is mixed with 480 g cyclohexane and charged to the gas-liquid stirred reactor.
  • the reaction mixture is pressurized to 20 kg/cm 2 total pressure using nitrogen and healed to I OO°C. ⁇ ir is bubbled through the agitated liquid al an hourly space velocity of 35 hr. " .
  • the reaction is carried out for 500 minutes.
  • the reaction mixture is cooled and products recovered. Total weight of product recovered is 289g. Conversion of cyclohexane is 43%.
  • 66g cobalt acetate is dissolved in 2060 g acetic acid and activated in the presence of cyclohexanone of about 15g.
  • the activated catalyst along with acetic acid is mixed with 480g cyclohexane and charged to the gas-liquid stirred reactor.
  • the reaction mixture is pressurized to 20 kg/cm total pressure using nitrogen and healed to 90°C.
  • Oxygen is bubbled through the agitated liquid at an hourly space velocity of 20 hr "1 .
  • the reaction is carried out for 120 minutes.
  • the reaction mixture is cooled and products recovered. Total weight of product recovered is 142g. Conversion of cyclohexane is 21 %.
  • the one-step oxidation of cyclohexane to adipic acid is carried out in the presence of pre-activatcd catalyst (Co-Fe) using molecular oxygen.
  • pre-activatcd catalyst Co-Fe
  • Analysis method using esterification by diazomethane of the reaction products provides an accurate picture of the product distribution as compared to methanol method which though widely employed, leads to gross overestimation of the selectivity to adipic acid.
  • Selectivity to adipic acid is obtained to be greater than 90% with oxygen as the oxidant and with preactivated catalyst when the conversion of Cyclohexane is restricted to 20-30%.
  • Amount of glutaric and succinic acid, the lower homologous molecules formed is less than any of the conventionally known processes.
  • the present invention relates to a process where formation of the cyclohexane unrecoverable is less than any of the earlier works. This greatly improves the economics of the process.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)

Abstract

La présente invention concerne un procédé d'oxydation en une seule étape, utile pour transformer un cyclohexane en acide adipique au moyen d'oxygène moléculaire, en phase liquide, en présence d'un catalyseur contenant du cobalt ou du cobalt et du fer. Le catalyseur est activé à l'extérieur du réacteur et l'oxygène moléculaire est utilisé comme oxydant. L'utilisation d'oxygène moléculaire comme oxydant conjointement avec un catalyseur préactivé dans le réacteur, ainsi que la limitation de la conversion de cyclohexane à un taux compris entre 20 et 30 % à l'aide du catalyseur dans le réacteur permettent d'obtenir une sélectivité renforcée pour l'acide adipique. Le mélange réactionnel de cyclohexane et du catalyseur préactivé est soumis à une oxydation par bullage d'oxygène moléculaire pur avec agitation du mélange homogène ; le bullage de l'oxygène est mis en oeuvre dans des conditions de température, de pression et de vitesse spatiale prédéterminées. La sélectivité du produit à former de l'acide adipique est meilleure de 5 % au moins par rapport au maximum pouvant être atteint par des procédés classiques.
EP99935040A 1999-06-25 1999-06-25 Procede de preparation d'acide adipique Withdrawn EP1196367A1 (fr)

Applications Claiming Priority (1)

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PCT/IN1999/000027 WO2001000555A1 (fr) 1999-06-25 1999-06-25 Procede de preparation d'acide adipique

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EP1196367A1 true EP1196367A1 (fr) 2002-04-17

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JP (1) JP2003503375A (fr)
KR (1) KR20020037729A (fr)
WO (1) WO2001000555A1 (fr)

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Publication number Priority date Publication date Assignee Title
EP2441747A1 (fr) 2010-10-15 2012-04-18 Petrochemicals Research Institute King Abdulaziz City for Science and Technology Procédé de préparation d'acides dicarboxyliques à partir d'hydrocarbures saturés linéaires ou cycliques par oxydation catalytique
CN102040504B (zh) * 2010-10-29 2013-04-10 华南理工大学 用填充磁性铁粒子的碳纳米管为催化剂制备己二酸的方法
CN109456167A (zh) * 2018-12-20 2019-03-12 福州大学 一种使用微通道反应器由环己酮合成己二酸的方法
CN112441904B (zh) * 2019-09-04 2023-04-07 中国石油化工股份有限公司 环己烷直接氧化法制己二酸工艺分离和母液回用的连续方法
CN112742366B (zh) * 2019-10-29 2023-06-09 中国石油化工股份有限公司 纳米碳基材料及其制备方法和环烷烃的催化氧化方法
CN113457687B (zh) * 2020-03-31 2023-08-08 中国石油化工股份有限公司 一种纳米材料及其制备方法和环烷烃的催化氧化方法
CN114426473A (zh) * 2020-10-14 2022-05-03 中国石油化工股份有限公司 环己烷直接氧化制备己二酸的方法
CN114057567B (zh) * 2021-12-13 2024-01-26 大连普莱瑞迪化学有限公司 一种异辛酸的无碱氧化生产工艺

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US3231608A (en) * 1961-08-28 1966-01-25 Gulf Research Development Co Preparation of dibasic acids
US4032569A (en) * 1975-07-14 1977-06-28 Gulf Research & Development Company Process for converting cyclohexane to adipic acid
TW238299B (fr) * 1992-09-25 1995-01-11 Bayer Ag
US5547905A (en) * 1994-07-27 1996-08-20 Council Of Scientific & Industrial Research Catalyst and a process for preparing carboxylic acids using the catalyst

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Title
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KR20020037729A (ko) 2002-05-22
JP2003503375A (ja) 2003-01-28

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