ES2339081A1 - Procedure for the treatment and degradation of toxic gases of organic origin through photocatalytic techniques. (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

Procedure for the treatment and degradation of toxic gases of organic origin by photocatalytic techniques. The present invention refers to a method of treatment and degradation of toxic gases of organic origin that allows to transform and mineralize gases of organic origin, decontaminating in this way the emission of gases. It is a continuous process that involves passing an air flow containing vapors of toxic organic gas to demineralize through a reactor (3) in whose inner walls a catalyst has been impregnated and applying a source of radiation (2), by means of photocatalytic techniques, the flow of air in contact with the catalyst is obtained as a final result of the process the mineralization of the toxic gas of organic origin through the oxidation of organic compounds up to co 2 or less toxic species. (Machine-translation by Google Translate, not legally binding)

Description

Procedure for treatment and degradation of toxic gases of organic origin using techniques Photocatalytic

Technical sector

The present invention refers to a procedure for the treatment and degradation of toxic gases of Organic origin through photocatalytic techniques.

State of the art

In the last decades there has been a growing concern to control and treat the gaseous emissions produced in the different industrial or daily processes due to the activity of man. Thus, in 1997, the governments of 55 nations agreed through the Kyoto Protocol to reduce the emissions of greenhouse gases responsible for climate change by 5.2%. Among these gases are mainly carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorinated (HFC), perfluorocarbons (PFC) and sulfur hexafluoride. However, in addition to these gases there are other volatile compounds for everyday use whose toxic effect, on the health of man, is more immediate. Among these compounds is methyl-terbutyl ether (MTBE), a gasoline ingredient formed from natural gas.

Volatile organic compounds (VOCs) are released into the atmosphere, mainly in different processes industrial through the combustion of gasoline, wood, coal or natural gas. Also many of them are emitted when used as industrial solvents such as toluene, xylene or perchlorethylene. These compounds released into the atmosphere contribute to tropospheric ozone formation (ozone in the lower atmosphere, at ground level). In large quantities this ozone impoverishes air quality, proving harmful to the environment environment and carcinogen and toxic to human health. Also, the Long-term exposure to volatile organic compounds may cause lesions of the liver, kidneys and nervous system.

That is why they have developed different regulations, including Community Directive 13/1999 European, which establishes emission measures and limitations of VOC.

Currently photocatalytic techniques for the treatment of contaminants they have been applied only in sewage Therefore the present invention proposes a novel way of applying photocatalytic techniques for removal and mineralization of gaseous pollutants in a system in continuous.

Explanation of the invention.

The present invention refers to a procedure of treatment and degradation of toxic gases of organic origin that allows to transform and mineralize gases of organic origin, thus decontaminating the emission of gases. It is a continuous procedure that involves passing an air flow containing vapors of the toxic gas of origin organic to demineralize through a reactor in whose walls interiors has been impregnated a catalyst and applying a source of radiation, by photocatalytic techniques, to the air flow in contact with the catalyst is obtained as a final result of mineralization process of toxic gas of organic origin by the oxidation of organic compounds to CO2 or species less toxic

Description of the figures

Figure 1 represents a scheme where they can appreciate all the stages of the treatment procedure and degradation of toxic gases of organic origin.

Preferred embodiment of the invention

Although the invention is described in terms of a specific preferred embodiment will be readily apparent to the experts in this technique that can be made diverse modifications, redispositions and replacements. The scope of the invention is defined by the claims appended to the same.

To explain in detail the mode of preferred embodiment of the invention the methyl terbutyl ether (MTBE) as an organic compound volatile.

First we proceeded to prepare the catalyst from the mixture of TiO2 with a solution aqueous of CuSO4, stirring the mixture for 48 hours.

To impregnate the catalyst in the walls reactor interiors (3) first the water was evaporated from the mixture by heating it, at 100 ° C and for 24 hours, then the resulting CuTiO2 was calcined at 400 ° C and for about 5 hours.

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Once the catalyst is prepared and impregnated in the reactor walls (3) the treatment procedure and degradation of toxic gases of organic origin continued as It is represented in figure 1.

In a bowl (1) it was heated continuously, at 40 ° C, an aqueous solution where the MTBE in a 2: 1 volume ratio, the pH of the solution being 5. This vessel was continuously injected with a flow of air (4) of 150 cm3 / min. The resulting air flow, which it contained water vapors and MTBE, it was introduced in a reactor (3) of spiral cylindrical glass of 2 mm internal diameter.

A source of radiation (2), using common lamps as energy source ultraviolet radiation, to the air flow that contained vapors of water and MTBE.

The exhaust gases of these systems were continuously analyzed by a gas chromatograph (5) (GC They vary Star 3600) equipped with a gas injection valve. This chromatograph (5) is equipped with an EDF detector for the MTBE monitoring and detection and reaction intermediates such as alcohols or carboxylic acids and a TCD detector for monitoring and detection of CO2. Also a catalytic chamber It was used for monitoring by FTIR spectroscopy of reaction intermediates on the catalyst surface.

This technique is based on the lighting of a semiconductor, TiO2 doped with Cu in this case, which acts as catalyst and that in the presence of ultraviolet radiation generates highly oxidizing radicals capable of degrading matter organic The reactions that take place in this process are the following:

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Thus the TiO2 in the presence of radiation ultraviolet with enough energy is able to excite an electron (e ^ -) at higher levels of energy while generating a gap (h +). These photogenerated holes can react directly with the organic compounds oxidizing them to CO2 or species less toxic organic. The hydroxyl groups (OH -) present on the surface of the catalyst can react with the gaps generating highly oxidizing radicals (OH) that degrade matter organic Similarly, oxygen adsorbed on the surface of the catalyst can react with photogenerated electrons to produce radicals (O 2 -).

In this system no processes of deactivation since the Cu + generated by its reaction with the Photogenerated electrons are again oxidized to Cu 2+ by the Oxigen.

Industrial application

The main industrial application is the installation of this system in chimneys or extractor hoods of the industries where these gases are generated thus avoiding emission of these compounds. Some of the advantages it presents This system is its low cost and the low maintenance that presents.

Claims (2)

1. Procedure for treatment and degradation of toxic gases of organic origin comprising following stages: a) A catalyst is prepared comprising the least one component selected from a list of items in which TiO_ {2} and CuSO_ {4} are found. b) The walls of at least one are impregnated reactor with the catalyst previously prepared. c) A mixture is continuously heated aqueous comprising at least one component selected from a list of elements in which the toxic gas of origin is found organic that you want to treat and degrade. d) An air flow is injected, so Continue to the previous mix. e) The resulting air flow, which contains vapors of the mixture, it is passed through at least one reactor whose walls are impregnated with the catalyst above prepared. f) A radiation source is applied, by photocatalytic techniques, to the air flow, which contains vapors of the mixture, in contact with the catalyst. g) Toxic gas of origin is mineralized organic by oxidation of organic compounds until CO2 or less toxic species. 2. Procedure for the treatment and degradation of toxic gases of organic origin according to claim 1 characterized in that the impregnation of the catalyst comprises the following steps: a) Evaporation of the solution water catalytic by heating at 100 ° C for 15-30 hours b) Calcination of the catalyst resulting from the First stage at 400 ° C for 3-8 hours.