WO1998046336A1 - Procede pour decomposer des hydrocarbures halogenes au moyen d'un catalyseur, fabrication de celui-ci et installation pour mettre en oeuvre le procede - Google Patents

Procede pour decomposer des hydrocarbures halogenes au moyen d'un catalyseur, fabrication de celui-ci et installation pour mettre en oeuvre le procede

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Publication number
WO1998046336A1
WO1998046336A1 PCT/EP1998/002088 EP9802088W WO9846336A1 WO 1998046336 A1 WO1998046336 A1 WO 1998046336A1 EP 9802088 W EP9802088 W EP 9802088W WO 9846336 A1 WO9846336 A1 WO 9846336A1
Authority
WO
WIPO (PCT)
Prior art keywords
catalyst
centers
brönstedt
halogenated hydrocarbons
zirconium oxide
Prior art date
Application number
PCT/EP1998/002088
Other languages
German (de)
English (en)
Inventor
Erhard Kemnitz
Original Assignee
Adelmann Ag
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 Adelmann Ag filed Critical Adelmann Ag
Priority to AU76425/98A priority Critical patent/AU7642598A/en
Publication of WO1998046336A1 publication Critical patent/WO1998046336A1/fr

Links

Classifications

    • 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
    • B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
    • B01J21/066—Zirconium or hafnium; Oxides or hydroxides thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/8659—Removing halogens or halogen compounds
    • B01D53/8662—Organic halogen compounds
    • 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
    • B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof

Definitions

  • the invention relates to a process for the degradation of gaseous and / or halogenated hydrocarbons, in particular chlorofluorocarbons, with a catalyst, its production and plants for carrying it out.
  • halohydrocarbons denotes all aliphatic hydrocarbon compounds in which H atoms have been replaced by halogens. In their short form, they are also called freons or halons and are used extensively as refrigerants, blowing agents, fire extinguishing agents and solvents. In this context, examples are the brominated hydrocarbons, which have found widespread use as effective fire extinguishing agents in fires in closed rooms and electrical systems.
  • This group of compounds also includes chlorofluorocarbons, in which the H atoms are substituted by chlorine and fluorine atoms. They are often referred to as chlorofluorocarbons - CFCs.
  • the invention has set itself the task of creating a process which can be carried out on an industrial scale, in which the halogenated hydrocarbons and in particular the fluorocarbons are broken down into components which are harmless to ozone.
  • the gas mixture flows through the reactor charged with the catalyst.
  • a minimum residence time in the catalyst is required.
  • the current speed must be set accordingly.
  • the decisive factor is the catalyst, which initiates the decomposition of the halogenated hydrocarbons at low temperatures and therefore with the lowest energy consumption. With regard to its chemical composition, it consists of a pure or modified zirconium oxide.
  • the surface of the catalyst has Brönstedt acid centers, which are permanently present or can regenerate during the reaction.
  • the halogenated hydrocarbons in particular chlorofluorocarbons, break down into hydrogen halide, in particular hydrogen fluoride (HF) and in particular hydrogen chloride (HCl) and carbon dioxide (C0 2 ).
  • sulfur compounds in the form of sulfates S0 and / or sulfites S0 3 are additionally introduced on the surface of the catalyst. They ensure that the production of Brönstedt centers is promoted and, because of their exposed position on the surface, they intensify the reactions taking place, so that as a result better conversions occur and a higher yield occurs. An extension of the service life is also achieved.
  • sulfur compounds with a sulfur content of 3 to 10 atom%, in particular 7 to 8 atom% are to be regarded as particularly preferred.
  • the prerequisite for the catalytic reaction to take place is the presence of Brönstedt centers, it being irrelevant whether the Brönstedt centers are permanently present or - if necessary temporarily - only develop under the reaction conditions.
  • One of the possible measures for generation under reaction conditions is to provide Lewis centers, preferably on the surface of the catalyst. In the presence of water, the Lewis centers produce the Brönstedt centers in the desired manner, which are solely responsible for the catalytic decomposition.
  • the surface area of the catalyst should be chosen to be as large as possible, since the Response times are the lowest.
  • Experimental investigations have shown that satisfactory reaction rates first occur when the surface measured by the BET method is between 120 and 180 m 2 / g.
  • the BET process reference is made to the article in the Journal American Chemical Society (J. Am. Chem. Soc. 60 (1938,309)).
  • Brönstedt centers which desorb previously adsorbed ammonia above 350 ° C. to characterize their strength are particularly preferred. There are then medium-strong acidic Brönstedt centers, which can be detected by the temperature-programmed desorption TPD of the ammonia.
  • the catalyst should have a porous structure.
  • the diameter of the pores is an optimal compromise, on the one hand, between a large radius of the pores, which is necessary to prevent the pores from clogging early and thus a short service life, and, on the other hand, a small pore diameter, which allows a higher pore density per unit area and thus also to achieve a higher surface.
  • the optimal solution of these conflicting points of view leads to the fact that the pores are located in the area between mesopores and micropores, that is to say they have a pore radius which, in its most common distribution, is in the range between 1.9 and 5 nm, preferably 1.9 to 3 nm.
  • hydrofluoric acid can be obtained from hydrogen fluoride under the influence of water and hydrochloric acid from hydrochloric acid and thus economically interesting products.
  • the decisive advantage of the method according to the invention consists in low procedural costs, which are based on a departure from the state of the art Technically necessary high decomposition temperatures establish, since the decomposition reaction is initiated catalytically.
  • a homogenized mixture of solid zirconium oxide hydrate and solid (NH) 2 S0 4 is treated according to a multi-stage calcination program up to 600 ° C.
  • the mass ratio of zirconium oxide hydrate to ammonium sulfate can vary between 50/50 to 95/05, but is advantageously in the range 75/25 to 90/10 mass%.
  • Sulfuric acid serves as the sulfate source, the amount of which varies between 2 to 20, preferably 2 to 4,% by mass.
  • the sulfation with SF 4 takes place in such a way that the transition metal oxide hydrate is treated at temperatures between 120 and 180 ° C., preferably between 140 and 160 ° C., for 30-90 minutes using gaseous sulfur tetrafluoride.
  • the sulfated oxide formed by treatment with sulfates is crystalline and can be detected by X-ray diffraction.
  • Zirconyl chloride hydrate is hydrolyzed in an aqueous ammonia solution until a pH of 8 is reached. The precipitate is separated off, washed chlorine-free with water and added for 6 to 10 hours Calcined temperatures between 90 and 120 ° C.
  • the zirconium oxide hydrate thus obtained is treated at temperatures between 120 and 180 ° C, preferably between 140 and 160 ° C, for 30 to 90 minutes using gaseous sulfur tetrafluoride. A purging is then carried out using inert gas to remove the absorbed SF 4 .
  • the resulting dark red to black product is then subjected to a temperature program to generate the special catalytic properties.
  • the material is first annealed at 150 ° C for 90 minutes; This is followed by continuous heating over 45 minutes to temperatures between 550 and 650 ° C, preferably 590 to 610 ° C. The material is left isothermal at this temperature for 3 hours and then cooled to 110 ° C. within 60 minutes. Here the material has reached its high activity.
  • Solid ammonium sulfate is added to the zirconium oxide hydrate obtained by hydrolysis of zirconium chloride and already calcined at 110 ° C.
  • Mass ratio of zirconium oxide hydrate to ammonium sulfate can be between
  • 50/50 to 95/05 vary, but is advantageously in the range 25/75 to
  • reaction mixture is initially left isothermal at 150 ° C. for 90 minutes. Thereafter, the temperature is raised to 400 to 600 ° C., preferably to 480 to 520 ° C. within 45 minutes and the reaction mixture at this temperature for
  • Activated carbon is added to an aqueous solution of zirconyl chloride until these grains are loaded with the solution.
  • the mass ratio of zirconium oxide hydrate to ammonium sulfate can vary between 50/50 to 95/05, but is advantageously in the range 75/25 to 90/10 mass%.
  • the zirconium content, based on the activated carbon component can be between 1 and 30% by mass, but advantageously in the range from 2 to 8% by mass.
  • the reaction mixture is first left at 150 ° C. for 90 minutes. The temperature is then raised to 400 to 600 ° C., preferably to 450 to 500 ° C. within 45 minutes, and the reaction mixture is kept at this temperature for 180 minutes. It is then cooled to a temperature of 110 ° C. within 60 minutes. This gives the desired catalyst.
  • the decomposition of dichlorodifluoromethane takes place under normal pressure conditions in a continuously operated flow reactor in which the catalyst is located.
  • the reactor itself is made of corrosion-resistant material and is heated by means of an adjustable electric furnace.
  • the catalyst prepared according to Example 2 was used in the form of pressed pellets with a particle diameter of 250 to 500 ⁇ m. After one hour Calcination of the catalyst at 500 ° C, a constant gas flow of dichlorodifluoromethane and water vapor was passed over the catalyst at a reactor temperature of 480 ° C.
  • the ratio of water to dichlorodifluoromethane can be varied within the limits 2 to 4, but should advantageously be between 2.1 and 2.4.
  • the temperature varies between 400 and 550 ° C, is preferably in the range between 450 and 500 ° C.
  • the average residence time of the reaction gas can vary within wide limits between 0.1 and 3 seconds, but is selected between 0.2 and 0.5 seconds to optimize the process.
  • Example 5 Decomposition of dichlorodifluoromethane with the aid of the invention
  • Fig. 1 shows an inventive plant for the degradation of gaseous halogenated hydrocarbons
  • Fig. 2 shows another embodiment of the invention for the degradation of liquid halogenated hydrocarbons
  • the halogenated hydrocarbon gas to be mined is cleaned of dust particles and preheated in a first stage 2.
  • Water 3 is then added to the gas 4.
  • the gas-water mixture passes through a heating stage 6 to the flow-through reactor 7, in the interior of which the catalyst 8 is located.
  • the desired reaction temperature is maintained using a temperature control device. Due to the properties of the catalyst, it is broken down into hydrogen halide and carbon dioxide. Controlled cooling 9 ensures a gas temperature of less than 600 ° C. It is then washed out in a gas scrubber 10, for example by adding calcium hydroxide, calcium chloride and calcium fluoride, so that pure air can leave the gas scrubber 10, the degree of purity of which can be checked with a measuring device 11.
  • liquid halogenated hydrocarbon 13 is split.
  • This liquid CFC is converted into the gaseous state by mixing 14 with air, preheated 15 and then enriched with water 16.
  • the further process sequence corresponds to that according to FIG. 1.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Environmental & Geological Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Biomedical Technology (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Catalysts (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

Ce procédé pour décomposer des hydrocarbures halogénés comprend les étapes suivantes: (a) adjonction d'eau à l'hydrocarbure halogéné dans une proportion stoechiométrique 2 à 5 fois supérieure, de préférence à peu près 3,5 fois supérieure à celle des halogènes; (b) échauffement jusqu'à au moins 400 °C, de préférence 400 à 550 °C; (c) utilisation d'un catalyseur de composition suivante: (aa) oxyde de zirconium acide contenant jusqu'à 5 % d'oxyde de hafnium; (bb) des centres de Brönstedt, qui se situent ou se forment à la surface pendant les réactions; (d) une durée de séjour suffisante pour obtenir la réaction escomptée.
PCT/EP1998/002088 1997-04-12 1998-04-11 Procede pour decomposer des hydrocarbures halogenes au moyen d'un catalyseur, fabrication de celui-ci et installation pour mettre en oeuvre le procede WO1998046336A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU76425/98A AU7642598A (en) 1997-04-12 1998-04-11 Process for decomposing halogenated hydrocarbons with a catalyst, its productionand installation for carrying out the process

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19715260 1997-04-12
DE19715260.0 1997-04-12

Publications (1)

Publication Number Publication Date
WO1998046336A1 true WO1998046336A1 (fr) 1998-10-22

Family

ID=7826298

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP1998/002088 WO1998046336A1 (fr) 1997-04-12 1998-04-11 Procede pour decomposer des hydrocarbures halogenes au moyen d'un catalyseur, fabrication de celui-ci et installation pour mettre en oeuvre le procede

Country Status (2)

Country Link
AU (1) AU7642598A (fr)
WO (1) WO1998046336A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2399662A1 (fr) * 2010-06-28 2011-12-28 Honeywell International, Inc. Procédés de pyrolyse, catalyseurs et appareils permettant de traiter et/ou détecter des gaz contaminés

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0259105A2 (fr) * 1986-09-03 1988-03-09 The British Petroleum Company p.l.c. Réactions catalysées par protons
EP0485787A1 (fr) * 1990-10-26 1992-05-20 Tosoh Corporation Equipement pour le traitement de gaz d'échappement contenant des composés halogénés organiques
EP0520543A1 (fr) * 1991-06-28 1992-12-30 ENIRICERCHE S.p.A. Catalyseur superacide et procédé pour sa préparation
US5283041A (en) * 1992-08-13 1994-02-01 Engelhard Corporation Catalytic incineration of organic compounds
EP0715888A2 (fr) * 1994-12-07 1996-06-12 Basf Aktiengesellschaft Catalyseur pour exécuter des réactions catalysées par des acides de Lewis

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0259105A2 (fr) * 1986-09-03 1988-03-09 The British Petroleum Company p.l.c. Réactions catalysées par protons
EP0485787A1 (fr) * 1990-10-26 1992-05-20 Tosoh Corporation Equipement pour le traitement de gaz d'échappement contenant des composés halogénés organiques
EP0520543A1 (fr) * 1991-06-28 1992-12-30 ENIRICERCHE S.p.A. Catalyseur superacide et procédé pour sa préparation
US5283041A (en) * 1992-08-13 1994-02-01 Engelhard Corporation Catalytic incineration of organic compounds
EP0715888A2 (fr) * 1994-12-07 1996-06-12 Basf Aktiengesellschaft Catalyseur pour exécuter des réactions catalysées par des acides de Lewis

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2399662A1 (fr) * 2010-06-28 2011-12-28 Honeywell International, Inc. Procédés de pyrolyse, catalyseurs et appareils permettant de traiter et/ou détecter des gaz contaminés

Also Published As

Publication number Publication date
AU7642598A (en) 1998-11-11

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