CN112774723B - Method for improving SCR denitration stability of catalyst by acid treatment - Google Patents

Method for improving SCR denitration stability of catalyst by acid treatment Download PDF

Info

Publication number
CN112774723B
CN112774723B CN202011523300.XA CN202011523300A CN112774723B CN 112774723 B CN112774723 B CN 112774723B CN 202011523300 A CN202011523300 A CN 202011523300A CN 112774723 B CN112774723 B CN 112774723B
Authority
CN
China
Prior art keywords
acid
solution
stirring
equal
catalyst
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN202011523300.XA
Other languages
Chinese (zh)
Other versions
CN112774723A (en
Inventor
周立坤
胡明明
陈爱民
滕厚开
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
CNOOC Tianjin Chemical Research and Design Institute Co Ltd
Original Assignee
CNOOC Tianjin Chemical Research and Design Institute Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by CNOOC Tianjin Chemical Research and Design Institute Co Ltd filed Critical CNOOC Tianjin Chemical Research and Design Institute Co Ltd
Priority to CN202011523300.XA priority Critical patent/CN112774723B/en
Publication of CN112774723A publication Critical patent/CN112774723A/en
Application granted granted Critical
Publication of CN112774723B publication Critical patent/CN112774723B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively
    • B01J29/42—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively containing iron group metals, noble metals or copper
    • B01J29/46—Iron group metals or copper
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/8637—Simultaneously removing sulfur oxides and nitrogen oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/0201—Impregnation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/0215—Coating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/06—Washing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/30—Sulfur compounds
    • B01D2257/302—Sulfur oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/40—Nitrogen compounds
    • B01D2257/404—Nitrogen oxides other than dinitrogen oxide
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
    • B01D2258/02—Other waste gases
    • B01D2258/0283—Flue gases
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
    • B01J2229/10—After treatment, characterised by the effect to be obtained
    • B01J2229/18—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself
    • B01J2229/186—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself not in framework positions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
    • B01J2229/30—After treatment, characterised by the means used
    • B01J2229/37—Acid treatment
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Environmental & Geological Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Biomedical Technology (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Catalysts (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)

Abstract

The invention discloses a method for improving the stability of a catalyst for SCR denitration by an acid treatment mode. The purposes of improving the hydroxylation degree of the slurry, increasing the cohesiveness and improving the integral strength of the catalyst are achieved by adjusting and optimizing the types, concentration and dripping speed of the added acid, the adjusted pH value, the stirring speed, the time and other parameters. The catalyst has the advantages of steam aging resistance, good stability and the like. The catalyst active component adopts a ZSM-5 molecular sieve impregnated by iron salt or a mixed solution of iron salt and copper salt, can efficiently remove nitrogen oxides under the low-temperature condition, and has the advantages of reducing the denitration reaction temperature, widening the active temperature window in the denitration process, improving the flexibility of the design of the denitration and desulfurization process flow and the like.

Description

Method for improving SCR denitration stability of catalyst by acid treatment
Technical Field
The invention relates to a method for improving the stability of a catalyst for SCR denitration by an acid treatment mode.
Background
The nitrogen oxides discharged in the industrial process can cause great harm to the living environment of human beings, animals and plants. At present, NO x The discharge was performed at 100mg/m 3 The concentration limit of (2). Therefore, more efficient treatment of plant off-gases is required for safe emission.
The catalyst is the core of the SCR denitration technology, and because the gas flow in the SCR denitration process is large and the flow speed is high, in order to avoid the blockage of the pore channel caused by the long-time contact abrasion of the gas and the catalyst, a certain pore is required to be formed in the filling or preparation of the catalyst. There is also a need for improving the abrasion resistance, stability, etc. of the catalyst by improving the preparation process. During the preparation process of the SCR denitration catalyst, the types and properties of the acid, the adding effect and the like are different. Patent CN103203243B discloses a preparation method of a catalyst suitable for high space velocity and having excellent thermal stability. Will P 2 O 5 And Nb 2 O 5 Acidic oxide is taken as a modified component and loaded to the CeO of the active coating of the catalyst by an immersion method 2 Modifying, and controlling stirring speed, time and other factors in the dipping process. The prepared catalyst has excellent thermal stability, and meets the emission standard of the tail gas of the diesel vehicle after long-distance running.In some studies, the addition of acid was used to adjust the pH during the preparation of the coating slurry precursor in order to improve the adhesion properties of the desired components. [ document 1: acid-modified CeO for denitration, prepared from Wengcheng, maziran, wuxiandong, etc 2 Based SCR catalyst and its preparation method CN103203243B [ P ]].2015-02-18.]. Patent CN105363486B describes a method for preparing Al by coprecipitation 2 O 3 -ZrO 2 The composite sol is used as a component of SCR catalyst coating slurry. Adding oxalic acid to form zirconium oxalate precursor, and adding nitric acid into the mixed solution of aluminum and zirconium source to adjust the pH value to form composite sol. In the process, the amount of oxalic acid and nitric acid added is controlled. The sol prepared by the method can effectively improve the loading capacity and uniformity of the active components of the catalyst, thereby achieving the purpose of improving the activity and stability of the catalyst. [ document 2: a molecular sieve-based SCR catalyst for treating the diseases caused by sunmin, royal flush, zhu Zen, etc is prepared from CN105363486B [ P].2018-05-15.]. Patent CN107930652A provides a glacial acetic acid regulating sol precursor and active components, and a method for preparing a medium-low temperature SCR catalyst. Adding CuSO into Ti precursor sol 4 After the active ingredient, the pH of the solution was adjusted with glacial acetic acid, respectively. Adding MnO into the mixed solution x 、FeO x The active ingredient, each time after addition of a new component, requires stirring under nitrogen and time control. And aging, drying, roasting, grinding and the like are carried out on the mixed solution to obtain a finished catalyst product. The preparation process also utilizes a coprecipitation method, and the purpose of adding glacial acetic acid is to ensure the formation of Ti precursor sol and better combination of the sol and active components. [ document 3: mnO of von Lin x -FeO x -CuSO 4 /TiO 2 Medium-low temperature SCR catalyst and its preparation method CN107930652A P].2018-04-20.]。
Disclosure of Invention
The invention aims to provide a method for improving the stability of a catalyst for SCR denitration by an acid treatment mode so as to improve the whole abrasion resistance and strength of the catalyst.
In order to realize the purpose, the invention adopts the technical scheme that:
a method for improving SCR denitration stability of a catalyst by an acid treatment mode is characterized by comprising the following steps:
the SCR denitration catalyst coating slurry is formed by mixing a molecular sieve, ceramic powder, a binder and an additive solution under the stirring condition, the SCR denitration catalyst coating slurry needs to be treated by acid in advance before mixing, and the treatment steps are as follows:
(1) Acid treatment of the molecular sieve solution: adding a molecular sieve into deionized water for uniform dispersion, adding an acid solution at a constant speed under the stirring condition to ensure that the pH value of the solution meets 1.5-3.5, the acid addition speed is less than or equal to (1 ml/min)/100 ml of the solution, stirring for more than or equal to 1h at a stirring speed of more than or equal to 400r/min, and repeating the operations of adjusting the pH value by adding acid and stirring for more than or equal to 1 time;
(2) Acid treatment of ceramic powder solution: adding the ceramic powder into deionized water for uniform dispersion, adding an acid solution at a constant speed under the stirring condition to ensure that the pH value of the solution meets 1.5-3.5, and stirring for more than or equal to 1 hour;
(3) Acid treatment of binder solution: adding the binder into deionized water for uniform dispersion, adding an acid solution at a constant speed under the stirring condition to ensure that the pH value of the solution meets 2.0-4.0, the acid addition speed is less than or equal to (1 ml/min)/100 ml of the solution, stirring for more than or equal to 2 hours at a stirring speed of more than or equal to 400r/min, and repeating the pH value adjustment and stirring operation of adding acid for more than or equal to 1 time;
(4) Preparing an additive solution: adding the additive into deionized water, and stirring until the additive is uniformly dispersed;
(5) Preparing coating slurry: adding the molecular sieve solution subjected to acid treatment in the steps (1) and (2), the ceramic powder solution and the additive solution uniformly dispersed in the step (4) into the binder solution subjected to acid treatment in the step (3) under the condition of stirring, adding an acid solution at a constant speed for regulation to ensure that the pH value of the slurry meets 1.5-3.5, adding the acid at a speed of less than or equal to (1 ml/min)/100 ml of the solution, and stirring for more than or equal to 1h at a stirring speed of more than or equal to 400r/min to prepare coating slurry;
the acid is formic acid, acetic acid, citric acid, or one or more of hydrochloric acid, nitric acid and nitrous acid, the concentration of the formic acid, the acetic acid and the citric acid is more than or equal to 50wt%, and the concentration of the hydrochloric acid, the nitric acid and the nitrous acid is more than or equal to 10wt%;
the molecular sieve is a ZSM-5 molecular sieve impregnated by a mixed solution of iron salt or iron salt and copper salt, and the ceramic powder is one or more of cordierite, mullite, activated alumina, aluminum titanate, zirconia and silicon nitride; the binder is one or a composite matrix consisting of two or more of pseudo-boehmite, silica sol, aluminum sol and titanium sol.
In the scheme, the concentration of the formic acid, the acetic acid and the citric acid is preferably equal to or more than 65wt%, and the concentration of the hydrochloric acid, the nitric acid and the nitrous acid is preferably equal to or more than 25wt%.
In the scheme, the molecular sieve in the step (1) is a ZSM-5 molecular sieve impregnated by a mixed solution of iron salt or iron salt and copper salt, the pH value is preferably 2.5-3.2 after the acid solution is added, the acid adding speed is less than or equal to (1 ml/min)/200 ml of solution, the stirring time is preferably more than or equal to 2 hours, and the stirring speed is preferably more than or equal to 600r/min.
In the scheme, the ceramic powder in the step (2) is sieved by sieve holes with 50 meshes or more before use, the pH value is preferably 2.5-3.2 after the acid solution is added, and the stirring time is preferably 2 hours or more.
In the scheme, the pH value of the solution added in the step (3) is preferably 3.0-4.0, the acid adding speed is less than or equal to (1 ml/min)/200 ml of the solution, the stirring time is preferably more than or equal to 3 hours, and the stirring speed is preferably more than or equal to 600r/min.
In the scheme, the solute type of the additive solution in the step (4) comprises organic matter sawdust powder, rice hull powder, starch and sesbania powder, or one of inorganic matter coal powder and carbon powder or a composite agent consisting of two or more of the organic matter coal powder and the carbon powder, and the additive solution is sieved by sieve holes with the mesh size of more than or equal to 50 meshes before use.
In the scheme, the acid solution is added into the coating slurry in the step (5) for adjustment, the pH value is preferably 2.5-3.2, the acid adding speed is less than or equal to (1 ml/min)/200 ml of solution, the stirring time is preferably greater than or equal to 2h, and the stirring speed is preferably greater than or equal to 600r/min.
In the scheme, the sieve holes of the ceramic powder and the additive after sieving are preferably more than or equal to 80 meshes.
The invention has the following technical characteristics:
(1) In the preparation process of the catalyst, the addition mode of the acid can improve the hydroxylation effect of the binder slurry, increase the cohesiveness, improve the integral abrasion resistance of the catalyst and improve the strength;
(2) The acidified modified molecular sieve is used as an active component, so that the use temperature of the SCR denitration catalyst can be effectively reduced, the active temperature window in the denitration process can be greatly widened, and the flexibility of the design of the process flow for removing nitrogen oxides and sulfur oxides is improved;
(3) The ceramic powder treated by acid is used as the composition of coating slurry, so that the abrasion resistance of the catalyst can be improved;
(4) The added additive components can effectively increase the porosity of the catalyst, enhance the contact space of gas and the catalyst and improve the activity of the catalyst while ensuring the integral strength of the catalyst;
(5) The prepared catalyst does not generate harmful substances with secondary pollution in the using, replacing and regenerating processes, and has the advantage of obvious environmental protection compared with the traditional SCR denitration catalyst.
Detailed Description
The present invention will be described in detail with reference to specific examples, but the present invention is not limited to these examples. The embodiment comprises the influence of the prepared catalyst on the removal treatment effect of the nitrogen oxide-containing tail gas when parameters such as the type, concentration and dripping speed of acid, the adjusted pH value, stirring speed, time and the like are changed in the acid treatment process. It is not excluded that the removal rate of nitrogen oxides can be further improved by other optimization based on the above-mentioned preparation method or process operation conditions.
Typical evaluation conditions of the SCR denitration catalyst prepared by acid treatment:
loading the acid-treated coating slurry to prepare a monolithic catalyst, adjusting the feed N 2 、NO/N 2 Gas distribution and NH 3 /N 2 Distributing air and ensuring N (NH) 3 ) The catalyst volume space velocity of the catalyst is 4050/h, and the reaction temperature is 350 ℃ or 180 ℃. The intake NO content was set to 1110ppm and the oxygen concentration was set to 1.1%.
Before reaction, the reactor is installed without catalyst, gas channels are communicated, the gas flow of each channel is regulated, and the reactor is communicated after stabilizationAnalyzing the mixed gas by a flue gas analyzer, and measuring the NO content before reaction in . Filling catalyst, starting gas intake after the temperature is raised to the reaction temperature, setting flow rate, analyzing and recording tail gas composition at intervals after the reaction is started, and measuring the NO content NO after the reaction out 。
The formula for the calculation of NO conversion is:
Figure GDA0002974320080000041
in the formula, Y NO Is the conversion of NO, NO in NO content (ppm) in intake air out Is the NO content (ppm) in the exhaust gas.
NO concentration C in the exhaust gas under standard conditions NO The calculation formula of (2) is as follows:
Figure GDA0002974320080000042
in the formula, C NO Is the concentration of NO in the exhaust gas (mg/m) 3 )，NO out Is the NO content (ppm) in the exhaust gas.
Example 1
Preparing 25wt% molecular sieve Fe 2 O 3 200ml of/ZSM-5 aqueous solution, 600r/min 75wt% formic acid solution was added dropwise at a rate of 1ml/min with stirring, and the pH was adjusted to =2.8. Sieving cordierite powder through a sieve with 80 meshes to prepare 40ml of 25wt% aqueous solution, adding 75wt% formic acid solution under stirring, and adjusting the pH to be =2.8. 250ml of an 8wt% aqueous solution of pseudoboehmite was prepared, and a 75wt% formic acid solution was added at a dropping rate of 1.25ml/min under stirring at 600r/min, to adjust the pH =3.7. The aqueous solutions are stirred for 5 hours at the speed of 600r/min for standby. Sieving the carbon powder through a sieve with 80 meshes, and uniformly dispersing the carbon powder in water, wherein the adding amount of the carbon powder accounts for 4% of the total amount of the solid. Mixing the aqueous solution into a pseudo-boehmite aqueous solution under the condition of stirring, placing the honeycomb cordierite carrier into the mixed solution after stirring for 2 hours for dip coating, placing the catalyst in a ventilation place for drying at normal temperature after dipping, and repeating the operation of dip drying for 3 times. Is arranged at a muffleAnd roasting the furnace at the temperature of 560 ℃ for 2h to prepare the acid-treated integrally-coated SCR denitration catalyst.
The reaction temperature of the catalyst was evaluated to be 370 ℃ and the results are shown in Table 1.
Example 2
Preparing 25wt% molecular sieve Fe 2 O 3 200ml of/ZSM-5 aqueous solution, adding a 65wt% acetic acid solution at a dropping rate of 1ml/min with stirring at 600r/min, and adjusting pH =3.0. Sieving cordierite powder through a sieve with 80 meshes to prepare 40ml of 25wt% aqueous solution, adding 65wt% acetic acid solution under stirring, and adjusting the pH to be =3.0. 250ml of an 8wt% aqueous pseudoboehmite solution was prepared, and a 65wt% acetic acid solution was added thereto at a dropping rate of 1ml/min with stirring at 600r/min, to adjust pH =3.5. The aqueous solutions are stirred for 5 hours at the speed of 600r/min for standby. Sieving the carbon powder through a sieve with 80 meshes, and uniformly dispersing the carbon powder in water, wherein the adding amount of the carbon powder accounts for 4% of the total amount of the solid. Mixing the aqueous solution into a pseudo-boehmite aqueous solution under the condition of stirring, placing the honeycomb cordierite carrier into the mixed solution after stirring for 2 hours for dip coating, placing the catalyst in a ventilation place for drying at normal temperature after dipping, and repeating the operation of dip drying for 3 times. And (3) roasting the catalyst in a muffle furnace at the temperature of 560 ℃ for 2h to prepare the acid-treated integrally-coated SCR denitration catalyst.
The reaction temperature of the catalyst was evaluated to be 370 ℃ and the results are shown in Table 1.
Example 3
Preparing 20wt% of molecular sieve Fe 2 O 3 250ml of an aqueous ZSM-5 solution was added to a concentrated hydrochloric acid solution at a dropping rate of 2.5ml/min with stirring at 700r/min to adjust the pH =2.9. The cordierite powder is sieved through a sieve with 80 meshes to prepare 50ml of 20wt% aqueous solution, concentrated hydrochloric acid solution is added under the stirring condition, and the pH is adjusted to be =2.9. 250ml of 8wt% alumina sol aqueous solution was prepared, and concentrated hydrochloric acid solution was added thereto at a dropping rate of 2.5ml/min under stirring at 700r/min to adjust the pH =3.4. The aqueous solutions are stirred for 5h at the speed of 700r/min for standby. Sieving sesbania powder through a 80-mesh sieve, and uniformly dispersing in water, wherein the addition amount of the sesbania powder accounts for 4% of the total amount of the solid. Mixing the above aqueous solution with alumina sol aqueous solution under stirring, stirring for 2 hr, and mixing with honeycomb cordieriteAnd placing the bluestone carrier into the mixed solution for dip coating, placing the catalyst in a ventilation place for normal temperature air drying after dipping, and repeating the operation of dip air drying for 3 times. And (3) roasting the catalyst in a muffle furnace at the temperature of 560 ℃ for 2h to prepare the acid-treated integrally-coated SCR denitration catalyst.
The reaction temperature of the catalyst was evaluated to be 370 ℃ and the results are shown in Table 1.
Example 4
Preparing 20wt% of molecular sieve Fe 2 O 3 250ml of/ZSM-5 aqueous solution, adding concentrated nitric acid solution at the dropping speed of 2.5ml/min under the stirring condition of 700r/min, and adjusting the pH to be =2.85. And sieving cordierite powder through a sieve with 80 meshes to prepare 50ml of 20wt% aqueous solution, adding concentrated nitric acid solution under the stirring condition, and adjusting the pH to be =2.85. 250ml of 8wt% aluminum sol aqueous solution is prepared, a concentrated nitric acid solution is added at a dropping speed of 2.5ml/min under the stirring condition of 700r/min, and the pH is adjusted to be =3.3. The aqueous solutions are stirred for 5 hours at the speed of 700r/min for standby. Sieving sesbania powder through a sieve with 80 meshes, and uniformly dispersing the sesbania powder in water, wherein the addition amount of the sesbania powder accounts for 4% of the total amount of the solid. And mixing the aqueous solution into an aluminum sol aqueous solution under the stirring condition, stirring for 2 hours, putting the honeycomb cordierite carrier into the mixed solution for dip coating, putting the catalyst in a ventilation place for normal temperature airing after dipping, and repeating the dip airing operation for 3 times. And (3) roasting the catalyst in a muffle furnace at the temperature of 560 ℃ for 2h to prepare the acid-treated integrally-coated SCR denitration catalyst.
The reaction temperature of the catalyst was evaluated to be 370 ℃ and the results are shown in Table 1.
Example 5
The catalyst prepared in example 1 was tested for sulfur oxide resistance and SO was increased 2 Gas source, regulating SO 2 The feed gas content was 0.1% by volume, and the reaction temperature was 370 ℃ and the results are shown in Table 1.
Example 6
The hydrothermal aging performance of the catalyst prepared in example 1 was examined. The catalyst was aged for 24h at 550 ℃ with 1.2% steam. The catalyst was evaluated after the aging treatment at a reaction temperature of 370 ℃ and the results are shown in Table 1.
TABLE 1 acid treatmentSCR denitration catalyst Fe 2 O 3 Effect of/ZSM-5 on NO removal Performance
Figure GDA0002974320080000061
In summary, the SCR denitration catalyst Fe 2 O 3 In the preparation process of the ZSM-5, the prepared catalyst has certain influence on the removal treatment of the tail gas containing the nitrogen oxides by changing the parameters such as the type, concentration and dropping speed of the added acid, the adjusted pH value, the stirring speed, time and the like, and the parameters such as the existence of the sulfur oxides, hydrothermal steam aging and the like. After the catalyst is operated, the NO removal rate of the catalyst is gradually improved and is stable after a period of time. As shown in Table 1, under certain conditions, the organic acid has better treatment effect than the inorganic acid, the acid concentration and the stirring speed are increased, the acid treatment time is prolonged, and the catalyst activity and stability are improved when the dropping speed is reduced. In addition, the type and the amount of the additive can affect the activity and the strength of the catalyst, and the type and the amount of the additive have an inverse correlation in a certain range. SO 2 The catalyst activity is obviously reduced due to the existence of the catalyst, and parameters such as the content of water vapor, the temperature, the aging time and the like are important factors influencing the stable operation of the catalyst. Experimental results show that the catalyst can still obtain higher NO conversion rate in the hydrothermal steam aging process. Moreover, the catalyst with better catalytic effect can be further obtained by optimizing the proportion through the scheme description.
Example 7
Preparing 25wt% molecular sieve Fe 2 O 3 200ml of-CuO/ZSM-5 aqueous solution, 600r/min stirring, 85wt% formic acid solution was added at a dropping rate of 1ml/min, and pH =2.85 was adjusted. The cordierite powder is sieved through a sieve with 80 meshes to prepare 40ml of 25wt% aqueous solution, 85wt% formic acid solution is added under the stirring condition, and the pH is adjusted to be =2.85. 250ml of an 8wt% aqueous solution of pseudoboehmite was prepared, and an 85wt% formic acid solution was added at a dropping rate of 1.25ml/min under stirring at 600r/min, and the pH was adjusted to =3.6. The aqueous solutions are stirred for 5h at the speed of 600r/min for standby. Sieving sesbania powder with 80 mesh sieve, and uniformly dividing in waterThe addition amount of the sesbania powder in the powder accounts for 4.5 percent of the total amount of the solid. Mixing the aqueous solution into a pseudo-boehmite aqueous solution under the condition of stirring, placing the honeycomb cordierite carrier into the mixed solution after stirring for 2 hours for dip coating, placing the catalyst in a ventilation place for drying at normal temperature after dipping, and repeating the operation of dip drying for 3 times. And roasting the mixture for 2 hours at the temperature of 550 ℃ in a muffle furnace to prepare the acid-treated integrally-coated SCR denitration catalyst.
The catalyst was evaluated at a reaction temperature of 180 ℃ and the results are shown in Table 2.
Example 8
Preparing 25wt% molecular sieve Fe 2 O 3 200ml of-CuO/ZSM-5 aqueous solution, 600r/min stirring, 75wt% citric acid solution was added at a dropping rate of 1ml/min, and pH =2.85 was adjusted. Sieving cordierite powder through a sieve with 80 meshes to prepare 40ml of 25wt% aqueous solution, adding 75wt% citric acid solution under stirring, and adjusting the pH to be =2.85. 250ml of an 8wt% alumina sol aqueous solution was prepared, and a 75wt% citric acid solution was added thereto at a dropping rate of 1.25ml/min under stirring at 600r/min to adjust the pH =3.5. The aqueous solutions are stirred for 5h at the speed of 600r/min for standby. Sieving the carbon powder through a sieve with 80 meshes, and uniformly dispersing the carbon powder in water, wherein the adding amount of the carbon powder accounts for 4.5 percent of the total amount of the solid. And mixing the aqueous solution into an aluminum sol aqueous solution under the stirring condition, stirring for 2 hours, putting the honeycomb cordierite carrier into the mixed solution for dip coating, putting the catalyst in a ventilation place for normal temperature airing after dipping, and repeating the dip airing operation for 3 times. And roasting the mixture for 2 hours at the temperature of 550 ℃ in a muffle furnace to prepare the acid-treated integrally-coated SCR denitration catalyst.
The catalyst was evaluated at a reaction temperature of 180 ℃ and the results are shown in Table 2.
Example 9
Preparing 20wt% of molecular sieve Fe 2 O 3 250ml of-CuO/ZSM-5 aqueous solution, adding a concentrated nitric acid solution at a dropping speed of 2.5ml/min under stirring at 700r/min, and adjusting the pH to be =2.8. And sieving the cordierite powder through a sieve with a 80-mesh sieve to prepare 50ml of 20wt% aqueous solution, adding a concentrated nitric acid solution under the stirring condition, and adjusting the pH to be =2.8. 250ml of 8wt% aluminum sol aqueous solution is prepared, 2.5ml/min is carried out under the stirring condition of 700r/minConcentrated nitric acid solution was added at the drop rate and pH =3.4 was adjusted. The aqueous solutions are stirred for 5h at the speed of 700r/min for standby. Sieving the carbon powder through a 80-mesh sieve, and uniformly dispersing in water, wherein the adding amount of the carbon powder accounts for 4.5% of the total amount of the solid. And mixing the aqueous solution into an alumina sol aqueous solution under the condition of stirring, placing the honeycomb cordierite carrier into the mixed solution after stirring for 2 hours for dip coating, placing the catalyst in a ventilated place for normal temperature air drying after dipping, and repeating the operation of dip air drying for 3 times. And roasting the mixture for 2 hours at the temperature of 550 ℃ in a muffle furnace to prepare the acid-treated integrally-coated SCR denitration catalyst.
The catalyst was evaluated at a reaction temperature of 180 ℃ and the results are shown in Table 2.
Example 10
The catalyst prepared in example 7 was tested for sulfur oxide resistance and SO was increased 2 Gas source, regulating SO 2 The feed gas content was 0.1% by volume, the reaction temperature was 180 ℃ and the results are shown in Table 2.
Example 11
Hydrothermal aging performance test was performed on the catalyst prepared in example 7. The catalyst was aged for 24h at 550 ℃ with 1.2% steam. The catalyst was evaluated after the aging treatment at a reaction temperature of 180 ℃ and the results are shown in Table 2.
TABLE 2 acid treated SCR denitration catalyst Fe 2 O 3 Effect of-CuO/ZSM-5 on NO removal Performance
Figure GDA0002974320080000081
In conclusion, it can be seen that the acid-treated SCR denitration catalyst Fe 2 O 3 the-CuO/ZSM-5 can obtain higher NO removal efficiency under the condition that the reaction temperature is 180 ℃. The sulfur oxides have obvious influence on the catalyst, but in the actual operation process, the catalyst can show good catalytic denitration activity at a lower temperature, so that the tail gas to be treated can be subjected to desulfurization treatment in advance through design, and the sulfur poisoning can be avoided by reducing the concentration of the sulfur oxides entering a denitration system. And the desulfurization process causesThe normal operation of the denitration process can be met due to the temperature loss. The results in the presence of hydrothermal steam show that the acid treatment is effective in improving the stability of the catalyst.

Claims (7)

1. A method for improving SCR denitration stability of a catalyst by an acid treatment mode is characterized by comprising the following steps:
the SCR denitration catalyst coating slurry is formed by mixing a molecular sieve, ceramic powder, a binder and an additive solution under the stirring condition, the SCR denitration catalyst coating slurry needs to be treated by acid in advance before mixing, and the treatment steps are as follows:
(1) Acid treatment of the molecular sieve solution: adding a molecular sieve into deionized water for uniform dispersion, adding an acid solution at a constant speed under the stirring condition to enable the pH value of the solution to meet 1.5-3.5, wherein the acid addition speed is less than or equal to (1 mL/min)/100 mL of the solution, stirring for more than or equal to 1h, wherein the stirring speed is more than or equal to 400r/min, and repeating the operations of adjusting the pH value by adding acid and stirring for more than or equal to 1 time;
(2) Acid treatment of ceramic powder solution: adding the ceramic powder into deionized water for uniform dispersion, adding an acid solution at a constant speed under the stirring condition to enable the pH value of the solution to meet 1.5-3.5, and stirring for more than or equal to 1h;
(3) Acid-treated binder solution: adding the binder into deionized water for uniform dispersion, adding an acid solution at a constant speed under the stirring condition to ensure that the pH value of the solution meets 2.0 to 4.0, the acid addition speed is less than or equal to (1 mL/min)/100 mL of the solution, stirring for more than or equal to 2 hours at a stirring speed of more than or equal to 400r/min, and repeating the pH value adjustment and stirring operation of adding acid for more than or equal to 1 time;
(4) Preparing an additive solution: adding the additive into deionized water, and stirring until the additive is uniformly dispersed;
(5) Preparing coating slurry: adding the molecular sieve solution subjected to acid treatment in the steps (1) and (2), the ceramic powder solution and the additive solution uniformly dispersed in the step (4) into the binder solution subjected to acid treatment in the step (3) under the condition of stirring, adding an acid solution at a constant speed for regulation to enable the pH value of the slurry to meet 1.5-3.5, wherein the acid adding speed is less than or equal to (1 mL/min)/100 mL, stirring for more than or equal to 1h, and the stirring speed is more than or equal to 400r/min to prepare a coating slurry;
the acid is one or more of formic acid, acetic acid and citric acid, or hydrochloric acid, nitric acid and nitrous acid, the concentration of the formic acid, the acetic acid and the citric acid is more than or equal to 50wt%, and the concentration of the hydrochloric acid, the nitric acid and the nitrous acid is more than or equal to 10wt%;
the molecular sieve is a ZSM-5 molecular sieve impregnated by a mixed solution of iron salt or iron salt and copper salt, and the ceramic powder is one or two or more of cordierite, mullite, activated alumina, aluminum titanate, zirconia and silicon nitride; the binder is one or a composite matrix consisting of two or more of pseudo-boehmite, silica sol, aluminum sol and titanium sol;
the additive in the step (4) comprises organic matter sawdust powder, rice hull powder, starch and sesbania powder, or one or a composite additive consisting of two or more of inorganic matter coal powder and carbon powder, and the additive is sieved by a sieve mesh with a mesh size of more than or equal to 50 meshes before use.
2. The method of claim 1, wherein: the concentration of the formic acid, the acetic acid and the citric acid is more than or equal to 65wt%, and the concentration of the hydrochloric acid, the nitric acid and the nitrous acid is more than or equal to 25wt%.
3. The method of claim 1, wherein: in the step (1), after the acid solution is added, the pH value is 2.5 to 3.2, the acid adding speed is less than or equal to (1 mL/min)/200 mL of the solution, the stirring time is more than or equal to 2 hours, and the stirring speed is more than or equal to 600r/min.
4. The method of claim 1, wherein: sieving by sieve holes with the size of more than or equal to 50 meshes before use in the step (2), adding an acid solution, and then stirring for more than or equal to 2 hours, wherein the pH value is 2.5-3.2.
5. The method of claim 1, wherein: after the acid solution is added in the step (3), the pH value is 3.0 to 4.0, the acid adding speed is not more than (1 mL/min)/200 mL of the solution, the stirring time is not less than 3h, and the stirring speed is not less than 600r/min.
6. The method of claim 1, wherein: and (5) adding an acid solution into the coating slurry to adjust the pH value to be 2.5 to 3.2, wherein the acid adding speed is not more than 1 mL/min)/200 mL of the solution, the stirring time is not less than 2h, and the stirring speed is not less than 600r/min.
7. The method of claim 4, wherein: the sieve holes of the ceramic powder and the additive after sieving are more than or equal to 80 meshes.
CN202011523300.XA 2020-12-21 2020-12-21 Method for improving SCR denitration stability of catalyst by acid treatment Active CN112774723B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202011523300.XA CN112774723B (en) 2020-12-21 2020-12-21 Method for improving SCR denitration stability of catalyst by acid treatment

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202011523300.XA CN112774723B (en) 2020-12-21 2020-12-21 Method for improving SCR denitration stability of catalyst by acid treatment

Publications (2)

Publication Number Publication Date
CN112774723A CN112774723A (en) 2021-05-11
CN112774723B true CN112774723B (en) 2023-01-17

Family

ID=75751604

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202011523300.XA Active CN112774723B (en) 2020-12-21 2020-12-21 Method for improving SCR denitration stability of catalyst by acid treatment

Country Status (1)

Country Link
CN (1) CN112774723B (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113976169A (en) * 2021-11-16 2022-01-28 浙江大学 Corrugated molecular sieve supported catalyst and preparation method and application thereof
CN114309119B (en) 2021-12-29 2023-10-20 常州大学 Graphene/copper composite deformed copper-chromium-zirconium alloy layered strip and preparation method thereof

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101797518B (en) * 2010-04-14 2012-08-22 太原理工大学 Method for preparing monolithic catalyst for purification of diesel exhaust
CN106732758A (en) * 2015-11-19 2017-05-31 中国石油化工股份有限公司 A kind of low-temperature denitration catalyst and preparation method thereof
CN109499607A (en) * 2018-11-13 2019-03-22 中节能万润股份有限公司 A kind of copper and iron composite honeycomb coating type denitrating catalyst and its preparation method and application
CN109317188A (en) * 2018-11-14 2019-02-12 福州大学 A kind of preparation method and application of mesoporous FeCu-ZSM-5 molecular sieve
CN110947416B (en) * 2019-12-18 2023-06-13 武汉科技大学 For NH 3 Iron/molecular sieve catalyst of SCR (selective catalytic reduction), and preparation method and application thereof

Also Published As

Publication number Publication date
CN112774723A (en) 2021-05-11

Similar Documents

Publication Publication Date Title
US20200188894A1 (en) Chabazite zeolite catalysts having low silica to alumina ratios
CN112657541B (en) Preparation method of molecular sieve based low-temperature environment-friendly SCR denitration catalyst
CN110614101A (en) Catalyst for catalytic combustion of VOCs and preparation method thereof
CN112774723B (en) Method for improving SCR denitration stability of catalyst by acid treatment
US20100143223A1 (en) Denitrification Catalyst, Honeycomb Structure Type Denitrification Catalyst, and Method of Denitrification with the Same
WO2012128297A1 (en) Catalyst for exhaust gas purification, method for producing same, and exhaust gas purification method using same
CN109590014B (en) Integral diesel vehicle tail gas oxidation catalyst and preparation method thereof
CN111229305B (en) Molybdenum modified Fe-ZSM5 molecular sieve catalyst and preparation method and application thereof
US5141906A (en) Catalyst for purifying exhaust gas
CN112058261B (en) Integral diesel exhaust oxidation catalyst, preparation method and application
CN1711134A (en) Exhaust gas purifying catalyst and method for purifying exhaust gas
US20170128914A1 (en) Exhaust gas treatment system
CN111111656B (en) High-temperature-resistant catalytic combustion catalyst capable of catalyzing and igniting VOCs (volatile organic compounds) to perform self-sustaining combustion at normal temperature and preparation method and application thereof
CN112547090A (en) Monolithic catalyst, preparation method and application thereof
CN110479359A (en) Low silica-alumina ratio high stability cupric molecular sieve catalyst and preparation method thereof
US20140349840A1 (en) Ammonia oxidation catalyst in scr system
CN112934234A (en) DOC catalyst for diesel tail gas after-treatment system
KR102193496B1 (en) Diesel oxidation catalyst with excellent heat durability and Method thereof
US10801384B2 (en) Diesel oxidation catalyst containing manganese
US20160279610A1 (en) Zoned diesel oxidation catalyst
CN114797893A (en) Ammonia oxidation catalyst and preparation method and application thereof
KR100275301B1 (en) Method for removing nox using the natural manganese ores
EP3015167A1 (en) Ammonia oxidation catalyst in scr system
CN105772098A (en) Catalyst for removing NOx by ammonia selective catalytic reduction and preparation method thereof
CN115591575B (en) Denitration catalyst and preparation method and application thereof

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant