CN103316585B - A kind of method of organic pollution in nanometer mineral material Purge gas - Google Patents

Abstract

A kind of method of organic pollution in nanometer mineral material Purge gas, it is characterized in that, preparing particle diameter within the scope of 0.5-10mm has ferriferous oxide, an iron sulfide granular material of nano-pore structure, granular material diluted acid is flooded, then load and form filtering layer in a reservoir, the filter course that waste gas containing volatile organic contaminant penetrates through nano-pore structure iron mineral material after mixing with the hydrogen peroxide of volatilization is formed, in filter course, there is the reaction of heterogeneous Fenton oxidation, thoroughly remove volatile organic matter.

Description

A method for purifying organic pollutants in gas with nanometerized mineral materials

1. Technical field

The invention belongs to the technical field of environmental protection, and in particular relates to purification technology and materials of volatile organic pollutants.

2. Background technology

Volatile organic compounds (VOCs) usually refer to organic compounds with a boiling point of 50-260°C under normal pressure, such as alkanes, alkenes, aromatic hydrocarbons, chlorinated aromatic hydrocarbons, saturated and unsaturated aldehydes, ketones, etc. VOCs mainly come from exhaust gases emitted by industries such as petroleum, chemical industry, papermaking, paint coatings, mining, metal electroplating, and textiles, as well as exhaust gases emitted by many vehicles.

According to statistics, from 2005 to 2010, the total emission of VOCs in my country was about 26.5-31 million tons. In 2010, only about 3.88 million tons of VOCs were released into the atmosphere during the coating application process in my country, accounting for a large proportion of the total emissions of volatile organic waste gases. . Five types of compounds, such as benzene series, alcohol, vinegar, ether, and ketone, are the main components of organic waste gas emitted by current coating applications, accounting for 29%, 19%, 13%, 10%, and 11% of the total, of which 31% It is a toxic and harmful substance, mainly toluene and xylene. With the development of society and the improvement of people's requirements for environmental quality, countries around the world have formulated strict environmental protection regulations on the discharge of organic waste gas, such as the United States, Japan, Germany, etc., have formulated strict organic waste gas emission standards, especially for benzene series , polycyclic aromatic hydrocarbons, polychlorinated biphenyls, dioxins and other common and highly toxic industrial organic waste gases have attracted the attention of people and environmental protection workers. Among the 189 priority toxic air pollutants that are required to be monitored in the United States Clean Air Amendment (1990), about 100 are volatile organic pollutants; the "Comprehensive Emission Standards for Atmospheric Pollutants" promulgated and implemented in my country in 1997 The emission limits of 33 kinds of pollutants are limited, including various VOCs such as benzene series (benzene, toluene and xylene). At present, the control and treatment of air pollution in my country are mostly focused on the technical research and industrial promotion of flue gas dust removal, desulfurization, and denitrification of large-scale fixed sources such as power plants and boilers. In contrast, volatile organic waste gases, such as benzene series organic waste gases emissions have not received enough attention. Therefore, the development of economical and efficient organic waste gas treatment technology will have important environmental, economic and social significance for improving my country's air quality and realizing the control and governance of air pollution.

There are two main methods for the purification and treatment of organic pollutants in gas: one is the recovery method, and the other is the destruction method. The recovery methods mainly include carbon adsorption, pressure swing adsorption, condensation method and membrane separation technology. The recovery method uses pressure, temperature, selective adsorbent and selective permeable membrane to separate VOCs through physical methods. Destruction methods include high-temperature combustion method, catalytic low-temperature combustion method, catalytic oxidation method, biological oxidation and integrated technology. The destruction method mainly uses catalysts, heat or microorganisms to convert volatile organic compounds into carbon dioxide and water through chemical or biochemical reactions. Among these pollution control technologies, thermal destruction method, adsorption method, absorption method, condensation method, etc. have been widely studied and widely used. New control technologies formed in recent years include biofilm method, ozonolysis method, corona method, plasma pollution method, etc. body decomposition, etc.

The heat generated by the catalytic low-temperature combustion method is difficult to maintain self-heating, and the gas still needs to be heated to reach the required temperature, and the energy consumption is high. The adsorption method has the advantages of high removal efficiency, thorough purification, low energy consumption, mature process and easy promotion, and has good environmental and economic benefits. The disadvantage is that the treatment equipment is huge and the process is complicated. When the adsorbent is easy to fail, and the material must be reprocessed when it is regenerated, it will easily cause secondary pollution, thereby increasing the cost of treatment. The absorption method is to use the gaseous pollutants to have good solubility in some liquid solvents, and use the liquid as an absorbent to make the harmful components in the exhaust gas absorbed by the liquid, so as to achieve the purpose of separating pollutants and purifying the gas, but there is still absorption Solvent volatilization and absorbent regeneration. The cost of biodegradation is low, but the biodegradability of many organic pollutants is not high, which limits the application of biological methods. Photocatalytic oxidation has been widely studied, but this method still has many shortcomings in the purification of VOCs. For example, organic intermediate products such as ketones, aldehydes, and acids will be produced during the photocatalytic oxidation reaction, which may cause Secondary pollution. In addition, the photocatalytic oxidation method can only be used to treat low-concentration VOCs, and the catalyst also has disadvantages such as easy deactivation and difficulty in fixing. The characteristics of plasma technology are simple operation process, convenient equipment maintenance, short work process and good operability, but this method has some disadvantages: high energy consumption, and the energy utilization rate needs to be further improved; the side effects of discharge The product may cause secondary pollution, such as NO _x , CO, O ₃ and other gases.

3. Contents of the invention

The present invention aims to provide a method for purifying volatile organic pollutants. The technical problem to be solved is to design suitable catalytic materials and processes to remove volatile organic pollutants in gas by catalyzing the chemical oxidation of hydrogen peroxide.

The present invention solves technical problem and adopts following technical scheme:

Reactor shell (1), air inlet (2), perforated gas distribution plate (3), iron oxide filter material layer (4), gas outlet (5), hydrogen peroxide storage tank (6), hydrogen peroxide feed port (7 ).

The method of purifying organic pollutants in gas is:

The gas enters from the inlet (2) and contacts with the hydrogen peroxide in the hydrogen peroxide storage tank (6);

Regulate the volatilization rate of hydrogen peroxide by adjusting the concentration of hydrogen peroxide in the storage tank, the speed of intake air, and the contact mode between intake air and hydrogen peroxide solution, so that the amount of hydrogen peroxide in the gas is 100-110% of the theoretical amount of hydrogen peroxide required to oxidize organic pollutants;

The volatilized hydrogen peroxide is evenly mixed with the gas and passes through the perforated gas distribution plate (3), the gas passes through the fixed filter layer filled with nano-sized mineral material particles, and oxidizes volatile organic pollutants through the heterogeneous Fenton reaction of nano-sized mineral materials .

Compared with the prior art, the beneficial effects of the present invention are reflected in:

1. The inventor took advantage of the fact that hydrogen peroxide has a certain volatility. The lower part of the reactor is equipped with a hydrogen peroxide storage tank. The intake air flow is in contact with the hydrogen peroxide, and part of the volatilized hydrogen peroxide is mixed with the gas. The method of contacting the gas with the hydrogen peroxide solution regulates the volatilization rate of the hydrogen peroxide and provides an appropriate proportion of oxidants for the oxidation of organic pollutants. Hydrogen peroxide is completely compatible with the intake air, which is beneficial to improve the reaction rate.

2. The key to the method for purifying organic pollutants in gas of the present invention is to use nanometerized mineral materials as catalysts to catalyze hydrogen peroxide to oxidize and purify pollutants. The nano-mineral materials used have nanocrystals and nano-pores, belong to nano-structure materials, have a large specific surface area and reactivity, show very excellent catalytic activity, and improve the effect of gas-solid phase Fenton oxidation; the nano-minerals used The preparation method of the material is simple, the raw materials are mineral resources with abundant reserves, such as limonite ore and pyrite ore, the sources are extensive, and the preparation cost is low.

3. The nanometerized mineral material used is particles with a particle size of 0.5-5mm, which is filled into a fixed filter layer with large porosity and low gas resistance.

4. Use low-concentration hydrochloric acid, sulfuric acid, or nitric acid to treat the filled nano-mineral material filter material, making the surface of the nano-mineral material acidic, and improving the efficiency of catalyzing hydrogen peroxide to oxidize organic pollutants, because it is more efficient under acidic conditions. It is beneficial to the reaction of hydrogen peroxide to oxidize organic pollutants.

4. Description of drawings

Figure 1 Schematic diagram of the reactor structure for purifying volatile gaseous pollutants with nano-sized mineral materials: 1-housing; 2-inlet; 3-perforated gas distribution plate; - Hydrogen peroxide storage tank; 7 - Hydrogen peroxide filling port.

Figure 2 X-ray diffraction pattern of nano-iron mineral materials, showing the composition and structural characteristics of the nano-mineral materials used.

Figure 3 Catalytic efficiency of hydrogen peroxide oxidation methane by several nano-iron mineral materials (the volume fraction of methane in the gas is 5%)

Figure 4 Catalytic efficiency of hydrogen peroxide oxidation of toluene by several nano-iron mineral materials (the concentration of toluene in the gas is 2.43g/Nm ³ )

5. Specific implementation

Example 1:

The limonite ore is crushed and sieved to obtain particles with a particle size of 0.5-1mm (Figure 2).

The prepared granules were impregnated with 2% nitric acid, drained, and loaded into the upper part of the reactor.

The device for purifying organic pollutants in the gas is shown in Figure 1, 1-housing; 2-inlet; 3-perforated gas distribution plate; 4-nanometer mineral material filter layer; 5-gas outlet; 6-hydrogen peroxide storage tank ; 7-hydrogen peroxide feed port.

Use an air pump to pass the air through 0.1% formaldehyde aqueous solution, and use a mass flow meter to adjust the gas flow to obtain a simulated gas containing 334mg/ ^m3 of formaldehyde.

Enter the simulated gas containing formaldehyde from the air inlet (2), contact with the hydrogen peroxide in the hydrogen peroxide storage tank (6), and set the concentration of hydrogen peroxide in the storage tank to 15% for the test; the volatilized hydrogen peroxide and the gas are mixed evenly and pass through the perforation The gas distribution plate (3) passes through the filter layer of nano-sized mineral materials to catalyze the organic pollutants in the hydrogen peroxide oxidation gas.

The gas discharged from the gas outlet (5) of the purification device is absorbed with distilled water, the amount of formaldehyde in the solution is measured by acetylacetone spectrophotometry, and the formaldehyde concentration in the gas is calculated according to the gas flow rate and the formaldehyde concentration in the solution. The formaldehyde removal rate is greater than 90%.

Example 2:

The limonite ore is crushed and sieved to obtain particles with a particle size of 1.0~5mm, and 50g of the sample is put into a muffle furnace for calcination at 300°C for 1 hour to obtain a nano-sized mineral with nanopores and a high specific surface area composed of nanocrystalline hematite Materials (Figure 2).

The prepared nanometerized mineral material particles are impregnated with 5% nitric acid, drained, and loaded into the upper part of the reactor.

Use an air pump to pass the air through 0.1% formaldehyde aqueous solution, and use a mass flow meter to adjust the gas flow to obtain a simulated gas containing 334mg/ ^m3 of formaldehyde.

Enter the simulated gas containing formaldehyde from the air inlet (2), contact with the hydrogen peroxide in the hydrogen peroxide storage tank (6), and set the concentration of hydrogen peroxide in the storage tank to 30% for the test; the volatilized hydrogen peroxide and the gas are mixed evenly and pass through the perforation The gas distribution plate (3) passes through the filter layer of nano-sized mineral materials to catalyze the organic pollutants in the hydrogen peroxide oxidation gas.

The gas discharged from the gas outlet (5) of the purification device is absorbed with distilled water, the amount of formaldehyde in the solution is measured by acetylacetone spectrophotometry, and the formaldehyde concentration in the gas is calculated according to the gas flow rate and the formaldehyde concentration in the solution. The formaldehyde removal rate is greater than 95%.

Example 3:

Limonite ore is crushed and sieved to obtain particles with a particle size of 0.5~1mm, 50g of the sample is put into a tube furnace, and hydrogen gas is introduced into it for calcination at 300°C for 2 hours to obtain nanopores composed of nanocrystalline magnetite and nano-iron , Nano-sized mineral materials with high specific surface area.

The prepared nano mineral material particles are impregnated with 5% sulfuric acid, drained, and loaded into the upper part of the reactor;

Use an air pump to pass air through 0.1% formaldehyde aqueous solution, and use a mass flow meter to adjust the gas flow to obtain a simulated gas containing formaldehyde.

Enter the simulated gas containing formaldehyde from the air inlet (2) and contact with the hydrogen peroxide in the hydrogen peroxide storage tank (6). The hydrogen peroxide and the gas are evenly mixed and passed through the perforated air distribution plate (3) and then through the nano-sized mineral material filter layer to catalyze the hydrogen peroxide to oxidize the organic pollutants in the gas.

The gas discharged from the gas outlet (5) of the purification device is absorbed with distilled water, the amount of formaldehyde in the solution is measured by acetylacetone spectrophotometry, and the formaldehyde concentration in the gas is calculated according to the gas flow rate and the formaldehyde concentration in the solution. The formaldehyde removal rate is greater than 95%.

Example 4:

The pyrite ore is crushed and sieved to obtain particles with a particle size of 0.5~1mm, and 50g of the sample is put into a tube furnace, fed with nitrogen, and calcined at 550°C for 1 hour to obtain nanopore, high Nanosized mineral materials with specific surface area (Figure 2).

The prepared nano mineral material particles are impregnated with 0.5% sulfuric acid, drained, and loaded into the upper part of the reactor;

Use an air pump to pass air through 0.1% formaldehyde aqueous solution, and use a mass flow meter to adjust the gas flow to obtain a simulated gas containing formaldehyde.

Enter the simulated gas containing formaldehyde from the air inlet (2) and contact with the hydrogen peroxide in the hydrogen peroxide storage tank (6). The hydrogen peroxide and the gas are evenly mixed and passed through the perforated air distribution plate (3) and then through the nano-sized mineral material filter layer to catalyze the hydrogen peroxide to oxidize the organic pollutants in the gas.

The gas discharged from the gas outlet (5) of the purification device is absorbed with distilled water, the amount of formaldehyde in the solution is measured by acetylacetone spectrophotometry, and the formaldehyde concentration in the gas is calculated according to the gas flow rate and the formaldehyde concentration in the solution. The formaldehyde removal rate is greater than 95%.

Example 5:

The pyrite ore is crushed and sieved to obtain particles with a particle size of 0.5~1mm, and 50g of the sample is put into a tube furnace, fed with nitrogen, and calcined at 550°C for 1 hour to obtain nanopore, high Nanosized mineral materials with specific surface area (Figure 2).

The prepared nano mineral material particles are impregnated with 0.5% sulfuric acid, drained, and loaded into the upper part of the reactor;

The pure methane standard gas and air are respectively controlled and configured by the mass flow meter to form a mixed gas with a volume fraction of 1%, 2%, 3%, 4%, and 5%, and the simulated gas containing methane enters from the injection port (2) , in contact with the hydrogen peroxide in the hydrogen peroxide storage tank (6), the concentration of hydrogen peroxide in the storage tank is 5%, the volatilized hydrogen peroxide is mixed with the gas evenly and passes through the perforated gas distribution plate (3) and then passes through the nanometerized mineral material filter layer to catalyze the hydrogen peroxide Oxidizes methane in the gas.

The gas discharged from the outlet (5) of the purification device is analyzed by a gas chromatograph. When the methane volume fraction is less than 5%, the methane removal rate is greater than 95% (Figure 3).

Embodiment 6:

The pyrite ore is crushed and sieved to obtain particles with a particle size of 0.5~1mm, and 50g of the sample is put into a tube furnace, fed with nitrogen, and calcined at 550°C for 1 hour to obtain nanopore, high Nano-sized mineral materials with specific surface area.

The prepared nanometerized mineral material particles are impregnated with 0.1% sulfuric acid, drained, and loaded into the upper part of the reactor. Use an air pump to pass 10mL/min of air through pure liquid toluene to obtain a gas containing high concentration of toluene, and control the gas through a mass flow meter and mix it with another air in a mixing bottle to obtain 10mg/m ³ , 100mg/m ³ , 500mg/m ³ , 1000mg/m ³ , and 5000mg/m ³ simulated gas with different formaldehyde concentrations, the simulated gas containing toluene enters the reactor from the injection port (2), and contacts with the hydrogen peroxide in the hydrogen peroxide storage tank (6), The concentration of hydrogen peroxide in the storage tank is 5%, and the volatilized hydrogen peroxide and gas are evenly mixed and pass through the perforated gas distribution plate (3) and then through the filter layer of nano-sized mineral materials, and catalyze the oxidation of toluene by hydrogen peroxide through the Fenton reaction.

The gas discharged from the outlet (7) of the purification device is adsorbed by activated carbon, analyzed by carbon disulfide, and then analyzed by gas chromatography to calculate the toluene concentration and removal efficiency after treatment. The removal rate of toluene is 95% (Figure 4).

Claims (2)

1. the method for organic pollution in nanometer mineral material Purge gas, is characterized in that: to have the ferriferous oxide of nano-pore structure or iron sulfide granular materials for catalyst, the organic pollution in catalysis hydrogen peroxide oxidation waste gas; Purifier comprises shell of reactor (1), air inlet (2), perforation air distribution plate (3), nanometer mineral material filter material layer (4), gas outlet (5), hydrogen peroxide storage pond (6), hydrogen peroxide charge door (7);

In its Purge gas, the method for organic pollution is:

(1) prepare nanometer mineral material, natural limonite ore is broken, screening, obtains the particle of 0.5-5mm, changes nanometer bloodstone into as catalysis material at 250-500 DEG C of calcining 1h;

Or using obtain 0.5-5mm limonite particle under reducing atmosphere 300-700 DEG C of calcining change nano magnetite into as catalysis material;

Or pyrite Ore is broken, screening obtains the particle of 0.5-5mm, 550-800 DEG C of calcining 1h changes nano magnetic pyrite into;

(2) above-mentioned graininess nanometer mineral material filling is become fixing filtering layer;

(3) with the hydrochloric acid of mass concentration 0.1-5% or sulfuric acid or nitric acid or phosphoric acid, make nanometer mineral material surface presentation acid;

(4) need the gas of purification to enter from air inlet (2), hydrogen peroxide store up in pond (6) with hydrogen peroxide contacts, the hydrogen peroxide of volatilization and gas and vapor permeation evenly together with pass through to bore a hole air distribution plate (3);

(5) mist is again through the fixing filtering layer that nanometer iron mineral material granule is housed, thickness of filter bed 5-50cm, nanometer mineral filtrate heterogeneous catalysis hydrogen peroxide oxidation volatile organic contaminant.

2. the method for organic pollution in nanometer mineral material Purge gas according to claim 1, by regulating hydrogen peroxide concentration, intake velocity, air inlet and the hydrogen peroxide solution way of contact in hydrogen peroxide storage pond to regulate and control the evaporation rate of hydrogen peroxide, make the 100-110% of the amount of hydrogen peroxide in gas hydrogen peroxide theoretical amount needed for oxidation organic pollution.