CN106731234B - A kind of preparation method of binary denitration sulfur resistant catalyst composite filtering material - Google Patents

Abstract

The invention provides a method for preparing a composite filter material of a binary denitrification and antisulfur catalyst. The surfactant-treated polyphenylene sulfide filter material is used as the carrier, KMnO ₄ and MnSO ₄ ·H ₂ O and (NH ₄ ) ₆ Mo ₇ O ₂₄ ·4H ₂ O are used as catalyst precursors, and deionized water is used as the solvent , the composite filter material is prepared by high temperature and high pressure hydrothermal method. Because the present invention adopts a binary denitrification and antisulfur catalyst, it has better denitrification and antisulfur performance than a single-component catalyst, and adopts a high-temperature, high-pressure hydrothermal method, which is beneficial to the formation and loading of the catalyst on the surface of the polyphenylene sulfide filter material. Good denitrification performance can be obtained when the loading amount is greater than 5mg/cm ² . The reaction synthesis method of the invention is quick and easy to operate, and the prepared composite filter material is suitable for dust remover and denitrification agent.

Description

Preparation method of a binary denitrification and anti-sulfur catalyst composite filter material

technical field

The invention belongs to the technical field of functional composite filter materials, and in particular relates to a method for preparing a composite filter material for binary denitrification and anti-sulfur catalysts.

Background technique

China is a country short of oil, gas, and rich in coal. Coal is the main energy source in our country. The combustion of coal raw materials will produce a large number of pollutants. Among the air pollutants, 87% are sulfur dioxide (SO ₂ ), and 71% are carbon monoxide ( CO), 67% of nitrogen oxides (NO _x ) and 60% of soot all come from the combustion of coal raw materials. A large part of the pollutants are nitrogen oxides. NO _x has become one of the main sources of air pollution with the same name as SO ₂ and CO. It mainly includes nitric oxide (NO), nitrogen dioxide (NO ₂ ) and di Nitrogen (N ₂ O), of which NO accounts for 90-95%, NO ₂ accounts for 5-10%, and N ₂ O only accounts for about 1%. NO _x in the air is a serious hazard to human health and ecological environment. NO is a colorless and odorless gas. It has a strong ability to combine with oxygen in hemoglobin, which will seriously affect the oxygen transport capacity of the blood and stimulate human eyes and respiratory organs. In severe cases, it will induce cell cancer. In addition, NO is easily oxidized into NO ₂ spontaneously in the air, causing more serious consequences.

Another part of the pollutants is sulfide, and the sulfur element in the final coal-fired flue gas exists in the form of SO ₂ . SO ₂ is a colorless gas with a strong pungent odor, easily soluble in human blood and other viscous fluids. SO ₂ in the atmosphere can cause respiratory inflammation, bronchitis, emphysema, conjunctival inflammation, etc. At the same time, it will reduce the immunity of young people and weaken their disease resistance. Under the action of oxidants and light, SO ₂ can generate sulfate aerosols, which can make people sick and increase the mortality of patients. According to the research of the Organization for Economic Co-operation and Development (OECD), when the annual concentration of sulfate is around 10 μg/m ³ , every 10% reduction in the concentration can reduce the mortality rate by 0.5%; SO ₂ can also adhere to the floating dust in the atmosphere. When the human body inhales the floating dust with SO ₂ , the toxicity of SO ₂ will be enhanced. Studies have shown that under the influence of high concentrations of SO ₂ , plants are acutely damaged, resulting in necrotic spots on the surface of leaves, or directly causing the leaves of plants to wither and fall off; under the influence of low concentrations of SO ₂ , the growth function of plants is affected, resulting in yield loss. decline, the quality deteriorates.

At present, filter materials are mainly used to treat and absorb the waste gas produced by coal-fired boilers and waste incineration in power plants. Among them, polyphenylene sulfide (PPS) filter materials are the preferred materials for coal-fired boilers in power plants and waste incineration filter bags, because of their unique properties. Excellent properties of high temperature resistance, hydrolysis resistance, high flame retardancy, acid and alkali resistance. However, the temperature window of commercial catalysts is in the high-temperature region of 300-400°C, which is much higher than the use temperature of polyphenylene sulfide filter media (about 170°C); in addition, the inert molecular structure of polyphenylene sulfide also makes it difficult to Holds catalyst particles. Therefore, the research and development of low-temperature and high-efficiency binary denitrification and anti-sulfur catalysts and their composite technology with filter materials have become the research focus.

The commercialized vanadium-titanium system catalyst has a high activation temperature (>300°C), which is difficult to apply at the end of the flue gas treatment system, and the installation and operation costs are high. Therefore, low-temperature SCR technology that is economical and suitable for end treatment has become a hot spot for researchers. The unsupported Mn- _MoOx catalyst has been recorded in many literatures for its high denitrification efficiency at low temperatures, and its denitrification ability can almost completely convert NOx into _N2 at 120 °C. It is the first choice for denitrification treatment, but there is no suitable technology to convert It is successfully applied to the filter material. Therefore, this patent breakthrough uses high temperature and high pressure hydrothermal method to load it on the filter material.

Contents of the invention

The purpose of the present invention is to prepare a method of combining an efficient denitrification and anti-sulfur binary catalyst with polyphenylene sulfide (PPS), and load the catalyst on the surface of polyphenylene sulfide (PPS) in one step through the hydrothermal method. Due to the hydrothermal method of high temperature and high pressure, the Mn-MoO _x catalyst is evenly and firmly loaded on the surface of PPS, and has a high stock removal rate and a good anti-sulfur effect.

The technical scheme adopted in the present invention is:

A preparation method of a binary denitrification antisulfur catalyst composite filter material: using surfactant-treated polyphenylene sulfide as a carrier, KMnO ₄ and MnSO ₄ ·H ₂ O and (NH ₄ ) ₆ Mo ₇ O ₂₄ ·4H ₂ O is used as catalyst precursor, and deionized water is used as solvent to prepare composite filter material by high temperature and high pressure hydrothermal method.

Specific steps are as follows:

(1) Dissolve 0.0273g of sodium lauryl sulfate in 50ml of deionized water, then put it into the polyphenylene sulfide filter material cut into small discs, ultrasonically treat it for 1 hour, then take it out and dry it for later use;

(2) Add ammonium molybdate tetrahydrate ((NH ₄ ) ₆ Mo ₇ O ₂₄ 4H ₂ O) into a beaker filled with 20ml of deionized water, put it into a stirring bar, stir at room temperature for 5min, and wait for tetrahydration After the ammonium molybdate is fully dissolved, add 20-80ml of 0.2M KMnO ₄ solution and stir at room temperature for 10min.

(3) After 10 minutes, when the solution is stirred evenly, prepare 30ml of 0.006~0.024mol MnSO ₄ ·H ₂ O solution and dissolve it in an ultrasonic environment, then add the previously mixed solution, and add the previously treated PPS filter material at the same time, and then Stir at room temperature for 15 min.

(4) Pour the uniformly mixed solution into a polytetrafluoroethylene liner, put it in an autoclave, and place it in a vacuum oven at 180°C to react for 18 hours, then take out the autoclave, cool to room temperature, open the autoclave and take out the PPS The filter material was washed and dried for testing.

Further, in terms of mass ratio, polyphenylene sulfide:potassium permanganate=1:1.5-2.5.

Further, the molar ratio of Mn:Mo in the solution is 1˜3:1.

The filter material is polyphenylene sulfide needle-punched filter material, which is prepared from polyphenylene sulfide fibers through opening, compound mixing, carding, net laying, acupuncture, heat setting and singeing. into, with an average pore size of 40 μm.

The composite filter material can be used as a dedusting agent and a denitration agent at the same time, and better denitrification performance can be obtained when the loading amount of the catalyst is greater than 5 mg/cm ² .

The present invention utilizes surfactant SDS to pre-treat polyphenylene sulfide PPS filter material to obtain more active oxygen-containing functional groups on its surface, such as hydroxyl group and carboxyl group. Due to the existence of these oxygen-containing functional groups, the original inert polyphenylene sulfide surface is activated, and can absorb Mo ⁴⁺ in (NH ₄ ) ₆ Mo ₇ O ₂₄ ·4H ₂ O and MnSO ₄ ·H ₂ O through electrostatic effect. and Mn ²⁺ , which provide the basis for the formation of catalysts on the surface of the PPS filter material.

Beneficial effects of the present invention:

1. Compared with the out-of-stock filter material based on the monobasic Mn base, during the denitrification process, SO ₂ in the exhaust gas is easy to react with the efficient denitration catalyst MnO _x to form MnSO ₄ . At this time, the catalyst is denatured and deactivated, resulting in the out-of-stock rate of the filter material The denitrification performance is greatly reduced, or even almost lost. This method has a better denitrification resistance than the single-component catalyst due to the addition of rare earth element Mo, and Mo is the current mainstream antisulfur agent, which has a good antisulfur effect. sulfur properties.

2. The catalyst is loaded on polyphenylene sulfide (PPS) through high temperature and high pressure hydrothermal method. First, the catalyst is generated on the surface of PPS through high temperature reaction, and second, the rest of the catalyst in the solution is loaded on PPS by strong pressure. Efficient utilization and stable load.

3. The reaction synthesis method and operation are very simple, and the reaction is fast, the reaction vessel is generally easy to use, and the synthetic substance does not pollute the environment, the surface load of the synthetic filter material is uniform and firm, and the out-of-stock rate is high.

4. The catalyst produced in the synthesis process can be recycled and used, which is environmentally friendly and efficient.

Description of drawings

Fig. 1 Diagram of self-made tubular SCR reactor device in catalyst activity test. In the figure, 1 is a gas source; 2 is a pressure reducing valve; 3 is a mass flow meter; 4 is a mixer; 5 is an air preheater; 6 is a catalytic bed; 7 is a filter material; 8 is a flue gas analyzer. ; Fig. 2 is the scanning electron micrograph of the sample prepared when the element Mn:Mo molar ratio is 2:1.

Detailed ways

The following are several specific embodiments of the present invention to further illustrate the present invention, but the present invention is not limited thereto.

The PPS needle-punched felt filter material in the following examples is prepared by the following method: using polyphenylene sulfide (PPS) fibers as raw materials, through opening, compound mixing, carding, web laying, needle punching, heat setting and singeing The needle-punched felt filter material was prepared by calendering, with an average pore size of 40 μm.

Example 1

First weigh 0.0273g of sodium lauryl sulfate and add it to 50ml of deionized water, then put it into a PPS filter disc with a cut mass of 0:4213g, ultrasonically treat it for 1 hour, take it out and dry it for later use. Then weigh 20ml of deionized water and add it to a 250ml beaker. Then accurately weigh 1.7651 g of ammonium molybdate tetrahydrate ((NH ₄ ) ₆ Mo ₇ O ₂₄ ·4H ₂ O), add a magnet and stir for 5 minutes until the solution is evenly mixed. Prepare 20ml of potassium permanganate solution with a concentration of 0.2M, sonicate or shake the prepared solution until the solute is completely dissolved, add it to the previous beaker, and mix and stir for 4 minutes. Then configure 30ml of 0.006mol manganese sulfate monohydrate, and add it to the solution that was mixed uniformly before. At this time, the ratio of Mn:Mo in the solution is 1:1, and add the previously dried PPS filter disc into it, and place it at room temperature Stir for 15 minutes, and the solution is brown after mixing evenly.

After mixing evenly, transfer the solution to a polytetrafluoroethylene liner, seal it well, package it in an autoclave, and place it in a vacuum drying oven at 180°C for 18 hours. After the reaction is completed, place it at room temperature and cool it down to room temperature Finally, open the autoclave to take out the PPS filter material, wash it with deionized water and ethanol, and dry it at 105°C for 4 hours before testing. The mass of potassium permanganate is calculated as follows: 0.2×0.02×158=0.632g.

The denitrification performance of the composite filter material was evaluated in a self-made tubular SCR reactor. The volume fractions of NO and NH ₃ are both 0.05%, the volume fraction of O ₂ is 5%, and the rest is N ₂ , the gas flow rate is 700mL·min ^-1 , the temperature is set at 140°C, and the denitrification rate is measured by the British KM940 flue gas analyzer The temperature is set at 160°C, the denitrification rate is 80%, and the temperature is set at 180°C, the denitrification rate is 99%. The anti-sulfur ability was tested at 180°C at intervals of 30 minutes, and the final out-of-stock rate was basically stable at 44%.

Example 2

First weigh 0.0273g of sodium lauryl sulfate and add it to 50ml of deionized water, then put it into a PPS filter disc with a cut mass of 0.6320g, ultrasonically treat it for 1 hour, take it out and dry it for later use. Then weigh 20ml of deionized water and add it to a 250ml beaker. Then accurately weigh 1.7651 g of ammonium molybdate tetrahydrate ((NH ₄ ) ₆ Mo ₇ O ₂₄ ·4H ₂ O), add a magnet and stir for 5 minutes until the solution is evenly mixed. Prepare 40ml of potassium permanganate solution with a concentration of 0.2M, sonicate or shake the prepared solution until the solute is completely dissolved, add it to the previous beaker, and mix and stir for 4 minutes. Then configure 30ml of 0.012mol manganese sulfate monohydrate, and add it to the solution that was mixed uniformly before. At this time, the ratio of Mn:Mo in the solution is 2:1. Add the previously dried PPS filter disc into it, and place it at room temperature Stir for 15 minutes, and the solution is brown after mixing evenly.

After mixing evenly, transfer the solution to a polytetrafluoroethylene liner, seal it well, package it in an autoclave, and place it in a vacuum drying oven at 180°C for 18 hours. After the reaction is completed, place it at room temperature and cool it down to room temperature Finally, open the autoclave to take out the PPS filter material, wash it with deionized water and ethanol, and dry it at 105°C for 4 hours before testing. The mass of potassium permanganate is calculated as follows: 0.2×0.04×158=1.264g.

The denitrification performance of the composite filter material was evaluated in a self-made tubular SCR reactor. The volume fractions of NO and NH ₃ are both 0.05%, the volume fraction of O ₂ is 5%, and the rest is N ₂ , the gas flow rate is 700mL·min ^-1 , the temperature is set at 140°C, and the denitrification rate is measured by the British KM940 flue gas analyzer is 77%; the temperature is set to 160°C, and the denitrification rate is 100%. The anti-sulfur ability was tested at 180°C at intervals of 30 minutes, and the final out-of-stock rate was basically stable at 55%.

Example 3

First weigh 0.0273g of sodium lauryl sulfate and add it to 50ml of deionized water, then put it into a PPS filter disc with a mass of 1.011g, ultrasonicate for 1 hour, take it out and dry it for later use. Then weigh 20ml of deionized water and add it to a 250ml beaker. Then accurately weigh 1.7651 g of ammonium molybdate tetrahydrate ((NH ₄ ) ₆ Mo ₇ O ₂₄ ·4H ₂ O), add a magnet and stir for 5 minutes until the solution is evenly mixed. Prepare 80ml of potassium permanganate solution with a concentration of 0.2M, sonicate or shake the prepared solution until the solute is completely dissolved, add it to the previous beaker, and mix and stir for 4 minutes. Then configure 30ml of 0.009mol manganese sulfate monohydrate, and add it to the solution that was mixed uniformly before. At this time, the ratio of Mn:Mo in the solution is 2.5:1. Add the previously dried PPS filter disc into it, and place it at room temperature Stir for 15 minutes, and the solution is brown after mixing evenly.

After mixing evenly, transfer the solution to a polytetrafluoroethylene liner, seal it well, package it in an autoclave, and place it in a vacuum oven at 200°C for 18 hours of reaction. After the reaction, place it at room temperature and cool it down to room temperature Finally, open the autoclave to take out the PPS filter material, wash it with deionized water and ethanol, and dry it at 105°C for 4 hours before testing. The mass of potassium permanganate is calculated as follows: 0.2×0.08×158=2.528g.

The denitrification performance of the composite filter material was evaluated in a self-made tubular SCR reactor. The volume fractions of NO and NH ₃ are both 0.05%, the volume fraction of O ₂ is 5%, and the rest is N ₂ , the gas flow rate is 700mL·min ^-1 , the temperature is set at 140°C, and the denitrification rate is measured by the British KM940 flue gas analyzer is 70%; the temperature is set to 160°C, and the denitrification rate is 81%; the temperature is set to 180°C, and the out-of-stock rate is 100%. The anti-sulfur ability was tested at 180°C at intervals of 30 minutes, and the final out-of-stock rate was basically stable at 48%.

Example 4

First weigh 0.0273g of sodium lauryl sulfate and add it to 50ml of deionized water, then put it into a PPS filter disc with a mass of 1.011g, ultrasonicate for 1 hour, take it out and dry it for later use. Then weigh 20ml of deionized water and add it to a 250ml beaker. Then accurately weigh 1.7651 g of ammonium molybdate tetrahydrate ((NH ₄ ) ₆ Mo ₇ O ₂₄ ·4H ₂ O), add a magnet and stir for 5 minutes until the solution is evenly mixed. Prepare 80ml of potassium permanganate solution with a concentration of 0.2M, sonicate or shake the prepared solution until the solute is completely dissolved, add it to the previous beaker, and mix and stir for 4 minutes. Then configure 30ml of 0.014mol manganese sulfate monohydrate, and add it to the solution that was mixed uniformly before. At this time, the ratio of Mn:Mo in the solution is 3:1. Add the previously dried PPS filter disc into it, and place it at room temperature Stir for 15 minutes, and the solution is brown after mixing evenly.

After mixing evenly, transfer the solution to a polytetrafluoroethylene liner, seal it well, package it in an autoclave, and place it in a vacuum oven at 200°C for 18 hours of reaction. After the reaction, place it at room temperature and cool it down to room temperature Finally, open the autoclave to take out the PPS filter material, wash it with deionized water and ethanol, and dry it at 105°C for 4 hours before testing. The mass of potassium permanganate is calculated as follows: 0.2×0.08×158=2.528g.

The denitrification performance of the composite filter material was evaluated in a self-made tubular SCR reactor. The volume fractions of NO and NH ₃ are both 0.05%, the volume fraction of O ₂ is 5%, and the rest is N ₂ , the gas flow rate is 700mL·min ^-1 , the temperature is set at 140°C, and the denitrification rate is measured by the British KM940 flue gas analyzer The temperature is set at 160°C, and the denitrification rate is 77%; the temperature is set at 180°C, and the out-of-stock rate is 99%. The anti-sulfur ability was tested at 180°C at intervals of 30 minutes, and the final out-of-stock rate was basically stable at 47%.

Activity evaluation: The catalyst was evaluated in a self-made tubular SCR reactor. The reactor was heated externally, and a thermocouple was placed next to the catalyst bed in the reaction tube to measure the temperature. The flow chart of the experimental device is shown in Figure 1. The composition of flue gas is simulated by steel cylinders. The flue gas includes NO, O ₂ , N ₂ , and NH ₃ as reducing gases. The volume fractions of NO and NH ₃ are both 0.04-0.06%, and the volume fraction of O ₂ is 4-6%. The rest is N ₂ , the gas flow rate is 700mL·min ^-1 , the temperature is controlled between 120 and 200°C, and the gas flow and composition are regulated and controlled by mass flow meters. The gas analysis adopts the British KM940 flue gas analyzer. In order to ensure the stability and accuracy of the data, each working condition is stable for at least 30 minutes.

Table 1 The influence of various factors on the denitrification rate of the composite filter material (reaction temperature is 180°C):

It can be seen from the data in Table 1 that at 140°C, as the molar ratio of the two metal elements increases, the denitrification rate first increases to a maximum value and then decreases, and appears at 1:2 the maximum value. And when it reaches 180℃, the denitrification rate basically reaches 100%. And it shows the best anti-sulfur performance at 180°C.

Claims (4)

1. a kind of preparation method of binary denitration sulfur resistant catalyst composite filtering material, it is characterised in that：By at surfactant The polyphenyl thioether filter material of reason is carrier, KMnO₄And MnSO₄·H₂O and (NH₄)₆Mo₇O₂₄·4H₂O is catalyst precursor, to go Ionized water is solvent, and compound filter material is made by high temperature and pressure hydro-thermal method；The polyphenyl thioether filter material is with polyphenylene sulfide Fiber is raw material, is prepared through shredding, compound mixing, combing, lapping, needle thorn, thermal finalization and press polish of singing, average pore size 40 μm；Specific preparation process is as follows：

（1）Claim 0.0273g lauryl sodium sulfate to be dissolved in 50ml deionized water, is then placed in the polyphenylene sulfide for being cut into sequin Filtrate is ultrasonically treated 1h, further takes out and be dried for standby；

（2）By (NH₄)₆Mo₇O₂₄·4H₂O is dissolved in 20ml deionized water, stirs and evenly mixs 5min；

（3）Prepare the KMnO of 0.2M₄20 ~ 80ml of solution, and and step（2）Solution is mixed together stirring 4min；

（4）Prepare the MnSO of 0.006 ~ 0.024mol₄·H₂O solution 30ml, with step（3）Mixed liquor mixing, while by step （1）Polyphenyl thioether filter material disk be added thereto, be placed in and stir 15min at room temperature, after mixing solution be sepia；

（5）By step（4）Mixed solution is transferred in polytetrafluoroethylliner liner, and post package is sealed in autoclave, is placed in 18h is reacted in 180 ~ 200 DEG C of vacuum oven, room temperature is cooling after reaction, takes out polyphenyl thioether filter material, and use deionization Water and ethyl alcohol are cleaned, and dry 4h is placed in 105 DEG C.

2. the preparation method of binary denitration sulfur resistant catalyst composite filtering material according to claim 1, it is characterised in that：By matter Amount is than meter, polyphenyl thioether filter material：Potassium permanganate=1:1.5-2.5.

3. the preparation method of binary denitration sulfur resistant catalyst composite filtering material according to claim 1, it is characterised in that：Solution In Mn:The molar ratio of Mo is 1 ~ 3:1.

4. a kind of application of the binary denitration sulfur resistant catalyst composite filtering material of the preparation of preparation method according to claim 1, feature It is：The composite filtering material is applied to dedusting agent and denitrfying agent.