阅读说明：本技术 烟气脱硝催化剂用纳米二氧化钛粉体脱硝率的测定方法 (Method for measuring denitration rate of nano titanium dioxide powder for flue gas denitration catalyst ) 是由 钱笑雄 钱邦正 赵义凯 于 2021-08-04 设计创作，主要内容包括：本发明公开了烟气脱硝催化剂用纳米二氧化钛粉体脱硝率的测定方法,包括以下步骤：将一定量的V-(2)O-(5)/MoO-(3)与脱硝催化剂用纳米二氧化钛混合煅烧后,添加CMC、PEO将脱硝纳米二氧化钛粉体挤压制成一定体积和形状的样品,样品经300℃高温预处理后,再经微型催化剂活性检测装置检测样品脱硝率。本发明的有益效果是具有测试结果稳定,重现性高等优点。(The invention discloses a method for measuring the denitration rate of nano titanium dioxide powder for a flue gas denitration catalyst, which comprises the following steps: a certain amount of V 2 O 5 /MoO 3 Mixing and calcining the denitration catalyst with nano titanium dioxide, adding CMC and PEO to extrude denitration nano titanium dioxide powder into a sample with a certain volume and shape, pretreating the sample at the high temperature of 300 ℃, and detecting the denitration rate of the sample by a micro catalyst activity detection device. The method has the advantages of stable test result, high reproducibility and the like.)

1. The method for measuring the denitration rate of the nano titanium dioxide powder for the flue gas denitration catalyst is characterized by comprising the following steps of: the method comprises the following steps: (1) and powder prefabrication: taking two parts of nano titanium dioxide for flue gas denitration catalysts from different sources, respectively adding ammonium metavanadate, ammonium heptamolybdate, triethanolamine and distilled water into the nano titanium dioxide, putting the nano titanium dioxide into a constant-temperature water bath kettle with stirring, setting the temperature to be 70 ℃, and stirring the nano titanium dioxide to be semi-dry at constant temperature to obtain two parts of semi-dry materials; (2) and powder calcination: transferring the two half-dried materials into a crucible, and putting the crucible into a 500 ℃ drying oven to calcine for 1 hour to obtain two calcined materials; (3) and preparing a test sample: cooling the two calcined materials to room temperature, putting the calcined materials into a mortar, adding about 1% of PEO and CMC, grinding, slowly adding distilled water, grinding carefully until the materials are agglomerated but not pasty, and obtaining two agglomerated samples; (4) and test sample pressing: putting the two agglomerated samples into a cylindrical die with the inner diameter of 6mm, and extruding two samples with certain length; (5) and pretreating a test sample: placing the two pressed samples into a muffle furnace at 300 ℃ for calcining for 1h to obtain two pretreated samples; (6) and testing a sample: placing two pretreated samples into a sample rack, then placing the sample rack into a micro-catalyst activity detection device to detect the denitration rate of the sample, and setting the NO concentration at an initial state to be 500ppm and the O concentration at an initial state₂The concentration is 5 percent, the ammonia nitrogen molar ratio is 1:1, the total flue gas flow rate is 1L/min, and the reaction temperature is 380 ℃; (7) and calculating: the denitration efficiency of the samples per unit length was calculated as two samples per unit length = (initial NO concentration-post-reaction NO concentration)/(initial NO concentration x sample length).

2. The method for measuring the denitration rate of the nano titanium dioxide powder for the flue gas denitration catalyst, according to claim 1, is characterized in that: the using amount of the nano titanium dioxide used for the flue gas denitration catalyst in the step (1) is 10g, the using amount of the ammonium metavanadate is 0.14g, the using amount of the ammonium heptamolybdate is 0.32g, the using amount of the triethanolamine is 0.2g, and 50ml of distilled water is used.

3. The method for measuring the denitration rate of the nano titanium dioxide powder for the flue gas denitration catalyst, according to claim 1, is characterized in that: and (4) plugging one end of the cylindrical mold after the sample is placed in the cylindrical mold, compacting the sample by using a stainless steel rod, placing a certain amount of agglomerated sample, compacting, and pushing out the sample by using the stainless steel rod.

4. The method for measuring the denitration rate of the nano titanium dioxide powder for the flue gas denitration catalyst, according to claim 1, is characterized in that: the activity detection device of the micro catalyst in the step (6) comprises a reactor and a detector, wherein the reactor is a hollow glass tube with the inner diameter of 10mm, and NO and O are contained in the reactor₂、NH₃And reacting the pretreated sample in a reactor, and measuring the concentration of NO after reaction by feeding the residual NO after the reaction in a detector.

Technical Field

The invention relates to the field of preparation of nano titanium dioxide, in particular to a method for measuring the denitration rate of nano titanium dioxide powder for a flue gas denitration catalyst.

Background

Along with the increasing of the national environmental protection monitoring strength, the burning denitration uses the SCR flue gas denitration technology to obtain the long-standing development. From the initial electric power industry, the technology is expanded to various industries using coal burning or straw burning, such as glass, steel, coke ovens, ships and the like. Research on the denitration catalyst has been advanced unprecedentedly, and the application of the denitration catalyst is expanded from the initial active temperature range of about 350-400 ℃ to about 150-200 ℃. An SCR denitration catalyst system containing a large number of active components such as a rare earth system and a manganese system was developed from the first vanadium-titanium system.

With the continuous widening of the application range of the SCR denitration technology, the research on the SCR catalyst in the SCR catalyst industry is also continuous and deep. The nano titanium dioxide for SCR denitration catalysis is used as a carrier material of the SCR catalyst and accounts for more than 80 percent of the total volume of the SCR catalyst, and the application performance of the SCR catalyst is directly determined by the performance of the nano titanium dioxide for the SCR catalyst. In the production of SCR denitration catalyst manufacturers, the nano titanium dioxide for SCR denitration catalysts of different manufacturers is found to have different denitration activities even if the SCR catalysts produced by the same formula and process are used. With the increasing amount of denitration catalysts in the market, some waste denitration catalysts are treated and also permeate into the raw material end, so that the market of nano titanium dioxide powder for the denitration catalysts is not uniform, and therefore, a detection method capable of identifying the quality of the nano titanium dioxide for the catalysts is urgently needed by catalyst manufacturers.

At present, the identification of the nano titanium dioxide is mainly directly detected by using instruments, such as a particle size analyzer (for measuring particle size), an electron microscope photograph (for measuring approximate particle size), a specific surface area detector (for measuring specific surface area, the difference between nano-scale and common specific surface area is large), an ultraviolet visible light photometer (for measuring the transmittance of light under the wavelength of ultraviolet to visible light, namely 200 nm-800 nm, and also the apparent density (g/cubic centimeter), the national standard requirement of nano-scale is less than or equal to 0.3 g/cubic centimeter, but the denitration activity which is most concerned in the field of denitration catalysts has no systematic identification method.

Disclosure of Invention

The invention aims to solve the technical problem that the existing method for identifying the quality of the nano titanium dioxide powder for the denitration catalyst directly detects various parameters through an instrument and cannot link the performance of the nano titanium dioxide powder for the denitration catalyst with the denitration activity of the denitration catalyst, so that the method for measuring the denitration rate of the nano titanium dioxide powder for the flue gas denitration catalyst can link the performance of the nano titanium dioxide powder for the denitration catalyst with the denitration activity of the denitration catalyst.

Before, the connection between the performance of the nano titanium dioxide powder for the denitration catalyst and the denitration activity of the denitration catalyst cannot be established, because even though various parameters influencing the denitration activity of the denitration catalyst such as the particle size, the specific surface area, the light transmittance, the apparent density and the like are measured by an instrument, after the nano titanium dioxide powder for the denitration catalyst loads active ingredients, the main factor influencing the denitration rate is the active ingredients, and the influence of the nano titanium dioxide powder for the denitration catalyst is covered, so that the nano titanium dioxide powder for the flue gas denitration catalyst skillfully utilizes two groups of nano titanium dioxide powder for the flue gas denitration catalyst from different sources to carry out a comparative test, and the influence of external factors is eliminated.

The method comprises mixing a certain amount of V₂O₅/MoO₃Mixing and calcining the denitration catalyst with nano titanium dioxide, adding CMC and PEO to extrude denitration nano titanium dioxide powder into a sample with a certain volume and shape, pretreating the sample at the high temperature of 300 ℃, and detecting the denitration rate of the sample by a micro catalyst activity detection device. The method has the advantages of stable test result, high reproducibility and the like.

The technical scheme of the invention is as follows: the method for measuring the denitration rate of the nano titanium dioxide powder for the flue gas denitration catalyst comprises the following steps: (1) and powder prefabrication: prefabricating powder: taking two parts of nano titanium dioxide for flue gas denitration catalysts from different sources, respectively adding ammonium metavanadate, ammonium heptamolybdate, triethanolamine and distilled water into the nano titanium dioxide, putting the nano titanium dioxide into a constant-temperature water bath kettle with stirring, setting the temperature to be 70 ℃, and stirring the nano titanium dioxide to be semi-dry at constant temperature to obtain two parts of semi-dry materials; (2) and powder calcination: transferring the two half-dried materials into a crucible, and putting the crucible into a 500-degree oven to calcine for 1 hour to obtain two calcined materials; (3) and preparing a test sample: cooling the two calcined materials to room temperature, putting the calcined materials into a mortar, adding about 1% of PEO and CMC, grinding, slowly adding distilled water, grinding carefully until the materials are agglomerated but not pasty, and obtaining two agglomerated samples; (4) and test sample pressing: putting the two agglomerated samples into a cylindrical die with the inner diameter of 6mm, and extruding two samples with certain length; (5) and pretreating a test sample: placing the two pressed samples into a muffle furnace at 300 ℃ for calcining for 1h to obtain two pretreated samples; (6) and testing a sample: putting two pretreated samples into a sample rack, and then putting the sample rack into a micro-catalyst activity detection device for detecting the samplesDenitration rate, setting NO concentration at 500ppm and O in initial state₂The concentration is 5 percent, the ammonia nitrogen molar ratio is 1:1, the total flue gas flow rate is 1L/min, and the reaction temperature is 380 ℃; (7) and calculating: calculating the denitration efficiency of the two samples with unit length, wherein the denitration efficiency of the samples with unit length = (initial NO concentration-NO concentration after reaction)/(initial NO concentration x sample length), and the nano titanium dioxide for the flue gas denitration catalyst of the samples with unit length with higher denitration efficiency has better performance.

In the scheme, the dosage of the nano titanium dioxide used for the flue gas denitration catalyst in the step (1) is 10g, the ammonium metavanadate is 0.14g, the ammonium heptamolybdate is 0.32g, the triethanolamine is 0.2g, and the distilled water is 50 ml.

In the scheme, the cylindrical mould in the step (4) is a hollow stainless steel pipe, after the sample is placed in the cylindrical mould, one end of the cylindrical mould is blocked, the sample is compacted by a stainless steel rod, and after a certain amount of agglomerated sample is placed in the cylindrical mould and compacted, the sample is pushed out by the stainless steel rod.

The activity detection device for the micro catalyst in the step (6) in the scheme comprises a reactor and a detector, wherein the reactor is a hollow glass tube with the inner diameter of 10mm, and NO and O are contained in the reactor₂、NH₃And reacting the pretreated sample in a reactor, and measuring the concentration of NO after reaction by feeding the residual NO after the reaction in a detector.

The method has the advantages that the influence of the loaded active ingredients on the denitration activity of the denitration catalyst is eliminated, and the influence of the performance of the nano titanium dioxide for the denitration catalyst and the influence of the nano titanium dioxide for the denitration catalyst on the denitration activity of the denitration catalyst are verified₂O₅/MOO₃The influence of the sulfate radical content, the particle size distribution, the pore volume, the pore diameter and other properties of the nano titanium dioxide for the denitration catalyst on the denitration rate of the denitration catalyst can be verified through the method. The method can provide an indirect detection means for judging the denitration rate by the performance of the nano titanium dioxide powder for the denitration catalyst, and has the advantages of simple test, easy operation and stable test result.

Detailed Description

The technical solution of the present invention is clearly and completely described below with reference to the following embodiments. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments based on the embodiments in the present invention, without any inventive work, will be apparent to those skilled in the art from the following description.

The invention comprises the following steps: (1) prefabricating powder: taking two parts of nano titanium dioxide for 10g of denitration catalyst from different sources, respectively adding 0.14g of ammonium metavanadate, 0.32g of ammonium heptamolybdate, 0.2g of triethanolamine and 50ml of distilled water into the nano titanium dioxide, putting the nano titanium dioxide into a constant-temperature water bath kettle with a stirrer, setting the temperature to be 70 ℃, and stirring the mixture to be semi-dry at constant temperature to obtain two parts of semi-dry materials. (2) Powder calcination: and transferring the two half-dried materials into a crucible, and putting the crucible into a 500 ℃ oven to calcine for 1 hour to obtain two calcined materials. (3) Test sample preparation: cooling the two calcined materials to room temperature, putting the calcined materials into a mortar, adding about 1% of PEO and CMC, grinding, slowly adding distilled water, grinding carefully until the materials are agglomerated but not pasty, and obtaining two agglomerated samples; (4) pressing a test sample: putting the two agglomerated samples into a cylindrical die with the inner diameter of 6mm, and extruding two samples with certain length; (5) pretreatment of a test sample: placing the two pressed samples into a muffle furnace at 300 ℃ for calcining for 1h to obtain two pretreated samples, (6) testing the samples: placing two pretreated samples into a sample rack, and then placing the sample rack into a micro-catalyst activity detection device to detect the denitration rate of the sample, wherein the concentration of NO in an initial state is 500ppm, the concentration of O2 is 5%, the molar ratio of ammonia nitrogen is 1:1, the flow rate of total flue gas is 1L/min, and the reaction temperature is 380 ℃. (7) And (3) calculating: calculating the denitration efficiency of the sample with the unit length, namely the denitration efficiency of the sample with the unit length = (initial NO concentration-NO concentration after reaction)/(initial NO concentration x sample length), wherein the nano titanium dioxide for the flue gas denitration catalyst of the sample with the unit length and higher denitration efficiency has better performance.

The following examples were tested using a vodo VDRT-200ST catalyst reaction apparatus and a German MRU VARIO PLUS enhanced flue gas analyzer.

Example 1:

(1) prefabricating powder: taking two different 10g specific surfacesProduct 82.56m²Adding 0.14g of ammonium metavanadate, 0.32g of ammonium heptamolybdate, 0.2g of triethanolamine and 50ml of distilled water into per gram of nano titanium dioxide for the denitration catalyst, respectively, putting the mixture into a constant-temperature water bath kettle with a stirrer, setting the temperature to be 70 ℃, and stirring the mixture to be semi-dry at constant temperature to obtain two parts of semi-dry materials; (2) and powder calcination: transferring the two half-dried materials into a crucible, and putting the crucible into a 500 ℃ drying oven to calcine for 1 hour to obtain two calcined materials; (3) and preparing a test sample: cooling the two calcined materials to room temperature, putting the calcined materials into a mortar, adding about 1% of PEO and CMC, grinding, slowly adding distilled water, grinding carefully until the materials are agglomerated but not pasty, and obtaining two agglomerated samples; (4) and test sample pressing: putting the two agglomerated samples into a cylindrical die with the inner diameter of 6mm, and extruding two samples with certain lengths of 3.7cm, 4.5cm and 5.7cm respectively; (5) and pretreating a test sample: placing the two pressed samples with different lengths into a muffle furnace at 300 ℃ for calcining for 1h to obtain two pretreated samples; (6) and testing a sample: placing two pretreated samples into a sample rack, then placing the sample rack into a micro-catalyst activity detection device to detect the denitration rate of the sample, and setting the NO concentration at an initial state to be 500ppm and the O concentration at an initial state₂The concentration is 5 percent, the ammonia nitrogen molar ratio is 1:1, the total flue gas flow rate is 1L/min, and the reaction temperature is 380 ℃; (7) and calculating: the denitration efficiency of the samples per unit length, i.e., = (initial NO concentration-post-reaction NO concentration)/(initial NO concentration x sample length) was calculated for two samples per unit length, and the test results are shown in table 1:

tests 1-1, 1-2 and 1-3 in table 1 respectively have two groups, which represent two different sources of the nano titanium dioxide for the denitration catalyst, and it can be seen that, under the condition that the sample lengths are the same, the denitration rates and the unit length sample denitration rates are different, which indicates that the performances of the nano titanium dioxide for the denitration catalysts from the two different sources have influence on the denitration rates of the catalysts, and the data comparison shows that which source of the nano titanium dioxide for the denitration catalyst has better performances. In addition, it can be seen that the denitration rate is in direct proportion to the length of the sample.

Example 2: the difference from example 1 is that the surface area of the nano titania for denitration catalyst in step (1) is 98.14m²(ii) in terms of/g. The test results are shown in table 2:

tests 2-1, 2-2 and 2-3 in table 2 are respectively provided with two groups, which represent two different sources of the nano titanium dioxide for the denitration catalyst, and it can be seen that the denitration rate and the unit length sample denitration rate are different under the condition that the sample lengths are the same, which indicates that the performances of the nano titanium dioxide for the denitration catalyst from the two different sources have influence on the denitration rate of the catalyst, and the data comparison shows that which source of the nano titanium dioxide for the denitration catalyst has better performances. As compared with the test results of example 1, it was found that the specific surface area was large and the denitration rate of the catalyst was high.

Example 3: the difference from example 1 is that 0.16g of ammonium metavanadate was added in step (1), and the test results are shown in Table 3:

tests 3-1, 3-2 and 3-3 in table 3 respectively have two groups, which represent two different sources of the nano titanium dioxide for the denitration catalyst, and it can be seen that, under the condition that the sample lengths are the same, the denitration rates and the unit length sample denitration rates are different, which indicates that the performances of the nano titanium dioxide for the denitration catalysts from the two different sources have influence on the denitration rates of the catalysts, and the data comparison shows that which source of the nano titanium dioxide for the denitration catalyst has better performances. As compared with the test results of example 1, it can be found that the higher the active ingredient loading, the higher the denitration rate of the catalyst.

The two types of nano titanium dioxide with different sources for the flue gas denitration catalyst have different specific surface areas or different sulfate radical contents, particle size distribution, pore volumes and pore diameters, so that the performance of the nano titanium dioxide for the flue gas denitration catalyst can be related to the denitration rate of the catalyst, and the quality of the nano titanium dioxide for the flue gas denitration catalyst can be identified.