WO1991009823A1 - Procede photocatalytique de degradation de matieres organiques a l'etat vaporise ou gazeux - Google Patents

Procede photocatalytique de degradation de matieres organiques a l'etat vaporise ou gazeux Download PDF

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Publication number
WO1991009823A1
WO1991009823A1 PCT/US1990/007651 US9007651W WO9109823A1 WO 1991009823 A1 WO1991009823 A1 WO 1991009823A1 US 9007651 W US9007651 W US 9007651W WO 9109823 A1 WO9109823 A1 WO 9109823A1
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reaction
gaseous
organic material
organic
degradation
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PCT/US1990/007651
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English (en)
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Norman N. Lichtin
Kallambella M. Vijayakumar
Junchang Dong
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Trustees Of Boston University
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    • 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
    • A62D3/17—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 electromagnetic radiation, e.g. emitted by a laser
    • A62D3/176—Ultraviolet radiations, i.e. radiation having a wavelength of about 3nm to 400nm
    • 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
    • A62D3/17—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 electromagnetic radiation, e.g. emitted by a laser
    • 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
    • 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
    • B01D53/8668—Removing organic compounds not provided for in B01D53/8603 - B01D53/8665
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07B—GENERAL METHODS OF ORGANIC CHEMISTRY; APPARATUS THEREFOR
    • C07B61/00—Other general methods
    • 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
    • A62D2101/06—Explosives, propellants or pyrotechnics, e.g. rocket fuel or napalm
    • 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
    • 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
    • A62D2101/22—Organic substances containing halogen
    • 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
    • A62D2101/26—Organic substances containing nitrogen or phosphorus
    • 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
    • A62D2101/28—Organic substances containing oxygen, sulfur, selenium or tellurium, i.e. chalcogen
    • 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
    • A62D2203/00—Aspects of processes for making harmful chemical substances harmless, or less harmful, by effecting chemical change in the substances
    • A62D2203/10—Apparatus specially adapted for treating harmful chemical agents; Details thereof

Definitions

  • the present invention is directed to photo- catalytic processes and reaction methods for the controlled degradation of organic materials present in a gaseous state such that environmentally compatible reaction products alone are yielded.
  • the thermal volatilization technique has major drawbacks, which include: often incomplete destruc ⁇ tion of the organic material; the frequently inadequate disposal of the incinerated products, if they are not released into the ambient air and environment at large; the common release of toxic products of partial combustion which when volatilized become health hazards for the employees and the public; and the general limitations and costs a process dedicated to thermal destruction of the organic material.
  • the second general approach is also applica- tion-oriented and is intended primarily for treating domestic water sources for the removal of hazardous natural and/or synthetic organic compounds which are present in relatively low concentration levels, typically 50-500 parts per billion.
  • a constant requirement and characteristic of this approach is the use of an ultraviolet light initiated reaction in combination with a chemical oxidizing agent for the degradation of the hazardous organic compounds in the water or other aqueous liquid. Either ozone gas or hydrogen peroxide is typically used as the chemical oxidizing agent.
  • ozone gas or hydrogen peroxide is typically used as the chemical oxidizing agent.
  • ozone gas is employed as the oxidizing agent, the gas must be generated where it will be used because ozone is an unstable gas; freshly generated ozone will react in the presence of ultraviolet light with organic compounds to yield a wide diversity of oxidized carbon-containing reaction products, most often peroxides and hydroxyl derivatives of the hazardous organic compounds present initially. In addition, the rate of reaction is often dependent on ultraviolet light intensity.
  • Representative publications describing this technique include: William H. Glaze, Enviro . Sci. Technol . 1:224-230 (1987); Masten and Butler, Ozone Science and Engineering 8_:339-353 (1987); Peyton and Glaze, "Mechanism of Photolytic Ozonation," in Photo ⁇ chemistry of Environmental Aquatic Systems . American Chemical Society, 1987, pages 76-88.
  • the third general approach is far more theoretical and research oriented. It focuses upon the photopromoted catalytic degradation of organic material in aqueous suspensions or solutions and in liquid mixtures of water and organic solvents. All of these investigations utilize molecular oxygen [0 hail] as an oxidizing agent in the form of oxygen saturated or aerated water in combination with a solid catalyst, most often a semiconductor transition element oxide in powder form.
  • This reaction process often termed “heterogeneous photocatalysis , " utilizes a continuously illuminated, photoexcitable solid catalyst to convert reactants adsorbed on the photocatalyst surface.
  • photocatalysts are semi-conductors which are believed to bring the reactants in the fluid into contact with electrons and/or positive holes which are generated within the solid by photons of energy equal to or higher than the band-gap of the solid catalyst [Teichner and Formenti], "Heterogeneous Photocatalysis,” Photoelectrochemistry , Photocatalysis, and Photo- reactors (M. Schiavello, editor), D. Reidel Publishing Company, 1985, pages 457-489].
  • These investigations are particularly concerned with purification of drinking water supplies and the aquatic environment; and seek to degrade organic materials such as organo-chlorine compounds in aqueous suspensions or solutions.
  • the present invention provides a photocatalytic ⁇ rocess for the degradation of organic materials in a gaseous state, this process comprising the steps of: obtaining the organic material to be degraded in a gaseous state; combining the gaseous organic material with a solid catalyst comprising at least one transition element, with molecular oxygen, and with water vapor to form a reaction mixture; and adding photoenergy absorbable at least in part by said solid catalyst energy to said reaction mixture such that environmentally compatible reaction products comprising at least carbon dioxide are yielded.
  • the process may be utilized with all organic materials in gaseous or vaporized form without regard to actual formulation, structure, or concentration so long as adequate quantities of molecular oxygen and water vapor are present in the reaction mixture.
  • the present invention has a plurality of applications and uses as a photocatalytic process for elimination of a wide variety of hazardous and/or toxic organic matter which can be converted, made, or obtained in a gaseous state.
  • FIG. 1 is a view of a closed, single batch reaction apparatus useful in practicing the present invention
  • Fig. 2 is a flow diagram of a continuous flow reaction apparatus useful in practicing the present invention
  • Fig. 3 is a detailed frontal view of the continuous flow reaction chamber in the apparatus of Fig. 2;
  • Fig. 4 is a graph illustrating the photo- catalytic degradation of trichloroethylene in a static reactor as a function of time using the present invention
  • Fig. 5 is a graph illustrating the effect of photoenergy upon the degradation of trichloroethylene in a static reactor as a function of time
  • Fig. 6 is a graph illustrating the photo ⁇ catalytic degradation of trichloroethylene as a function of flow rate using a continuous flow reaction apparatus
  • Fig. 7 is a graph illustrating the effect of initial concentration upon the rate of degradation for trichloroethylene in a continuous flow reaction apparatus
  • Fig. 8 is a graph illustrating the photo- catalytic degradation of benzene as a function of flow rate in a continuous flow reaction apparatus
  • Fig. 9 is a graph illustrating the photo- catalytic degradation of toluene as a function of initial concentration using a continuous flow reaction apparatus
  • Fig. 10 is a graph illustrating the photo- catalytic degradation of iso-octane as a function of varying initial concentration in a continuous flow reaction apparatus
  • Fig. 11 is a graph illustrating the photo- catalytic degradation of commercial freon (C-F-C1-) as a function of flow rate using a continuous flow reaction apparatus
  • Fig. 12 is a graph illustrating the effect of temperature upon the degradation of trichloro ⁇ ethylene in a static, single batch reactor apparatus
  • Fig. 13 is a graph illustrating th-e effect of varying quantities of water vapor upon the degradation of trichloroethylene in a static, single batch reaction apparatus.
  • the present invention is a photocatalytic process for the controlled degradation of one or more organic materials in a gaseous state into environmentally compatible reaction products comprising at least carbon dioxide.
  • this catalytic process comprises three steps: obtaining the organic material to be degraded in a gaseous state; combining the gaseous organic material with a solid catalyst comprising at least one transition element, molecular oxygen, and water vapor as a reaction mixture; and adding photoenergy in the ultraviolet and/or visible and/or near infrared regions which is absorbable at least in part by the solid catalyst to the reaction mixture to yield environmentally compatible reaction products comprising at least carbon dioxide.
  • reaction products produced by the present photocatalytic process provide environ ⁇ mentally compatible reaction products which can be released directly into the ambient environment; or can be easily controlled and quickly disposed in an environmentally safe manner.
  • the final reaction products will be gaseous in form; and will include carbon dioxide; and when a halogen (X) and/or hydrogen (H) and/or nitrogen (N) are present originally, will also typically include HX, water, and/or some nitrogen containing composi ⁇ tions such as ammonia or various nitrogen oxides.
  • Such reaction products are environmentally compatible themselves; as in the instance of C0_ production, or are easily neutralized as in the instance of HX production by subsequent reaction to give sodium or calcium salts; or are otherwise containable.
  • Such reaction products also avoid and eliminate the real and present dangers of releasing hazardous, toxic, or biologically non-degradable materials into the air, water, and soil as is unfortunately the present practice with waste disposal management methods today.
  • the photocatalytic process of the present invention is able to provide a complete degradation of both simple and complex organic materials generally. Unlike methods previously known in this art, this general catalytic process will completely degrade arenes, alkanes, alkenes , aryl halides, alkyl halides, haloalkanes, alkyl aryl halides, and their derivatives into environmentally compatible reaction products in which carbon is completely converted to carbon dioxide. Moreoever, the present process is able to completely degrade organic compositions which in the past have been most difficult to eliminate on any scale.
  • the photocatalytic process of the present invention avoids the unintended formation of hazardous and/or toxic reaction intermediates and reaction by-products.
  • the process intermediates and products In order for a chemical process used for the destruction of toxic/hazardous organic pollutants to be truly viable and practically employed, the process intermediates and products must be of known, acceptable chemical identify and be non-toxic. In comparison, a degradation process which is capable under operating conditions of producing an exhaust containing unknown or toxic intermediate products and/or hazardous reaction by-products is neither viable nor practical.
  • the present method is not limited in its applicability to only very dilute solutions (e.g., parts per million levels) of pollutants. This capability is empirically documented hereinafter and satisfies a generally recognized and long-standing need in this art.
  • the present invention also allows for the purposeful concentration of reactants and degradation of hazardous and/or toxic organic materials in vaporized form at concentration levels never before possible. It is clear that supplying the reactants in the gas phase makes conveniently available an enormous range of reactant concentra- tions. This, in turn, provides a much broader range of options for the concentration of reactants than is generally available when the reaction involves a catalyst in contact with a liquid phase substance. For example, the concentration of molecular oxygen [0_] in the gas phase at any partial pressure of oxygen is about 100 times greater than its concentra ⁇ tion in a saturated aqueous solution in equilibrium with 0- at that pressure.
  • the user may employ either high, moderate, or low concentra- tions of 0 spirits as seems best under .the actual use conditions.
  • the organic material to be degraded, being in a vaporized state can be concentrated or diluted, if desired or required.
  • the photocatalytic process of the present invention intends and expects that the gaseous organic material to be degraded be combined with molecular oxygen and water vapor.
  • the amount of molecular oxygen required for the photocatalytic degradation mechanism to proceed must be sufficient for both a complete conversion of such carbon as is present initially into carbon dioxide; and for a conversion into H-0 of such hydrogen as is not converted into HX if a halogen is present, or into hydrides of elements other than X or C if such elements are present.
  • the introductory gaseous stream containing the organic material to be degraded may contain a wide range of proportions of organic matter, dioxygen, water vapor, and an inert gaseous carrier such as nitrogen. Alternatively, air may be used directly as both a carrier gas and as a source for dioxygen.
  • the photocatalytic process of the present invention is able to be utilized at ambient environ ⁇ ment temperatures. It is expected that the ambient temperature will vary within the extremes considered normal in the temperate zone, that is, substantially in the range from 0-40°C. In certain applications, however, the catalytic process will be employed at elevated temperatures, up to and exceeding 125°C. As will be empirically demonstrated hereinafter, the present invention may be affected by temperature in a most unusual and unexpected way; increases in temperature may directly reduce and diminish the rapidity and efficacy of the degradation process. This characteristic of the methodology, when encountered, should be considered carefully when practicing the invention; and is deemed to be a distinguishing phenomenon which differentiates the present methodology from its predecessors.
  • the present photocatalytic process is extraordinarily and uniquely rapid in its degradation effects.
  • the bulk of the gaseous organic matter can be destroyed in a matter of seconds once photoenergy has been added to the prepared reaction mixture.
  • the entire effective concentration of the organic material (at least 99%) is degraded in less than 3 minutes' duration.
  • the user can optimize ' and meaningfully reduce the total real operating time required for destroying concentrated, bulk quantities of gaseous organic matter by employing a continuous flow reactor apparatus rather than a single batch, closed volume reaction chamber.
  • the organic material able to be degraded by the present invention is at least one, and typically a mixture of different organic compositions in admixture - all of which are present in a gaseous or- vaporized state.
  • the source of the organic material is expected to be waste including: commercial and industrial waste products; toxic and non-toxic chemical compositions; environmentally hazardous and non-hazardous substances; volatile organic solvents; monomers or other volatile organic compounds used in industrial production of polymers; petrochemicals; fine or heavy chemicals; liquid fuels; lubricants; propellants; refrigerants; cleaning agents; and gaseous mixtures of organic matter and non-reactive carrier gases (such as molecular nitrogen or argon) in combination.
  • non-reactive carrier gases such as molecular nitrogen or argon
  • a large, diverse, and varied range of chemical compositions are included within the general class of vaporized or gaseous organic material to be completely degraded. These include relatively low molecular weight saturated organic substances such as alkanes, substituted alkanes without limitation; haloalkanes and perhaloalkanes; vaporized higher molecular weight unsaturated compounds including arenes, aryl alkanes and their derivatives, aryl halides, aryl alkyl halides, olefins and haloolefins; oxygen-containing organic compounds; and nitrocompounds, amines, and other nitrogen containing classes.
  • Table I A representative, but non-exhaustive listing of different kinds and types of vaporized or gaseous organic material able to be degraded is provided by Table I below,
  • Alkylbenzenes (such as toluene and xylenes)
  • Dichloroethanes and Dibromoethanes Trichloroethanes and Tribromoethanes Tetrachloroethanes and Tetrabromoethanes
  • the sources of these organic pollutants will be equally diverse.
  • the organic pollutants will not exist in gaseous form initially; rather, the organic matter will likely appear as solids, liquids, and/or mixtures of these.
  • these substances it is required that these substances be vaporized, preferably under controlled conditions, to yield gaseous organic materials of mixed or pure chemical content.
  • the state and form of the organic material to be degraded initially may appear as a liquid containing varying amounts of water.
  • such an organic material is a solid or a mixture of solids and liquids in either pre- dominantly organic or aqueous form.
  • predominately aqueous mixtures are ground water; polluted potable water; and industrial waste water.
  • the common predominately organic liquid mixtures typically include industrial solvent residues; organic solvents used for dry cleaning and water proofing; organic cleansing agents and abstraction liquids in the petroleum industry and refining processes; and organic liquids used as degreasers and solvents for metals and metal deposition in the high technology industries. It will be recognized and appreciated also that many of the organic consumer and industrial waste liquids typically contain small amounts of water present inherently or obtained concomitantly as a result of their earlier uses.
  • organic solvents individually or in combination may be present alone or with water as the initial liquid or semi-liquid carriers for the organic material to be degraded. It is recognized that these- organic solvents may also be toxic and/or hazardous in themselves and should therefore be concomitantly degraded as much as possible. Such would be the case if a particular pollutant is most effectively dissolved in a highly toxic or carcinogenic organic solvent. Under these circumstances, it is most desirable that the organic solvent itself be consumed during the degradation process in addition to destruction of the intended organic pollutant.
  • Table II A representative listing of organic solvents generally desired to be concomitantly degraded is provided by Table II below.
  • An essential and required co-reactant for the photocatalytic degradation process of the present invention is molecular oxygen [0-] or dioxygen as it is sometimes called. Quantitatively, the amount of molecular oxygen to be made available should be stoichiometrically sufficient for complete conversion of carbon to CO-; and for conversion of hydrogen into H-0 - if the hydrogen is not converted to HX or another compound not comprising either carbon or halogen.
  • the source, origin, or point of supply for the molecular oxygen is not of important or relevance.
  • Ambient air is an excellent source of molecular oxygen for purposes of practicing the present methodology; the other gaseous components of clean, ambient air (N 2 » CO-, Ar, H-0) need not be separated from the molecular oxygen prior to its use as a reactant.
  • sealed tanks large or small containing compressed air, or mixed gases including molecular oxygen, or pure 0- can be utilized. If desired, the molecular oxygen can be generated physically or chemically in the field or on-site; and employed as a reactant immediately after its generation.
  • water vapor, H-0 in gaseous form be present as a part of the prepared reaction mixture for degradation purposes.
  • the water vapor need be present only in a measurable amount; or in an amount sufficient to supply a stoichiometric requirement, for - hydrogen.
  • the actual purity of the water vapor employed and its source of origin are neither important nor relevant factors.
  • Environmental air is an excellent source of water vapor without regard to the percentage of water vapor in the air, the true amount or quality* of the other gaseous components of the air, or its status (ambient, compressed, treated, filtered, etc.).
  • the percentage content by volume of the water vapor in a gaseous carrying stream can be increased by purposeful evaporation of liquid water, production of steam, and any other conventionally known means for intentionally increasing water vapor content and concentration.
  • the act of converting the organic material into a gaseous state will typically also provide abundant quantities of water vapor as a concomitant result.
  • the catalysts used in the present invention are solids preferably used in a powdered or subdivided form in order to expose a large surface area for reaction.
  • Each solid catalyst contains at least one transition element ' able to absorb photoenergy of a specified type and wavelength range.
  • Transition elements are those which, as elements or in any of their commonly occurring oxidation states, have partly filled “d” or "f” shells. The reader is presumed to have both knowledge and familiarity of the properties and characteristics of transition elements generally as these are described in F.A. Cotton and G. Wilkinson, Advanced Inorganic Chemistry , 5th edition, John Wiley and Sons, New York, 1988 - the text of which is expressly incorporated by reference herein.
  • solids containing oxides of transition elements are highly preferred.
  • a repre ⁇ sentative, but not-inclusive listing of preferred metal oxide catalysts includes those listed in Table III below.
  • Degussa prepared titanium dioxide is primarily in the anatase form (rather than the rutile form) and has been demonstrated to be highly active in the complete degradation of alkanes, arenes, haloalkanes, haloalkenes, haloaromatic phenolics, halophenolics , and other classes of organic compounds into carbon dioxide and other products.
  • the catalysts used in the present process may be selected and used individually or employed in combination as a mixture of two or more catalysts.
  • the preparation of solid catalysts suitable for use in the present catalytic process are conventionally known in the art and may be prepared in accordance with their published methods of preparation or can be commercially purchased from a variety of different suppliers.
  • the present invention is unique in its ability to photocatalytically degrade gaseous or vaporized organic material in a controlled manner into environ ⁇ mentally compatible reaction products comprising at least carbon dioxide.
  • the gaseous organic materials are degraded at very rapid rates in the presence of photoenergy by combining them with molecular oxygen, water vapor, and a suitable solid catalyst.
  • photoenergy is defined as electromagnetic radiation of any wavelength. It will be appreciated also that the entirety of the catalytic reaction process may be conducted on demand for preset time periods, continuously or cyclically as desired or required by the user.
  • photoenergy When photoenergy is added to the reaction mixture, it is the ultraviolet, visible, and near infrared wavelengths (200-1,000 nm) which are most effective in enhancing the activity of the catalysts.
  • photoenergy when photoenergy was added to the reaction mixture, such photoenergy was obtained using laboratory scale lamps and illumination devices having a limited and identifiable range of light wavelengths. In larger scale industrial or commercial applications, it is expected that sunlight or artificial light from a variety of different sources may be employed to provide wavelengths in the 200-1,000 nm range.
  • photoenergy When such incident photoenergy is added, there is substantial enhancement of gaseous organic material degradation per Einstein of incident energy above those obtainable by known processes which do not utilize transition element catalysts.
  • the use of photoenergy provides substantially increased yields of organic material degradation in comparison to those yields obtained by conventional processes.
  • the catalytic process of the present invention be conducted at ambient environmental temperature, that is within the temperature range of the surrounding environment generally presumed to be between 0-40°C. Higher temperatures may be required to maintain desired partial pressures of pollutants and/or to keep pollutants in the vapor phase. Such increases in temperature will not substantially change the resulting reaction products.
  • the photocatalytic process of the present inven ⁇ tion provides complete degradation of gaseous organic material into environmentally compatible reaction products which include at least carbon dioxide in every instance. It is expected that the reaction products will evolve in a gaseous state; and will then be removed or effectively neutralized using conventional chemical means. Clearly, the exact identity of the reaction products will vary and depend upon the particular chemical formulation and structure of the gaseous organic material being degraded; and will, at least in some instances, also vary with the composition of the other vaporized organic compounds (solvents, etc.) which initially carried the particular organic material and were concomitantly converted into a gaseous state. Nevertheless, a variety of typical reactions and reaction products which are merely illustrative of the present invention as a whole are provided by Reactions A-F of Table IV below.
  • reaction A represents the complete degradation of vaporized organic solvents which are not resistant to decomposition by the present catalytic process. While carbon tetrachloride serves as the immediate example, it is clear that other vaporized chloro derivatives of saturated carbon (such as chloroform) and other halogen derivatives of carbon in a gaseous state will react in a similar fashion to yield carbon dioxide and HX (wherein X is any halogen).
  • Reaction B is representative of saturated hydrocarbons and saturated alkyl derivatives generally which are obtained or have been converted into gaseous form. Linear, branched, and cyclic alkanes and alkyl derivatives in a gaseous state will also be completely decomposed.
  • Reaction C represents vaporized linear and branched halo-olefins in both substituted and non-substituted form.
  • Reaction D illustrates the complete degradation of an aromatic hydrocarbon and is intended to represent all arenes generally obtainable or convertable in gaseous form.
  • Reaction E illustrates the complete degradation of a halo-substituted aromatic compound.
  • Reaction F exemplifies the degradation of a class of compounds encountered as industrial waste by-products for which there is presently no safe method of decomposition and elimination; the nitrogen containing reaction products may also include other oxygen derivatives of nitrogen in addition to or instead of that specifically identified.
  • Table IV is merely representative of the variety of photocatalytic reactions provided by the present invention.
  • the gaseous reaction products comprise at least carbon dioxide in each and every instance; and include other environmentally compatible products which are either non-toxic and non-hazardous in themselves, or can be chemically neutralized or otherwise converted quickly and easily into environ ⁇ mentally compatible products.
  • One characteristic feature of the present methodology is its ability to be performed either as a single batch reaction or as a continuous flow reaction process.
  • two different kinds of apparatus were employed to demonstrate each capability.
  • the single batch reaction system is illustrated using the apparatus shown in Fig. 1.
  • the apparatus includes a pyrex flask 10, typically of one liter volume, having a plurality of ports or openings 12a-12c.
  • the internal surface of the reaction flask 10 has been coated with a solid catalyst 14 comprising at least one transition element; and experimentally was always Degussa P25 titanium oxide (TiO-) which was prepared and introduced onto the internal surface of the reaction flask as will be described hereinafter.
  • TiO- Degussa P25 titanium oxide
  • thermometer 16 has been inserted into the interior volume of the reaction flask 10.
  • an ultraviolet lamp 18 ' has been inserted into the interior of the pyrex flask 10 such that ultraviolet photoenergy will be radiated throughout the interior of the reaction flask.
  • the third port 12c supports the inlet 24 for the introduction of a gaseous stream comprising the organic material in a gaseous state to be degraded, the water vapor, and the molecular oxygen. After the gaseous reactants have been intro ⁇ quizd via the inlet 24 into the interior of the reaction flask 10, the port 12c is sealed using a valve or other conventional means effective to achieve this purpose.
  • the reaction flask 10 is itself disposed within a heating mantle 20 which, in turn, is electrically connected to a transformer 22 a shown.
  • the heating mantle 20 and transformer 22 serve as the heating means to provide and maintain a prechosen temperature at which the degradation reaction is to proceed.
  • the resulting gaseous reaction products are withdrawn for analysis by gas chromato- graphy, ion-selective potentiometric analysis, or other analytical assays as will be described hereinafter .
  • the continuous flow reaction apparatus employed experimentally is illustrated by Figs. 2 and 3 respectively.
  • Fig. 2 is a flow diagram of the continuous reactor apparatus employed for the experiments to be described hereinafter.
  • an introductory (or eluent) gaseous stream comprising air or a carrier gas mixed with molecular oxygen is introduced through a piping and tubing system 31 including a pressure regulator 40, a plurality of flow controller valves 42, and a plurality of flow meters 44.
  • the gaseous organic material to be degraded and water vapor are contained within thermostatically controlled chambers 46 and are intermixed with the gaseous stream containing molecular oxygen by piping 33 and the three-way valve 50.
  • the eluent gaseous stream now containing the organic material to be degraded, the water vapor, and molecular oxygen are introduced via flow tubing 35 to the interior of the reaction chamber 52.
  • the resulting reaction products are discharged as an effluent via tubing 37 into a water trap 54 for any gaseous acids in the effluent stream.
  • the gaseous effluent then proceeds via tubing 39 through another three-way valve 42 directly to a gas chromatograph 56 for analysis of the reaction products in the effluent gaseous stream.
  • valves 42 and 50 are appropriately set, the inlet gas composition can also be analyzed by gas chromatography.
  • this apparatus and design is merely of laboratory scale and convenience; many other different configurations and designs for a continuous flow apparatus and reactors are deemded possible and expected.
  • the system illustrated by Fig. 2 is intended to simulate practical use conditions.
  • the initial gaseous stream of air from the compressed tank source is split into three portions, one of which goes through a vessel to pick up the desired amount of organic substance to be degraded at a precisely controlled temperature.
  • the tempera ⁇ ture and the ratio of flow rates for each gaseous stream the composition of the gaseous stream can be altered over a wide range from a few percent to a few parts per million (ppm) allowing a huge variety of test conditions to be performed at will.
  • the gaseous stream carrying mixtures of organic pollutant, water vapor, and molecular oxygen is introduced into the photoreactor chamber; the reaction allowed to proceed; and the effluent gaseous stream is discharged through a trap and directed subsequently through analytical apparatus to detect and evaluate the totality of resulting reaction products accurately.
  • a detailed view of the photoreactor chamber 52 is provided by Fig. 3.
  • the photoreactor 52 is formed of two quartz shells or vessels 60, 62 wherein one vessel 60 has been- inserted into the spatial interior of the other vessel 62.
  • An inlet 64 and an outlet 66 are mounted at the two ends of the quartz shells.
  • a solid catalyst 68 comprising at least one transition element is disposed as a coating onto the inner surface of the quartz vessel 62.
  • the quartz shells have outer dimensions of thirty two centimeters length and 6 centimeters/5 centimeters outer/inner diameters.
  • a 13 watt, 254 nm ultraviolet lamp 70 is introduced into the interior volume of the quartz vessel 60.
  • the exterior of the quartz vessel 62 is wrapped by electrical heating tape 76 and a layer of insula ⁇ tion 78.
  • the reaction temperature is thus controlled by the heat released by the heating tape 76 and the cooling effect introduced by the air jet 72 within the inner quartz vessel.
  • an eluent gaseous stream containing a mixture of gaseous reactants is introduced into the confined space 80 formed by the individual walls of the two quartz vessels 60, 62.
  • the eluent gaseous stream is introduced via the inlet 64 at the bottom and then passes through the confined space 80 where reactive contact is made with the solid catalyst coating 68.
  • the degradation reaction proceeds at a controlled flow rate and temperature.
  • the gaseous effluent stream is discharged and removed via the outlet 66 for immediate analysis.
  • new reactants are continuously introduced in a gaseous stream via the inlet 64, are processed continuously within the confined space 80 in a controlled manner; and are subsequently discharged and removed via the outlet 66 upon completion of the desired reaction duration.
  • the reaction chamber was protected from extraneous light by careful masking of the ' exterior surfaces. Photoenergy was supplied to the prepared gaseous reaction mixture internally using a low pressure mercury lamp. The progress of the degrada ⁇ tion reactions was monitored by routinely measuring the amounts of gaseous organic pollutants in the introductory eluent and remaining within the discharged effluent gaseous stream. The organic pollutants, effluent, CO-., and any other carbon-con ⁇ taining products were detected, identified, and quantified by gas chromatography routinely.
  • the GOW-MAC series 55C gas chromatography apparatus used a 6 foot by 1/8 inch Porapak Q column and thermal conductivity detection.
  • Orion chloride-ion-selective electrode in conjunction with a Radiometer PHM-85 meter.
  • the single batch reactor apparatus illustrated within Fig. 1 was employed.
  • An introductory gaseous stream comprising 50% air (including molecular oxygen), and varying amounts of trichloroethylene (hereinafter "TCE") vapor and water vapor was introduced into the interior of a 1,050 ml reaction flask; 60% of the interior surface of the flask had been previously coated with 1.00 gram of TiO- catalyst.
  • the internal reaction temperature within the flask was maintained uniformly at 125°C and a 13 watt, 254 nm lamp was employed to irradiate the interior of the coated flask.
  • the concentration of TCE vapor in the introductory (eluent) gaseous stream was intentionally varied from about 1,000 ppm . to about 5.0%.
  • the results over varying reaction times ranging from 0-3 minutes are graphically illustrated by Fig. 4 for TCE at an introductory concentration of 1,000 parts per million.
  • a three minute duration of reaction reduces the total TCE content to only 50 ppm.
  • 90% of the TCE was converted in only one minute's reaction time. This observed rate corresponds to the capability of decomposing 11-12 grams of TCE per hour using a 13 watt, 254 nm lamp.
  • analysis of the resulting reaction products within the effluent gaseous stream revealed HC1 and CO- as the only compositions present.
  • the continuous flow reaction system represented by Figs. 2 and 3 was used with a reactor volume of 210 ml.
  • the dependence of TCE degradation on flow rate i.e., reactor residence time
  • the reaction conditions maintained were: water vapor at a concentration of 2,400 ppm; a reaction temperature of 100°C; and 254 nm photoenergy from a 13 watt lamp.
  • the weight of the Ti0_ catalytic coating was 0.4 g.
  • the introductory gaseous stream content and the discharged effluent gaseous stream were analyzed for carbon dioxide and TCE content via gas chromatography; chloride content of water trap 54 was analyzed by ion-selective electrode measurement and confirmed by pH measurement. The results are provided by Fig. 6.
  • Series B comprised a liquid state reaction mixture in 0.10 liter of liquid water containing 0.1 mole % TCE, (5.5 millimoles) 0.006 ml of liquid "Tide” detergent, and 0.1 gram of suspended Ti0 2 catalyst saturated with air at one atmosphere.
  • Series C was a liquid state reaction mixture in 0.10 liter of 3% aqueous H-0- containing 0.1 mole % TCE (5.5 millimoles) 0.006 ml of liquid "Tide” detergent, and 0.1 gram of suspended TiO- catalyst saturated with air at one atmosphere.
  • Vapor composition 89 mole % air, 5 mole % water vapor, 6 mole % TCE; reaction volume, 1.05 L.
  • This experimental series utilized the continuous flow reaction apparatus of Figs. 2 and 3 respectively for each experiment with a reactor volume of 210 ml.
  • the introductory gaseous stream comprised tank air as the carrier gas and source of dioxygen, vaporized organic material to be degraded, and water vapor.
  • organic pollutants were evaluated using the continuous flow apparatus. These were: benzene, toluene, iso-octane, and a commercially sold freon, trichlorofluoroethane .
  • the reaction temperature was 25°C in all instances.
  • the photocatalytic destruction of benzene is illustrated by Fig. 8.
  • the reaction conditions were: an initial benzene concentration of 390 ppm; water vapor at 2,410 ppm; 99.7% air; 0.4 g Ti0_ ; a reaction temperature maintained at 25°C; a reaction chamber volume of 210 ml; and a 13 watt, 254 nm radiation source.
  • Fig. 8 illustrates the photocatalytic destruc ⁇ tion of benzene at different flow rates between 5 and 120 ml/min, which corresponds to a reactor residence time between 42 minutes and 105 seconds respectively.
  • the experimental data presented therein demonstrate the generic principle that benzene in major quantities can be removed effectively using a continuous flow system at the laboratory scale.
  • Fig. 9 illustrates the photocatalytic decomposi- tion of toluene at different initial concentrations.
  • the flow rate of the reaction apparatus was 15 ml/min (corresponding to a reactor residence time of 14 minutes).
  • the eluent gaseous stream comprised 4,000 ppm water vapor, 99.6% air.
  • the gaseous stream was passed through a 210 ml reactor volume at 25°C and irradiated at 254 nm by a 13 watt lamp. 17% of the toluene was destroyed under the conditions of Fig. 8 except that the flow rate was 1.9 ml/min (a reaction residence time of 1 minute, 56 seconds) with an initial concentration of toluene of 310 ppm.
  • the only detectable carbon-containing degradation product was CO- which was formed in amounts stoichio- metrically equivalent to the quantities of toluene decomposed .
  • the photocatalytic decomposition of iso-octane is illustrated by Fig. 10.
  • the reaction conditions were: a continuous flow rate of 120 ml/min; a water vapor content of 2,410 ppm; tank air 99.7%; a Ti0_ catalyst coating of 0.4 grams; a reaction volume of 210 ml; and a 254 nm radiation source of 13 watts.
  • the reaction temperature was maintained uniformly at 25°C throughout each experiment. A complete conversion of iso-octane to CO- ws observed.
  • trichlorofluoroethane a commercial freon
  • reaction conditions maintained uniformly were: a 200 ⁇ ul amount of liquid TCE (corresponding to a vapor phase concentration of 5.9-7.4% over the temperature range employed); a reaction chamber volume of 1,050 ml; a ratio of combined TCE vapor and water vapor to air of 1:1 by volume; and a reaction time period of 3 minutes.
  • the reaction temperature was purposefully varied from 100-190°C. The results are graphically illustrated by Fig. 12.
  • the single batch, static reaction apparatus of Fig. 1 was employed for the destruction of TCE.
  • the reaction conditions were: an initial 200 ul amount of TCE corresponding to a vapor phase concentration of 5.9% at the reaction temperature of 100°C; and .a reaction chamber volume of 1,050 ml. The percentage of water vapor in the introductory gaseous stream

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Abstract

Nouveau procédé photocatalytique de dégradation régulée de matières organiques vaporisées et gazeuses en produits compatibles avec l'environnement, comprenant au moins du dioxyde de carbone. Le procédé emploie un catalyseur solide comprenant au moins un élément de transition, de la vapeur d'eau, ainsi que de l'oxygène moléculaire afin de former un mélange de réaction avec la matière organique, laquelle est dégradée en présence d'une photoénergie ultraviolette, visible ou proche de l'infra-rouge. Le procédé catalytique présente des applications multiples parmi lesquelles la destruction de solvants organiques; l'élimination de polluants de l'eau potable et d'eaux résiduelles industrielles; ainsi que l'élimination de substances organiques dangereuses et/ou toxiques de déchets collectés.
PCT/US1990/007651 1990-01-04 1990-12-26 Procede photocatalytique de degradation de matieres organiques a l'etat vaporise ou gazeux WO1991009823A1 (fr)

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Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0567602A1 (fr) * 1991-05-30 1993-11-03 LATER, Roger Carson Procede et appareil de decontamination de sols
EP0590202A1 (fr) * 1991-12-21 1994-04-06 PCP-PHOTOCATALYTIC PURIFICATION GmbH Procédé et installation pour éliminer des composés chimiques indésirables des gaz, gaz d'échappement, vapeurs et eaux salées
US5449443A (en) * 1994-06-13 1995-09-12 Jacoby; William A. Photocatalytic reactor with flexible supports
US5449466A (en) * 1993-04-23 1995-09-12 American Energy Technologies, Inc. Apparatus and method for photocatalytic treatment of a fluid
US5501801A (en) * 1993-11-30 1996-03-26 Board Of Control Of Michigan Technology University Method and apparatus for destroying organic compounds in fluid
US5549789A (en) * 1992-08-28 1996-08-27 The United States Of America As Represented By The Secretary Of Agriculture Oxidation of lignin and polysaccharides mediated by polyoxometalate treatment of wood pulp
US5616532A (en) * 1990-12-14 1997-04-01 E. Heller & Company Photocatalyst-binder compositions
WO1997031705A2 (fr) * 1996-03-01 1997-09-04 Volkswagen Aktiengesellschaft Procede et dispositif pour purifier des gaz d'echappement
US5790934A (en) * 1996-10-25 1998-08-04 E. Heller & Company Apparatus for photocatalytic fluid purification
EP0882674A2 (fr) * 1997-06-05 1998-12-09 ENITECNOLOGIE S.p.a. Procédé photocatalytique pour la purification des eaux polluées par tétrahydrothiphène
US5849200A (en) * 1993-10-26 1998-12-15 E. Heller & Company Photocatalyst-binder compositions
US5865959A (en) * 1995-05-23 1999-02-02 United Technologies Corporation Back-side illuminated organic pollutant removal system
EP0962426A1 (fr) * 1998-06-04 1999-12-08 ENITECNOLOGIE S.p.a. Procédé photocatalytique pour la purification des eaux polluées avec des substances odorantes contenant du soufre
US6120747A (en) * 1996-12-27 2000-09-19 Nippon Shokubai Co., Ltd. Catalyst for removing organic halogen compounds, preparation method therefor and method for removing organic halogen compounds
US6482376B2 (en) 1998-09-04 2002-11-19 Siemens Aktiengesellschaft Process for the catalytic removal of polycyclic aromatic nitro, nitroso and/or amino compounds
WO2009059616A1 (fr) * 2007-11-07 2009-05-14 Georg Josef Uphoff Procédé de conversion de substances
US10201809B2 (en) 2013-07-05 2019-02-12 Nitto Denko Corporation Photocatalyst sheet
US10391482B2 (en) 2013-07-05 2019-08-27 Nitto Denko Corporation Transparent photocatalyst coating and methods of manufacturing the same
US10549268B2 (en) 2013-07-05 2020-02-04 Nitto Denko Corporation Filter element for decomposing contaminants, system for decomposing contaminants and method using the system

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3977952A (en) * 1973-08-16 1976-08-31 C. F. Spiess & Sohn Process for decomposing carbon-containing compounds
US4547599A (en) * 1984-04-27 1985-10-15 The B. F. Goodrich Company Process for scavenging free chlorine in an ethylene dichloride stream
US4861484A (en) * 1988-03-02 1989-08-29 Synlize, Inc. Catalytic process for degradation of organic materials in aqueous and organic fluids to produce environmentally compatible products

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3977952A (en) * 1973-08-16 1976-08-31 C. F. Spiess & Sohn Process for decomposing carbon-containing compounds
US4547599A (en) * 1984-04-27 1985-10-15 The B. F. Goodrich Company Process for scavenging free chlorine in an ethylene dichloride stream
US4861484A (en) * 1988-03-02 1989-08-29 Synlize, Inc. Catalytic process for degradation of organic materials in aqueous and organic fluids to produce environmentally compatible products

Cited By (29)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5616532A (en) * 1990-12-14 1997-04-01 E. Heller & Company Photocatalyst-binder compositions
EP0567602A4 (en) * 1991-05-30 1993-11-18 Roger Carson Later Method and apparatus for decontamination of soils
EP0567602A1 (fr) * 1991-05-30 1993-11-03 LATER, Roger Carson Procede et appareil de decontamination de sols
EP0590202A1 (fr) * 1991-12-21 1994-04-06 PCP-PHOTOCATALYTIC PURIFICATION GmbH Procédé et installation pour éliminer des composés chimiques indésirables des gaz, gaz d'échappement, vapeurs et eaux salées
US5549789A (en) * 1992-08-28 1996-08-27 The United States Of America As Represented By The Secretary Of Agriculture Oxidation of lignin and polysaccharides mediated by polyoxometalate treatment of wood pulp
US5449466A (en) * 1993-04-23 1995-09-12 American Energy Technologies, Inc. Apparatus and method for photocatalytic treatment of a fluid
US5854169A (en) * 1993-10-26 1998-12-29 E. Heller & Company Photocatalyst-binder compositions
US5849200A (en) * 1993-10-26 1998-12-15 E. Heller & Company Photocatalyst-binder compositions
US6093676A (en) * 1993-10-26 2000-07-25 E. Heller & Company Photocatalyst-binder compositions
US5501801A (en) * 1993-11-30 1996-03-26 Board Of Control Of Michigan Technology University Method and apparatus for destroying organic compounds in fluid
US5449443A (en) * 1994-06-13 1995-09-12 Jacoby; William A. Photocatalytic reactor with flexible supports
US5865959A (en) * 1995-05-23 1999-02-02 United Technologies Corporation Back-side illuminated organic pollutant removal system
WO1997031705A2 (fr) * 1996-03-01 1997-09-04 Volkswagen Aktiengesellschaft Procede et dispositif pour purifier des gaz d'echappement
WO1997031705A3 (fr) * 1996-03-01 1997-12-24 Volkswagen Ag Procede et dispositif pour purifier des gaz d'echappement
US6153159A (en) * 1996-03-01 2000-11-28 Volkswagen Ag Method for purifying exhaust gases
US5790934A (en) * 1996-10-25 1998-08-04 E. Heller & Company Apparatus for photocatalytic fluid purification
US6120747A (en) * 1996-12-27 2000-09-19 Nippon Shokubai Co., Ltd. Catalyst for removing organic halogen compounds, preparation method therefor and method for removing organic halogen compounds
US6027654A (en) * 1997-06-05 2000-02-22 Enitechnologie S.P.A. Photocatalytic process for purifying water polluted by tetrahydrothiophene
EP0882674A3 (fr) * 1997-06-05 1998-12-23 ENITECNOLOGIE S.p.a. Procédé photocatalytique pour la purification des eaux polluées par tétrahydrothiphène
US6153112A (en) * 1997-06-05 2000-11-28 Enitecnologie, S.P.A. Photocatalytic process for purifying water polluted by tetrahydrothiophene
EP0882674A2 (fr) * 1997-06-05 1998-12-09 ENITECNOLOGIE S.p.a. Procédé photocatalytique pour la purification des eaux polluées par tétrahydrothiphène
EP0962426A1 (fr) * 1998-06-04 1999-12-08 ENITECNOLOGIE S.p.a. Procédé photocatalytique pour la purification des eaux polluées avec des substances odorantes contenant du soufre
US6165327A (en) * 1998-06-04 2000-12-26 Enitecnologie S.P.A. Photocatalytic process for the purification of water polluted by odorant compounds containing sulfur
US6482376B2 (en) 1998-09-04 2002-11-19 Siemens Aktiengesellschaft Process for the catalytic removal of polycyclic aromatic nitro, nitroso and/or amino compounds
WO2009059616A1 (fr) * 2007-11-07 2009-05-14 Georg Josef Uphoff Procédé de conversion de substances
US10201809B2 (en) 2013-07-05 2019-02-12 Nitto Denko Corporation Photocatalyst sheet
US10391482B2 (en) 2013-07-05 2019-08-27 Nitto Denko Corporation Transparent photocatalyst coating and methods of manufacturing the same
US10549268B2 (en) 2013-07-05 2020-02-04 Nitto Denko Corporation Filter element for decomposing contaminants, system for decomposing contaminants and method using the system
US10710063B2 (en) 2013-07-05 2020-07-14 Nitto Denko Corporation Transparent photocatalyst coating and methods of manufacturing the same

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