CN112169831A - Holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst and preparation method thereof - Google Patents

Holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst and preparation method thereof Download PDF

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CN112169831A
CN112169831A CN202011245537.6A CN202011245537A CN112169831A CN 112169831 A CN112169831 A CN 112169831A CN 202011245537 A CN202011245537 A CN 202011245537A CN 112169831 A CN112169831 A CN 112169831A
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sapo
molecular sieve
holmium
carrier
catalyst
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王新星
李飞
黄伟
仵静
李梦婕
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Xi'an Origin Chemical Technologies Co ltd
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    • 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
    • B01J29/82—Phosphates
    • B01J29/84—Aluminophosphates containing other elements, e.g. metals, boron
    • B01J29/85—Silicoaluminophosphates (SAPO compounds)
    • 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
    • B01D53/8621—Removing nitrogen compounds
    • B01D53/8625—Nitrogen oxides
    • B01D53/8628—Processes characterised by a specific catalyst
    • B01J35/61—
    • 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
    • B01J37/08—Heat treatment
    • B01J37/10—Heat treatment in the presence of water, e.g. steam
    • 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

Abstract

The invention discloses a holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst, which comprises a carrier Ce-SAPO-34 molecular sieve, an active modified component holmium and copper composite oxide loaded on the carrier, and an adhesive Al2O3(ii) a The invention also provides a preparation method of the catalyst, which comprises the following steps: firstly, preparing a carrier through a hydrothermal reaction; secondly, preparing impregnation liquid of soluble salt of the Ho and Cu precursors;thirdly, mixing and impregnating the impregnating solution and the carrier; fourthly, roasting after extrusion molding to obtain a target product. The catalyst disclosed by the invention improves the low-temperature denitration activity and the water and sulfur resistance of the catalyst, reduces the active temperature of the catalyst and widens the active temperature window by virtue of the synergistic effect of the holmium and copper composite oxides and Ce in the Ce-SAPO-34 molecular sieve and the tetrahedral small-aperture pore channel structure of the carrier; the preparation method is simple and feasible.

Description

Holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst and preparation method thereof
Technical Field
The invention belongs to the technical field of catalysts, and particularly relates to a holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst and a preparation method thereof.
Background
NOxMainly comprising N2O、NO、NO2And the like, which are a kind of atmospheric composite pollutants generated in tail gases of current industrial coal, gas-fired boilers, diesel engine moving sources and the like. NO volatilized in the atmospherexThe acid rain is combined with water vapor to generate acid rain which is harmful to crops, buildings and human health, and can react with volatile organic compounds to generate ozone and form photochemical smog under the action of illumination, and the generated greenhouse effect is approximately CO2200-300 times of the total amount of the active carbon, and has great harm to the environment.
With the continuous and stable development of national economy in recent years, NOxThe pollution is more and more serious, and NO is dischargedxThe treatment of (2) is already imminent. The destructive of the medicines is realized by all countries of the world, and related laws and regulations are issued successively to control NOxAnd (4) emission, wherein the German and Japanese control standards are the strictest. The energy structure of China is mainly coal, and NO generated by a thermal power plant is increased along with the continuous increase of the power demand of ChinaxAnd is also growing. The quantity of diesel vehicles in China is increasing continuously, and the diesel vehicles NOxEmissions are also a non-negligible source of pollution. China sets corresponding emission standards according to national conditions, and the national environmental protection department and the national quality supervision, inspection and quarantine bureau issue 2011 'emission standards of atmospheric pollutants for thermal power plants' (GB13223-2011) which stipulate NO in emitted smokexThe concentration is 100mg/Nm3On the basis, more severe discharge standards are established in various places according to the current development situation of the economic society. The industries of glass, cement, ceramics and steel have been issued or are planned to be issuedIn the cloth standard, NO is shrunkxThe emission limit of (c).
At present, the denitration technology is selected from a selective catalytic reduction method (SCR), a selective non-catalytic reduction method (SNCR), wet denitration and the like, the most applied and mature industrial technology is the selective catalytic reduction method (SCR), and the denitration technology is widely applied to denitration of industrial flue gas of thermal power plants, incineration plants and the like and purification of tail gas of diesel motor vehicles. The key of the technology is a high-activity, high-selectivity and high-stability catalyst. The traditional denitration catalyst is a vanadium-tungsten-titanium system, has been developed relatively well, and has the advantages that: (1) the denitration efficiency is high and can reach more than 90% under proper conditions; (2) the temperature range of the reaction window is wider, and the preferable temperature range is 300-420 ℃; (3) the cost is relatively low, the manufacturing process is mature, and the product quality can be effectively controlled; (4) the operation, the operation and the maintenance are stable; (5) anti-SO2The capability is stronger. Although vanadium tungsten titanium denitration catalysts are widely used, there are many problems to be solved in the application process, including: (1) the use temperature is high, and the operation and maintenance cost is high; (2) narrow temperature window, and is not suitable for low temperature of non-electric industries such as steel, glass and the like<200 ℃) denitration industry; (3) vanadium is easy to lose, and secondary environmental pollution risks exist; (4) the vanadium-based waste catalyst has environmental pollution, needs special treatment and has higher treatment cost. Aiming at the problems existing in the application of the current vanadium-tungsten-titanium denitration catalyst, a high-performance non-vanadium-based low-temperature molecular sieve denitration catalyst needs to be developed, so that the denitration treatment level is further improved.
Disclosure of Invention
The invention aims to solve the technical problem of providing a holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst aiming at the defects of the prior art. The catalyst improves the low-temperature denitration activity and the water and sulfur resistance of the catalyst, reduces the activity temperature of the catalyst, widens the activity temperature window and ensures that the NO conversion rate of the catalyst at 150-300 ℃ can reach 70-100% by combining the synergistic effect of the holmium and copper composite oxide and the Ce element in the Ce-SAPO-34 molecular sieve and the unique Si, P and Al tetrahedral small-aperture pore channel structure of the Ce-SAPO-34 molecular sieve.
In order to solve the technical problems, the invention adopts the technical scheme that: the catalyst is characterized by comprising a carrier Ce-SAPO-34 molecular sieve, an active modified component holmium and copper composite oxide loaded on the carrier, and a binder Al2O3In the catalyst, the mass content of the Ce-SAPO-34 molecular sieve as a carrier and the holmium and copper composite oxides as active modification components loaded on the carrier is 50-90%, and the balance is Al2O3Wherein, the loading capacity of holmium element in the active modification component is 0.5-2 percent and the loading capacity of copper element is 0.5-3 percent by taking the mass of the carrier Ce-SAPO-34 molecular sieve as a reference.
The catalyst comprises a carrier Ce-SAPO-34 molecular sieve and an active modified component holmium and copper composite oxide loaded on the carrier, wherein Ce is introduced into a framework of the carrier Ce-SAPO-34 molecular sieve, so that the catalyst has richer surface oxygen vacancies, stronger redox capability and stability, and H is effectively eliminated2Competitive adsorption of the nitrate substances by O, so that the sulfur resistance and the water resistance of the catalyst are improved; secondly, the holmium oxide in the activity modifying component increases the specific surface area of the catalyst, improves the concentration of oxygen chemically adsorbed by the catalyst, and enhances the acidity of the catalyst, thereby improving the low-temperature activity of the catalyst, and the holmium and copper composite oxide provides a more excellent metal active center for the catalyst. In conclusion, the catalyst disclosed by the invention synergistically modulates the properties of surface oxygen vacancy, specific surface area, acidity, metal activity and the like of the catalyst through the synergistic effect of the holmium and copper composite oxide and the Ce element in the Ce-SAPO-34 molecular sieve, and simultaneously combines the unique Si, P and Al tetrahedron small-aperture pore channel structure of the Ce-SAPO-34 molecular sieve, so that the low-temperature denitration activity, the water resistance and the sulfur resistance of the catalyst are improved, the activity temperature of the catalyst is reduced, the activity temperature window is widened, and the NO conversion rate of the catalyst at 150-300 ℃ can reach 70-100%.
The holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst is characterized in that Ce in the carrier Ce-SAPO-34 molecular sieve is introduced into the SAPO-34 molecular sieve through an in-situ hydrothermal synthesis method. Ce is preferably introduced into the SAPO-34 molecular sieve by an in-situ hydrothermal synthesis method to prepare the carrier Ce-SAPO-34 molecular sieve, so that the water resistance of the carrier Ce-SAPO-34 molecular sieve is enhanced.
The holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst is characterized in that the carrier Ce-SAPO-34 molecular sieve is used for preparing P in raw materials2O5、Al2O3、SiO2、CeO2、C6H15N and H2The mass ratio of O is 1.0: 1.0: 0.8: 0.2: 4.0: 60. the molecular sieve carrier with high crystallinity, small crystal grains and large specific surface area is prepared from the raw materials according to the proportion, so that a larger reaction contact area and an active center are provided for denitration reaction, and Ce is favorably introduced into a framework of the molecular sieve.
The holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst is characterized in that the adhesive Al is2O3The precursor of (A) is pseudo-boehmite. The preferable precursor is easy for catalyst molding and can provide a certain acid center for the catalyst, thereby improving the mechanical stability and catalytic reaction activity of the catalyst.
In addition, the invention also provides a method for preparing the holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst, which is characterized by comprising the following steps:
step one, respectively weighing orthophosphoric acid, pseudo-boehmite, silica sol, cerium nitrate, triethylamine and water, preparing to obtain uniform slurry, then placing the slurry in a hydrothermal reaction kettle for hydrothermal reaction, and then sequentially washing, drying and roasting to obtain a carrier Ce-SAPO-34 molecular sieve;
step two, weighing soluble salt of a holmium element precursor and soluble salt of a copper element precursor according to the loading capacity of the holmium element and the loading capacity of the copper element respectively, weighing deionized water according to the saturated water absorption capacity of the carrier Ce-SAPO-34 molecular sieve in the step one, adding the weighed soluble salt of the holmium element precursor and the weighed soluble salt of the copper element precursor into the weighed deionized water, fully stirring the mixture at room temperature until the mixture is completely dissolved, and preparing to obtain impregnation liquid;
step three, uniformly mixing the impregnation liquid obtained in the step two with the carrier Ce-SAPO-34 molecular sieve obtained in the step one, impregnating at room temperature, and drying to obtain a holmium element and copper element modified Ce-SAPO-34 molecular sieve;
step four, modifying the holmium element and copper element modified Ce-SAPO-34 molecular sieve obtained in the step three with an adhesive Al2O3And extruding the precursor into strips, drying, and roasting to obtain the holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst.
According to the invention, the Ce-SAPO-34 molecular sieve is used as a carrier, the composite oxide of holmium and copper is simultaneously loaded by an impregnation method to obtain the catalyst, and the low-temperature denitration activity, the water resistance and the sulfur resistance of the catalyst are improved, the active temperature of the catalyst is reduced, and the active temperature window is widened by virtue of the synergistic effect between the holmium and copper composite oxide and the Ce element in the SAPO-34 molecular sieve.
The method is characterized in that the temperature of the hydrothermal reaction in the step one is 200 ℃ and the time is 72 hours. The technological parameters of the hydrothermal reaction are beneficial to obtaining the Ce-SAPO-34 molecular sieve which is a carrier with high crystallinity, small crystal grains and large specific surface, and the Ce element in the raw materials for preparation is fully utilized, thereby avoiding waste.
The method is characterized in that the soluble salt of the holmium element precursor in the second step is Ho (NO)3)3·5H2O, the soluble salt of the copper element precursor is Cu (NO)3)2·6H2And O. The preferable salt is easy to dissolve to prepare an impregnation solution, and the preparation of the catalyst is convenient.
The method is characterized in that the time for soaking in the step three is 12 hours; the drying temperature is 110 ℃ and the drying time is 6 h. The optimal dipping time realizes full dipping, so that the soluble salt of the holmium element precursor and the soluble salt of the copper element precursor are uniformly dispersed on the Ce-SAPO-34 molecular sieve as the carrier; the preferable drying temperature and time effectively remove the moisture of the holmium element and copper element modified Ce-SAPO-34 molecular sieve, so that the soluble salt of the holmium element precursor and the soluble salt of the copper element precursor are uniformly adhered to the carrier Ce-SAPO-34 molecular sieve.
The method is characterized in that the roasting temperature in the fourth step is 500 ℃ and the roasting time is 4 hours. The preferable roasting temperature and time ensure that the soluble salt of the holmium element precursor and the soluble salt of the copper element precursor dispersed on the Ce-SAPO-34 molecular sieve of the carrier are completely decomposed into the composite oxide of holmium and copper, and are uniformly dispersed on the surface of the carrier without agglomeration.
Compared with the prior art, the invention has the following advantages:
1. the catalyst comprises a carrier Ce-SAPO-34 molecular sieve and an active modified component holmium and copper composite oxide loaded on the carrier, and by the synergistic effect between the holmium and copper composite oxide and the Ce element in the Ce-SAPO-34 molecular sieve and the combination of the unique Si, P and Al tetrahedron small-aperture pore channel structure of the Ce-SAPO-34 molecular sieve, the low-temperature denitration activity, the water resistance and the sulfur resistance of the catalyst are improved, the active temperature of the catalyst is reduced, the active temperature window is widened, and the NO conversion rate of the catalyst at 150-300 ℃ can reach 70-100%.
2. According to the invention, Ce is introduced into the SAPO-34 molecular sieve through the in-situ hydrothermal synthesis method to prepare the carrier Ce-SAPO-34 molecular sieve, so that the water resistance of the carrier Ce-SAPO-34 molecular sieve is enhanced, and the water resistance of the holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst is further improved.
3. The holmium oxide in the catalyst increases the specific surface area of the catalyst, improves the concentration of the oxygen chemically adsorbed by the catalyst, and enhances the acidity of the catalyst, thereby improving the low-temperature activity of the catalyst.
4. The preparation method is simple and convenient for large-scale production.
The technical solution of the present invention is further described in detail by the accompanying drawings and examples.
Drawings
FIG. 1 is an XRD pattern of Ce-SAPO-34 molecular sieves prepared in examples 1 to 5 of the invention.
Fig. 2 is a graph showing the denitration performance test of the composite oxide modified Ce-SAPO-34 molecular sieve denitration catalysts of holmium and copper according to examples 1 to 5 of the present invention and the copper oxide modified SAPO-34 molecular sieve denitration catalyst of comparative example 1.
FIG. 3 is a sulfur resistance and water resistance test chart of the composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst of holmium and copper of example 5 and the oxide modified SAPO-34 molecular sieve denitration catalyst of copper of comparative example 1.
Detailed Description
Example 1
The denitration catalyst of the holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve comprises a Ce-SAPO-34 molecular sieve as a carrier, holmium and copper composite oxides as active modified components loaded on the carrier, and an Al binder2O3In the catalyst, the mass content of the Ce-SAPO-34 molecular sieve as a carrier and the holmium and copper composite oxides as active modification components loaded on the carrier is 50%, and the balance is Al2O3Wherein the loading amount of holmium element in the active modification component is 0.5 percent and the loading amount of copper element is 0.5 percent by taking the mass of the carrier Ce-SAPO-34 molecular sieve as a reference.
The preparation method of the holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst comprises the following steps:
step one, 1493.2g of orthophosphoric acid solution with the mass concentration of 85 percent and 985.5gAl are weighed2O3Pseudo-boehmite with mass content of 67 percent and 778.2gSiO2Preparing uniform slurry by using 40% of silica sol by mass concentration, 562.4g of cerium nitrate hexahydrate with the mass purity of 99%, 2647.7g of triethylamine with the mass purity of 99% and 533g of deionized water, placing the slurry in a hydrothermal reaction kettle, carrying out hydrothermal reaction at the temperature of 200 ℃ for 72 hours, and then sequentially washing, drying and roasting to obtain a carrier Ce-SAPO-34 molecular sieve;
step two, weighing 0.67g Ho (NO) with the mass purity of 99.9%3)3·5H2O and 1.16g of Cu (NO) having a mass purity of 99.9%3)2·6H2Adding O into 25.0g of deionized water, and fully stirring at room temperature until the O is completely dissolved to prepare a dipping solution;
step three, uniformly mixing the impregnation liquid obtained in the step two with 50g of the carrier Ce-SAPO-34 molecular sieve obtained in the step one, impregnating for 12 hours at room temperature, and drying for 6 hours at 110 ℃ to obtain a holmium element and copper element modified Ce-SAPO-34 molecular sieve;
step four, mixing 50g of holmium element and copper element modified Ce-SAPO-34 molecular sieve obtained in the step three with 74.6gAl2O3And extruding and molding 67% of pseudo-boehmite by mass, drying, and roasting at 500 ℃ for 4h to obtain the holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst.
Example 2
The denitration catalyst of the holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve comprises a Ce-SAPO-34 molecular sieve as a carrier, holmium and copper composite oxides as active modified components loaded on the carrier, and an Al binder2O3In the catalyst, the mass content of the Ce-SAPO-34 molecular sieve as a carrier and the holmium and copper composite oxides as active modification components loaded on the carrier is 90%, and the balance is Al2O3Wherein the loading amount of holmium element in the active modification component is 0.5 percent and the loading amount of copper element is 3.0 percent based on the mass of the carrier Ce-SAPO-34 molecular sieve.
The preparation method of the holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst comprises the following steps:
step one, 1493.2g of orthophosphoric acid solution with the mass concentration of 85 percent and 985.5gAl are weighed2O3Pseudo-boehmite with mass content of 67 percent and 778.2gSiO2Preparing silica sol with the mass concentration of 40%, 562.4g of cerous nitrate hexahydrate with the mass purity of 99%, 2647.7g of triethylamine with the mass purity of 99% and 533g of deionized water to obtain uniform slurry, placing the slurry in a hydrothermal reaction kettle, carrying out hydrothermal reaction at the temperature of 200 ℃ for 72 hours, and then carrying out hydrothermal reaction on the slurry for 72 hoursWashing, drying and roasting in sequence to obtain a carrier Ce-SAPO-34 molecular sieve;
step two, weighing 1.20g Ho (NO) with the mass purity of 99.9%3)3·5H2O and 12.56g of Cu (NO) having a mass purity of 99.9%3)2·6H2Adding O into 45.0g of deionized water, and fully stirring at room temperature until the O is completely dissolved to prepare a dipping solution;
step three, uniformly mixing the impregnation liquid obtained in the step two with 90g of the carrier Ce-SAPO-34 molecular sieve obtained in the step one, impregnating for 12 hours at room temperature, and drying for 6 hours at 110 ℃ to obtain a holmium element and copper element modified Ce-SAPO-34 molecular sieve;
step four, mixing 90g of holmium element and copper element modified Ce-SAPO-34 molecular sieve obtained in the step three with 14.9gAl2O3And extruding and molding 67% of pseudo-boehmite by mass, drying, and roasting at 500 ℃ for 4h to obtain the holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst.
Example 3
The denitration catalyst of the holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve comprises a Ce-SAPO-34 molecular sieve as a carrier, holmium and copper composite oxides as active modified components loaded on the carrier, and an Al binder2O3In the catalyst, the mass content of the Ce-SAPO-34 molecular sieve as a carrier and the holmium and copper composite oxides as active modification components loaded on the carrier is 80 percent, and the balance is Al2O3Wherein the loading capacity of holmium element in the active modification component is 2.0 percent and the loading capacity of copper element is 0.5 percent by taking the mass of the carrier Ce-SAPO-34 molecular sieve as a reference.
The preparation method of the holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst comprises the following steps:
step one, 1493.2g of orthophosphoric acid solution with the mass concentration of 85 percent and 985.5gAl are weighed2O3Pseudo-boehmite with mass content of 67 percent and 778.2gSiO240% by mass of silica sol, 562.4g of 99% by mass purity cerium nitrate hexahydrate, 2647.7g of triethylamine with the mass purity of 99 percent and 533g of deionized water are prepared to obtain uniform slurry, then the slurry is placed in a hydrothermal reaction kettle to carry out hydrothermal reaction for 72 hours at the temperature of 200 ℃, and then the carrier Ce-SAPO-34 molecular sieve is obtained after washing, drying and roasting in sequence;
step two, weighing 4.28g Ho (NO) with the mass purity of 99.9%3)3·5H2O and 1.56g of Cu (NO) having a mass purity of 99.9%3)2·6H2Adding O into 40.0g of deionized water, and fully stirring at room temperature until the O is completely dissolved to prepare a dipping solution;
step three, uniformly mixing the impregnation liquid obtained in the step two with 80g of the carrier Ce-SAPO-34 molecular sieve obtained in the step one, impregnating for 12 hours at room temperature, and drying for 6 hours at 110 ℃ to obtain a holmium element and copper element modified Ce-SAPO-34 molecular sieve;
step four, mixing 80.0g of holmium element and copper element modified Ce-SAPO-34 molecular sieve obtained in the step three with 29.9gAl2O3And extruding and molding 67% of pseudo-boehmite by mass, drying, and roasting at 500 ℃ for 4h to obtain the holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst.
Example 4
The denitration catalyst of the holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve comprises a Ce-SAPO-34 molecular sieve as a carrier, holmium and copper composite oxides as active modified components loaded on the carrier, and an Al binder2O3In the catalyst, the mass content of the Ce-SAPO-34 molecular sieve as a carrier and the holmium and copper composite oxides as active modification components loaded on the carrier is 80 percent, and the balance is Al2O3Wherein the loading capacity of holmium element in the active modification component is 2.0 percent and the loading capacity of copper element is 3.0 percent based on the mass of the carrier Ce-SAPO-34 molecular sieve.
The preparation method of the holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst comprises the following steps:
step one, weighing 1493.2g of orthophosphoric acid solution with the mass concentration of 85 percentLiquid 985.5gAl2O3Pseudo-boehmite with mass content of 67 percent and 778.2gSiO2Preparing uniform slurry by using 40% of silica sol by mass concentration, 562.4g of cerium nitrate hexahydrate with the mass purity of 99%, 2647.7g of triethylamine with the mass purity of 99% and 533g of deionized water, placing the slurry in a hydrothermal reaction kettle, carrying out hydrothermal reaction at the temperature of 200 ℃ for 72 hours, and then sequentially washing, drying and roasting to obtain a carrier Ce-SAPO-34 molecular sieve;
step two, weighing 4.28g Ho (NO) with the mass purity of 99.9%3)3·5H2O and 11.17g of Cu (NO) having a mass purity of 99.9%3)2·6H2Adding O into 40.0g of deionized water, and fully stirring at room temperature until the O is completely dissolved to prepare a dipping solution;
step three, uniformly mixing the impregnation liquid obtained in the step two with 80g of the carrier Ce-SAPO-34 molecular sieve obtained in the step one, impregnating for 12h8 at room temperature, and drying for 6h8 at 110 ℃ to obtain a holmium element and copper element modified Ce-SAPO-34 molecular sieve;
step four, mixing 80.0g of holmium element and copper element modified Ce-SAPO-34 molecular sieve obtained in the step three with 29.9gAl2O3And extruding and molding 67% of pseudo-boehmite by mass, drying, and roasting at 500 ℃ for 4h to obtain the holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst.
Example 5
The denitration catalyst of the holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve comprises a Ce-SAPO-34 molecular sieve as a carrier, holmium and copper composite oxides as active modified components loaded on the carrier, and an Al binder2O3In the catalyst, the mass content of the Ce-SAPO-34 molecular sieve as a carrier and the holmium and copper composite oxides as active modification components loaded on the carrier is 70 percent, and the balance is Al2O3Wherein the loading amount of holmium element in the active modification component is 1.0 percent and the loading amount of copper element is 1.5 percent based on the mass of the carrier Ce-SAPO-34 molecular sieve.
The preparation method of the holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst comprises the following steps:
step one, 1493.2g of orthophosphoric acid solution with the mass concentration of 85 percent and 985.5gAl are weighed2O3Pseudo-boehmite with mass content of 67 percent and 778.2gSiO2Preparing uniform slurry by using 40% of silica sol by mass concentration, 562.4g of cerium nitrate hexahydrate with the mass purity of 99%, 2647.7g of triethylamine with the mass purity of 99% and 533g of deionized water, placing the slurry in a hydrothermal reaction kettle, carrying out hydrothermal reaction at the temperature of 200 ℃ for 72 hours, and then sequentially washing, drying and roasting to obtain a carrier Ce-SAPO-34 molecular sieve;
step two, weighing 1.87g Ho (NO) with the mass purity of 99.9%3)3·5H2O and 4.89g of Cu (NO) with a mass purity of 99.9%3)2·6H2Adding O into 35.0g of deionized water, and fully stirring at room temperature until the O is completely dissolved to prepare a dipping solution;
step three, uniformly mixing the impregnation liquid obtained in the step two with 70g of the carrier Ce-SAPO-34 molecular sieve obtained in the step one, impregnating for 12 hours at room temperature, and drying for 6 hours at 110 ℃ to obtain a holmium element and copper element modified Ce-SAPO-34 molecular sieve;
step four, mixing 70.0g of holmium element and copper element modified Ce-SAPO-34 molecular sieve obtained in the step three with 44.78gAl2O3And extruding and molding 67% of pseudo-boehmite by mass, drying, and roasting at 500 ℃ for 4h to obtain the holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst.
FIG. 1 is an XRD (X-ray diffraction) diagram of the Ce-SAPO-34 molecular sieve prepared in the embodiments 1 to 5 of the invention, and as can be seen from FIG. 1, the Ce-SAPO-34 molecular sieve prepared by the in-situ hydrothermal synthesis method has high crystallinity and small crystal grains.
Comparative example 1
The copper oxide modified SAPO-34 molecular sieve denitration catalyst comprises a carrier SAPO-34 molecular sieve, an active modified component copper oxide loaded on the carrier, and a binder Al2O3The carrier SAPO-34 mass percent of molecular sieve and active modified component copper oxide loaded on the carrier, and the balance of Al2O3Wherein the loading amount of the copper element in the active modification component is 3.0 percent by taking the mass of the carrier SAPO-34 molecular sieve as a reference.
The preparation method of the copper oxide modified SAPO-34 molecular sieve denitration catalyst comprises the following steps:
step one, weighing 9.77g of Cu (NO) with the mass purity of 99.9%3)2·6H2Adding O into 35.0g of deionized water, fully stirring at room temperature until the O is completely dissolved, and preparing to obtain an impregnation liquid;
step two, uniformly mixing the impregnation liquid obtained in the step one with 70g of carrier SAPO-34 molecular sieve, impregnating for 12 hours at room temperature, and drying for 6 hours at 110 ℃ to obtain copper element modified SAPO-34 molecular sieve; p in the carrier SAPO-34 molecular sieve2O5、Al2O3With SiO2The ratio of the amounts of substances (a) to (b) is 1.0: 1.0: 0.8;
step three, 70.0g of copper element modified SAPO-34 molecular sieve and 44.78gAl2O3And extruding and molding 67% of pseudo-boehmite by mass, drying, and roasting at 500 ℃ for 4h to obtain the copper modified SAPO-34 molecular sieve denitration catalyst.
The catalytic activities of the holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalysts of the examples 1 to 5 and the copper oxide modified SAPO-34 molecular sieve denitration catalyst of the comparative example 1 are detected, and the specific detection conditions are as follows: the catalyst was charged into a fixed bed reactor and the feed gases (NO and NH) were passed through3All of which are 500ppm, O2The volume content of the catalyst is 3 percent), carrying out catalytic denitration reaction, taking nitrogen as carrier gas, and setting the space velocity of raw material gas to 20000h-1The reaction temperature is 150-350 ℃, the reaction pressure is normal pressure, and the fixed bed reactor is a stainless steel tube with the inner diameter of 10 mm; analyzing the flue gas at the outlet of the reactor by using an on-line flue gas analyzer, and calculating the conversion rate X of NONOAnd with XNOEvaluation of the catalyst Activity, XNOThe calculation formula of (a) is as follows:
Figure BDA0002769885790000121
in the formula, NOin、NOoutThe NO concentrations of the fixed bed reactor inlet and outlet gases are indicated, respectively.
FIG. 2 is a graph showing the denitration performance of the Ce-SAPO-34 molecular sieve denitration catalysts modified by the composite oxides of holmium and copper in examples 1 to 5 of the invention and the copper oxide modified SAPO-34 molecular sieve denitration catalyst in comparative example 1. from FIG. 2, it can be seen that the NO conversion rates of the Ce-SAPO-34 molecular sieve denitration catalysts modified by the composite oxides of holmium and copper in examples 1 to 5 of the invention at 150 ℃ are all more than 70%, which is higher than the NO conversion rate of the copper oxide modified SAPO-34 molecular sieve denitration catalyst in comparative example 1 at 150 ℃, wherein the NO conversion rate of the catalyst in example 5 is the highest, that is, when the supported amounts of the Ho element and the Cu element in the catalyst were 1.0% and 1.5%, respectively, the catalytic activity of the catalyst is optimal, the NO conversion rate reaches 80% at 150 ℃, and the NO conversion rate reaches 100% at 275 ℃. The holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst disclosed by the invention widens the active temperature window of the catalyst through the synergistic effect of the holmium and copper composite oxide and the Ce element in the Ce-SAPO-34 molecular sieve.
The sulfur resistance and water resistance of the holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst of example 5 and the copper oxide modified SAPO-34 molecular sieve denitration catalyst of comparative example 1 were tested, and the specific test conditions were as follows: the catalyst was charged into a fixed bed reactor and the feed gases (NO and NH) were passed through3All of which are 500ppm, O2In an amount of 3% by volume, H2O content 10% by volume, SO2200ppm) is carried out, the carrier gas is nitrogen, the space velocity of the raw material gas is 20000h-1The reaction temperature is 250 ℃, the reaction pressure is normal pressure, and the fixed bed reactor is a stainless steel tube with the inner diameter of 10 mm; analyzing the flue gas at the outlet of the reactor by using an on-line flue gas analyzer, and calculating the conversion rate X of NONOAnd with XNOEvaluation of the Sulfur and Water resistance of the catalyst, XNOThe calculation formula of (A) is the same as X for detecting catalytic activityNOAnd (4) calculating a formula.
Fig. 3 is a test chart of sulfur resistance and water resistance of the composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst of example 5 of the invention and the oxide modified SAPO-34 molecular sieve denitration catalyst of comparative example 1 of the invention, and it can be seen from fig. 3 that the sulfur resistance and water resistance of the composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst of example 5 of the invention are superior to those of the oxide modified SAPO-34 molecular sieve denitration catalyst of comparative example 1 of the invention, which illustrates that the composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst of the invention enhances the sulfur resistance and water resistance of the catalyst through the synergistic effect between the composite oxide of holmium and copper and the Ce element in the Ce-SAPO-34 molecular sieve.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the present invention in any way. Any simple modification, change and equivalent changes of the above embodiments according to the technical essence of the invention still belong to the protection scope of the technical solution of the invention.

Claims (9)

1. The catalyst is characterized by comprising a carrier Ce-SAPO-34 molecular sieve, an active modified component holmium and copper composite oxide loaded on the carrier, and a binder Al2O3In the catalyst, the mass content of the Ce-SAPO-34 molecular sieve as a carrier and the holmium and copper composite oxides as active modification components loaded on the carrier is 50-90%, and the balance is Al2O3Wherein, the loading capacity of holmium element in the active modification component is 0.5-2 percent and the loading capacity of copper element is 0.5-3 percent by taking the mass of the carrier Ce-SAPO-34 molecular sieve as a reference.
2. The holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst according to claim 1, wherein Ce in the supported Ce-SAPO-34 molecular sieve is introduced into the SAPO-34 molecular sieve by an in-situ hydrothermal synthesis method.
3. The holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst as claimed in claim 1, wherein the supported Ce-SAPO-34 molecular sieve preparation raw material contains P2O5、Al2O3、SiO2、CeO2、C6H15N and H2The mass ratio of O is 1.0: 1.0: 0.8: 0.2: 4.0: 60.
4. the holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst according to claim 1, wherein the binder Al is2O3The precursor of (A) is pseudo-boehmite.
5. A method for preparing the holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst as claimed in any one of claims 1 to 4, which comprises the following steps:
step one, respectively weighing orthophosphoric acid, pseudo-boehmite, silica sol, cerium nitrate, triethylamine and water, preparing to obtain uniform slurry, then placing the slurry in a hydrothermal reaction kettle for hydrothermal reaction, and then sequentially washing, drying and roasting to obtain a carrier Ce-SAPO-34 molecular sieve;
step two, weighing soluble salt of a holmium element precursor and soluble salt of a copper element precursor according to the loading capacity of the holmium element and the loading capacity of the copper element respectively, weighing deionized water according to the saturated water absorption capacity of the carrier Ce-SAPO-34 molecular sieve in the step one, adding the weighed soluble salt of the holmium element precursor and the weighed soluble salt of the copper element precursor into the weighed deionized water, fully stirring the mixture at room temperature until the mixture is completely dissolved, and preparing to obtain impregnation liquid;
step three, uniformly mixing the impregnation liquid obtained in the step two with the carrier Ce-SAPO-34 molecular sieve obtained in the step one, impregnating at room temperature, and drying to obtain a holmium element and copper element modified Ce-SAPO-34 molecular sieve;
step four, modifying the holmium element and copper element modified Ce-SAPO-34 molecular sieve obtained in the step three with an adhesive Al2O3And extruding the precursor into strips, drying, and roasting to obtain the holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst.
6. The method according to claim 5, wherein the hydrothermal reaction in the first step is carried out at 200 ℃ for 72 hours.
7. The method of claim 5, wherein the soluble salt of the holmium element precursor in step two is Ho (NO)3)3·5H2O, the soluble salt of the copper element precursor is Cu (NO)3)2·6H2O。
8. The method according to claim 5, characterized in that the time of the impregnation in step three is 12 h; the drying temperature is 110 ℃ and the drying time is 6 h.
9. The method of claim 5, wherein the roasting in step four is carried out at 500 ℃ for 4 hours.
CN202011245537.6A 2020-11-10 2020-11-10 Holmium and copper composite oxide modified Ce-SAPO-34 molecular sieve denitration catalyst and preparation method thereof Pending CN112169831A (en)

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