Method for determining WO3 in waste denitration SCR honeycomb catalyst with TiO2 as carrier

Abstract

The invention discloses a method for measuring WO3 in a waste denitration SCR honeycomb catalyst with TiO2 as a carrier, which comprises the following steps: S, deashing, cleaning, drying, crushing, splitting and sieving the waste denitration catalyst generated by a certain denitration reactor, drying and recovering to room temperature, and weighing a sample in a microwave digestion tank; adding 5mL of HNO3 and 2mL of HF into the microwave digestion tank, and sufficiently and uniformly mixing the sample with the mixed acid; putting the prepared sample into a microwave digestion instrument, and heating and cooling according to a specified digestion program; carrying out acid removal on the digested sample, taking out the digested sample when 2-3mL of the digested sample is left in the digestion tank, cooling to room temperature, flushing the digestion tank with deionized water, transferring the flushed digestion tank into a 50mL plastic volumetric flask, fixing the volume, uniformly shaking, and carrying out determination by using ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometer). The method has the characteristics of short analysis period, low detection limit and high precision, the microwave digestion has the characteristics of small loss, high efficiency and the like, and the operation is simpler and quicker.

Description

Technical Field

[0001] The invention relates to the technical field of catalyst chemical analysis and testing, in particular to a method for determining WO3 in a waste denitration SCR honeycomb catalyst using TiO2 as a carrier. Background Art

[0002] Tungsten metal plays an important role and role in the fields of biomedicine, industry, materials, and environmental protection. Studies have shown that tungsten-containing catalysts have a highly efficient catalytic effect on chemical reactions such as dehydrogenation, alkylation, esterification, and dehydration.

[0003] As an important air pollution control equipment, waste denitration catalyst plays a vital role in reducing atmospheric nitrogen oxide emissions. Honeycomb vanadium-titanium waste denitration catalyst uses TiO2 as a carrier, V2O5 as the main active component, and WO3 as an auxiliary component. The active component is the main body of the multi-component catalyst and is an essential component. Without it, the required catalytic effect is lacking. The co-catalyst itself is inactive or has very little activity, but it can significantly improve the performance of the catalyst. Studies have found that WO3 can improve the thermal stability of the catalyst, improve the electronic interaction between V2O5 and TiO2, and improve the activity, selectivity and mechanical strength of the catalyst. It can also promote the desulfurization and denitrification of waste gas, effectively treat harmful gases, and reduce pollution to the environment.

[0004] At present, there is no requirement for WO3 content in GB / T 31587-2015 Honeycomb Flue Gas Denitration Catalyst, and the only method for determining WO3 in GB / T 31590-2015 Chemical Composition Analysis Method of Flue Gas Denitration Catalyst is X-ray fluorescence spectrometer. Traditional chemical analysis methods include volumetric method, gravimetric method, spectrophotometric method, etc. Among them, volumetric method and gravimetric method have long analysis time, complex operation and many interference factors; spectrophotometric method has low accuracy and precision, high detection limit, and this method has the disadvantages of slow analysis speed and cumbersome operation. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the existing defects and provide a method for determining WO3 in a waste denitrification SCR honeycomb catalyst with TiO2 as a carrier. The sample pretreatment only requires two acids for dissolution, and the reagent consumption is small. In addition, microwave digestion has the characteristics of small loss and high efficiency, and the operation is simpler and faster. In addition, the method has the characteristics of short analysis cycle, low detection limit and high precision. It is suitable for rapid detection and monitoring of product quality in production, and can effectively solve the problems in the background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a method for determining WO3 in a waste denitration SCR honeycomb catalyst using TiO2 as a carrier, comprising the following steps:

[0007] S1. After the waste denitration catalyst produced by a denitration reactor is cleaned, washed, dried, crushed, reduced, and sieved, it is dried at 105°C for 2 hours; then it is placed in a dryer to return to room temperature, and 0.1000-0.2000g (accurate to 0.0001g) of the sample is weighed in a microwave digestion tank;

[0008] S2. Add 5 mL HNO3 and 2 mL HF into the microwave digestion tank, and mix the sample and the mixed acid thoroughly;

[0009] At the same time, make a sample blank solution;

[0010] Place the prepared sample into a microwave digestion apparatus, cover it with a sealing stopper, and tighten the sealing cover;

[0011] Heating and cooling according to the specified digestion program;

[0012] S3. Place the sample digested in S2 into a 170℃ acid removal instrument for acid removal. When 2-3mL remains in the digestion tank, take it out for cooling. After cooling to room temperature, rinse the digestion tank with deionized water, transfer it to a 50mL plastic volumetric flask, make up the volume and shake well, and measure it by ICP-OES.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] 1. The method for determining WO3 in the waste denitration SCR honeycomb catalyst with TiO2 as the carrier in the example of the present invention only requires two acids to dissolve the sample pretreatment, and the reagent consumption is small. In addition, microwave digestion has the characteristics of small loss and high efficiency, and the operation is simpler and faster.

[0015] 2. The method for determining WO3 in the waste denitration SCR honeycomb catalyst with TiO2 as the carrier in the example of the present invention has the characteristics of short analysis cycle, low detection limit and high precision. The detection limit is 0.053 mg / L and the spiked recovery rate is 95.0% to 103.5%. It is suitable for rapid detection and monitoring of product quality in production.

[0016] 3. The method for determining WO3 in the waste denitration SCR honeycomb catalyst with TiO2 as the carrier exemplified in the present invention fills the gap that there is only one determination method for WO3 in the waste denitration SCR honeycomb catalyst, which is X-ray fluorescence spectrometer, and provides a reference for the determination of WO3 content in honeycomb vanadium-titanium waste denitration catalysts. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. 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.

[0018] Embodiment 1:

[0019] A method for determining WO3 in a waste denitration SCR honeycomb catalyst using TiO2 as a carrier, characterized in that it comprises the following steps:

[0020] S1. After the waste denitration catalyst produced by a denitration reactor is cleaned, washed, dried, crushed, reduced, and sieved, it is dried at 105°C for 2 hours; then it is placed in a dryer to return to room temperature, and 0.1000-0.2000g (accurate to 0.0001g) of the sample is weighed in a microwave digestion tank;

[0021] S2. Add 5 mL HNO3 and 2 mL HF into the microwave digestion tank, and mix the sample and the mixed acid thoroughly;

[0022] At the same time, make a sample blank solution;

[0023] Place the prepared sample into a microwave digestion apparatus, cover it with a sealing stopper, and tighten the sealing cover;

[0024] Heating and cooling according to the specified digestion program;

[0025] S3, put the sample digested in S2 into a 170℃ acid removal instrument for acid removal, and when 2-3mL is left in the digestion tank, take it out for cooling; after cooling to room temperature, rinse the digestion tank with deionized water, transfer it to a 50mL plastic volumetric flask, make up to volume and shake well, and measure it by ICP-OES;

[0026] S4. Prepare working curve solution: Take 5 identical 50mL volumetric flasks, add 0mL, 1mL, 2mL, 3mL, and 4mL of tungsten standard solution No. BW30041-100-50 with a concentration of 100mg / L, respectively, to prepare a standard series with concentrations of 0mg / L, 2mg / L, 4mg / L, 6mg / L, and 8mg / L, dilute with water to the scale, mix well, and prepare five working curve solutions;

[0027] S5. Set the instrument measurement conditions: Set the measurement parameters of the inductively coupled plasma emission spectrometer as follows: RF power 1.20 kW; plasma gas flow rate 12 L / min; atomizing gas flow rate 0.70 L / min; auxiliary gas flow rate 1.00 L / min; stabilization time 15 s; observation mode axial; wavelength for measuring tungsten is 207.912 nm;

[0028] S6. Draw a working curve: Use the inductively coupled plasma emission spectrometer with the measurement working conditions set in S5 to measure the intensity of the five working curve solutions prepared in S4 respectively, and use the measured intensity as the ordinate and the concentration of the tungsten standard solution as the abscissa to draw a working curve;

[0029] S7, determining the tungsten content in the sample solution: using argon as carrier gas, using the inductively coupled plasma emission spectrometer with the measurement working conditions set in S5 to determine the intensity I1 of the blank solution prepared in S3 and the intensity I2 of the sample, and then by checking the working curve drawn in S6, it is found that I1 and I2 correspond to the tungsten concentrations C1 and C2 respectively, in units of mg / L;

[0030] S8. Calculate the tungsten content of the sample:

[0031] The WO3 content in the spent denitration catalyst sample is expressed as mass fraction W (w), the value is expressed in %, and is calculated according to the following formula:

[0032] W(w)=[(C2*f-C1)*V / (m*10000)]*(232 / 184)

[0033] Where V is the volume of the sample solution, in mL; m is the mass of the catalyst sample weighed in S1, in g; f is the dilution factor; 232 / 184 is the coefficient for converting W to WO3.

[0034] Take two catalyst samples, marked as sample 1# and sample 2#, and repeat the measurement and calculation for 7 times on the same catalyst sample according to the steps and methods of Example 1. The mass fraction W(w) of WO3 in sample 1# and sample 2# calculated by the measurement method of Example 1 is shown in Table 1.

[0035] Table 1 Measurement results of mass fraction W(w) in sample 1# and sample 2#

[0036]

[0037] It can be seen from Table 1 that the relative standard deviation (RSD) of the calculated value of the measurement result is less than 1%, indicating that the present invention has good precision and stability in measuring the WO3 content in the waste denitration SCR honeycomb catalyst with TiO2 as the carrier.

[0038] In this method, sample pretreatment only requires two acids to dissolve, and the reagent consumption is small. Microwave digestion has the characteristics of small loss and high efficiency, and the operation is simpler and faster.

[0039] Embodiment 2:

[0040] The two solutions digested in steps S1-S3 of Example 1 were respectively transferred into two 50 mL volumetric flasks, and a certain amount of tungsten standard substance was added. The rest was analyzed according to the analysis steps of this example. The ratio of the difference between the result obtained after adding the tungsten standard substance and the theoretical value of the added standard substance was the sample spike recovery rate. The measurement and calculation results are shown in Table 2. It can be seen from the data in Table 2 that the spike recovery rate is between 95.0% and 103.5%, indicating that the present invention has good accuracy.

[0041] Table 2 Spiked recovery of W mass fraction W(w) in sample 1# and sample 2#

[0042]

[0043] This method has the characteristics of short analysis cycle, low detection limit and high precision. The detection limit is 0.053 mg / L and the spike recovery rate is 95.0% to 103.5%. It is suitable for rapid detection and monitoring of product quality in production.

[0044] Embodiment three:

[0045] The method for determining the WO3 content in the spent denitration catalyst by ICP-OES in this embodiment comprises the following steps:

[0046] S1. Weigh four samples of honeycomb waste denitration catalysts with TiO2 as carrier and different WO3 contents (WO3 contents of about 0.5%, 1.0%, 4.0%, and 10%) in a microwave digestion tank;

[0047] S2. Add 5 mL HNO3 and 2 mL HF to the microwave digestion tank to mix the sample and the mixed acid thoroughly; prepare a sample blank solution at the same time; put the prepared sample into the microwave digestion instrument, cover it with a sealing stopper, and tighten the sealing cover; heat up and cool down according to the specified digestion program;

[0048] S3, put the sample digested in S2 into a 170℃ acid removal instrument for acid removal; when there is 2-3mL left in the digestion tank, take it out and cool it; after cooling to room temperature, rinse the digestion tank with deionized water, transfer it to a 50mL plastic volumetric flask, make up the volume and shake it well, and measure it by ICP-OES; the measurement results are shown in Table 3;

[0049] S4, the preparation of the standard solution and the ICP-OES instrument conditions are the same as those in Example 1;

[0050] S5. At the same time, 4 equal amounts of waste denitration SCR honeycomb catalyst samples were weighed respectively, and the WO3 content was determined by X-ray fluorescence spectrometer according to GB / T31590-2015 "Analysis Method for Chemical Composition of Flue Gas Denitration Catalyst". The determination results are shown in Table 3.

[0051] Table 3 Comparison of different determination methods of WO3 in waste denitration SCR honeycomb catalyst

[0052]

[0053] It can be seen from Table 3 that the relative standard deviation (RSD) of the calculated values ​​of the measurement results of different instruments is less than 3%, indicating that the present invention has good precision and accuracy in measuring the WO3 content in the waste denitration honeycomb catalyst with TiO2 as the carrier.

[0054] The present invention fills the gap that there is only one determination method for WO3 in waste denitration SCR honeycomb catalyst, which is X-ray fluorescence spectrometer, and provides a reference basis for the determination of WO3 content in honeycomb vanadium-titanium waste denitration catalyst.

[0055] The undisclosed parts in the present invention are all prior art, and their specific structures, materials and working principles are not described in detail. Although the embodiments of the present invention have been shown and described, it is understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for determining WO3 in a waste denitration SCR honeycomb catalyst using TiO2 as a carrier, characterized in that: The following steps are involved: S1. After the waste denitration catalyst produced by a denitration reactor is cleaned, washed, dried, crushed, reduced, and sieved, it is dried at 105°C for 2 hours; then it is placed in a dryer to return to room temperature, and 0.1000-0.2000g (accurate to 0.0001g) of sample is weighed in a microwave digestion tank; S2. Add 5 mL HNO3 and 2 mL HF into the microwave digestion tank, and mix the sample and the mixed acid thoroughly; At the same time, make a sample blank solution; Place the prepared sample into a microwave digestion apparatus, cover it with a sealing stopper, and tighten the sealing cover; Heating and cooling according to the specified digestion program; S3. Place the sample digested in S2 into a 170℃ acid removal instrument for acid removal. When 2-3mL remains in the digestion tank, take it out for cooling. After cooling to room temperature, rinse the digestion tank with deionized water, transfer it to a 50mL plastic volumetric flask, make up the volume and shake well, and measure it by ICP-OES.

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