CN110013885B

CN110013885B - Regeneration method of denitration catalyst

Info

Publication number: CN110013885B
Application number: CN201810016692.7A
Authority: CN
Inventors: 马子然; 王宝冬; 马静; 孙永伟; 林德海; 马少丹; 李永龙; 孙琦
Original assignee: China Energy Investment Corp Ltd; National Institute of Clean and Low Carbon Energy
Current assignee: China Energy Investment Corp Ltd; National Institute of Clean and Low Carbon Energy
Priority date: 2018-01-08
Filing date: 2018-01-08
Publication date: 2022-12-09
Anticipated expiration: 2038-01-08
Also published as: CN110013885A

Abstract

The invention relates to the field of denitration catalyst regeneration, and discloses a regeneration method of a denitration catalyst. The method comprises the following steps: 1) Pretreating the waste denitration catalyst to obtain a dry spent catalyst; 2) Putting the spent agent into a priming solution for primary impregnation, and removing redundant priming solution to obtain a primary impregnant; 3) Putting the primary impregnant into an active supplementary liquid for secondary impregnation, and removing the redundant active supplementary liquid to obtain a secondary impregnant; 4) Drying and roasting the secondary impregnant to obtain a regenerated denitration catalyst; wherein the priming solution is an alkaline solution. Provides a simple and convenient denitration catalyst regeneration method, realizes the denitration performance recovery of the denitration catalyst and the SO reduction ₂ The oxidation rate.

Description

Regeneration method of denitration catalyst

Technical Field

The invention relates to the field of denitration catalyst regeneration, in particular to a regeneration method of a denitration catalyst.

Background

Coal is mainly used in energy structures in China, but a large amount of Nitrogen Oxides (NO) are discharged to the atmospheric environment in the combustion process of the coal _x ) The composite material is an important precursor for causing pollution events such as regional dust haze, acid rain and the like, and is one of the most main atmospheric pollutants in China. Under this situation, china is aiming at NO _x Environmental regulations for emissions are becoming more stringent. No of newly built thermal power generating unit is specified in the emission standard of atmospheric pollutants of thermal power plant, which is implemented in 1 month and 1 day 2012 _x The discharge amount is 100mg/Nm ³ . 23 days 8 and 8 months in 2014, the three committees of the national institute of energy and Power improvement, the department of environmental protection and the national energy agency jointly issue a coal and electricity energy conservation and emission reduction upgrading and improvement action plan (2014-2020), and provide NO for the coal fired units _x The discharge amount is less than 50mg/Nm ³ Are strictly required. China's NO of 2020 years _x The total emission of the fuel is reduced by 15 percent on the basis of the emission of 2046.2 ten thousand tons in 2015. By the end of 2016, the unit for removing nitrate from flue gas in operation accounts for 93.6% of the capacity of coal-electricity units in China.

As an important component of the denitration engineering, the service life of the denitration catalyst is about 24000 hours, namely after the denitration catalyst runs for three to four years, the catalytic activity of the denitration catalyst cannot meet the requirements of the denitration engineering, and the denitration catalyst needs to be replaced by a new catalyst or regenerated to recover the activity. In 11.8.2013, the preparation and regeneration of the denitration catalyst are pointed out to be vigorously developed in the opinion on the accelerated development of the energy-saving and environment-friendly industry released in China. In 8 months 2014, the ministry of environmental protection issues "notice about strengthening the supervision work of the waste flue gas denitration catalyst" that is also clear: the waste flue gas denitration catalyst (vanadium-titanium system) is encouraged to be preferentially regenerated. The method has the advantages that the waste flue gas denitration catalyst is regenerated, the disposal cost of the waste catalyst and the purchase cost of a new catalyst can be saved, the pollution to the environment is reduced, and the method has good economic benefit and environmental benefit.

The SCR denitration catalyst mainly contains denitration titanium dioxide, tungsten trioxide, vanadium pentoxide and the like. In most cases the intrinsic catalytic activity of the spent SCR catalyst is not significantly reduced, and the catalyst can recover 90-100% of the initial activity by regeneration. The regeneration technology is an effective way for recovering the activity of the catalyst, prolonging the service life, reducing the operation cost and reducing the waste treatment. Therefore, the waste denitration catalyst with a complete structure is regenerated by a physical and chemical method, and the activity of the catalyst is recovered.

At present, the domestic regeneration process of a catalyst which is applied more mainly comprises four working procedures, namely mechanical ash removal, chemical cleaning, active implantation and heat treatment. The most common active implantation process is to completely dry the cleaned denitration catalyst, immerse the denitration catalyst in an active replenisher containing vanadium for a certain time, and then cure the vanadium loaded in micropores of the catalyst after heat treatment. However, this process results in an even distribution of vanadium in the matrix of the catalyst, which does not allow the vanadium to be selectively distributed on the surface of the catalyst. Generally, the vanadium loading is increased to improve the denitration performance of the regenerated catalyst, but the higher SO content is caused ₂ /SO ₃ Conversion rate of SO in flue gas in the course of operation of denitration reactor ₃ And NH ₃ More ammonium bisulfate is produced, and further, a plurality of engineering problems such as blockage and corrosion of a downstream air preheater are caused. In addition, too much vanadium is loaded into the catalyst resulting in higher regeneration costs.

Reported in the literature due to NO _x The reduction reaction is controlled by mass transfer, the reaction speed is high, and the reaction only occurs in the 0-200 mu m area of the surface of the catalyst. SO ₂ The oxidation reaction is kinetically controlled and the reaction speed is slower, SO ₂ The oxidation reaction occurs mainly in the region 200 μm deeper from the surface. Therefore, when the catalyst is implanted actively, vanadium is selectively distributed on the surface of the catalyst by 0-200 mu mIn the region, not only can the denitration reaction of the catalyst be effectively improved, but also SO can be realized ₂ /SO ₃ The conversion rate is not increased.

CN105665036A discloses a method for supplementing impregnated active components during denitration catalyst regeneration, comprising the following steps: 1) Pretreating the inactivated denitration catalyst to remove the deposited ash on the surface of the catalyst and in the pore channels and remove toxic substances on the catalyst; 2) Vacuumizing the pretreated denitration catalyst in the step 1), soaking in an organic solvent for 0.5-2h, and then performing primary drying for 0.1-1h at the temperature of 30-80 ℃; 3) Soaking the denitration catalyst subjected to primary drying in the step 2) in a mixed aqueous solution containing an active component element, an auxiliary element and a competitive adsorbent for 4-8h, performing secondary drying at 80-120 ℃ for 4-10h, and roasting at 450-550 ℃ for 5-8h to obtain the regenerated denitration catalyst. The method is characterized in that the active components and the auxiliary active components are intensively distributed at the orifices of the catalyst, and simultaneously the supplementary impregnated active components and auxiliary active components are controlled to be positioned on the outer surface of the catalyst, SO is inhibited while the denitration activity of the denitration catalyst is recovered ₂ /SO ₃ And (4) conversion rate. The active component distribution on the surface layer of the catalyst is controlled by using a two-step impregnation method and an organic solvent.

CN105536884A discloses a regeneration method of an exhaust gas denitration catalyst selectively implanted with active ingredients, which comprises the following steps: 1) Pretreating, 2) dipping for the first time, soaking the blocky waste denitration catalyst treated in the step (1) into a container containing a blocking liquid, and carrying out disturbance treatment on the blocking liquid; 3) Partially drying; placing the catalyst block treated in the step 2) in a room temperature or negative pressure drying system, drying until the mass is reduced to 50% of the increased weight, and taking out the catalyst; the weight gain is the difference between the mass of the catalyst after primary impregnation and the mass of the catalyst before primary impregnation; 4) Secondary impregnation: putting the catalyst treated in the step 3) into active liquid with a certain concentration, and soaking for 90-240min at normal temperature; 5) And (3) completely drying: putting the catalyst treated in the step 4) into a blast type drying box, quickly heating the catalyst to 100-110 ℃ from room temperature, and preserving the heat for 60-120min; 6) Roasting: quickly putting the catalyst treated in the step 5) into a horseAnd (3) heating to a certain temperature in a muffle furnace at the speed of 4-6 ℃/min, roasting for a certain time, and cooling to room temperature along with the furnace. The method adds two working procedures of drying and primary dipping for introducing the blocking liquid, and the blocking liquid is used for blocking the active supplementary liquid from entering the inner part of the catalyst micropore. The chemical composition of the blocking liquid is not disclosed, but is limited to a concentration of less than 0.1%, a viscosity at room temperature of between 5 and 10 mPas and V ₂ O ₅ Aqueous solution immiscible aqueous solution.

In the prior art, a certain blocking agent is used in micropores of the denitration catalyst to block the effective components in the active compensation liquid from diffusing to the deep level of the wall of the denitration catalyst, and the implanted active components are solidified on the surface layer of the catalyst. The above-mentioned techniques all require two impregnation processes and two drying steps, so that the regeneration period is prolonged, the energy consumption is increased, and the method is very unfavorable for the production of power plants.

Disclosure of Invention

The invention aims to overcome the regeneration problem of a denitration catalyst in the prior art and provide a regeneration method of the denitration catalyst.

In order to achieve the above object, the present invention provides a method for regenerating a denitration catalyst, comprising:

1) Pretreating the waste denitration catalyst to obtain a dry spent catalyst;

2) Putting the spent agent into a priming solution for primary impregnation, and removing redundant priming solution to obtain a primary impregnant;

3) Putting the primary impregnant into an active supplementary solution for secondary impregnation, and removing redundant active supplementary solution to obtain a secondary impregnant;

4) Drying and roasting the secondary impregnant to obtain a regenerated denitration catalyst;

wherein the priming solution is an alkaline solution.

Preferably, the pH of the priming solution is greater than 7 and below 9; preferably, the priming solution is at least one of a urea solution, an ammonium carbonate solution and an ammonium bicarbonate solution.

Preferably, the concentration of the urea solution is 1-6mol/L, the concentration of the ammonium carbonate solution is 0.5-1mol/L, and the concentration of the ammonium bicarbonate solution is 1-2mol/L.

Preferably, the primary impregnation in step 2) is carried out at a temperature of 20-30 ℃ for 15-30min.

Preferably, the pretreatment process in step 1) comprises: carrying out ash removal, chemical cleaning and predrying on the waste denitration catalyst; the pore rate of the spent catalyst reaches more than 95 percent, and the water content is not more than 5 percent by weight.

Preferably, the chemical cleaning process comprises: putting the waste denitration catalyst into a chemical cleaning solution to be cleaned under the conditions of ultrasound and bubbling; wherein the chemical cleaning solution contains at least one of a sulfuric acid solution, an ammonium sulfate solution and a nitric acid solution with the concentration of 0.05-0.5 mol/L; the ultrasonic frequency is 28-80kHz, the pressure of compressed gas for bubbling is 0.2-0.4MPa, and the ultrasonic bubbling time is 5-30min.

Preferably, the pre-drying temperature is 90-120 ℃, and the pre-drying time is 60-120min.

Preferably, the active replenisher comprises an active ingredient at a concentration of 0.5 to 2% by weight, an adjuvant ingredient at a concentration of 1 to 4% by weight, and a carrier at a concentration of 4 to 8% by weight; the active component is ammonium metavanadate and/or vanadyl sulfate; the auxiliary agent component is salt containing at least one element of W, mo, nb, cu, mn, P, ce and La; the carrier is titanyl sulfate and/or titanium sulfate.

Preferably, the secondary impregnation in step 3) is carried out at a temperature of 20-30 ℃ for 5-15min.

Preferably, in step 4), the drying is carried out at 70-90 ℃ for 1-3h; the roasting is carried out for 3-5h at 400-500 ℃.

Through the technical scheme, the invention provides a simple and convenient denitration catalyst regeneration method, the used priming solution can be remained on the spent catalyst, the drying and roasting steps are omitted, and the impregnation activity supplementing solution can be carried out again to complete the supplement of the denitration active component, so that the regenerated denitration catalyst is obtained. The remaining initiating fluid also helps the active ingredients of the active make-up fluid to produce a precipitate of very small particle size in the pores of the catalyst and may also help to reduce the formation of a precipitate of very small particle sizeSO as to prevent the effective components in the active supplementing liquid from further diffusing into the catalyst, realize the recovery of the denitration performance of the denitration catalyst and reduce SO ₂ The oxidation rate.

Drawings

Fig. 1 is a schematic flow diagram of a denitration catalyst regeneration method of the present invention.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to these ranges or values. For ranges of values, one or more new ranges of values may be obtained from combinations of values between the endpoints of each range, the endpoints of each range and the individual values, and the individual values of the points, and these ranges of values should be considered as specifically disclosed herein.

The invention provides a regeneration method of a denitration catalyst, which comprises the following steps:

1) Pretreating the waste denitration catalyst to obtain a dry spent catalyst;

3) Putting the primary impregnant into an active supplementary liquid for secondary impregnation, and removing the redundant active supplementary liquid to obtain a secondary impregnant;

wherein the priming solution is an alkaline solution.

In the invention, although the spent catalyst is impregnated twice, conventional drying and roasting are not needed after the primary impregnation, so that the regeneration step and energy consumption can be saved, the priming solution remained on the primary impregnating agent can be contacted with the active replenishing solution for the secondary impregnation, and the priming solution and the active replenishing solution can react in the final drying process, so that the effective components in the active replenishing solution are distributed on the surface layer of the catalyst, and the activity recovery of the regenerated denitration catalyst is facilitated. Wherein the components of the priming solution can be burnt off in the subsequent roasting step without remaining.

In the invention, the step 1) realizes that the waste denitration catalyst is cleaned, and the requirement of subsequent primary impregnation and secondary impregnation can be met. The waste denitration catalyst mainly refers to an inactivated catalyst which cannot meet the denitration performance of the flue gas of the power plant. Preferably, the pretreatment process in step 1) comprises: carrying out ash removal, chemical cleaning and predrying on the waste denitration catalyst; the porosity of the spent agent reaches more than 95%, and the water content does not exceed 5%. Most of the waste denitration catalysts are honeycomb catalysts, and the waste denitration catalysts are provided with a large number of parallel through pore channels, and the cross section of each pore channel is square or regular triangle. The length of the sides of the holes may be a minimum of about 1mm. The effective components for denitration are distributed on the pore walls of the pore channels. The pore channels of the spent denitration catalyst are clogged with ash. The porosity in the present invention means that the number of the open pores accounts for the percentage of the total number of the pore channels of the entire catalyst after the ash content blocking the pore channels is removed. The water content can be determined by weighing the catalyst before and after drying.

In the invention, the chemical cleaning can be used for better removing toxic substances in micropores of the waste denitration catalyst. Physical means may be aided in this process. Preferably, the chemical cleaning process comprises: putting the waste denitration catalyst into a chemical cleaning solution to clean under the conditions of ultrasound and bubbling; wherein the chemical cleaning solution contains at least one of a sulfuric acid solution, an ammonium sulfate solution and a nitric acid solution with the concentration of 0.05-0.5 mol/L; the ultrasonic frequency is 28-80kHz, the pressure of compressed gas for bubbling is 0.2-0.4MPa, and the ultrasonic bubbling time is 5-30min. The ultrasonic power can be determined according to 30-50W/L (30-50W per liter of catalyst).

In the invention, compressed air or negative pressure dust collection equipment can be adopted to finish the ash removal. The chemical cleaning may be accomplished by placing the spent denitration catalyst in an ultrasonic bubbling tank containing the chemical cleaning fluid. The pre-drying may be performed by placing the spent denitration catalyst in a circulating hot air roasting furnace.

In the present invention, it is preferable that the pre-drying temperature is 90 to 120 ℃. The pre-drying time has the effect that the water content of the spent agent does not exceed 5 wt.%. The pre-drying time may be about 60-120min.

In step 2), the priming solution is introduced to the spent agent by the primary impregnation. The excess trigger solution can be removed by draining the spent starter after the primary impregnation until no more water drips after standing. Preferably, the pH of the priming solution is greater than 7 and below 9; preferably, the priming solution is at least one of a urea solution, an ammonium carbonate solution and an ammonium bicarbonate solution.

In the invention, preferably, the concentration of the urea solution is 1-6mol/L, the concentration of the ammonium carbonate solution is 0.5-1mol/L, and the concentration of the ammonium bicarbonate solution is 1-2mol/L.

In the present invention, the primary impregnation may be performed only if the spent agent is completely impregnated. Preferably, the primary impregnation in step 2) is carried out at a temperature of 20-30 ℃ for 15-30min.

In the present invention, step 3) is used to replenish the deactivated catalytically active sites. Preferably, the active replenisher comprises an active ingredient at a concentration of 0.5 to 2% by weight, an adjuvant ingredient at a concentration of 1 to 4% by weight, and a carrier at a concentration of 4 to 8% by weight; the active component is ammonium metavanadate and/or vanadyl sulfate; the auxiliary agent component is salt containing at least one element of W, mo, nb, cu, mn, P, ce and La; the carrier is titanyl sulfate and/or titanium sulfate. Preferably, the active supplementary liquid is an aqueous solution containing the above active ingredient, an auxiliary ingredient and a carrier. Preferably, the auxiliary ingredient may be selected from at least one of ammonium metatungstate, ammonium paratungstate, ammonium molybdate, phosphomolybdic acid, niobium oxalate, niobium chloride, copper nitrate, copper sulfate, manganese nitrate, manganese acetate, ammonium phosphate, phosphomolybdic acid, cerous nitrate, ammonium ceric nitrate, lanthanum nitrate, and lanthanum trichloride.

In the present invention, the secondary impregnation may be carried out as long as it is sufficient to complete the supplementation of the active ingredient. Preferably, the secondary impregnation in step 3) is carried out at a temperature of 20-30 ℃ for 5-15min.

In the present invention, step 4) is used to transfer the secondary impregnant to a regenerant. Preferably, in step 4), the drying is carried out at 70-90 ℃ for 1-3h; the roasting is carried out for 3-5h at 400-500 ℃. The secondary impregnant contains the priming solution and the active replenisher thereon. During the drying process, the trigger solution can chemically react with the effective components in the activity supplement solution, so that the effective components generate precipitate substances with smaller particle sizes in the micropores of the catalyst and are left at the pore openings of the micropores of the catalyst and do not diffuse into the micropores. And as drying proceeds, the precipitated material may further solidify on the catalyst surface. In the roasting process, the precipitated substances can be converted into oxides, and the regenerated catalyst with the surface dispersed with the oxides of the components in the active replenisher is obtained.

The present invention will be described in detail below by way of examples.

Example 1

1) Selecting a honeycomb-shaped failure denitration catalyst module (a power plant belonging to Shenhua province), and removing fly ash on the surface of the catalyst module and in a pore channel by using compressed air to achieve the porosity of more than 95%.

The module was then placed in a chamber containing 0.25mol/L H ₂ SO ₄ In an ultrasonic bubbling tank of the solution, ultrasonic bubbling is carried out for 20min, the ultrasonic frequency is 28kHz, the power is 40W/L, and the pressure of bubbling compressed air is 0.2MPa.

The modules were then pre-dried in a circulating hot air oven at 100 ℃ for 60min until the water content did not exceed 5%. The spent agent is obtained.

2) Soaking the spent agent in 3mol/L urea solution (pH 7) at 25 deg.C for 20min, and draining until the spent agent does not drip water to obtain primary impregnant.

3) Immersing the primary impregnant into an active supplementary liquid for secondary impregnation at 30 ℃ for 10min, and then draining until no water is dropped to obtain a secondary impregnant; wherein the active replenishing liquid contains ammonium metavanadate with the concentration of 1 weight percent, ammonium metatungstate with the concentration of 2 weight percent and titanyl sulfate aqueous solution with the concentration of 6 weight percent.

4) Drying the secondary impregnant in a circulating hot air roasting furnace at the temperature of 80 ℃ for 1h; followed by calcination at 450 ℃ for 4h.

Thereby obtaining the regenerated denitration catalyst A1.

Example 2

And then placing the module in an ultrasonic bubbling tank containing 0.5mol/L nitric acid solution, and carrying out ultrasonic bubbling for 30min, wherein the ultrasonic frequency is 40kHz, the power is 50W/L, and the pressure of bubbling compressed air is 0.3MPa.

The modules were then pre-dried in a circulating hot air oven at a temperature of 90 ℃ for 60min until the water content did not exceed 5%. The spent agent is obtained.

2) The spent agent is immersed in 0.75mol/L ammonium carbonate solution (pH is about 8.9) for primary immersion at 20 ℃ for 30min, and then water is drained until the spent agent does not drip water, so that the primary impregnant is obtained.

3) Immersing the primary impregnant into an active replenisher for secondary impregnation at 20 ℃ for 10min, and then draining until no water is dropped to obtain a secondary impregnant; wherein the active replenishment solution contains 0.5 wt% ammonium metavanadate, 1 wt% ammonium metatungstate and 4 wt% titanyl sulfate aqueous solution.

4) Drying the secondary impregnant in a circulating hot air roasting furnace at the temperature of 80 ℃ for 2 hours; followed by calcination at 450 ℃ for 3h.

To obtain the regenerated denitration catalyst A2.

Example 3

1) Selecting a honeycomb-shaped ineffective denitration catalyst module (Shenhua power plant), and removing fly ash on the surface of the catalyst module and in a pore channel by using compressed air to achieve the porosity of more than 95%.

And then placing the module in an ultrasonic bubbling tank containing 0.05mol/L ammonium sulfate solution, ultrasonically bubbling for 10min at the ultrasonic frequency of 30kHz and the power of 30W/L, and bubbling the compressed air at the pressure of 0.2MPa.

The modules were then pre-dried in a circulating hot air oven at a temperature of 90 ℃ for 100min until the water content did not exceed 5%. The spent agent is obtained.

2) The spent agent is immersed in 1.5mol/L ammonium bicarbonate solution (pH is 8.0) for primary immersion at 30 ℃ for 30min, and then water is drained until the spent agent does not drip water, so as to obtain the primary immersion agent.

3) Immersing the primary impregnant into an active supplementary liquid for secondary impregnation at 25 ℃ for 10min, and then draining until no water is dropped to obtain a secondary impregnant; wherein the active replenishing liquid contains an aqueous solution of 2 weight percent ammonium metavanadate, 4 weight percent ammonium metatungstate and 8 weight percent titanyl sulfate.

4) Drying the secondary impregnant in a circulating hot air roasting furnace at the temperature of 80 ℃ for 3 hours; followed by calcination at 450 ℃ for 5h.

To obtain the regenerated denitration catalyst A3.

Example 4

The procedure of example 1 was followed except that "secondary dipping 10min" in step 3) was replaced with "secondary dipping 5min".

To obtain the regenerated denitration catalyst A4.

Example 5

The method of example 1 was followed except that "secondary dipping 10min" in step 3) was replaced with "secondary dipping 15min".

To obtain the regenerated denitration catalyst A5.

Example 6

The process of example 1 was followed except that "drying at 80 ℃" in step 4) was replaced with "drying at 70 ℃.

To obtain the regenerated denitration catalyst A6.

Example 7

The procedure of example 1 was followed except that "drying at 80 ℃" in step 4) was replaced with "drying at 90 ℃.

To obtain the regenerated denitration catalyst A7.

Example 8

The process of example 1 was followed except that "baking at 450 ℃" in step 4) was replaced with "baking at 400 ℃.

To obtain the regenerated denitration catalyst A8.

Example 9

The process of example 1 was followed except that "baking at 450 ℃" in step 4) was replaced with "baking at 500 ℃.

To obtain the regenerated denitration catalyst A9.

Comparative example 1

2) Soaking the agent to be generated in active supplementary liquid at 30 deg.C for 10min, and draining water until no water drops to obtain the impregnant; wherein the active replenishing liquid contains ammonium metavanadate with the concentration of 1 weight percent, ammonium metatungstate with the concentration of 2 weight percent and aqueous solution of titanyl sulfate with the concentration of 6 weight percent.

3) Drying the secondary impregnant in a circulating hot air roasting furnace at the temperature of 80 ℃ for 1h; followed by calcination at 450 ℃ for 4h.

To obtain the regenerated denitration catalyst D1.

Comparative example 2

A honeycomb-shaped spent catalyst (cut into test sample blocks with 3X 3 holes X200 mm and originated from a Shenhua affiliated power plant) is selected as a comparative catalyst D2.

Comparative example 3

A honeycomb-shaped fresh catalyst (cut into test sample blocks with 3X 3 holes X200 mm, and the spent catalyst in the comparative example 2 is a fresh catalyst produced in the same batch and originated from a Shenhua institute power plant) is selected as a comparative catalyst D3.

Evaluation examples

Testing of catalyst components: respectively grinding the surface layer and the matrix of the catalyst into powder, preparing a sample by adopting a solid powder/boric acid tabletting method, and measuring V by using an X-ray fluorescence spectrometer ₂ O ₅ Content, the test result is calculated by the oxide of the element.

And (3) testing the denitration performance: and selecting the catalysts A1-A9 and D1-D3 to respectively perform denitration performance test.

Putting the catalyst into a stainless steel fixed bed reactor, heating to 360 ℃, and introducing simulated flue gas (SO) ₂ =500 ppm by volume, NO _x ＝NH ₃ =200 ppm by volume, O ₂ =7 vol%, H ₂ O =10 vol%, N ₂ As balance gas), space velocity =9000h ^-1 . Testing catalyst inlet and outlet NO with American MKS6030 flue gas analyzer _x The concentration of (2).

Conversion rate of NO:

in the formula:

is reactor inlet NO _x Concentration in ppm by volume;

is reactor outlet NO _x Concentration in ppm by volume.

SO ₂ /SO ₃ And (3) testing the conversion rate: selecting the catalysts A1-A9 and D1-D3 to respectively carry out SO ₂ /SO ₃ And (4) testing the conversion rate.

Putting the catalyst into an SCR reactor, and introducing simulated flue gas (SO) ₂ =500 ppm by volume, O ₂ = 7% by volume, N ₂ As balance gas), space velocity =9000h ^-1 . Sampling at the inlet of an SCR reactor, adopting hydrogen peroxide as absorption liquid, simultaneously measuring the flow and time of sampled flue gas, and analyzing and determining the SO at the inlet by using an ion chromatograph ₂ The content, averaged and recorded as S ₁ The unit is mg.

Sampling at the inlet and outlet of SCR reactor, and collecting SO at inlet and outlet by temperature-controlled condensation method ₃ . Determination of import and export SO by ion chromatograph analysis ₃ The content, averaged and recorded as S ₂ In mg. And calculating SO of the catalyst based thereon ₂ /SO ₃ The conversion rate alpha is higher than the conversion rate alpha,

the test results are shown in Table 1.

TABLE 1

As can be seen from the examples, comparative examples and data in Table 1, examples 1-9 are denitration catalysts regenerated using the method of the present invention, and supplemental V can be achieved compared to the catalyst regenerated using the conventional regeneration method (comparative example 1) ₂ O ₅ The substance can be effectively distributed on the surface (V) ₂ O ₅ High surface content), not only the denitration efficiency is improved, but also the SO ₂ /SO ₃ The conversion rate is greatly reduced.

Examples 1-9 show 24-28% increase in activity over the spent catalyst (comparative example 2) and SO ₂ /SO ₃ The conversion is reduced.

The denitration efficiency of examples 1-9 can reach 98-102% of that of the fresh catalyst (comparative example 3).

The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims

1. A method of regenerating a denitration catalyst, comprising:

1) Pretreating the waste denitration catalyst to obtain a dry spent catalyst;

2) Putting the spent agent into a priming solution for primary impregnation, and removing redundant priming solution to obtain a primary impregnant, wherein the pH value of the priming solution is more than 7 and less than 9; the priming solution is at least one of a urea solution, an ammonium carbonate solution and an ammonium bicarbonate solution;

3) Putting the primary impregnant into an active supplementary solution for secondary impregnation, and removing redundant active supplementary solution to obtain a secondary impregnant; the active supplementary liquid comprises an active component with the concentration of 0.5-2 wt%, an auxiliary component with the concentration of 1-4 wt% and a carrier with the concentration of 4-8 wt%; the active component is ammonium metavanadate and/or vanadyl sulfate; the auxiliary agent component is salt containing at least one element of W, mo, nb, cu, mn, P, ce and La; the carrier is titanyl sulfate and/or titanium sulfate;

4) Drying and roasting the secondary impregnant to obtain a regenerated denitration catalyst; the drying is carried out at 70-90 ℃ for 1-3h.

2. The regeneration method according to claim 1, wherein the concentration of the urea solution is 1-6mol/L, the concentration of the ammonium carbonate solution is 0.5-1mol/L, and the concentration of the ammonium bicarbonate solution is 1-2mol/L.

3. The regeneration process according to claim 1, wherein the primary impregnation in step 2) is carried out at a temperature of 20-30 ℃ for 15-30min.

4. Regeneration method according to any one of claims 1 to 3, wherein the pre-treatment in step 1) comprises: carrying out ash removal, chemical cleaning and predrying on the waste denitration catalyst; the pore rate of the spent catalyst reaches more than 95 percent, and the water content is not more than 5 percent by weight.

5. The regeneration method of claim 4, wherein the chemical cleaning process comprises: putting the waste denitration catalyst into a chemical cleaning solution to clean under the conditions of ultrasound and bubbling; wherein the chemical cleaning solution contains at least one of a sulfuric acid solution, an ammonium sulfate solution and a nitric acid solution with the concentration of 0.05-0.5 mol/L; the ultrasonic frequency is 28-80kHz, the pressure of compressed gas for bubbling is 0.2-0.4MPa, and the ultrasonic bubbling time is 5-30min.

6. The regeneration method according to claim 4, wherein the pre-drying temperature is 90-120 ℃ and the pre-drying time is 60-120min.

7. Regeneration process according to claim 1, in which the secondary impregnation in step 3) is carried out at a temperature of 20-30 ℃ for 5-15min.

8. The regeneration method according to claim 1, wherein the calcination is performed at 400-500 ℃ for 3-5h in step 4).