A method for preparing low-temperature flue gas denitration catalyst using electrolytic manganese anode mud

Abstract

The invention discloses a method for preparing a low-temperature flue gas denitration catalyst by utilizing electrolytic manganese anode mud, comprising the following steps: step one, material selection; step two, drying and grinding; step three, leaching; step four, solid-liquid separation; step five, multiple washing and filtering; wherein in the above step one, firstly, electrolytic manganese anode mud is selected as the raw material for preparing the low-temperature flue gas denitration catalyst; wherein in the above step two, the electrolytic manganese anode mud selected in step one is placed in a drying box for drying treatment. The invention has a simple synthesis method, and the raw materials used are from industrial waste residues, thereby reducing the impact on the environment. At the same time, the synthesized catalyst is conducive to efficient operation at ultra-low temperature, expanding the application scenarios of the catalyst, and at the same time, the electrolytic manganese anode mud is modified by soluble chloride salt, and the modification treatment of the electrolytic manganese anode mud is utilized, thereby greatly reducing the complexity of the subsequent process for preparing the catalyst.

Description

Technical Field

[0001] The invention relates to the technical field of solid waste treatment, and in particular to a method for preparing a low-temperature flue gas denitration catalyst by utilizing electrolytic manganese anode mud. Background Art

[0002] The flue gas emitted by thermal power plants contains a large amount of nitrogen oxides (NO x , mainly including NO, NO2, N2O, etc.). NOx is the main atmospheric pollutant that produces acid rain, brings photochemical smog, causes greenhouse effect and damages the ozone layer. One of the main methods to control NOx pollution is to reduce NOx in flue gas to nitrogen (N2, this process is called flue gas denitrification), and ammonia (NH3) is the most effective reducing agent discovered so far. Among them, the selective catalytic reduction (SCR) denitrification method in which a catalytic device and its catalyst are added to the denitrification device is much superior to the non-selective catalytic reduction (SNCR) denitrification method using only the reducing agent NH3. The former not only has a much higher denitrification rate than the latter, but also has lower NH3 consumption and escape than the latter. In other words, the catalyst is the key to improving the denitrification rate and reducing the cost of controlling NOx. All known catalysts of this type are metal oxides, especially V2O5, which has the highest catalytic activity. Currently, the catalytic system that can be used commercially is one that uses TiO2 as a carrier and V2O5 as the main active component loaded on the carrier. Application number 200810224389.2, entitled "A denitrification catalyst using TiO2 as raw material and its preparation method" is one of them. However, this type of catalyst has the disadvantages of high raw material cost and relatively complex preparation process of the catalyst itself; since this type of catalyst can only work at a higher flue gas temperature (generally 300°C to 400°C), and at higher temperatures, high concentrations of dust and SO2 in the flue gas can easily cause poisoning of this type of catalyst, so this type of catalyst also has the disadvantage of a short service life. In short, the use of this type of catalyst to control NO x The cost is higher.

[0003] China's electrolytic manganese (EMM) industry has developed rapidly and has become the world's largest producer and exporter. The electrolytic manganese production process produces a large amount of waste residue in the anode area of ​​the electrolytic cell. This waste is usually called electrolytic manganese anode mud (EMAM). As a hazardous waste, it contains a variety of heavy metal elements, including manganese, lead, cobalt, nickel, tin, and other soluble salts. The Mn content is generally above 75wt%. Therefore, extracting or using Mn in EMAM to prepare Mn-based LT SCR catalysts will have great environmental and economic significance. Summary of the invention

[0004] The object of the present invention is to provide a method for preparing a low-temperature flue gas denitration catalyst by utilizing electrolytic manganese anode mud, so as to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for preparing a low-temperature flue gas denitration catalyst using electrolytic manganese anode mud, comprising the following steps: step one, material selection; step two, drying and grinding; step three, leaching; step four, solid-liquid separation; step five, multiple washing and filtering;

[0006] In the above step 1, electrolytic manganese anode mud is first selected as the raw material for preparing the low-temperature flue gas denitration catalyst;

[0007] In the above step 2, the electrolytic manganese anode mud selected in step 1 is placed in a drying box for drying, and during the drying process, the electrolytic manganese anode mud is regularly turned over so as to fully dry the electrolytic manganese anode mud. After the drying is completed, the dried electrolytic manganese anode mud is ground by a grinding device to obtain electrolytic manganese anode mud powder, and the ground electrolytic manganese anode mud powder is sieved;

[0008] In the above step 3, the electrolytic manganese anode mud powder obtained in step 2 is evenly placed in a reactor, and then a modified leaching treatment is performed using a leaching agent, and the electrolytic manganese anode mud particles are stirred during the leaching process;

[0009] In the above step 4, the solid-liquid mixture obtained by leaching in step 3 is subjected to solid-liquid separation treatment, the obtained solid is the low-temperature flue gas denitration catalyst, and the obtained liquid is subjected to the next step of treatment;

[0010] In the above step five, the liquid obtained in step four is filtered once to obtain a primary filtrate, and a primary filter agent is added during the primary filtration to remove lead sulfate, and then the secondary filtrate obtained is filtered twice to obtain a tertiary filtrate, and a secondary filter agent is added during the secondary filtration to remove heavy metal sludge in the secondary solution, and then the tertiary filtrate obtained is evaporated to obtain sodium chloride for standby use.

[0011] Preferably, in step 2, the particle size of the electrolytic manganese anode mud powder obtained is 50-100 microns.

[0012] Preferably, in step three, the leaching solution used is a soluble chloride salt, and NaCl, KCl, CaCl2 and MgCl2 solutions can all be used.

[0013] Preferably, in step three, the temperature during the leaching process is 25-100°C.

[0014] Preferably, in step 4, solid-liquid separation is performed by centrifugal force.

[0015] Preferably, in step five, the primary filter added is NaHSO4, or other soluble sulfates, the secondary filter added is Na2S, and the obtained sodium chloride can be used as a raw material for preparing the leaching solution.

[0016] Compared with the prior art, the invention has the following beneficial effects: the method for preparing a low-temperature flue gas denitration catalyst using electrolytic manganese anode mud has a simple synthesis method, and the raw materials used are from industrial waste residues, thereby reducing the impact on the environment. In the preparation process, after the electrolytic manganese anode mud powder is leached by NaCl solution (chloride salt), the obtained material has a higher specific surface area, a better microscopic morphology, a higher nitrogen oxide removal efficiency and a wider temperature window, which is conducive to efficient operation at ultra-low temperatures, and expands the application scenarios of the catalyst. In the preparation process, the leached liquid is filtered and evaporated by multi-stage filtration to recover sodium chloride, thereby reducing the amount of waste generated. At the same time, the electrolytic manganese anode mud is modified by soluble chloride salt, and the modification treatment of the electrolytic manganese anode mud is used, which greatly reduces the complexity of the subsequent process of preparing the catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a flow chart of the method of the present invention;

[0018] Figure 2 The morphology of the electrolytic manganese anode mud powder before and after modification in the present invention;

[0019] Figure 3 The denitrification efficiency diagram of the catalyst before and after modification at different temperatures;

[0020] Figure 4 This is a graph showing the denitrification efficiency of the catalyst before and after modification at different times and temperatures. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] See also Figure 1-4The present invention provides an embodiment: a method for preparing a low-temperature flue gas denitration catalyst using electrolytic manganese anode mud, comprising the following steps: step one, material selection; step two, drying and grinding; step three, leaching; step four, solid-liquid separation; step five, multiple washing and filtering;

[0023] In the above step 1, electrolytic manganese anode mud is first selected as the raw material for preparing the low-temperature flue gas denitration catalyst;

[0024] In the above step 2, the electrolytic manganese anode mud selected in step 1 is placed in a drying box for drying, and during the drying process, the electrolytic manganese anode mud is regularly turned over so as to fully dry the electrolytic manganese anode mud. After the drying is completed, the dried electrolytic manganese anode mud is ground by a grinding device to obtain electrolytic manganese anode mud powder, and the ground electrolytic manganese anode mud powder is sieved to obtain electrolytic manganese anode mud powder with a particle size of 50-100 microns;

[0025] In the above step 3, the electrolytic manganese anode mud powder obtained in step 2 is evenly placed in a reactor, and then a modified leaching treatment is performed using a leaching agent. The leaching solution used is a NaCl solution, and a soluble chloride salt can also be used. At the same time, the electrolytic manganese anode mud particles are stirred during the leaching process, and the temperature during the leaching process is 25-100° C.;

[0026] In the above step 4, the solid-liquid mixture obtained by leaching in step 3 is subjected to solid-liquid separation, and the solid-liquid separation is carried out by centrifugal force, and the obtained solid is the low-temperature flue gas denitration catalyst, and the obtained liquid is subjected to the next step of treatment;

[0027] In the above step five, the liquid obtained in step four is filtered once to obtain a primary filtrate, and a primary filter agent is added during the primary filtration to remove lead sulfate, and then the secondary filtrate obtained is filtered twice to obtain a tertiary filtrate, and a secondary filter agent is added during the secondary filtration to remove heavy metal sludge in the secondary solution, and then the tertiary filtrate obtained is evaporated to obtain sodium chloride for standby use, and the primary filter agent added is NaHSO4, or other soluble sulfates, and the secondary filter agent added is Na2S, and the obtained sodium chloride can be used as a raw material for preparing a leachate.

[0028] The morphology of the electrolytic manganese anode mud powder obtained above was tested before and after modification with NaCl solution, and the morphology before and after modification is as follows: Figure 2 ,in Figure 2 (a) and (c) are the morphologies before modification. Figure 2(b) and (d) are the morphologies after modification; and the changes in specific surface area of ​​electrolytic manganese anode mud powder before and after modification are tested, and the test results are as follows:

[0029]

[0030] Based on the above, the advantage of the present invention is that when the present invention is used, the electrolytic manganese anode mud in the industrial waste slag is used as the raw material for preparing the catalyst, thereby reducing the impact on the environment, and in the preparation process, after the electrolytic manganese anode mud powder is modified and leached by NaCl solution (chloride salt), the obtained catalyst material has a higher specific surface area, a better microscopic morphology, a higher nitrogen oxide removal efficiency and a wider temperature window, which is conducive to efficient operation at ultra-low temperature, and expands the application scenarios of the catalyst. At the same time, in the preparation process, the sodium chloride is recovered by multi-stage filtration and evaporation of the liquid after leaching, which reduces the amount of waste generated and is beneficial to environmental protection. At the same time, the electrolytic manganese anode mud is modified by soluble chloride salt, and the modification treatment of the electrolytic manganese anode mud is used, which greatly reduces the complexity of the subsequent process of preparing the catalyst.

[0031] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A method for preparing a low-temperature flue gas denitration catalyst using electrolytic manganese anode mud, comprising the following steps: Step 1, material selection; Step 2, drying and grinding; Step 3, leaching; Step 4, solid-liquid separation; Step 5, multiple washing and filtering; It is characterized by: In the above step 1, electrolytic manganese anode mud is first selected as the raw material for preparing the low-temperature flue gas denitration catalyst; In the above step 2, the electrolytic manganese anode mud selected in step 1 is placed in a drying box for drying, and during the drying process, the electrolytic manganese anode mud is regularly turned over so as to fully dry the electrolytic manganese anode mud. After the drying is completed, the dried electrolytic manganese anode mud is ground by a grinding device to obtain electrolytic manganese anode mud powder, and the ground electrolytic manganese anode mud powder is sieved; In the above step 3, the electrolytic manganese anode mud powder obtained in step 2 is evenly placed in a reactor, and then a leaching solution is used for modified leaching treatment, and the electrolytic manganese anode mud particles are stirred during the leaching process, and the leaching solution is a soluble NaCl, KCl, CaCl2 or MgCl2 chloride salt solution; In the above step 4, the solid-liquid mixture obtained by leaching in step 3 is subjected to solid-liquid separation treatment, the obtained solid is the low-temperature flue gas denitration catalyst, and the obtained liquid is subjected to the next step of treatment; In the above step five, the liquid obtained in step four is filtered once to obtain a primary filtrate, and a primary filter agent is added during the primary filtration to remove lead sulfate, and then the secondary filtrate obtained is filtered twice to obtain a tertiary filtrate, and a secondary filter agent is added during the secondary filtration to remove heavy metal sludge in the secondary solution, and then the tertiary filtrate obtained is evaporated to obtain sodium chloride for standby use.

2. The method for preparing a low-temperature flue gas denitration catalyst using electrolytic manganese anode mud according to claim 1, characterized in that: In the step 2, the particle size of the electrolytic manganese anode mud powder obtained is 50-100 microns.

3. The method for preparing a low-temperature flue gas denitration catalyst using electrolytic manganese anode mud according to claim 1, characterized in that: In the step 3, the temperature during the leaching process is 25-100°C.

4. The method for preparing a low-temperature flue gas denitration catalyst using electrolytic manganese anode mud according to claim 1, characterized in that: In the step 4, solid-liquid separation is performed by centrifugal force.

5. The method for preparing a low-temperature flue gas denitration catalyst using electrolytic manganese anode mud according to claim 1, characterized in that: In the step 5, the primary filter added is NaHSO4 or other soluble sulfates, the secondary filter added is Na2S, and the obtained sodium chloride is used as a raw material for preparing the leaching solution.

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