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  • B01D53/34—Chemical or biological purification of waste gases
  • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
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  • B01D53/007—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 by irradiation
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  • 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
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  • B01J35/64—Pore diameter
  • B01J35/647—2-50 nm
• • B—PERFORMING OPERATIONS; TRANSPORTING
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  • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
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  • B01J35/657—Pore diameter larger than 1000 nm
• • B—PERFORMING OPERATIONS; TRANSPORTING
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  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/02—Impregnation, coating or precipitation
  • B01J37/0201—Impregnation
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  • B01J37/02—Impregnation, coating or precipitation
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• • B—PERFORMING OPERATIONS; TRANSPORTING
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  • B01D2255/9202—Linear dimensions
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• • B—PERFORMING OPERATIONS; TRANSPORTING
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  • B01D2257/00—Components to be removed
  • B01D2257/70—Organic compounds not provided for in groups B01D2257/00 - B01D2257/602
  • B01D2257/708—Volatile organic compounds V.O.C.'s
• • B—PERFORMING OPERATIONS; TRANSPORTING
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  • B01D2259/00—Type of treatment
  • B01D2259/80—Employing electric, magnetic, electromagnetic or wave energy, or particle radiation
  • B01D2259/804—UV light
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
  • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
  • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Definitions

• the field of the invention is that of the decontamination of a gaseous medium comprising volatile organic compounds by means of a photocatalytic process.
• VOCs volatile organic compounds
• a first way consists in bringing the gaseous medium into contact with an adsorbent (also called here a collection mass) consisting mainly of activated carbon.
• an adsorbent also called here a collection mass
• the disadvantage of this type of adsorbent is that it must be replaced periodically to ensure the efficiency of the system.
• the FR2975309 discloses the monoliths of Ti0 2 or Ti0 2 -Si0 2 self-supporting as photocatalysts for the decontamination of air.
• both types of materials have low levels of adsorption of volatile organic compounds.
• the materials Ti0 2 -Si0 2 the preparation process of which provides for the supply of Simultaneous Si precursor and Ti precursor exhibit no photocatalytic activity.
• the Applicant has discovered that the use of a monolith based on silica and titanium dioxide, comprising a specific macroporous structure, makes it possible to reach much higher adsorption capacities compared with the adsorbents based on coals. and porous monoliths known from the state of the art, while having improved properties in photocatalytic activity, in terms of stability, and rate of mineralization, compared to photocatalytic materials according to the prior art.
• the implementation of a monolithic material according to the invention thus makes it possible to combine the two functions of the materials commonly proposed for the decontamination application of the effluents to be treated, that is to say the capture impurities contained in the effluent to be treated and their degradation, while avoiding the spread of nanoparticles in the effluent, inducing significant performance gains.
• the present invention relates to a method for treating a gaseous feedstock containing oxygen and one or more volatile compounds, which process comprises the following steps:
• said gaseous feed containing oxygen and one or more volatile organic compounds is brought into contact with a monolith comprising silica and titanium dioxide, said monolith comprising a macroporous volume of type I, the pore diameter of which is greater than 50 nm and less than or equal to 1000 nm, between 0.1 to 3 ml / g, and a macroporous volume of type II, whose pore diameter is greater than 1 ⁇ m and less than or equal to 10 ⁇ m, between 1 at 8 mL / g;
• said monolith is irradiated with at least one irradiation source producing at least a wavelength of less than 400 nm in order to convert said volatile organic compounds to carbon dioxide, said step b) being carried out at a temperature of between ° C and + 200 ° C and at a pressure between 0.01 MPa and 70 MPa.
• said gaseous feed containing oxygen and one or more volatile organic compounds is diluted with a diluent fluid.
• the irradiation source is a source of artificial irradiation.
• the irradiation source produces at least one wavelength of between 300 and 400 nm.
• step a) is carried out in a cross-bed fixed bed reactor or in a fixed licking bed.
• said monolith has a mesoporous volume, whose pore diameter is greater than 2 nm and less than or equal to 50 nm, of between 0.01 and 1 ml / g, preferably between 0.05 and 0.5 ml. /boy Wut.
• said monolith additionally has a macroporous volume, the pore diameter of which is greater than 10 ⁇ m, less than 0.5 ml / g.
• said monolith has a bulk density of between 0.05 and 0.5 g / ml.
• said monolith has a specific surface area of between 10 and 1000 m 2 / g, preferably between 50 and 600 m 2 / g.
• said monolith comprises a content of titanium dioxide of between 5 and 70% by weight relative to the total weight of the monolith.
• said monolith is prepared according to the following steps:
• step 2 at least one soluble precursor of silica is added to the solution obtained in step 1);
• step 3 optionally, is added to the solution obtained in step 2) at least one liquid organic compound, immiscible with the solution obtained in step 2) to form an emulsion;
• step 4 the solution obtained in step 2) or the emulsion obtained in step 3) is allowed to mature in the wet state in order to obtain a gel;
• step 5 the gel obtained in step 4) is washed with an organic solution
• step 6) the gel obtained in step 5) is dried and calcined to obtain a silica-based monolith
• step 6 impregnating a solution comprising at least one soluble precursor of titanium dioxide in the porosity of the monolith obtained in step 6);
• step 8) optionally, the product obtained in step 7) is dried and calcined to obtain a monolith based on silica and containing titanium dioxide.
• step 8) is carried out at a temperature of between 5 and 120 ° C.
• step 8 calcination in air is carried out with a first temperature stage of between 80 and 150 ° C. for 1 to 10 hours, then a second stage in temperature between 150 and 250 ° C for 1 to 10 hours, and finally a third temperature level between 300 and 950 ° C for 0.5 to 24 hours.
• group VIII according to the CAS classification corresponds to the metals of columns 8, 9 and 10 according to the new IUPAC classification.
• micropores means pores whose diameter is less than 2 nm; mesopores pores whose diameter is greater than 2 nm and less than or equal to 50 nm and macropores pores whose diameter is greater than 50 nm, and more particularly macropores type I pores whose diameter is greater than 50 nm and less or equal to 1000 nm (1 ⁇ m), and type II macropores pores whose diameter is greater than 1 ⁇ m and less than or equal to 10 ⁇ m.
• volatile organic compounds means any compound containing at least the carbon element and one or more of the following elements: hydrogen, halogen, oxygen, sulfur , phosphorus, silicon or nitrogen, with the exception of carbon dioxide, and having a vapor pressure of 0.01 kPa or more at a temperature of 273.15 K.
• the macroporous and mesoporous volumes are measured by mercury intrusion porosimetry according to ASTM D4284-83 at a maximum pressure of 4000 bar (400 MPa), using a surface tension of 484 dyne / cm and a contact angle of 140 °. .
• Total pore volume is the volume measured by mercury porosimeter intrusion according to ASTM D4284-83 at a maximum pressure of 4000 bar (400 MPa), using a surface tension of 484 dyne / cm and a contact angle of 140 °.
• the anchoring angle was taken equal to 140 ° according to the recommendations of the book "Techniques of the engineer, treated analysis and characterization", pages 1050-1055, written by Jean Charpin and Bernard Rasneur.
• the specific surface is measured by nitrogen adsorption according to the ASTM D 3663-78 standard established from the Brunauer, Emmett, Teller method, ie the BET method, as defined in S. Brunauer, PH Emmett, E. Teller, J. Am Chem. Soc., 1938, 60 (2), pp. 309-319. Description
• the present invention relates to a method for treating a gaseous feedstock comprising dioxygen, such as air, which may contain one or more volatile organic compounds (VOCs), said process comprising the following steps:
• a gaseous feedstock containing one or more volatile organic compounds and dioxygen is contacted with a monolith based on silica and titanium dioxide, said monolith comprising a macroporous volume of type I, ie a macroporous volume whose diameter of pores is greater than 50 nm and less than or equal to 1000 nm (1 ⁇ m), between 0.1 to 3 ml / g, preferably between 0.2 and 2.5 ml / g, and a macroporous volume of type II , ie a macroporous volume, the pore diameter of which is greater than 1 ⁇ m and less than or equal to 10 ⁇ m, of between 1 and 8 ml / g, preferably of between 2 and 8 ml / g and even more preferentially between 3 and 8 ⁇ m.
• mL / g a gaseous feedstock containing one or more volatile organic compounds and dioxygen
• step a) of the process according to the invention the monolith is brought into contact with a gaseous feedstock containing one or more volatile organic compounds and dioxygen.
• the feedstock treated by the process is in gaseous form, and contains volatile organic compounds as well as dioxygen.
• the feedstock treated by the process is air containing up to 10,000 ppm of volatile organic compounds.
• volatile organic compounds include the following families of molecules: halogenated hydrocarbons, aromatic hydrocarbons, alkanes, alkenes, alkynes, aldehydes, ketones.
• the charge is diluted with a gaseous diluent fluid.
• a diluent fluid is not required for carrying out the invention, however it may be useful to add to the charge to ensure the dispersion of the charge in the medium, a control of the adsorption of the reagents / products in the porosity of the monolith, the dilution of the products to limit their recombination and other similar parasitic reactions.
• the presence of a diluent fluid also makes it possible to control the temperature of the reaction medium, thus being able to compensate for the possible exo / endothermicity of the photocatalyzed reaction.
• the nature of the diluent fluid is chosen such that its influence is neutral on the reaction medium or that its possible reaction does not interfere with the achievement of the desired reaction. degradation of volatile organic compounds.
• the gaseous diluent fluid is selected from N 2 , O 2 , or air.
• Contacting the gaseous feed containing one or more volatile organic compounds and oxygen with said monolith can be done by any means known to those skilled in the art.
• the contacting of the gaseous feedstock containing one or more volatile organic compounds and oxygen with said monolith is carried out in a fixed-bed reactor or in a fixed licking bed.
• said monolith When the implementation is in fixed bed traversed, said monolith is preferably fixed within the reactor, and the gaseous feed containing one or more volatile organic compounds and oxygen is sent through the photocatalytic bed.
• said monolith is preferably fixed within the reactor and the gaseous feed containing one or more volatile organic compounds and oxygen is sent to the photocatalytic bed.
• the implementation When the implementation is in fixed bed or in bed licking, the implementation can be done continuously.
• said monolith is irradiated with at least one irradiation source producing at least a wavelength of less than 400 nm so as to degrade the volatile organic compounds to carbon dioxide by photocatalysis.
• Photocatalysis is based on the principle of activation of a semiconductor (such as TiO 2 ) or of a set of semiconductors such as the photocatalyst used in the process according to the invention, using the energy provided by irradiation.
• Photocatalysis can be defined as the absorption of a photon whose energy is greater than or equal to the forbidden bandgap or "bandgap" according to the English terminology between the valence band and the conduction band, which induces the formation of an electron-hole pair in the semiconductor. We therefore have the excitation of an electron at the level of the conduction band and the formation of a hole on the valence band.
• This electron-hole pair will allow the formation of free radicals that will either react with compounds present in the medium, or recombine according to various mechanisms.
• Each semiconductor has a difference in energy between its conduction band and its valence band, or "bandgap" according to the Anglo-Saxon terminology, which is peculiar to it.
• a photocatalyst composed of one or more semiconductors can be activated by the absorption of at least one photon.
• Absorbable photons are those whose energy is greater than bandgap, or semiconductor.
• the photocatalysts can be activated by at least one photon of a wavelength corresponding to the energy associated with the bandgap widths of the semiconductors constituting the photocatalyst or of a lower wavelength.
• the maximum wavelength absorbable by a semiconductor is calculated using the following equation:
• any irradiation source emitting at least one wavelength suitable for activation of said photocatalyst, that is to say absorbable by Ti0 2 , therefore less than 400 nm, can be used according to the invention. It is possible, for example, to use natural solar radiation or a source of artificial irradiation of the laser type, Arc Mercure Hg, Xenon Xe, Mercury-Xenon Hg (Xe), Deuterium D 2 or Quarte Tungsten Halogne QTH lamps, incandescent lamp, fluorescent tube, plasma or light emitting diode (LED, or LED in English for Light-Emitting Diode).
• the irradiation source is an artificial irradiation.
• the irradiation source produces radiation of which at least a portion of the wavelengths is less than the maximum absorbable wavelength (A max ) by the Ti0 2 contained in the monolith.
• a max maximum absorbable wavelength
• the irradiation source is solar irradiation, it generally emits in the ultraviolet spectrum, visible and infra-red, that is to say it emits a wavelength range of 280 nm to 2500 nm about (according to ASTM G173-03).
• the source emits at least in a wavelength range greater than 280 nm, very preferably 300 nm to 400 nm.
• the irradiation source provides a photon flux that irradiates the reaction medium containing the monolith.
• the interface between the reaction medium and the light source varies depending on the applications and the nature of the light source.
• the irradiation source is located outside the reactor and the interface between the two may be an optical window pyrex, quartz, organic glass or any other interface allowing the photons absorbable by the monolith according to the invention to diffuse external medium within the reactor.
• the realization of said method is conditioned by the adsorption capacity of said monolith as well as by the provision of photons adapted to the photocatalytic system for the reaction envisaged, and therefore is not limited to a pressure or temperature range. other than those for ensuring the stability of the material (s).
• the temperature range employed for the process is generally from -30 ° C to + 200 ° C, preferably from -10 to 150 ° C, and most preferably from -10 to 100 ° C.
• the pressure range employed for the process is generally from 0.01 MPa to 70 MPa (0.1 to 700 bar), more preferably from 0.5 MPa to 2 MPa (0.5 to 20 bar).
• the process according to the invention can be carried out with a dry or wet gas up to 100% relative humidity, preferably the gas to be treated contains 0 to 60% relative humidity.
• the monolith used in the context of the process for treating a gaseous feedstock according to the invention comprises silica and titanium dioxide.
• Said monolith has a macroporous volume of type I, ie a macroporous volume whose pore diameter is greater than 50 nm and less than or equal to 1000 nm (1 ⁇ m), of between 0.1 to 3 ml / g, preferably between 0.2 and 2.5 ml / g, and even more preferably between 1 and 2 ml / g.
• said monolith has a macroporous volume of type II, ie a macroporous volume whose pore diameter is greater than 1 ⁇ m and less than or equal to 10 ⁇ m, between 1 and 8 ml / g, preferably between 2 and 8. mL / g, and even more preferably between 3 and 8 mL / g.
• a macroporous volume of type II ie a macroporous volume whose pore diameter is greater than 1 ⁇ m and less than or equal to 10 ⁇ m, between 1 and 8 ml / g, preferably between 2 and 8. mL / g, and even more preferably between 3 and 8 mL / g.
• the monolith comprises a content of titanium dioxide of between 5 and 70% by weight relative to the total weight of the monolith.
• the monolith can optionally be doped with one or more elements chosen from metal elements, such as, for example, elements V, Ni, Cr, Mo, Fe, Sn, Mn, Co, Re, Nb, Sb, La, Ce, Ta.
• metal elements such as, for example, elements V, Ni, Cr, Mo, Fe, Sn, Mn, Co, Re, Nb, Sb, La, Ce, Ta.
• non-metallic elements such as, for example, C, N, S, F, P, or a mixture of metallic and non-metallic elements.
• the titanium dioxide contained in the monolith can be surface-sensitized with any organic molecules capable of absorbing photons.
• said monolith may contain at least one element M chosen from an element of groups VIIIB, IB, MB and NIA of the periodic classification of elements in the metallic state and / or oxide.
• the content of element (s) M in the metallic state and / or oxide is between 0.001 and 20% by weight relative to the total weight of the monolith.
• said monolith has a mesoporous volume, whose pore diameter is greater than 2 nm and less than or equal to 50 nm, of between 0.01 and 1 ml / g, preferably between 0.05 and 0.5 ml. /boy Wut.
• said monolith furthermore has a macroporous volume, whose pore diameter is greater than 10 ⁇ m, less than 0.5 ml / g.
• said monolith has a bulk density of between 0.05 and 0.5 g / ml. The apparent density is calculated by making the ratio between the mass of catalyst and its geometric volume.
• said monolith has a BET surface area of between 10 and 1000 m 2 / g, preferably between 50 and 600 m 2 / g, and even more preferably between 100 and 300 m 2 / g.
• the monolith used in the context of the process according to the invention may be prepared by a specific preparation process, in which the synthesis of the silica and titanium dioxide phases takes place in two distinct steps.
• the realization of two distinct stages makes it possible in particular to avoid the formation of mixed SiO 2 -TiO 2 compounds in the structure of the monolith itself, which would lead to a loss of available photocatalytic material.
• the process for preparing said monolith comprises the following steps:
• step 2 at least one soluble precursor of silica is added to the solution obtained in step 1);
• step 3 optionally, is added to the solution obtained in step 2) at least one liquid organic compound, immiscible with the solution obtained in step 2) to form an emulsion;
• step 4 the solution obtained in step 2) or the emulsion obtained in step 3) is allowed to mature in the wet state in order to obtain a gel;
• step 5 the gel obtained in step 4) is washed with an organic solution
• step 6) drying and calcining the gel obtained in step 5) to obtain a monolith based on silica;
• step 6 impregnating a solution comprising at least one soluble precursor of titanium dioxide in the porosity of the monolith obtained in step 6);
• step 8) optionally, the product obtained in step 7) is dried and calcined to obtain a monolith based on silica and containing titanium dioxide.
• Step 11 In step 1) of the process for preparing the monolith, a solution containing one or more surfactants is mixed with an acidic aqueous solution to obtain an acidic aqueous solution comprising one or more surfactants.
• the surfactants may be anionic, cationic, amphoteric or nonionic.
• the surfactants are chosen from poly (ethylene glycol), cetyl trimethylammonium bromide and myristyltrimethylammonium bromide, alone or as a mixture.
• the acidic agent is preferably selected from inorganic acids such as nitric, sulfuric, phosphoric, hydrochloric, hydrobromic acid and organic acids such as carboxylic or sulphonic acids, alone or as a mixture.
• the pH of the mixture is preferably less than 4.
• step 2) of the process for preparing the monolith at least one soluble precursor of silica, preferably selected from tetraethylorthosilicate and tetramethylorthosilicate, is added alone or as a mixture.
• the mass ratio precursors / surfactants is between 0.1 and 10.
• step 3 at least one liquid organic compound immiscible with the solution obtained in step 2) is added to the solution obtained in step 2) to form an emulsion.
• the liquid organic compound is a hydrocarbon or a mixture of hydrocarbons having 5 to 15 carbon atoms.
• the liquid organic compound / solution ratio obtained in step 2) is between 0.2 and 5.
• step 4 the solution obtained in step 2) or the emulsion obtained in step 3) is allowed to mature in the wet state in order to obtain a gel;
• the maturation is carried out at a temperature between 5 and 80 ° C.
• the maturation is carried out for 1 to 30 days. It is during this step 4) that the synthesis of the silica (SiO 2 ) takes place.
• step 5 the gel obtained in step 4) is washed with an organic solution.
• the organic solution is acetone, ethanol, methanol, isopropanol, tetrahydrofuran, ethyl acetate or methyl acetate, alone or as a mixture.
• the washing step is repeated several times.
• step 6 the gel obtained in step 5) is dried and calcined to obtain a silica-based monolith.
• the drying is carried out at a temperature between 5 and 80 ° C. Preferably, the drying is carried out for 1 to 30 days.
• paper towels can be used to accelerate the drying of the materials.
• the calcination is carried out as follows: a first temperature stage of between 120 and 250 ° C. for 1 to 10 hours, then a second temperature stage of between 300 and 950 ° C. for 2 to 24 hours.
• a solution comprising at least one soluble precursor of titanium dioxide is impregnated into the porosity of the monolith obtained in step 6).
• the titanium precursor is chosen from an alkoxide, very preferably the titanium precursor is chosen from titanium isopropoxide and tetraethylorthotitanate, alone or as a mixture.
• a maturation step is carried out in a humid atmosphere after the impregnation.
• step 8 the product obtained in step 7) is dried and calcined to obtain a monolith.
• a drying step is carried out at a temperature between 5 and 120 ° C and for 0.5 to 20 days.
• a calcination step under air is then carried out with a first temperature stage of between 80 and 150 ° C. for 1 to 10 hours, then a second temperature stage of between 150 and 250 ° C. for 1 to 10 hours. and finally a third temperature stage of between 300 and 950 ° C for 0.5 to 24 hours.
• Any element, or precursor element, M selected from an element of groups VIIIB, IB, 11 B and II IA of the periodic table of elements can be introduced at any stage of the process.
• Example 1 Material A (not according to the invention ' )
• Material A is a commercial activated carbon in the form of pellets (WS490, MBRAUN
• Example 2 Material B (not in accordance with the invention ' )
• Material B is a commercial material consisting of nanoparticles of Ti0 2 supported by quartz fibers sold under the name Quartzel TM by Saint Gobain®. Quartzel TM is known to those skilled in the art for its excellent photocatalytic properties in air purification.
• Example 3 Material C (not in accordance with the invention)
• the material C is a monolith containing silica and titanium dioxide, in which the SiO 2 and TiO 2 phases were synthesized during the same step, such as the solid called TiO 2 / SiO 2 -Dodecane described in FIG . example 1 of the patent application FR2975309.
• Material C has a total porosity of 2.44 cm 3 / g, with a mesoporous volume of 0.47 ml / g, a macroporous volume of type I of 0.79 ml / g and a macroporous volume of type II of 1 18 mL / g, and a bulk density of 0.33 g / cm 3 .
• Material C has a specific surface area of 365 m 2 / g.
• the Ti element content measured by ICP-AES is 47.72% by weight, which is equivalent to 79.55% by weight of TiO 2 in the material C
• Example 4 Material D (not in accordance with the invention ' )
• the material D is a TiO 2 monolith, such as the so-called TiO 2 -Heptane solid described in Example 1 of the patent application FR2975309.
• Material D has a total porosity of 0.52 ml / g, of which a mesoporous volume of 0.29 ml / g, a macroporous volume of type I of 0.07 ml / g and a macroporous volume of type II of 0, 16 mL / g, and a bulk density of 1.1 g / cm 3 .
• Material D has a specific surface area of 175 m 2 / g.
• Example 5 Material E (in accordance with the invention ' )
• the emulsion is then poured into a petri dish of 5.5 cm internal diameter, which is installed in a saturator for 7 days for gelation.
• the gel obtained is then washed a first time with anhydrous tetrahydrofuran (Aldrich TM, purity> 99%), then with a mixture of anhydrous tetrahydrofuran / acetone (VWR TM, ACS grade) at 70/30 by volume twice in succession.
• Aldrich TM anhydrous tetrahydrofuran
• VWR TM a mixture of anhydrous tetrahydrofuran / acetone
• the gel is then dried at room temperature for 7 days.
• the gel is finally calcined in air in a muffle furnace at 180 ° C. for 2 hours, then at 650 ° C. for 5 hours.
• a solution containing 34 mL of distilled water, 44.75 mL of isopropanol (Aldrich TM, purity> 99.5%), 10.74 mL of hydrochloric acid (37% by weight, Aldrich TM, purity 97%) and 10.50 mL of titanium isopropoxide (Aldrich TM, 97% purity) is prepared with stirring. Part of this solution corresponding to the pore volume is impregnated in the porosity of the monolith and then left to mature for 12 hours. The monolith is then dried under ambient atmosphere for 24 hours. The step is repeated a second time.
• the monolith is finally calcined in air in muffle furnace at 120 ° C for 2 hours, then at 180 ° C for 2 hours and finally at 400 ° C for 1 hour.
• a monolith comprising TiO 2 in an SiO 2 matrix is thus obtained, such that the syntheses of the silica and titanium dioxide phases have been carried out in two distinct steps.
• the material E has a mesoporous volume of 0.20 ml / g, a macroporous volume of type I of 1.15 ml / g and a macroporous volume of type II of 5.8 ml / g.
• Material E has a surface area of 212 m 2 / g.
• the Ti element content measured by ICP-AES is 27.35% by weight, which is equivalent to 52.1% by weight of TiO 2 in the material E.
• the material E has a bulk density of 0.14 g / ml.
• Example 6 Embodiment of materials in adsorption and photooxidation of acetone
• Materials A, B, C, D and E are subjected to a gas phase acetone adsorption and photooxidation test in a continuous steel through-bed reactor equipped with a quartz optical window and a grid in front of the optical window on which the material is deposited. Before each test, the materials were conditioned by thermodesorption at 15 ° C for 12h. The tests are carried out at room temperature under atmospheric pressure by passing a dry air containing 480 ppmV of acetone at a flow rate of 60 ml / min. The residual content of acetone and the production of carbon dioxide gas produced by the photooxidation of acetone are followed by an analysis of the effluent every 7 minutes by gas chromatography (FID GC / FID methanizer).
• FID methanizer gas chromatography
• the UV irradiation source is provided by a LED type lamp (High Power single LED chip 1W 365nm Roithner Lasertechnik GmbM TM).
• the irradiation power is maintained at 30 W / m 2 for a range of wavelengths between 315 and 380 nm.
• the overall duration of each test is approximately 200 hours. The tests are carried out in two steps: a first step of equilibrium without irradiation which makes it possible to estimate the quantity of acetone adsorbed, a second step of photooxidation under irradiation which makes it possible to estimate the photocatalytic performances.
• Materials B and E are subjected to a gas phase toluene adsorption and photooxidation test in a continuous steel through-bed reactor equipped with a quartz optical window and a sintered glass in front of the optical window. which is deposited the material. Before each test, the materials were conditioned by thermodesorption at 115 ° C. for 12 hours. The tests are carried out at ambient temperature under atmospheric pressure by passing a dry air containing 70 ppmV of toluene at a flow rate of 60 ml / min. The residual toluene content and the production of carbon dioxide gas produced by the photooxidation of toluene are followed by an analysis of the effluent every 7 minutes by gas chromatography (FID GC / FID methanizer).
• FID methanizer gas chromatography
• the UV irradiation source is provided by a LED type lamp (High Power single LED chip 1W 365nm Roithner Lasertechnik GmbM TM).
• the irradiation power is always maintained at 30W / m 2 for a range of wavelengths between 315 and 380 nm.
• the overall duration of each test is approximately 100 hours. The tests are carried out in two stages: a first step of equilibrium without irradiation which makes it possible to estimate the quantity of toluene adsorbed, a second step of photooxidation under irradiation which makes it possible to estimate the photocatalytic performances.
• toluene The adsorption values of toluene show that the implementation according to the invention makes it possible to reach significantly higher levels than known implementations of the state of the art. On the other hand, the degree of mineralization of toluene is significantly higher for an implementation according to the invention. Finally, the use of the material E according to the invention makes it possible to obtain very stable photocatalytic activities contrary to the implementation of the Quartzel® (material B). With the Quartzel® material, there is a rapid deactivation of the material which is characterized by a decrease in the production of carbon dioxide and a significant yellowing of the material during the test phase under irradiation.

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  • 2018-04-26 FR FR1853644A patent/FR3080545B1/fr not_active Expired - Fee Related
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