WO1998007512A1 - Wet oxidation processing of a solution or suspension of organic compounds - Google Patents

Wet oxidation processing of a solution or suspension of organic compounds Download PDF

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Publication number
WO1998007512A1
WO1998007512A1 PCT/FR1997/001506 FR9701506W WO9807512A1 WO 1998007512 A1 WO1998007512 A1 WO 1998007512A1 FR 9701506 W FR9701506 W FR 9701506W WO 9807512 A1 WO9807512 A1 WO 9807512A1
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Prior art keywords
catalyst
solution
suspension
ruthenium
active phase
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PCT/FR1997/001506
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French (fr)
Inventor
Pascal Isnard
Stéphane CHAUMET
Pierre Gallezot
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Rhodia Chimie
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Application filed by Rhodia Chimie filed Critical Rhodia Chimie
Priority to AU40195/97A priority Critical patent/AU4019597A/en
Publication of WO1998007512A1 publication Critical patent/WO1998007512A1/en

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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F11/00—Treatment of sludge; Devices therefor
    • C02F11/06—Treatment of sludge; Devices therefor by oxidation
    • C02F11/08—Wet air oxidation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/18—Carbon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • B01J23/46—Ruthenium, rhodium, osmium or iridium
    • B01J23/462—Ruthenium
    • B01J35/615—

Definitions

  • the present invention relates to a wet oxidation process of a solution or suspension of organic and / or nitrogenous compounds, in particular for reducing the chemical oxygen demand (COD) to a determined level.
  • COD chemical oxygen demand
  • CIBA-GEIGY has developed a wet oxidation process using air as the oxidant, the temperature range is 250-300 ° C, the pressure being between 50 and 200 bars. This oxidation is carried out in the presence of a catalyst composed of copper salts. On the basis of this process, many companies have proposed new catalytic systems making it possible to reduce the reaction times and / or to lower the temperature or pressure conditions.
  • the company OSAKA GAS describes in French patent 2,361,308 the use of ruthenium oxide as a catalytically active phase.
  • This active phase is deposited on a support conventionally used in heterogeneous catalysis, such as alumina, silica or activated carbon.
  • the reaction is carried out under a pressure between 70 and 90 bars and a temperature between 250 and 280 ° C, the reaction times are then between 1 and 3 hours.
  • the company NIPPON SHOKUBAI has also proposed catalysts comprising as active phase metals such as palladium or platinum, supported on supports comprising in particular rare earth oxides such as cerium oxide.
  • One of the aims of the present invention is to propose a new catalytic system making it possible to accelerate the reaction at pressure and temperature conditions similar or lower than those used in the known processes.
  • the invention provides a new oxidation catalyst comprising a catalytically active phase supported on a support, characterized in that the support is a graphite.
  • the graphite used here has, according to a preferred characteristic of the invention, a specific surface of at least 10 m 2 / g, preferably greater than 100 m 2 / g and more advantageously greater than 250 m 2 / g
  • specific surface means the BET specific surface area determined by nitrogen adsorption in accordance with standard ASTM D 3663-78 established on the basis of the BRUNAUER - EMMETT-TELLER method described in the periodical "The Journal of the American Society, 6_0_, 309 (1938) ".
  • the catalytically active phase comprises at least ruthenium.
  • This is advantageously in metallic or oxide form. However, it can be present in the form of other compounds without thereby departing from the scope of the invention.
  • the catalysts according to the invention are advantageously prepared by a process consisting successively.
  • the catalysts of the invention can also be prepared according to conventional techniques for the preparation of supported catalysts, for example by impregnating the support with a solution of a compound of the catalytically active metal and oxidative or reducing heat treatment to obtain a catalytically active phase with the desired state.
  • the weight content of the catalytically active element is advantageously between 0.05 and 10%, preferably between 0.1 and 5%
  • the subject of the invention is also a process for the oxidation of an aqueous solution or suspension containing organic and / or nitrogenous compounds, using as catalyst a catalyst conforming to the description above.
  • oxidizable compounds the organic compounds and / or nitrogen contained in the suspension will hereinafter be called oxidizable compounds.
  • the invention provides a process for treating an aqueous solution or suspension of compounds which can be oxidized at a high temperature and pressure by oxidation.
  • the catalyst as described above above comprises a catalytically active phase deposited on a graphite support.
  • atomic or molecular oxygen gases containing oxygen generated in atomic form by a compound, molecular oxygen or ozone.
  • the catalytically active phase consists of ruthenium advantageously in metal form or in oxide form.
  • the oxidation reaction is carried out by using as gas oxidizing a gas containing atomic or molecular oxygen, such as for example pure oxygen, air, air enriched in oxygen or ozone, waste gases containing oxygen, or oxygen enriched in ozone.
  • a gas containing atomic or molecular oxygen such as for example pure oxygen, air, air enriched in oxygen or ozone, waste gases containing oxygen, or oxygen enriched in ozone.
  • the quantity of gas supplied is determined from the COD of the solution to be treated.
  • the oxygen-containing gas is used in an amount 1 to 1.5 times the theoretical amount of oxygen.
  • the partial oxygen pressure is between 1 and 50 bars, the total pressure of the gases being high enough to maintain the solution or suspension in the liquid state at the reaction temperature.
  • This reaction temperature is advantageously between 100 and 350 ° C, preferably between 120 and 200 ° C. This temperature depends in particular on the nature of the oxidizable compounds present in the effluents to be treated.
  • aqueous solutions or suspensions which can be treated by the process of the invention are waters which preferentially contain organic and or nitrogenous oxidizable substances such as aqueous effluents having a moderately concentrated chemical oxygen demand, advantageously less than 200 g / l
  • the nature of organic compounds can be very varied.
  • Examples ⁇ "water to be treated are in particular waste water coming in particular from industrial installations such as the chemical or petroleum industries, municipal effluents, waste water containing oils, waste water coming from gas purification process or activated sludge process.
  • these waters can be filtered before being treated by the method of the invention.
  • the catalyst of the invention can be in different forms such as a honeycomb-shaped cylinder, beads, pellets, powders or extrusions.
  • the catalyst is used in the form of a fixed bed in a reactor of sufficient capacity to ensure contact. solution / gas, for a fixed duration usually of the order of a few minutes to several hours
  • the catalyst in the form of a fluidized bed or to introduce the catalyst in suspension in the solution to be treated.
  • the catalyst is recovered at the end of the reaction by any known means of solid / liquid separation.
  • the catalytic activity of these catalysts will be determined by carrying out a wet oxidation of an aqueous solution of acetic acid.
  • This organic compound was chosen as test compound because its oxidation is more difficult than that of most organic compounds. oxidizable present in the aqueous effluents to be treated.
  • the graphite support is a powdered graphite of which 99% of the particles have a diameter of less than 50 ⁇ m, and a BET specific surface of 300 m 2 / g
  • This product is marketed under the commercial reference HSAG300 by the company LONZA (TIMCAL)
  • the suspension is then filtered.
  • the filter cake is then washed with a solution of N hydrochloric acid, then with water and dried under vacuum.
  • a 2 g / l solution of [Ru (NH 3 ) 6 ] CI 3 in ammonia is passed over anion exchange resin to obtain a solution of [Ru (NH 3 ) 6 ] (OH) 3
  • This solution is added to a suspension of 20 g of support previously treated in a molar ammonia solution After stirring for 24 hours, the suspension is filtered. The filter cake is then washed with water, then dried under a stream of nitrogen at 100 ° C. The catalyst is then reduced under a stream of hydrogen for 3 hours at 300 ° C.
  • the graphite support identical to that used in Example 1 (9.5 g) is dispersed in a solution of RuCI 3 (1.1 g) in 25 ml of water containing 2 ml of 12N HCl. The mixture is stirred for 12 hours under a stream of nitrogen. The suspension is then filtered and the filter cake is washed with water to a pH of 7. The catalyst obtained is dried under nitrogen, then reduced under a stream of hydrogen for 3 hours at 300 ° C.
  • the oxidation of acetic acid leads to a total reaction, the oxidation products of which are water and carbon dioxide.
  • This oxidation is carried out in an autoclave equipped with agitation.
  • the 0.08 M acetic acid solution (50 cm 3 ) is added to the reactor with 0.6 g of catalyst. After purging the reactor with argon, the reaction medium is heated to 200 ° C. Air is introduced at a pressure of 100 bars.
  • the evolution of the oxidation reaction is followed by determining the concentration of acetic acid and or the total concentration of organic carbon in the reaction medium as a function of the reaction time.
  • the measurement of the acetic acid concentration is carried out by analysis by SHIMADZU high performance liquid chromatography, that of the organic carbon is carried out by a SHIMADZU 5050 A analyzer.
  • catalyst II graphite support HSAG300 from LONZA, deposition of the active phase Ru by impregnation method according to the method of example 2, Ru content of 1% by weight, - Catalyst A (comparative): ruthenium catalyst on activated carbon support sold by the company ENGELHARD, Ru content of 2% by weight.
  • the reaction was carried out under conditions identical to those of Example 3. However, the solution contains 0.4 g of catalyst I (catalyst of Example 1) instead of 0.6 g and 0.64 g of acetate ammonium instead of acetic acid. All of the ammonium ions are oxidized after 100 minutes of reaction with an oxidation rate of 0.094 mol / h. g of Ru. The acetate ions are completely oxidized after 350 minutes of reaction.

Abstract

The invention concerns the wet oxidation processing of a solution or suspension of organic and/or nitrogenous compounds for reducing the chemical oxygen demand (COD) to a predetermined level. More particularly it concerns a wet oxidation process carried out on presence of an oxidising catalyst comprising, as catalytic active phase, ruthenium or one of its compounds, and, as support of the active phase, a graphite, advantageously with high specific surface area.

Description

PROCEDE DE TRAITEMENT D UNE SOLUTION OU SUSPENSION DE COMPOSES ORGANIQUES PAR OXYDATION EN VOIE HUMIDE PROCESS FOR TREATING A SOLUTION OR SUSPENSION OF ORGANIC COMPOUNDS BY WET OXIDATION
La présente invention concerne un procédé d'oxydation en voie humide d'une solution ou suspension de composés organiques et/ou azotés notamment pour diminuer la demande chimique en oxygène (DCO) à un niveau déterminé.The present invention relates to a wet oxidation process of a solution or suspension of organic and / or nitrogenous compounds, in particular for reducing the chemical oxygen demand (COD) to a determined level.
Elle concerne plus particulièrement l'utilisation d'un système catalytique particulier pour la mise en oeuvre de cette oxydation en voie humide.It relates more particularly to the use of a particular catalytic system for the implementation of this wet oxidation.
L'oxydation en voie humide des composés organiques contenus dans un milieu aqueux a été utilisée pour réduire, à un niveau acceptable pour l'environnement, la demande chimique en oxygène (DCO) des effluents aqueux.Wet oxidation of organic compounds in an aqueous medium has been used to reduce the chemical oxygen demand (COD) of aqueous effluents to an environmentally acceptable level.
Différents procédés sont exploités. On peut citer à titre d'exemple le procédé ZIMPRO qui utilise un gaz oxydant (air ou oxygène ) avec une température comprise entre 175 et 320 °C sous une pression de 20 à 210 bars. Dans ce procédé la réaction est réalisée en absence de catalyseur.Different processes are used. By way of example, mention may be made of the ZIMPRO process which uses an oxidizing gas (air or oxygen) with a temperature between 175 and 320 ° C. under a pressure of 20 to 210 bars. In this process the reaction is carried out in the absence of catalyst.
La société CIBA-GEIGY a développé un procédé d'oxydation en voie humide en utilisant comme oxydant de l'air, le domaine de température est de 250-300 °C, la pression étant comprise entre 50 et 200 bars. Cette oxydation est réalisée en présence d'un catalyseur composé de sels de cuivre. Sur la base de ce procédé, de nombreuses sociétés ont proposé de nouveaux systèmes catalytiques permettant de diminuer les temps de réaction et/ou d'abaisser les conditions de température ou de pression.CIBA-GEIGY has developed a wet oxidation process using air as the oxidant, the temperature range is 250-300 ° C, the pressure being between 50 and 200 bars. This oxidation is carried out in the presence of a catalyst composed of copper salts. On the basis of this process, many companies have proposed new catalytic systems making it possible to reduce the reaction times and / or to lower the temperature or pressure conditions.
Ainsi, la société OSAKA GAS décrit dans le brevet français 2 361 308 l'utilisation d'oxyde de ruthénium comme phase catalytiquement active. Cette phase active est déposée sur un support classiquement utilisé en catalyse hétérogène, tel que l'alumine, la silice ou le charbon actif. La réaction est conduite sous une pression comprise entre 70 et 90 bars et une température comprise entre 250 et 280 °C, les durées de réaction sont alors comprises entre 1 et 3 heures.Thus, the company OSAKA GAS describes in French patent 2,361,308 the use of ruthenium oxide as a catalytically active phase. This active phase is deposited on a support conventionally used in heterogeneous catalysis, such as alumina, silica or activated carbon. The reaction is carried out under a pressure between 70 and 90 bars and a temperature between 250 and 280 ° C, the reaction times are then between 1 and 3 hours.
La société NIPPON SHOKUBAI a également proposé des catalyseurs comprenant comme phase active des métaux tels que le palladium ou le platine, supportés sur des supports comprenant notamment des oxydes de terres rares comme l'oxyde de cérium.The company NIPPON SHOKUBAI has also proposed catalysts comprising as active phase metals such as palladium or platinum, supported on supports comprising in particular rare earth oxides such as cerium oxide.
Ces procédés sont utilisés industriellement dans le monde entier. Toutefois, l'amélioration des conditions de réaction est un problème constant qui demande la mise au point de nouveaux dispositifs pour favoriser la réaction gaz/liquide, ou diminuer les temps de réaction.These processes are used industrially worldwide. However, improving the reaction conditions is a constant problem which requires the development of new devices to promote the gas / liquid reaction, or to decrease the reaction times.
Un des buts de la présente invention est de proposer un nouveau système catalytique permettant d'accélérer la réaction à des conditions de pression et de température semblables ou inférieures à celles utilisées dans les procédés connus. A cet effet, l'invention propose un nouveau catalyseur d'oxydation comprenant une phase catalytiquement active supportée sur un support, caractérisé en ce que le support est un graphite.One of the aims of the present invention is to propose a new catalytic system making it possible to accelerate the reaction at pressure and temperature conditions similar or lower than those used in the known processes. To this end, the invention provides a new oxidation catalyst comprising a catalytically active phase supported on a support, characterized in that the support is a graphite.
Le graphite utilise ici possède, selon une caractéristique préférentielle de l'invention, une surface spécifique d'au moins 10 m2/g, de préférence supérieure a 100 m2/g et plus avantageusement supérieure à 250 m2/gThe graphite used here has, according to a preferred characteristic of the invention, a specific surface of at least 10 m 2 / g, preferably greater than 100 m 2 / g and more advantageously greater than 250 m 2 / g
Pour la suite de la description, on entend par surface spécifique, la surface spécifique BET déterminée par adsorption d'azote conformément à la norme ASTM D 3663-78 établie à partir de la méthode BRUNAUER - EMMETT- TELLER décrite dans le périodique "The Journal of the American Society, 6_0_, 309 (1938)".For the remainder of the description, the term "specific surface" means the BET specific surface area determined by nitrogen adsorption in accordance with standard ASTM D 3663-78 established on the basis of the BRUNAUER - EMMETT-TELLER method described in the periodical "The Journal of the American Society, 6_0_, 309 (1938) ".
Selon une caractéristique préférentielle de l'invention, la phase catalytiquement active comprend au moins du ruthénium. Celui-ci est avantageusement sous forme métallique ou oxyde Toutefois, il peut être présent sous forme d'autres composés sans pour cela sortir du cadre de l'invention Les catalyseurs conformes à l'invention sont avantageusement préparés par un procédé consistant successivement .According to a preferred characteristic of the invention, the catalytically active phase comprises at least ruthenium. This is advantageously in metallic or oxide form. However, it can be present in the form of other compounds without thereby departing from the scope of the invention. The catalysts according to the invention are advantageously prepared by a process consisting successively.
- à activer la surface du support en graphite par oxydation partielle pour générer des fonctions carboxyliques,to activate the surface of the graphite support by partial oxidation to generate carboxylic functions,
- à disperser ledit graphite activé dans une solution d'un complexe ammoniacal de l'élément catalytiquement actif pour réaliser l'échange avec les carbones oxydés du graphite,- dispersing said activated graphite in a solution of an ammoniacal complex of the catalytically active element to carry out the exchange with the oxidized carbons of graphite,
- à récupérer le graphite échangé et à réduire le complexe ammoniacal par traitement thermique sous atmosphère d'hydrogène.- to recover the exchanged graphite and to reduce the ammoniacal complex by heat treatment under a hydrogen atmosphere.
Les catalyseurs de l'invention peuvent également être préparés selon les techniques classiques de préparation des catalyseurs supportés, par exemple par imprégnation du support avec une solution d'un composé du métal catalytiquement actif et traitement thermique oxydant ou réducteur pour obtenir une phase catalytiquement active à l'état désiré.The catalysts of the invention can also be prepared according to conventional techniques for the preparation of supported catalysts, for example by impregnating the support with a solution of a compound of the catalytically active metal and oxidative or reducing heat treatment to obtain a catalytically active phase with the desired state.
Ainsi, la teneur pondérale de l'élément catalytiquement actif, exprimée en poids de métal formant la phase active par rapport au poids de catalyseur, est avantageusement comprise entre 0,05 et 10 %, préférentiellement entre 0,1 et 5 %Thus, the weight content of the catalytically active element, expressed by weight of metal forming the active phase relative to the weight of catalyst, is advantageously between 0.05 and 10%, preferably between 0.1 and 5%
L'invention a également pour objet un procédé d'oxydation d'une solution ou suspension aqueuse contenant des composés organiques et/ou azotés, utilisant comme catalyseur un catalyseur conforme à la description ci-dessus Pour plus de clarté, les composés organiques et/ou azotés contenus dans la suspension seront appelés ci-après composés oxydables.The subject of the invention is also a process for the oxidation of an aqueous solution or suspension containing organic and / or nitrogenous compounds, using as catalyst a catalyst conforming to the description above. For greater clarity, the organic compounds and / or nitrogen contained in the suspension will hereinafter be called oxidizable compounds.
Ainsi, l'invention propose un procédé de traitement de solution ou suspension aqueuse de composes oxydables à une température et pression élevée par oxydation O 98/07512Thus, the invention provides a process for treating an aqueous solution or suspension of compounds which can be oxidized at a high temperature and pressure by oxidation. O 98/07512
de ces composés par un gaz contenant de l'oxygène atomique ou moléculaire en présence d'un catalyseur d'oxydation pour réduire la demande chimique en oxygène de ladite solution ou suspension à un niveau prédéterminé, caractérisé en ce que le catalyseur tel que décrit ci-dessus comprend une phase catalytiquement active déposée sur un support graphite.of these compounds with a gas containing atomic or molecular oxygen in the presence of an oxidation catalyst to reduce the chemical oxygen demand of said solution or suspension to a predetermined level, characterized in that the catalyst as described above above comprises a catalytically active phase deposited on a graphite support.
Par oxygène atomique ou moléculaire, il faut comprendre les gaz contenant de l'oxygène généré sous forme atomique par un composé, de l'oxygène moléculaire ou de l'ozone.By atomic or molecular oxygen is meant gases containing oxygen generated in atomic form by a compound, molecular oxygen or ozone.
Les caractéristiques particulières de ce catalyseur et notamment la nature du support conduisent à réaliser un catalyseur d'oxydation en voie humide présentant une activité nettement supérieure aux catalyseurs connus comprenant des phases catalytiquement active semblables.The particular characteristics of this catalyst and in particular the nature of the support lead to producing a wet oxidation catalyst having an activity clearly superior to known catalysts comprising similar catalytically active phases.
Selon une caractéristique préférentielle de l'invention, la phase catalytiquement active est constituée par du ruthénium avantageusement sous forme métal ou sous forme oxyde.According to a preferred characteristic of the invention, the catalytically active phase consists of ruthenium advantageously in metal form or in oxide form.
La réaction d'oxydation est réalisée en mettant en œuvre comme gaz oxydant un gaz contenant de l'oxygène atomique ou moléculaire, tel que par exemple de l'oxygène pur, l'air, l'air enrichi en oxygène ou en ozone, des gaz résiduaires contenant de l'oxygène, ou de l'oxygène enrichi en ozone. La quantité de gaz alimenté est déterminée à partir de la DCO de la solution à traiter. Généralement, le gaz contenant l'oxygène est utilisé à une quantité 1 à 1 ,5 fois la quantité théorique en oxygène.The oxidation reaction is carried out by using as gas oxidizing a gas containing atomic or molecular oxygen, such as for example pure oxygen, air, air enriched in oxygen or ozone, waste gases containing oxygen, or oxygen enriched in ozone. The quantity of gas supplied is determined from the COD of the solution to be treated. Generally, the oxygen-containing gas is used in an amount 1 to 1.5 times the theoretical amount of oxygen.
Avantageusement la pression partielle en oxygène est comprise entre 1 et 50 bars, la pression totale des gaz étant suffisamment élevée pour maintenir la solution ou suspension à l'état liquide à la température de la réaction.Advantageously, the partial oxygen pressure is between 1 and 50 bars, the total pressure of the gases being high enough to maintain the solution or suspension in the liquid state at the reaction temperature.
Cette température de réaction est avantageusement comprise entre 100 et 350 °C, de préférence entre 120 et 200 °C. Cette température dépend notamment de la nature des composés oxydables présents dans les effluents à traiter.This reaction temperature is advantageously between 100 and 350 ° C, preferably between 120 and 200 ° C. This temperature depends in particular on the nature of the oxidizable compounds present in the effluents to be treated.
Les solutions ou suspensions aqueuses pouvant être traitées par le procédé de l'invention sont des eaux qui contiennent préferentiellement des substances oxydables organiques et ou azotées telles que des effluents aqueux présentant une demande chimique en oxygène moyennement concentrée, avantageusement inférieure à 200 g/lThe aqueous solutions or suspensions which can be treated by the process of the invention are waters which preferentially contain organic and or nitrogenous oxidizable substances such as aqueous effluents having a moderately concentrated chemical oxygen demand, advantageously less than 200 g / l
Comme composés azotés oxydables, on peut citer les sels d'ammonium minéraux ou organiques. La nature des composés organiques peut être très variée. Des exemples ό"eaux à traiter sont notamment les eaux résiduelles provenant en particulier d'installations industrielles telles que les industries chimiques ou pétrolières, les effluents municipaux, les eaux résiduelles contenant des huiles, des eaux résiduelles provenant de procédé d'épuration de gaz ou de procédé à boue activée. Avantageusement, pour éviter un encrassage des installations et du catalyseur, ces eaux peuvent être filtrées avant d'être traitées par le procède de l'inventionMention may be made, as oxidizable nitrogen compounds, of inorganic or organic ammonium salts. The nature of organic compounds can be very varied. Examples ό "water to be treated are in particular waste water coming in particular from industrial installations such as the chemical or petroleum industries, municipal effluents, waste water containing oils, waste water coming from gas purification process or activated sludge process. Advantageously, to avoid fouling of the installations and of the catalyst, these waters can be filtered before being treated by the method of the invention.
Le catalyseur de l'invention peut être sous différentes formes telles que cylindre en forme de nid d'abeille, billes, pastilles, poudres ou extrudés Généralement, le catalyseur est utilisé sous forme de lit fixe dans un réacteur de capacité suffisante pour assurer un contact solution/gaz, pendant une durée déterminée habituelement de l'ordre de quelques minutes a plusieurs heuresThe catalyst of the invention can be in different forms such as a honeycomb-shaped cylinder, beads, pellets, powders or extrusions. Generally, the catalyst is used in the form of a fixed bed in a reactor of sufficient capacity to ensure contact. solution / gas, for a fixed duration usually of the order of a few minutes to several hours
Il est également possible d'utiliser le catalyseur sous forme de lit fluidisé ou d'introduire le catalyseur en suspension dans la solution à traiter Le catalyseur est récupéré en fin de reaction par tout moyen connu de séparation solide/liquideIt is also possible to use the catalyst in the form of a fluidized bed or to introduce the catalyst in suspension in the solution to be treated. The catalyst is recovered at the end of the reaction by any known means of solid / liquid separation.
L'invention sera illustrée et d'autres caractéristiques et avantages apparaîtront encore plus clairement dans les exemples ci-dessous donnés uniquement a titre indicatifThe invention will be illustrated and other characteristics and advantages will appear even more clearly in the examples below, given for information only.
Des exemples de préparation de plusieurs catalyseurs conformes à l'invention et des catalyseurs illustrant l'art antérieur seront décritsExamples of preparation of several catalysts according to the invention and catalysts illustrating the prior art will be described
L'activité catalytique de ces catalyseurs sera déterminée par réalisation d'une oxydation en voie humide d'une solution aqueuse d'acide acétique Ce composé organique a été choisi comme composé test car son oxydation est plus difficile que celle de la plupart des composes organiques oxydables présents dans les effluents aqueux à traiter.The catalytic activity of these catalysts will be determined by carrying out a wet oxidation of an aqueous solution of acetic acid. This organic compound was chosen as test compound because its oxidation is more difficult than that of most organic compounds. oxidizable present in the aqueous effluents to be treated.
Exemple 1 . Préparation d'un catalyseur I conforme a l'inventionExample 1. Preparation of a catalyst I according to the invention
Le support de graphite est un graphite en poudre dont 99 % des particules ont un diamètre inférieur à 50 μm, et une surface spécifique BET de 300 m2/g Ce produit est commercialisé sous la référence commerciale HSAG300 par la société LONZA (TIMCAL)The graphite support is a powdered graphite of which 99% of the particles have a diameter of less than 50 μm, and a BET specific surface of 300 m 2 / g This product is marketed under the commercial reference HSAG300 by the company LONZA (TIMCAL)
20 g de ce graphite sont activés par traitement pendant 24 heures par une solution de NaOCI a 15 % en chlore actif Ce traitement permet d'augmenter le nombre de groupes fonctionnels échangeables, notamment des groupes carboxyliques20 g of this graphite are activated by treatment for 24 hours with a NaOCI solution containing 15% active chlorine This treatment makes it possible to increase the number of exchangeable functional groups, in particular carboxylic groups
Puis, la suspension est filtrée Le gâteau de filtration est ensuite lavée par une solution d'acide chlorhydnque N, puis avec de l'eau et séché sous videThe suspension is then filtered. The filter cake is then washed with a solution of N hydrochloric acid, then with water and dried under vacuum.
Une solution a 2 g/1 de [Ru(NH3)6]CI3 dans de l'ammoniaque est passée sur résine échangeuse d'anions pour obtenir une solution de [Ru(NH3)6](OH)3 Cette solution est ajoutée dans une suspension de 20 g de support traité précédemment dans une solution d'ammoniaque molaire Après maintien sous agitation pendant 24 heures, la suspension est filtrée. Le gâteau de filtration est ensuite lavé à l'eau, puis séché sous courant d'azote à 100 °C Le catalyseur est ensuite réduit sous courant d'hydrogène pendant 3 heures à 300 °C.A 2 g / l solution of [Ru (NH 3 ) 6 ] CI 3 in ammonia is passed over anion exchange resin to obtain a solution of [Ru (NH 3 ) 6 ] (OH) 3 This solution is added to a suspension of 20 g of support previously treated in a molar ammonia solution After stirring for 24 hours, the suspension is filtered. The filter cake is then washed with water, then dried under a stream of nitrogen at 100 ° C. The catalyst is then reduced under a stream of hydrogen for 3 hours at 300 ° C.
Exemple 2 : Préparation d'un catalyseur II conforme à l'inventionExample 2: Preparation of a catalyst II according to the invention
Le support graphite identique à celui utilisé dans l'exemple 1 (9,5 g) est dispersé dans une solution de RuCI3 (1 ,1 g) dans 25 ml d'eau contenant 2 ml de HCI 12N. Le mélange est agité pendant 12 heures sous courant d'azote. La suspension est ensuite filtrée et le gâteau de filtration est lavée avec de l'eau jusqu'à un pH de 7. Le catalyseur obtenu est séché sous azote, puis réduit sous courant d'hydrogène pendant 3 heures à 300 °C.The graphite support identical to that used in Example 1 (9.5 g) is dispersed in a solution of RuCI 3 (1.1 g) in 25 ml of water containing 2 ml of 12N HCl. The mixture is stirred for 12 hours under a stream of nitrogen. The suspension is then filtered and the filter cake is washed with water to a pH of 7. The catalyst obtained is dried under nitrogen, then reduced under a stream of hydrogen for 3 hours at 300 ° C.
Exemple 3 : Réaction d'oxvdation de l'acide aπétioue en milieu aqueuxEXAMPLE 3 Oxidation reaction of aπétioue acid in an aqueous medium
L'oxydation de l'acide acétique conduit à une réaction totale dont les produits d'oxydation sont l'eau et du gaz carbonique.The oxidation of acetic acid leads to a total reaction, the oxidation products of which are water and carbon dioxide.
Cette oxydation est réalisée dans un autoclave équipé d'une agitation. La solution d'acide acétique de concentration 0,08 M (50 cm3) est ajoutée dans le réacteur avec 0,6 g de catalyseur. Après purge du réacteur avec de l'argon, le milieu réactioπnel est chauffé à 200 °C. De l'air est introduit sous une pression de 100 bars. L'évolution de la réaction d'oxydation est suivie par détermination de la concentration en acide acétique et ou de la concentration totale en carbone organique dans le milieu réactionnel en fonction du temps de réaction. La mesure de la concentration en acide acétique est réalisée par analyse par chromatographie en phase liquide haute performance SHIMADZU, celle du carbone organique est effectuée par un analyseur SHIMADZU 5050 A.This oxidation is carried out in an autoclave equipped with agitation. The 0.08 M acetic acid solution (50 cm 3 ) is added to the reactor with 0.6 g of catalyst. After purging the reactor with argon, the reaction medium is heated to 200 ° C. Air is introduced at a pressure of 100 bars. The evolution of the oxidation reaction is followed by determining the concentration of acetic acid and or the total concentration of organic carbon in the reaction medium as a function of the reaction time. The measurement of the acetic acid concentration is carried out by analysis by SHIMADZU high performance liquid chromatography, that of the organic carbon is carried out by a SHIMADZU 5050 A analyzer.
Les résultats de cette étude cinétique pour différents catalyseurs conformes ou non à l'invention sont rassemblés dans le tableau I ci-dessous. Les activités de chaque catalyseur sont exprimées en mole d'acide acétique (AA) oxydé par heure et par gramme de ruthénium (mol de AA/h.g de Ru ). Les catalyseurs testés sont :The results of this kinetic study for various catalysts, whether or not conforming to the invention, are collated in Table I below. The activities of each catalyst are expressed in moles of acetic acid (AA) oxidized per hour and per gram of ruthenium (mol of AA / h.g of Ru). The catalysts tested are:
- catalyseur I : support graphite HSAG300 de LONZA, dépôt de la phase active Ru par méthode d'échange selon procédé de l'exemple 1 , teneur en Ru de 3,4 % en poids,- catal sor y I: graphite carrier HSAG300 of LONZA, deposition of the active phase Ru exchange method according to method of Example 1, Ru content of 3.4% by weight,
- catalyseur II : support graphite HSAG300 de LONZA, dépôt de la phase active Ru par méthode d'imprégnation selon procédé de l'exemple 2, teneur en Ru de 1 % en poids, - catalyseur A (comparatif) : catalyseur au ruthénium sur support charbon actif commercialisé par la société ENGELHARD, teneur en Ru de 2 % en poids.catalyst II: graphite support HSAG300 from LONZA, deposition of the active phase Ru by impregnation method according to the method of example 2, Ru content of 1% by weight, - Catalyst A (comparative): ruthenium catalyst on activated carbon support sold by the company ENGELHARD, Ru content of 2% by weight.
- catalyseur B (comparatif) : support charbon actif commercialisé sous la dénomination commerciale ROX 0,8 par la société NORIT, dépôt de la phase active Ru par méthode d'échange selon procédé de l'exemple 1 , teneur en Ru de 1 ,2 % en poids,- Catalyst B (comparative): activated carbon support sold under the trade name ROX 0.8 by the company NORIT, deposition of the active phase Ru by exchange method according to the method of Example 1, Ru content of 1, 2 % in weight,
- catalyseur C ( comparatif ) : catalyseur au ruthénium sur support charbon actif commercialisé par la société ENGELHARD sous la dénomination commerciale ESCAT 40, teneur en Ru de 5 % en poids.- Catalyst C (comparative): ruthenium catalyst on an activated carbon support sold by the company ENGELHARD under the trade name ESCAT 40, Ru content of 5% by weight.
Tableau ITable I
Figure imgf000008_0001
Figure imgf000008_0001
Le tableau ci-dessus démontre clairement l'activité nettement supérieure des catalyseurs conformes à l'invention par rapport aux catalyseurs de l'art antérieur.The table above clearly demonstrates the significantly higher activity of the catalysts according to the invention compared to the catalysts of the prior art.
Exemple 4 : Essai d'oxvdation d'acétate d'ammoniumEXAMPLE 4 Oxidation Test of Ammonium Acetate
La réaction a été réalisée dans des conditions identiques à celles de l'exemple 3. Toutefois, la solution contient 0.4 g de catalyseur I (catalyseur de l'exemple 1) au lieu de 0,6 g et 0,64 g d'acétate d'ammonium au lieu de l'acide acétique. La totalité des ions ammonium est oxydée après 100 minutes de réaction avec une vitesse d'oxydation de 0,094 mol/h. g de Ru. Les ions acétates sont totalement oxydés après 350 minutes de réaction. The reaction was carried out under conditions identical to those of Example 3. However, the solution contains 0.4 g of catalyst I (catalyst of Example 1) instead of 0.6 g and 0.64 g of acetate ammonium instead of acetic acid. All of the ammonium ions are oxidized after 100 minutes of reaction with an oxidation rate of 0.094 mol / h. g of Ru. The acetate ions are completely oxidized after 350 minutes of reaction.

Claims

REVENDICATIONS
1 - Catalyseur d'oxydation comprenant une phase catalytiquement active sur un support, caractérisé en ce que le support est un graphite.1 - Oxidation catalyst comprising a catalytically active phase on a support, characterized in that the support is a graphite.
2 - Catalyseur selon la revendication 1 , caractérisé en ce que le graphite présente une surface spécifique d'au moins 10 m2/g.2 - Catalyst according to claim 1, characterized in that the graphite has a specific surface of at least 10 m 2 / g.
3 - Catalyseur selon la revendication 2, caractérisé en ce que le graphite présente une surface spécifique supérieure à 100 m2/g, de préférence supérieure à 250 m2/g.3 - Catalyst according to claim 2, characterized in that the graphite has a specific surface greater than 100 m 2 / g, preferably greater than 250 m 2 / g.
4 - Catalyseur selon l'une des revendications 1 , 2 ou 3 caractérisé en ce que la phase catalytiquement active comprend au moins du ruthénium ou un composé de ruthénium.4 - Catalyst according to one of claims 1, 2 or 3 characterized in that the catalytically active phase comprises at least ruthenium or a ruthenium compound.
5 - Catalyseur selon la revendication 4, caractérisé en ce que la teneur pondérale en ruthénium ou composé de ruthénium, exprimée en poids de ruthénium métal par rapport au poids de catalyseur, est comprise entre 0,05 % et 10 %, de préférence entre 0,1 % et 5 %.5 - Catalyst according to claim 4, characterized in that the weight content of ruthenium or ruthenium compound, expressed by weight of ruthenium metal relative to the weight of catalyst, is between 0.05% and 10%, preferably between 0 , 1% and 5%.
6 - Catalyseur selon l'une des revendications précédentes, caractérisé en ce que la phase catalytiquement active est déposée sur le support par un procédé d'imprégnation ou un procédé d'échange.6 - Catalyst according to one of the preceding claims, characterized in that the catalytically active phase is deposited on the support by an impregnation process or an exchange process.
7 - Procédé de traitement de solution ou suspension aqueuse de composés organiques et/ou azotés à une température et pression élevée par oxydation des composés organiques et/ou azotés par un gaz contenant de l'oxygène atomique ou moléculaire en présence d'un catalyseur d'oxydation pour réduire la demande chimique en oxygène de ladite solution ou suspension à un niveau prédéterminé, caractérisé en ce que ledit catalyseur est un catalyseur selon l'une des revendications 1 à 6.7 - Process for treating an aqueous solution or suspension of organic and / or nitrogenous compounds at a high temperature and pressure by oxidation of the organic and / or nitrogenous compounds with a gas containing atomic or molecular oxygen in the presence of a catalyst d oxidation to reduce the chemical oxygen demand of said solution or suspension to a predetermined level, characterized in that said catalyst is a catalyst according to one of claims 1 to 6.
8 - Procédé selon la revendication 7, caractérisé en ce que la phase catalytiquement active du catalyseur comprend au moins du ruthénium, sous forme métal ou oxyde.8 - Process according to claim 7, characterized in that the catalytically active phase of the catalyst comprises at least ruthenium, in metal or oxide form.
9 - Procédé selon l'une des revendications 7 et 8, caractérisé en ce que le traitement est réalisé à une pression suffisante pour maintenir la solution ou suspension de composés organiques et/ou azotés à l'état liquide. 10 - Procédé selon l'une des revendications 7 à 9, caractérisé en ce que le traitement est réalisé à une température comprise entre 100 et 350 °C, de préférence entre 120 et 200 °C.9 - Method according to one of claims 7 and 8, characterized in that the treatment is carried out at a pressure sufficient to maintain the solution or suspension of organic and / or nitrogen compounds in the liquid state. 10 - Method according to one of claims 7 to 9, characterized in that the treatment is carried out at a temperature between 100 and 350 ° C, preferably between 120 and 200 ° C.
11 - Procédé selon l'une des revendications 7 à 10, caractérisé en ce que le traitement est réalisé sous une pression partielle en oxygène comprise entre 1 et 50 bars.11 - Method according to one of claims 7 to 10, characterized in that the treatment is carried out under a partial oxygen pressure between 1 and 50 bars.
12 - Procédé selon l'une des revendications 7 à 11 , caractérisé en ce que la solution ou suspension en composés organiques et ou azotés à traiter possède une demande chimique en oxygène maximale de 200 g/l. 12 - Method according to one of claims 7 to 11, characterized in that the solution or suspension of organic and or nitrogen compounds to be treated has a maximum chemical oxygen demand of 200 g / l.
PCT/FR1997/001506 1996-08-22 1997-08-20 Wet oxidation processing of a solution or suspension of organic compounds WO1998007512A1 (en)

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Citations (3)

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Publication number Priority date Publication date Assignee Title
FR2361308A1 (en) * 1976-08-10 1978-03-10 Osaka Gas Co Ltd RESIDUAL WATER TREATMENT PROCESS BY WET OXIDATION
GB2033776A (en) * 1978-10-24 1980-05-29 British Petroleum Co Catalyst for the production of ammonia
US4250057A (en) * 1976-11-03 1981-02-10 The British Petroleum Company Limited Process for producing a catalyst comprising a graphite containing carbon, a transitional metal and a modifying metal ion

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2361308A1 (en) * 1976-08-10 1978-03-10 Osaka Gas Co Ltd RESIDUAL WATER TREATMENT PROCESS BY WET OXIDATION
US4250057A (en) * 1976-11-03 1981-02-10 The British Petroleum Company Limited Process for producing a catalyst comprising a graphite containing carbon, a transitional metal and a modifying metal ion
GB2033776A (en) * 1978-10-24 1980-05-29 British Petroleum Co Catalyst for the production of ammonia

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