CN114471746A - SCR denitration catalyst regeneration method - Google Patents
SCR denitration catalyst regeneration method Download PDFInfo
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Abstract
The invention relates to the technical field of flue gas SCR denitration catalysts, in particular to a regeneration method of an SCR denitration catalyst. The method comprises the following steps: treating the waste catalyst, and adding sulfuric acid to react to obtain a supplementary liquid; and soaking the deactivated catalyst in a supplementary liquid for reaction, adding ammonia gas for neutralization, hydrolyzing, and calcining to obtain the regenerated SCR denitration catalyst. The method can recycle the waste catalyst, and the extracted effective components are directly used in the regeneration process of the deactivated catalyst, so that not only are the active components of the deactivated catalyst supplemented, but also a large amount of carrier components are supplemented, the mechanical strength of the regenerated catalyst is improved, and the important problem that the mechanical strength restricts the repeated regeneration and utilization of the catalyst is solved.
Description
Technical Field
The invention relates to the technical field of flue gas SCR denitration catalysts, in particular to a regeneration method of an SCR denitration catalyst.
Background
The vanadium-titanium SCR denitration catalyst is the most widely used flue gas denitration catalyst at present, the service life of the catalyst is generally 2-5 years, and the annual scrapped SCR denitration catalyst exceeds 30 ten thousand m3. Besides the causes of alkali metal and arsenic poisoning, pore channel blockage and the like, high-temperature sintering and mechanical abrasion are also important causes of the activity reduction of the SCR denitration catalyst. High-temperature sintering can cause active component agglomeration and irreversible reduction of the specific surface area of the catalyst, and mechanical abrasion can cause loss of the catalyst carrier and the active component, and also cause reduction of the mechanical strength of the catalyst.
The vanadium-titanium waste SCR denitration catalyst belongs to dangerous waste (waste HW50), and how to realize the reutilization of the deactivated catalyst as far as possible and strengthen the lithium treatment and recycling of the waste catalyst is a key starting point and an inevitable trend for the upgrading development of the existing denitration catalyst industry.
The patent CN105396626B, CN105665036B and CN104907107B disclose various regeneration methods of SCR catalysts, but these methods only supplement the active component V, W, Mo of the catalyst, and do not supplement the carrier component Ti of the catalyst, however, the carrier component provides the specific surface area and active component sites of the catalyst on the one hand, and its content directly affects the mechanical strength of the catalyst on the other hand. Therefore, there is a need to develop a regeneration method that supplements both the carrier and the active ingredient.
The patent CN106435197B, CN106011478B and CN108525709B all adopt the routes of dissolving, extracting, separating and purifying to recover valuable elements such as Ti, V and the like in the waste catalyst. It is worth noting that if the elements such as Ti, V and the like dissolved and extracted from the waste catalyst are directly used for supplementing the elements lost by the deactivated SCR catalyst, the links of separation and purification can be omitted, so that the waste catalyst can be directly recycled, and the method has high economic value and environmental protection value. Therefore, it is necessary to develop a more rapid and efficient method for recycling the spent catalyst.
Disclosure of Invention
The invention aims to provide a regeneration method of an SCR denitration catalyst, which takes a waste SCR catalyst as a raw material to regenerate the deactivated SCR denitration catalyst, thereby realizing the regeneration of the deactivated catalyst and simultaneously solving the treatment problem of the waste catalyst.
In order to achieve the above purpose, the technical scheme of the invention is as follows:
a method for regenerating an SCR denitration catalyst comprises the following steps:
s1: blowing soot on the deactivated catalyst by using compressed air, soaking for 8-20h by using 0.5-3% sulfuric acid, ultrasonically cleaning for 0.5-3h, and drying at the temperature of 100-150 ℃ to obtain a pretreated deactivated catalyst;
preferably, the mass fraction of the first sulfuric acid is 2%;
preferably, the soaking time is 12 hours.
S2: blowing soot on the waste catalyst by using compressed air, soaking for 8-20h by using 1-3% by mass of sulfuric acid II, ultrasonically cleaning for 0.5-3h, drying at the temperature of 100-150 ℃, and then crushing to obtain waste catalyst powder with the particle size of less than 100 meshes;
preferably, the mass fraction of the second sulfuric acid is 3%;
preferably, the soaking time is 12 hours.
The deactivated catalyst and the waste catalyst in the steps S1 and S2 belong to catalysts used for a long time, have different degrees of hole blockage and poisoning caused by K, Na and the like, and can dredge the pore channel and dissolve elements such as K, Na and the like by soaking in sulfuric acid.
S3: uniformly mixing and stirring the waste catalyst powder obtained in the step S2 and concentrated sulfuric acid with the mass fraction of 96-98% according to the mass ratio of 1:1.5-2.5, and reacting at the temperature of 200-280 ℃ for 3-5 h; cooling the reacted materials to 70-80 ℃, adding 5-20% of sulfuric acid III by mass, stirring uniformly and filtering; cooling the filtrate to below 40-50 ℃ to obtain an initial extracting solution containing a large amount of Ti element and a small amount of V, W, Mo element;
preferably, the mass fraction of the concentrated sulfuric acid is 98%;
preferably, the mass ratio of the waste catalyst powder to the concentrated sulfuric acid is 1: 2;
preferably, the reaction temperature of the waste catalyst powder and concentrated sulfuric acid is 220-260 ℃;
more preferably, the reaction temperature of the waste catalyst powder and concentrated sulfuric acid is 260 ℃;
preferably, the temperature of the reacted materials is reduced to 80 ℃;
preferably, the filtrate is cooled to 50 ℃.
In this step, the titanium dioxide in the waste catalyst powder reacts with concentrated sulfuric acid as follows:
TiO2+2H2SO4＝Ti(SO4)2+2H2O；
TiO2+H2SO4＝TiOSO4+H2O。
the raw carrier Ti in the spent catalyst remains in the initial extract in a large amount in the form of titanium sulfate and titanyl sulfate.
S4: adding 12-20 wt% of sulfuric acid IV into the initial extract of step S3 to obtain Ti concentration (in terms of TiO)2Metering) 100-300g/L of replenishing liquid;
preferably, the concentration of Ti (in TiO) in the replenishment solution2Calculated) was 250 g/L.
S5: soaking the deactivated catalyst in the step S1 in the supplementary liquid in the step S4 at 20-50 ℃ for 0.5-3h, taking out and draining the surface liquid to obtain a procatalyst;
in this step, the deactivated catalyst is replenished with Ti as a carrier by using a replenishing solution containing a large amount of Ti.
S6: putting the procatalyst of the step S5 into a drying furnace, heating to 70-120 ℃, introducing 5-100% by volume of ammonia and/or nitrogen for neutralization and hydrolysis reaction for 2-8h, wherein the mass ratio of the cumulative introduction amount of ammonia to the sulfuric acid absorbed by the procatalyst is 1: 3-12;
preferably, the temperature is raised to 85 ℃;
preferably, the volume fraction of the ammonia gas is 30-60%;
more preferably, the volume fraction of ammonia gas is 40%;
preferably, the neutralization and hydrolysis reaction time is 3 h;
preferably, the mass ratio of the ammonia gas to the sulfuric acid absorbed by the procatalyst is 1: 5-10;
more preferably, the mass ratio of the ammonia gas to the sulfuric acid absorbed by the procatalyst is 1: 6.
In this step, the following reaction takes place after the introduction of ammonia:
2NH3+H2SO4＝NH4HSO4；
2NH3+H2SO4＝(NH4)2SO4；
Ti(SO4)2+4H2O＝Ti(OH)4↓+2H2SO4；
Ti(SO4)2+3H2O＝TiO(OH)2↓+2H2SO4；
TiOSO4+2H2O＝TiO(OH)2↓+H2SO4。
the addition of ammonia gas promotes the hydrolysis reaction of titanium sulfate and titanyl sulfate produced in step S3, and titanic acid and metatitanic acid produced by the hydrolysis adhere to the catalyst.
S7: and (4) heating the product obtained in the step S6 to 330-450 ℃, and calcining for 1-8h to obtain the regenerated SCR denitration catalyst.
Preferably, the temperature of the product is raised to 380-420 ℃;
more preferably, the product is warmed to 400 ℃;
preferably, the calcination time is 4 to 6 hours.
The following reaction takes place in this step:
Ti(OH)4＝TiO2+2H2O；
TiO(OH)2＝TiO2+H2O。
the ammonium bisulfate and the ammonium sulfate are volatilized or decomposed to leave the catalyst, and titanium dioxide generated by the dehydration of titanic acid and metatitanic acid attached to the catalyst is remained in the catalyst, so that a carrier for deactivating the SCR denitration catalyst is supplemented.
The regeneration method provided by the invention comprises the steps of firstly dipping the deactivated catalyst into a replenishing solution containing a large amount of Ti element to replenish the Ti element as a carrier, then adding ammonia gas to promote the hydrolysis reaction of titanium sulfate and titanyl sulfate, then calcining, directly retaining the generated titanium dioxide in the catalyst, and replenishing the Ti carrier for the deactivated SCR denitration catalyst; if ammonia gas is added into the replenishing liquid, titanium sulfate and titanyl sulfate in the solution can be hydrolyzed in the solution in advance to generate precipitates, so that the Ti element contained in the solution is very few, and the aim of replenishing the carrier Ti cannot be achieved through impregnation.
Another object of the present invention is to provide a regenerated SCR denitration catalyst prepared by the above method.
The selection of the above-mentioned production method and the reactants, solvents, detergents and the like in the production steps thereof, and the selection of the reaction conditions such as temperature, time and the like are preferable, and are not limited to the above selection, and may be replaced and omitted as appropriate depending on the effect.
Compared with the prior art, the invention has the following advantages:
(1) the regeneration method provided by the invention extracts the carrier component Ti and the active component V, W, Mo from the waste SCR denitration catalyst, solves the problem of treatment of the waste catalyst, achieves recycling, is environment-friendly and saves the production cost;
(2) according to the regeneration method provided by the invention, the effective components extracted from the waste catalyst are directly used in the regeneration process of the deactivated catalyst, and the steps of separation and extraction and the like are not needed, so that the reaction process is saved; the method of soaking, neutralizing and hydrolyzing is adopted to directly supplement the carrier with large specific surface and highly dispersed active components for the deactivated catalyst, thus recovering the activity of the deactivated SCR denitration catalyst and realizing the regeneration and reuse of the deactivated catalyst;
(3) the regeneration method provided by the invention not only supplements the active components of the deactivated catalyst, but also more importantly supplements a large amount of carrier components, thereby improving the mechanical strength of the regenerated catalyst and solving the important problem that the mechanical strength restricts the repeated regeneration and utilization of the catalyst.
Drawings
FIG. 1 is a process flow diagram of the regeneration process of the present invention.
Detailed Description
The terms as used herein:
"prepared from … …" is synonymous with "comprising". The terms "comprises," "comprising," "includes," "including," "has," "having," "contains," "containing," or any other variation thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.
When an amount, concentration, or other value or parameter is expressed as a range, preferred range, or as a range of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. For example, when the range "1 ~ 5" is disclosed, the ranges described should be construed to include the ranges "1 ~ 4", "1 ~ 3", "1 ~ 2 and 4 ~ 5", "1 ~ 3 and 5", and the like. When a range of values is described herein, unless otherwise stated, the range is intended to include the endpoints thereof and all integers and fractions within the range.
"and/or" is used to indicate that one or both of the illustrated conditions may occur, e.g., a and/or B includes (a and B) and (a or B).
The technical solutions of the present invention will be described in detail with reference to specific examples, but those skilled in the art will understand that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention.
Example 1
The deactivated catalyst and the waste catalyst of the embodiment are from a vanadium-titanium honeycomb SCR denitration catalyst of a certain coal-fired power plant, the operation time is 3 years, the catalysts are screened, the catalyst without obvious defects, damages and serious pore plugging is used as the deactivated catalyst, and the rest are used as the waste catalyst.
As shown in fig. 1, a method for regenerating an SCR denitration catalyst includes the following steps:
s1: blowing soot on the deactivated catalyst by using compressed air, soaking for 20 hours by using sulfuric acid with the mass fraction of 0.5%, ultrasonically cleaning for 3 hours, and drying at 100 ℃ to obtain a pretreated deactivated catalyst;
s2: blowing soot on the waste catalyst by using compressed air, soaking the waste catalyst for 20 hours by using sulfuric acid with the mass fraction of 1%, ultrasonically cleaning the waste catalyst for 3 hours, drying the waste catalyst at 100 ℃, and then crushing the waste catalyst to obtain waste catalyst powder with the particle size of 120 meshes;
s3: mixing and stirring the waste catalyst powder obtained in the step S2 and concentrated sulfuric acid with the mass fraction of 96% uniformly according to the mass ratio of 1:1.5, and reacting for 5 hours at 200 ℃; cooling the reacted materials to 70 ℃, adding 5% sulfuric acid by mass fraction, stirring uniformly and filtering; cooling the filtrate to below 40 ℃ to obtain an initial extracting solution containing Ti as a main component and a small amount of V, W, Mo element;
s4: adding 12% by mass of sulfuric acid into the initial extraction solution obtained in step S3 to obtain Ti concentration (in TiO form)2Metering) 250g/L of a supplementary liquid;
s5: soaking the deactivated catalyst obtained in the step S1 in the replenishing liquid obtained in the step S4 at 20 ℃ for 3h, taking out and draining the surface liquid of the deactivated catalyst to obtain a procatalyst;
s6: putting the procatalyst of the step S5 into a drying furnace, heating to 70 ℃, introducing 5% by volume of ammonia gas and nitrogen gas for neutralization and hydrolysis reaction for 8h, wherein the mass ratio of the cumulative introduction amount of the ammonia gas to the sulfuric acid absorbed by the procatalyst is 1: 3;
s7: and (4) heating the product obtained in the step (S6) to 330 ℃ and calcining for 8h to obtain the regenerated SCR denitration catalyst.
Example 2
The deactivated catalyst and the waste catalyst of the embodiment are from a vanadium-titanium honeycomb SCR denitration catalyst of a coal-fired power plant, the operation time is 5 years, the catalysts are screened, the catalyst without obvious defects, damages and serious pore blocking is used as the deactivated catalyst, and the rest are used as the waste catalyst.
A method for regenerating an SCR denitration catalyst comprises the following steps:
s1: soot blowing is carried out on the deactivated catalyst by compressed air, then the deactivated catalyst is soaked for 16 hours by sulfuric acid with the mass fraction of 1%, ultrasonic cleaning is carried out for 2.5 hours, and drying is carried out at 120 ℃ to obtain the pretreated deactivated catalyst;
s2: blowing soot on the waste catalyst by using compressed air, soaking the waste catalyst for 16 hours by using sulfuric acid with the mass fraction of 1.5%, ultrasonically cleaning the waste catalyst for 2.5 hours, drying the waste catalyst at 120 ℃, and then crushing the waste catalyst to obtain waste catalyst powder with the particle size of 150 meshes;
s3: mixing and stirring the waste catalyst powder obtained in the step S2 and concentrated sulfuric acid with the mass fraction of 97% uniformly according to the mass ratio of 1:2, and reacting for 4.5h at 220 ℃; cooling the reacted materials to 75 ℃, adding 10% sulfuric acid by mass percent, uniformly stirring and filtering; cooling the filtrate to below 45 ℃ to obtain an initial extracting solution containing Ti as a main component and a small amount of V, W, Mo element;
s4: adding sulfuric acid with mass fraction of 15% into the initial extracting solution of the step S3 to obtain Ti concentration (as TiO)2Metering) 100g/L of a replenishing liquid;
s5: soaking the deactivated catalyst obtained in the step S1 in the replenishing liquid obtained in the step S4 at 30 ℃ for 2h, taking out and draining the surface liquid of the deactivated catalyst to obtain a procatalyst;
s6: putting the procatalyst of the step S5 into a drying furnace, heating to 80 ℃, introducing ammonia gas and nitrogen gas with volume fraction of 40% for neutralization and hydrolysis reaction for 6h, wherein the mass ratio of the cumulative introduction amount of the ammonia gas to the sulfuric acid absorbed by the procatalyst is 1: 6;
s7: and (4) heating the product obtained in the step (S6) to 380 ℃ and calcining for 6h to obtain the regenerated SCR denitration catalyst.
Example 3
The deactivated catalyst and the waste catalyst of the embodiment are medium-low temperature vanadium-titanium honeycomb SCR denitration catalysts from a certain steel mill, the operation time is 3 years, the catalysts are screened, the catalyst without obvious defects, damages and serious hole plugging is used as the deactivated catalyst, and the rest is used as the waste catalyst.
A method for regenerating an SCR denitration catalyst comprises the following steps:
s1: soot blowing is carried out on the deactivated catalyst by compressed air, then the deactivated catalyst is soaked for 12 hours by sulfuric acid with the mass fraction of 2%, ultrasonic cleaning is carried out for 2 hours, and drying is carried out at 140 ℃ to obtain the pretreated deactivated catalyst;
s2: blowing dust to the waste catalyst by using compressed air, soaking the waste catalyst for 12 hours by using sulfuric acid with the mass fraction of 2%, ultrasonically cleaning the waste catalyst for 2 hours, drying the waste catalyst at the temperature of 140 ℃, and then crushing the waste catalyst to obtain waste catalyst powder with the particle size of 200 meshes;
s3: mixing and stirring the waste catalyst powder obtained in the step S2 and 98% concentrated sulfuric acid in a mass ratio of 1:2.5 uniformly, and reacting for 4 hours at 260 ℃; cooling the reacted materials to 80 ℃, adding 15% by mass of sulfuric acid, uniformly stirring and filtering; cooling the filtrate to below 50 ℃ to obtain an initial extracting solution containing Ti as a main component and a small amount of V, W, Mo element;
s4: adding 18% by mass of sulfuric acid IV into the initial extracting solution of the step S3 to obtain Ti concentration (in terms of TiO)2Metering) 200g/L of a replenishing liquid;
s5: soaking the deactivated catalyst obtained in the step S1 in the replenishing liquid obtained in the step S4 at 40 ℃ for 1h, taking out and draining the surface liquid of the deactivated catalyst to obtain a procatalyst;
s6: putting the procatalyst of the step S5 into a drying furnace, heating to 100 ℃, introducing ammonia gas and/or nitrogen gas with volume fraction of 60% for neutralization and hydrolysis reaction for 4h, wherein the mass ratio of the cumulative introduction amount of the ammonia gas to the sulfuric acid absorbed by the procatalyst is 1: 8;
s7: and (4) heating the product obtained in the step (S6) to 420 ℃ and calcining for 4h to obtain the regenerated SCR denitration catalyst.
Example 4
The deactivated catalyst and the waste catalyst of the embodiment are medium-low temperature vanadium-titanium plate type SCR denitration catalysts from a certain steel mill, the operation time is 3 years, the catalysts are screened, the catalyst without obvious defects, damages and serious hole plugging is used as the deactivated catalyst, and the rest is used as the waste catalyst.
A method for regenerating an SCR denitration catalyst comprises the following steps:
s1: blowing soot on the deactivated catalyst by using compressed air, soaking for 8 hours by using sulfuric acid with the mass fraction of 3%, ultrasonically cleaning for 0.5 hour, and drying at 150 ℃ to obtain a pretreated deactivated catalyst;
s2: blowing soot on the waste catalyst by using compressed air, soaking for 8 hours by using sulfuric acid with the mass fraction of 3%, ultrasonically cleaning for 0.5 hour, drying at 150 ℃, and then crushing to obtain waste catalyst powder with the particle size of 250 meshes;
s3: mixing and stirring the waste catalyst powder obtained in the step S2 and 98% concentrated sulfuric acid in a mass ratio of 1:2.2 uniformly, and reacting for 3 hours at 280 ℃; cooling the reacted materials to 80 ℃, adding 20% sulfuric acid by mass percent, stirring uniformly and filtering; cooling the filtrate to below 50 ℃ to obtain an initial extracting solution containing Ti as a main component and a small amount of V, W, Mo element;
s4: adding 20% sulfuric acid into the initial extract of step S3 to obtain Ti concentration (as TiO)2Metering) 300g/L of a replenishing liquid;
s5: soaking the deactivated catalyst in the step S1 in the supplementary liquid in the step S4 at 50 ℃ for 0.5h, taking out and draining the surface liquid of the deactivated catalyst to obtain a procatalyst;
s6: putting the procatalyst of the step S5 into a drying furnace, heating to 120 ℃, introducing 100% by volume of ammonia gas for neutralization and hydrolysis reaction for 2h, wherein the mass ratio of the cumulative introduction amount of the ammonia gas to the sulfuric acid absorbed by the procatalyst is 1: 12;
s7: and (4) heating the product of the step S6 to 450 ℃ and calcining for 1h to obtain the regenerated SCR denitration catalyst.
Comparative example 1
The deactivated catalyst and the spent catalyst used in this comparative example were the same as in example 1.
A method for regenerating an SCR denitration catalyst comprises the following steps:
s1: blowing soot on the deactivated catalyst by using compressed air, soaking for 8 hours by using sulfuric acid with the mass fraction of 3%, ultrasonically cleaning for 0.5 hour, and drying at 150 ℃ to obtain a pretreated deactivated catalyst;
s2: blowing soot on the waste catalyst by using compressed air, soaking for 8 hours by using sulfuric acid with the mass fraction of 3%, ultrasonically cleaning for 0.5 hour, drying at 150 ℃, and then crushing to obtain waste catalyst powder with the particle size of 250 meshes;
s3: mixing and stirring the waste catalyst powder obtained in the step S2 and 98% concentrated sulfuric acid in a mass ratio of 1:2.2 uniformly, and reacting for 3 hours at 280 ℃; cooling the reacted materials to 80 ℃, adding 20% sulfuric acid by mass percent, stirring uniformly and filtering; cooling the filtrate to below 50 ℃ to obtain an initial extracting solution containing Ti as a main component and a small amount of V, W, Mo element;
s4: adding 20% sulfuric acid into the initial extract of step S3 to obtain Ti concentration (as TiO)2Metering) 250g/L of a supplementary liquid;
s5: introducing ammonia gas with the volume fraction of 100% into the supplementing liquid in the step S4, wherein the supplementing liquid begins to become turbid and becomes slurry, and introducing ammonia gas until the pH value of the slurry is adjusted to 6.5;
s6: dipping the deactivated catalyst obtained in the step S1 into the slurry obtained in the step S5 at 50 ℃ for 0.5h, taking out and draining the surface liquid of the deactivated catalyst to obtain a procatalyst;
s7: and (4) heating the procatalyst obtained in the step S6 to 450 ℃ and calcining for 1h to obtain the regenerated SCR denitration catalyst.
Test example 1
The activity of the regenerated SCR denitration catalysts prepared in examples 1 and 2 and comparative example 1 was tested under a fixed bed reactor simulated flue gas condition, and the test conditions were as follows: the reaction temperature is 380 ℃, the catalyst filling height is 2100mm, and the catalyst sectional area is 25cm2The flow rate of flue gas is 350L/min, the concentration of NO is 300ppm, the molar ratio of ammonia to nitrogen is 1.0, and SO is added2The concentration is 500ppm, the oxygen concentration is 4.0 percent, the water content is 10.0 percent, and nitrogen is balance gas. The test data are shown in table 1.
TABLE 1 test data for different regenerated SCR denitration catalysts
Test example 2
The activity of the regenerated SCR denitration catalyst prepared in example 3 was tested in a fixed bed reactor under simulated flue gas conditions, and the test conditions were as follows: the reaction temperature is 250 ℃, the catalyst filling height is 2100mm, and the catalyst sectional area is 25cm2The flow rate of flue gas is 260L/min, the concentration of NO is 200ppm, the molar ratio of ammonia to nitrogen is 1.0, and SO is added2150ppm of concentration, 10.0 percent of oxygen concentration, 10.0 percent of water content and nitrogen as balance gas. The test data are shown in Table 2.
TABLE 2 test data
The test data of the embodiment 1 and the embodiment 2 show that the activity of the regenerated catalyst is recovered, the radial and axial compressive strength and the specific surface area are greatly improved, and the waste catalyst realizes higher recovery rate.
The data of the embodiment 1 and the comparative example 1 show that the regeneration method of the invention has reasonable sequence, the embodiment 1 firstly soaks the deactivated catalyst in the supplementary liquid to supplement the carrier Ti element, then ammonia gas is added to promote the hydrolysis reaction, then the calcination is carried out, the generated titanium dioxide is directly left in the catalyst, the deactivated SCR denitration catalyst is supplemented with the carrier Ti, and the mechanical strength is recovered; in contrast, in comparative example 1, ammonia gas was added to the make-up solution, the purpose of making up the carrier Ti could not be achieved by impregnation, the mechanical strength of the catalyst could not be recovered, only the active component could be supplemented, and the reuse rate of the spent catalyst was low, and the spent catalyst could not be recycled.
The test data of example 3 shows that the specific surface area of the regenerated catalyst is obviously increased, the denitration rate is recovered, and the contents of the carrier and the active component of the unit volume of the catalyst are also obviously improved.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Furthermore, those skilled in the art will appreciate that while some embodiments herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the claims above, any of the claimed embodiments may be used in any combination. The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
Claims (10)
1. The method for regenerating the SCR denitration catalyst is characterized by comprising the following steps of:
s1: soot blowing, sulfuric acid soaking, ultrasonic cleaning and drying are carried out on the deactivated catalyst to obtain a pretreated deactivated catalyst;
s2: carrying out soot blowing on the waste catalyst, soaking with sulfuric acid II, ultrasonic cleaning, drying and crushing to obtain waste catalyst powder;
s3: mixing the waste catalyst powder obtained in the step S2 with concentrated sulfuric acid, reacting at the temperature of T1 for T1 time, adding sulfuric acid III at the temperature of T2, uniformly stirring, filtering, and cooling the filtrate to the temperature of T3 to obtain an initial extracting solution;
s4: adding sulfuric acid IV into the initial extracting solution obtained in the step S3 to obtain a supplementary solution;
s5: dipping the deactivated catalyst in the step S1 into the replenishing liquid in the step S4 at the temperature of T4 for T2 time, taking out and draining to obtain a procatalyst;
s6: putting the procatalyst obtained in the step S5 into a drying furnace, and introducing ammonia gas and/or nitrogen gas at the temperature of T5 for neutralization and hydrolysis reaction for T3 time;
s7: and calcining the product obtained in the step S6 at the temperature of T6 for T4 time to obtain the regenerated SCR denitration catalyst.
2. The method according to claim 1, wherein step S1 satisfies one or more of the following conditions:
a. the mass fraction of the first sulfuric acid is 0.5-3%;
preferably, the mass fraction of the first sulfuric acid is 2%;
b. the soaking time is 8-20 h;
preferably, the soaking time is 12 hours;
c. the ultrasonic cleaning time is 0.5-3 h;
d. the drying temperature is 100-150 ℃.
3. The method according to claim 1, wherein step S2 satisfies one or more of the following conditions:
e. the mass fraction of the second sulfuric acid is 1-3%;
preferably, the mass fraction of the second sulfuric acid is 3%;
f. the soaking time is 8-20 h;
preferably, the soaking time is 12 hours;
g. the ultrasonic cleaning time is 0.5-3 h;
h. the drying temperature is 100-150 ℃;
i. the particle size of the waste catalyst powder is less than 100 meshes.
4. The method according to claim 1, wherein step S3 satisfies one or more of the following conditions:
j. the mass fraction of the concentrated sulfuric acid is 96-98%;
preferably, the mass fraction of the concentrated sulfuric acid is 98%;
k. the mass ratio of the waste catalyst powder to the concentrated sulfuric acid is 1: 1.5-2.5;
preferably, the mass ratio of the waste catalyst powder to the concentrated sulfuric acid is 1: 2;
the temperature T1 is 200-280 ℃;
preferably, the temperature T1 is 220-260 ℃;
more preferably, the temperature T1 is 260 ℃;
m. the time t1 is 3-5 h;
n. the temperature T2 is 70-80 ℃;
preferably, the temperature T2 is 80 ℃;
the mass fraction of the third sulfuric acid is 5-20%;
p. the temperature T3 is between 40 and 50 ℃;
preferably, the temperature T3 is 50 ℃.
5. The method according to claim 1, wherein the initial extract of step S3 contains a large amount of Ti element and a small amount of V, W and Mo element.
6. The method according to claim 1, wherein step S4 satisfies one or more of the following conditions:
q. the mass fraction of the sulfuric acid IV is 12-20%;
the Ti concentration in the replenishment solution (in TiO)2Calculated) is 100-300 g/L;
preferably, the concentration of Ti (in TiO) in the replenishment solution2Calculated) was 250 g/L.
7. The method according to claim 1, wherein step S5 satisfies one or more of the following conditions:
s. the temperature T4 is 20-50 ℃;
t. the time t2 is 0.5-3 h.
8. The method according to claim 1, wherein step S6 satisfies one or more of the following conditions:
u. said temperature T5 is between 70 and 120 ℃,
preferably, the temperature T5 is 85 ℃;
v. the volume fraction of the ammonia gas is 5-100%;
preferably, the volume fraction of the ammonia gas is 30-60%;
more preferably, the volume fraction of ammonia gas is 40%;
w. the time t3 is 2-8 h;
preferably, the time t3 is 3 h;
x, the mass ratio of the ammonia gas to the sulfuric acid absorbed by the fore-catalyst is 1: 3-12;
preferably, the mass ratio of the ammonia gas to the sulfuric acid absorbed by the procatalyst is 1: 5-10;
more preferably, the mass ratio of the ammonia gas to the sulfuric acid absorbed by the procatalyst is 1: 6.
9. The method according to claim 1, wherein step S7 satisfies one or more of the following conditions:
y. the temperature T6 is 330-450 ℃;
preferably, the temperature T6 is 380-420 ℃;
more preferably, the temperature T6 is 400 ℃;
z. at time t4 of 1-8 h;
preferably, the time t4 is 4-6 h.
10. A regenerated SCR denitration catalyst prepared by the method of any one of claims 1 to 9.
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