Classifications

• • A—HUMAN NECESSITIES
  • A62—LIFE-SAVING; FIRE-FIGHTING
  • A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
  • A62D3/00—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances
  • A62D3/10—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances by subjecting to electric or wave energy or particle or ionizing radiation
  • A62D3/19—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances by subjecting to electric or wave energy or particle or ionizing radiation to plasma
• • A—HUMAN NECESSITIES
  • A62—LIFE-SAVING; FIRE-FIGHTING
  • A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
  • A62D2101/00—Harmful chemical substances made harmless, or less harmful, by effecting chemical change
• • A—HUMAN NECESSITIES
  • A62—LIFE-SAVING; FIRE-FIGHTING
  • A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
  • A62D2101/00—Harmful chemical substances made harmless, or less harmful, by effecting chemical change
  • A62D2101/20—Organic substances

Definitions

• the invention relates to a method for converting gaseous, liquid and / or solid pollutants in pollutant-free or low-pollution decomposition products by the pollutants excited by means of a plasma, if necessary pre-decomposed or chemically converted and catalytic be decomposed.
• the pollutants For exhaust gas cleaning and treatment with toxic or harmful substances contaminated liquids or solids it is known to be the pollutants to convert plasma chemical into non-toxic decomposition products.
• the pollutants are, for example, in one thermal plasma (equilibrium plasma) burned, wherein the thermal plasma by ionizing a gas by applying a high-frequency electromagnetic field by means of a plasma torch, by electrical discharges or photon beams, generated by arcing or the like can be.
• the pollutant molecules in one cold plasma stimulate and by adding oxidizing agents or reducing agents excited by the plasma be transformed into harmless substances.
• Such cold plasmas are caused, for example, by glow discharges, silent discharges, corona discharges or by applying a high-frequency electromagnetic field Microwave generators generated under vacuum.
• Such procedures are, however, not very effective, because despite high technical
• the pollutants are only partially implemented or only a few pollutants are selectively eliminated.
• the pollutant molecules decompose completely become.
• the use of catalysts is complex and expensive and performs due to the necessary regeneration very short downtimes of the system. this applies especially when catalyst poisons are in the medium to be cleaned are included.
• DE 28 15 430 A1 describes a method for reduction chemical oxygen demand from organic contaminants contaminated water and waste water by the Water mixed with ionized gases and the contained ones Impurities oxidative in the presence of a catalyst be dismantled. To maintain the activity of the catalyst this must be constantly replaced or regenerated or reactivated. This happens, for example in that the catalyst is continuously in a closed Cycle and with the addition of oxidizing agents is regenerated in the form of ionized gases.
• the invention has for its object a simple and cost-effective process for decomposing pollutants propose by pollutants using a plasma stimulated, possibly pre-decomposed or chemically reacted and be catalytically decomposed, which is a complete Sales of pollutants guaranteed and in particular does not require regeneration of the catalyst.
• this object is achieved in a method of type mentioned in that the plasma at least a starting material to form at least one under the conditions in the respective plasma active catalyst continuously added, the catalyst in the Plasma is formed in situ from the starting material and the Pollutants and / or their decomposition products on the catalyst are essentially completely decomposed.
• the plasma is on the one hand in itself known way to stimulate the pollutants used to to decompose or convert them into intermediate products, on the other hand, to form the for complete implementation the catalyst required for pollutants.
• the catalyst is constantly newly formed so that neither regeneration nor reactivation, an exchange of the same is still necessary.
• the method according to the invention is arbitrary for elimination Pollutants, e.g. in exhaust gases, waste water or solids suitable that interact with the plasma can.
• a thermal or a cold plasma which is generated in any known manner becomes.
• the catalyst is selected accordingly according to the type and concentration of the pollutants and the used Plasma.
• the plasma at least one starting material to form at least one from the respective plasma activatable photocatalyst continuously added to the photocatalyst in the plasma formed and activated in situ from the starting material and the pollutants and / or their decomposition products essentially completely decomposed on the photocatalyst become.
• Mainly metal oxides come as photocatalysts or metal sulfides in question, whereby by mixtures such catalysts the efficiency of the catalytic Decomposition depending on the type of plasma and The nature of the pollutants can be optimized.
• photocatalysts in the form of metal oxides, such as TiO 2 , ZnO 2 , Nb 2 O 5 , WO 3 , SnO 2 , ZrO 2 , SrTiO 2 , KTaO 3 , NiK 4 Nb 6 O 17 or the like, is preferred in Design provided that oxygen and at least one organometallic compound and / or at least one metal alcoholate are added to the plasma as starting materials to form the photocatalyst, preferably at least one metal from the group titanium (Ti), zinc (Zn), niobium, (Nb ), Tungsten (W), tin (Sn), zirconium (Zr), strontium (Sr), tantalum (Ta), potassium (K) containing organometallic compound and / or an alcoholate containing at least one such metal is added.
• Ti titanium
• Zn zinc
• niobium Nb
• Nb Tungsten
• W tin
• Sn zircon
• photocatalysts in the form of metal sulfides, such as CdS, ZnS or mixed sulfides, it is preferred in a preferred embodiment that sulfur or a sulfur-containing compound and at least one organometallic compound and / or at least one metal alcoholate are added to the plasma as starting materials for forming the photocatalyst, preferably an organometallic compound containing at least one metal from the group cadmium (Cd), zinc (Zn), selenium (Se), tellurium (Te), molybdenum (Mo), tungsten (W) and / or at least one alcoholate containing such a metal is added.
• Cd group cadmium
• Zn zinc
• Se selenium
• Te tellurium
• Mo molybdenum
• W tungsten
• W tungsten
• sulfur-containing compounds examples include sulfur oxides, such as SO, SO 2 , SO 3 , SO 4 , S 2 O, S 2 O 3 , S 2 O 7 or hydrogen sulfide.
• sulfur oxides such as SO, SO 2 , SO 3 , SO 4 , S 2 O, S 2 O 3 , S 2 O 7 or hydrogen sulfide.
• at least one organometallic compound containing sulfur or at least one metal alcoholate containing sulfur can be added.
• the catalyst that can be activated by the plasma around a photocatalyst so is more preferred Execution provided that an electromagnetic radiation with a frequency in the range of the excitation frequency of the Plasma emitting photocatalyst is used, so that the plasma as a light source to activate the photocatalyst serves.
• the plasma at least one additive can be added, which by plasma excitation with electromagnetic radiation Frequency in the range of the excitation frequency of the photocatalyst emitted.
• Such additives are preferred from selected the group of noble gases, since these decompose the Do not negatively affect pollutants.
• auxiliaries can either oxidizing auxiliaries, e.g. Oxygen, be added the oxygen in this case, on the one hand, for oxidation the pollutants, on the other hand to form a photocatalyst serve in the form of one or more metal oxides can.
• auxiliary substances reducing the plasma e.g. Hydrogen added.
• a photocatalyst in the form of one or more Metal sulfides, for example, also as hydrogen sulfide Starting material used to form the photocatalyst become.
• the plasma can be both oxidative and reductive acting auxiliaries are added, in particular such excipients come into question by plasma excitation into oxidizing and reducing decomposition products being transformed.
• Water is preferably added, which is plasma chemical in acting as an oxidizing agent Protons and hydroxide ions acting as reducing agents is split.
• a plasma is used Bulk material arranged from a dielectric with a large surface and the catalyst formed in situ on the dielectric continuously deposited.
• the surface of the bulk material becomes a large one for the pollutants Contact area provided with the catalyst and complete degradation thereof, e.g. a complete Oxidation to carbon dioxide and water.
• the latter becomes e.g. at least on all of them Areas facing the plasma source are deposited on the dielectric and optically excited by the plasma source.
• Bulk materials come primarily from porous ceramics or mineral ones Granules, such as clays, clay minerals, zeolites, corundum, or optically transparent materials, such as Glass, quartz wool or the like, in question.
• the process according to the invention can be carried out continuously, be carried out semi-continuously or in batches.
• a plate reactor is filled with a dielectric granulate in the form of quartz particles, evacuated and charged with argon.
• An argon plasma is generated by ionizing the argon atoms by applying a high-frequency electromagnetic field to the plate reactor.
• a photocatalyst in the form of titanium dioxide (TiO 2 ) both oxygen, for example atmospheric oxygen, and an organometallic titanium compound or a titanium alcoholate, for example Ti (OiC 3 H 7 ) 4 , are added to the reactor.
• TiO 2 is formed in the plasma, which is photoactive in the ultraviolet range and is attached to the quartz particles as a photocatalytically active layer.
• a gas contaminated with pollutants is passed through the reactor, the pollutants being excited, pre-decomposed or chemically converted and catalytically completely decomposed by means of the plasma.
• the continuous addition of oxygen and the titanium alcoholate continuously forms new TiO 2 , so that there is always sufficiently active catalyst material available.
• the oxygen also serves as an auxiliary or as a reaction partner for the pollutants for oxidative degradation thereof, whereby it is ionized in the high-frequency electromagnetic field.
• An oxygen plasma generated in this way is reactive on the one hand, and on the other hand it additionally emits electromagnetic radiation in the ultraviolet range in order to activate the photocatalyst deposited on the dielectric granulate.

Landscapes

• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Plasma & Fusion (AREA)
• Health & Medical Sciences (AREA)
• General Health & Medical Sciences (AREA)
• Toxicology (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Business, Economics & Management (AREA)
• Emergency Management (AREA)
• Catalysts (AREA)
• Treating Waste Gases (AREA)
• Exhaust Gas Treatment By Means Of Catalyst (AREA)

Applications Claiming Priority (2)

Publications (3)

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Citations (2)

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• 1999
  • 1999-11-04 DE DE19953110A patent/DE19953110A1/de not_active Withdrawn
• 2000
  • 2000-10-24 AT AT00123040T patent/ATE321593T1/de not_active IP Right Cessation
  • 2000-10-24 DE DE50013440T patent/DE50013440D1/de not_active Expired - Lifetime
  • 2000-10-24 EP EP00123040A patent/EP1097729B1/fr not_active Expired - Lifetime

Patent Citations (2)

Non-Patent Citations (1)

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