CN108187732B - Anti-sulfur and water-resistant CH4-SCR denitration catalyst and preparation method thereof - Google Patents

Anti-sulfur and water-resistant CH4-SCR denitration catalyst and preparation method thereof Download PDF

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CN108187732B
CN108187732B CN201711319123.1A CN201711319123A CN108187732B CN 108187732 B CN108187732 B CN 108187732B CN 201711319123 A CN201711319123 A CN 201711319123A CN 108187732 B CN108187732 B CN 108187732B
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sulfur
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CN108187732A (en
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朱荣淑
温正中
张改革
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Shenzhen Graduate School Harbin Institute of Technology
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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
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/70—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65
    • B01J29/72—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65 containing iron group metals, noble metals or copper
    • B01J29/76—Iron group metals or copper
    • B01J29/7615—Zeolite Beta
    • 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
    • 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
    • B01D53/90—Injecting reactants
    • 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
    • B01J37/082—Decomposition and pyrolysis
    • B01J37/088—Decomposition of a metal salt
    • 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
    • B01J37/30—Ion-exchange
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/20—Reductants
    • B01D2251/208—Hydrocarbons
    • 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

Abstract

The invention provides a sulfur-resistant and water-resistant CH4-SCR denitration catalyst and preparation method thereof, wherein the active ingredients of the SCR denitration catalyst are indium and Co3O4Said Co3O4Mixing with H-Beta molecular sieve, loading the indium on the H-Beta molecular sieve by ion exchange method, and loading Co on the H-Beta molecular sieve3O4The mass ratio of the H-Beta to the H-Beta is (2-20): 40, the indium accounts for 2-5 wt% of the catalyst. By adopting the technical scheme of the invention, the CH4In the SCR denitration catalyst, Co3O4Has synergistic catalytic action with In/H-Beta, and still has high denitration performance under the condition of containing sulfur and water.

Description

Anti-sulfur and water-resistant CH4-SCR denitration catalyst and preparation method thereof
Technical Field
The invention belongs to the technical field of catalysts, and particularly relates to sulfur-resistant and water-resistant CH4-SCR denitration catalyst and a preparation method thereof.
Background
With the rapid development of industry and traffic, Nitrogen Oxide (NO)x) The pollution is becoming more and more serious. NOxIs one of the main causes of serious air pollution such as acid rain, photochemical smog and the like, and the pollutants greatly harm human health and living environment. In recent years, CH4Selective reduction of (CH) as a reducing agent4-SCR)NOxThe technology is widely concerned by scholars at home and abroad, and the molecular sieve loaded In-containing catalyst is concerned because of high denitration efficiency. Wangxiangdong et al found that In/ZSM-5 can efficiently reduce NO, and the NO conversion rate can reach 100%. Panhua et al found that In/H-Beta catalyst is In CH4The denitration rate of the SCR system is high, and the denitration rate exceeds 90% at the temperature of more than 450 ℃. We are right toIn/H-ZSM-5 and In/H-Beta on NO under the same conditionsxThe conversion efficiency of the catalyst is respectively 50% and 90%, and the H-Beta loaded In catalyst shows more excellent catalytic activity. However, we have found that under aqueous sulfur-containing conditions, the catalytic denitration efficiency of In/H-Beta is reduced from 90% to 30%, and the sulfur resistance and water resistance of the In/H-Beta catalyst are poor. Schwara et al reported that a Co-In/H-Beta denitration catalyst prepared by an impregnation method has certain sulfur resistance and water resistance at a low space velocity In cooperation with a plasma technology. However, under the condition of high space velocity, the catalytic performance of Co-In/H-Beta prepared by the dipping method for catalyzing methane to reduce NOx is still low and needs to be improved.
Disclosure of Invention
Aiming at the technical problems, the invention discloses a sulfur-resistant and water-resistant CH4The SCR denitration catalyst and the preparation method thereof improve the water resistance and the sulfur resistance of the In/H-Beta catalyst and have good denitration rate.
In contrast, the technical scheme adopted by the invention is as follows:
anti-sulfur and water-resistant CH4SCR denitration catalyst with indium and Co as active components3O4Said Co3O4Mixing with H-Beta molecular sieve, and loading the indium on the H-Beta molecular sieve by an ion exchange method. By adopting the technical scheme, the CH4The SCR denitration catalyst still has good catalytic activity under the condition of containing sulfur and water and has high denitration rate.
As a further improvement of the invention, the Co3O4The mixing mass ratio of the H-Beta to the H-Beta is (2-20): 40.
as a further improvement of the invention, the indium accounts for 2-5% of the catalyst by weight. Further preferably, the weight percentage of the indium in the catalyst is 2.48-4.68 wt%.
As a further improvement of the invention, the weight percentage of the indium in the catalyst is 3.36-4.50 wt%, and preferably, the weight percentage of the indium in the catalyst is 4.50%.
As a further improvement of the invention, the Co3O4Mass with H-BetaThe ratio is (5-10): 40. preferably, said Co3O4The mass ratio of H-Beta is 5: 40.
as a further improvement of the invention, the silicon-aluminum ratio of the H-Beta molecular sieve is 25-40. Preferably, the molecular sieve has a silica to alumina ratio of 25.
As a further development of the invention, the CH4The SCR denitration catalyst is prepared by adopting an ion exchange method.
As a further improvement of the invention, the sulfur-resistant and water-resistant CH4The SCR denitration catalyst is prepared by adopting the following steps:
step S1: preparing an indium nitrate solution; preferably, the concentration of the indium nitrate solution is 0.0066-0.066 mol/L;
step S2: adding H-Beta molecular sieve raw powder and Co into the indium nitrate solution prepared in the step S13O4Uniformly mixing, stirring at a constant temperature of 75-95 ℃ for 2-10 h, then carrying out suction filtration and washing; preferably water washing until the pH of the lower clear solution is 7;
step S3: drying and grinding the filtered filter cake, and calcining to obtain the high-efficiency CH4-SCR denitration catalyst, wherein the calcination temperature is 400-600 ℃, and the calcination time is 2-6 h.
In a further improvement of the invention, in step S1, the concentration of the indium nitrate solution is 0.01-0.033 mol/L; in step S2, the mixture is uniformly mixed and stirred for 8-10 h at a constant temperature of 85 ℃.
Preferably, the concentration of the indium nitrate solution is 0.033 mol/L.
Preferably, in step S3, the calcination temperature is 400 to 500 ℃. Further preferably, the calcination temperature is 500 ℃.
The invention also discloses the sulfur-resistant and water-resistant CH4-a method for preparing an SCR denitration catalyst, characterized in that: which comprises the following steps:
step S1: preparing an indium nitrate solution, wherein the concentration of the indium nitrate solution is 0.0066-0.066 mol/L;
step S2: indium nitrate solution prepared in step S1Adding H-Beta molecular sieve raw powder and Co3O4Uniformly mixing, stirring at a constant temperature of 75-95 ℃ for 2-10 h, then carrying out suction filtration, and washing with water until the pH of the lower clear liquid is 7;
step S3: drying and grinding the filtered filter cake, and calcining to obtain the high-efficiency CH4-SCR denitration catalyst, wherein the calcination temperature is 400-600 ℃, and the calcination time is 2-6 h.
In a further improvement of the invention, in step S1, the concentration of the indium nitrate solution is 0.01-0.033 mol/L.
As a further improvement of the invention, in step S2, the mixture is uniformly mixed and stirred for 8-10 hours at a constant temperature of 85 ℃.
In a further improvement of the present invention, in step S3, the calcination temperature is 400 to 500 ℃. Further preferably, the calcination temperature is 500 ℃.
In a further improvement of the present invention, in step S1, the concentration of the indium nitrate solution is 0.033 mol/L.
As a further improvement of the invention, the Co3O4The mass ratio of H-Beta to H-Beta is (5-10): 40.
As a further improvement of the invention, in step S2, the mixture is stirred at a constant temperature of 85 ℃ for 8 hours after being uniformly mixed.
As a further improvement of the present invention, in step S3, the calcined catalyst is tableted, ground, and sieved with a sieve.
Our study protocol shows that: the literature data available show that NO2Formation is critical for methane activation. Co was discovered in our earlier work3O4The metal oxides exhibit good catalytic activity for the formation of NO 2. In this work, Co is compared3O4Co with best effect and In-H-Beta water-resistant and sulfur-resistant activity modified by equal metal oxides3O4The modified catalyst is optimized, and comprises a preparation method, an H-Beta silicon-aluminum ratio and Co3O4Content, In loading capacity, calcination temperature and other preparation conditions.
Compared with the prior art, the invention has the beneficial effects that:
by adopting the technical scheme of the invention, the CH4In the SCR denitration catalyst, Co3O4Has synergistic effect with the In-H-Beta molecular sieve, and still has high denitration rate under the condition of containing sulfur and water.
Drawings
FIG. 1 is a graph showing the catalytic activity of an ionic metal precursor modified In-H-Beta under aqueous sulfur-containing conditions In comparative example 1 of the present invention. Wherein FIG. 1(a) shows NO of In-H-Beta modified by ionic metal precursor under water-containing and sulfur-containing conditionsxFIG. 1(b) is a graph showing the CH modification of In-H-Beta by an ionic metal precursor under aqueous sulfur-containing conditions4FIG. 1(c) is a graph showing the conversion of an ionic metal precursor modified In-H-Beta CH under aqueous sulfur-containing conditions4For NOxComparison of the selectivities.
FIG. 2 is a graph showing the catalytic activity of In-H-Beta modified with a metal oxide under aqueous sulfur-containing conditions In example 2 of the present invention. Wherein FIG. 2(a) is NO of In-H-Beta modified by metal oxide under water-containing and sulfur-containing conditionsxFIG. 2(b) is a graph showing the comparison of the removal rate, and CH of In-H-Beta modified with a metal oxide under aqueous sulfur-containing conditions4FIG. 2(c) is a graph showing the CH content of a metal oxide-modified In-H-Beta molecular sieve under aqueous sulfur-containing conditions4For NOxComparison of the selectivities.
FIG. 3 shows In-Co prepared by different methods under the aqueous sulfur-containing conditions of comparative example 2 of the present invention3O4Catalytic activity diagram of/H-Beta. Wherein, FIG. 3(a) shows In-Co prepared by different methods under the conditions of water and sulfur3O4NO of/H-BetaxFIG. 3(b) is a graph showing comparison of removal rates of In-Co prepared by different methods under aqueous sulfur-containing conditions3O4CH of/H-Beta4FIG. 3(c) is a graph showing comparison of conversion rates of In-Co prepared by different methods under aqueous sulfur-containing conditions3O4CH of/H-Beta4For NOxComparison of the selectivities.
FIG. 4 shows In-Co with different Si/Al ratios under the water-containing and sulfur-containing conditions In example 3 of the present invention3O4Catalytic activity diagram of/H-Beta. Wherein, FIG. 4(a) shows In-Co3O4NO of/H-BetaxFIG. 4(b) is a graph showing comparison of removal rates of In-Co at different Si/Al ratios under the water-containing and sulfur-containing conditions3O4CH of/H-Beta4Comparative graph of conversion.
FIG. 5 shows In-Co with different Si/Al ratios under anhydrous and sulfur-free conditions In example 3 of the present invention3O4Catalytic activity diagram of/H-Beta. Wherein, FIG. 5(a) shows In-Co with different Si/Al ratios under anhydrous and sulfur-free conditions3O4NO of/H-BetaxFIG. 5(b) is a graph showing the comparison of removal rates of In-Co at different Si/Al ratios under anhydrous and sulfur-free conditions3O4CH of/H-Beta4FIG. 5(c) is a graph showing the conversion ratio of In-Co at various Si/Al ratios under anhydrous and sulfur-free conditions3O4CH of/H-Beta4For NOxComparison of the selectivities.
FIG. 6 shows different Co concentrations under aqueous sulfur conditions of example 4 of the present invention3O4In-Co of/H-Beta mass ratio3O4Catalytic activity diagram of/H-Beta. Wherein FIG. 6(a) shows different Co concentrations under water-containing and sulfur-containing conditions3O4In-Co of/H-Beta mass ratio3O4NO of/H-BetaxFIG. 6(b) is a graph showing comparison of removal rates of Co and Co under the conditions of water and sulfur3O4In-Co of/H-Beta mass ratio3O4CH of/H-Beta4FIG. 6(c) is a graph comparing the conversion of different Co under aqueous sulfur-containing conditions3O4In-Co of/H-Beta mass ratio3O4CH of/H-Beta4For NOxComparison of the selectivities.
FIG. 7 shows In-Co concentrations of different In concentrations In the presence of sulfur In water In example 5 of the present invention3O4Catalytic activity diagram of/H-Beta. Wherein, FIG. 7(a) shows In-Co concentrations of different In under aqueous sulfur-containing conditions3O4NO of/H-BetaxFIG. 7(b) is a graph showing comparison of removal rates of In-Co at different In concentrations under aqueous sulfur-containing conditions3O4CH of/H-Beta4FIG. 7(c) is a graph showing comparison of conversion rates of In-Co at different In concentrations under aqueous sulfur-containing conditions3O4CH of/H-Beta4For NOxComparison of the selectivities.
FIG. 8 shows In-Co obtained at different calcination temperatures under aqueous sulfur-containing conditions In example 6 of the present invention3O4Catalytic activity diagram of/H-Beta. Wherein, FIG. 8(a) shows In-Co obtained at different calcination temperatures under water-containing and sulfur-containing conditions3O4NO of/H-BetaxFIG. 8(b) is a graph showing comparison of removal rates of In-Co obtained at different calcination temperatures under the conditions of water and sulfur3O4CH of/H-Beta4FIG. 8(c) is a graph showing the comparison of the conversion rates of In-Co obtained at different calcination temperatures under the conditions of water and sulfur3O4CH of/H-Beta4For NOxComparison of the selectivities.
Detailed Description
Preferred embodiments of the present invention are described in further detail below.
Example 1
And (4) evaluating the activity of the catalyst.
The catalyst activity was evaluated by Temperature Programmed Surface Reaction (TPSR) technique. The evaluation experiments were carried out on a continuous flow fixed bed reactor. The evaluation system mainly comprises a gas circuit control system, a catalytic reaction device system and an online analysis test system. The gas used for the experiment is supplied by cylinder gas. The pressure stabilizing valve regulates gas pressure, the flow stabilizing valve and the mass flowmeter regulate flow, the gas pressure is 0.1MPa, the gas enters the mixing tube for mixing after being regulated by the pressure stabilizing valve, the flow stabilizing valve and the flowmeter, and enters the reaction tube for catalytic reaction. The concentration of each component in the reaction gas is as follows: NOxIs 400ppm, CH4Is 400ppm, O 210% of SO2100ppm, 5% water vapor and Ar is balance gas. The total flow of the gas is 100mL/min, the dosage of the catalyst is 100mg, and the space velocity is 23600h-1. The inner diameter of the used reaction tube is 6mm, the outer diameter of the used reaction tube is 10mm, the material of the reaction tube is a quartz glass tube, quartz wool is placed in the middle of the reaction tube to support the catalyst and enable the catalyst to be uniformly distributed, the reaction tube is placed in the electric tube resistance furnace, the temperature controller controls the heating rate of the resistance furnace, and the catalytic reaction temperature is adjusted by controlling the heating of the resistance furnace through the temperature controller. Before temperature programming, the reaction gas passes through the catalyst at normal temperature, and after the reaction gas is adsorbed for 1h, the reaction gas is heated until NOxThe analyzer readings do not change substantially, indicating that the catalyst is in an adsorption saturation state, and then the temperature programming is started to increase from 40 ℃ to 600 ℃ at the temperature increasing rate of 4 ℃/min. The on-line detection system consists of a gas chromatograph (Shimadzu GC2014C) and NOxAnalyzer (MODEL-T200H). NO, NO2、NOx(NOx＝NO+NO2) In a concentration of NOxAnd (5) measuring by an analyzer. CH (CH)4And CO produced during the reaction2Is measured by a gas chromatograph equipped with an FID detector. The gas is passed through a drying unit to remove water from the gas before it enters the detection instrument.
The activity of the catalyst in the reaction is derived from NOxIs measured as eta, as shown in equation (1). NOxThe higher the conversion of (b), the higher the catalyst activity, i.e. the greater η, the better the catalyst activity. CH (CH)4As reducing agent for the reaction, with NOxReacting according to a certain proportion relation, wherein the reaction chemical formula is CH4+2NO+O2＝CO2+N2+H2O, to some extent, CH4Can react to give NOxThus, observing CH during the reaction4Is also very necessary, CH4The conversion of (b) is represented by γ, as shown in formula (2). CH (CH)4For NOxOf (2), i.e. NOxConsumption of CH by reaction4In an amount of CH4The percentage of the total amount of reaction occurred is represented by α, as shown in equation (3).
Figure BDA0001504395080000051
Figure BDA0001504395080000052
Figure BDA0001504395080000061
In the formula c (NO)x-in)——NOxInitial concentration, mL/m3；
c(NOx-out)——NOxOutput concentration, mL/m3；
c(CH4-in)——CH4Initial concentration, mL/m3；
c(CH4-out)——CH4Output concentration, mL/m3。
Comparative example 1
The bimetallic ions are co-loaded.
The method comprises the following steps of taking ionic Co as a precursor and loading the ionic Co and In on an H-Beta molecular sieve together, and preparing the bimetallic supported H-Beta molecular sieve catalyst containing In by adopting an ion exchange method, wherein the preparation method comprises the following specific steps:
SiO of H-Beta molecular sieve2/Al2O325 (southern university catalyst works). The active phase precursor of the modified H-Beta is indium nitrate, and a certain amount of metal is added. 100mL of In ion solution with a certain concentration is prepared, 3g of molecular sieve raw powder and a certain amount of ionic metal Co salt are added into the solution and mixed uniformly, then the mixture is placed on a magnetic stirrer and stirred for 8 hours In a thermostatic water bath at the temperature of 85 ℃. The stirred solution was placed on a buchner funnel, filtered with a vacuum pump, and washed with water until the pH of the supernatant became 7. The filtrate was decanted off and the filter cake on the filter paper was removed and placed in an oven and dried at 80 ℃ for 12 hours. And taking out the dried catalyst, grinding, putting the catalyst into a tubular furnace, calcining for 3 hours at a certain temperature in an air atmosphere. And tabletting and grinding the calcined catalyst, and screening by using a screen of 40-60 meshes. And (4) placing the screened catalyst particles into a sample tube for sealed storage.
Meanwhile, seven transition metal elements Cr, Mn, Fe, Ni, Cu, Zn and In the fourth period of the periodic table are selected to prepare the In-containing bimetallic supported H-Beta molecular sieve catalyst as a comparative example, and the supporting method is the same as the above.
The catalytic activity of the obtained different second metal modified In-H-Beta catalysts was evaluated according to the above method, and the experimental results are shown In FIG. 1. As can be seen from FIG. 1(a), the loading of six metal ions of Cr, Mn, Fe, Ni, Cu and Zn can not improve the water and sulfur resistance of In-H-Beta, and the denitration rate is reduced to below 30%. In contrast, the Co load improves the water and sulfur resistance of the In-H-Beta, and the denitration rate reaches over 40 percent at 576 ℃, and reaches the highest value of 49 percent at 652 ℃.
FIG. 1(b) shows CH for different second metal-modified In-H-Beta catalysts at different temperatures4And (4) conversion rate. As can be seen from FIG. 1(b), the seven metal ions of Co, Cr, Mn, Fe, Ni, Cu and Zn are supported to promote CH4The conversion rate is increased, wherein Cr and Mn are most obvious. FIG. 1(c) shows that the catalysts are in the high temperature zone CH4For NOxSelectivity of (2). As can be seen from FIG. 1(c), the addition of the second metal reduced CH In the presence of aqueous sulfur as compared to In-H-Beta4For NOxIn which Co-In-H-Beta In the presence of aqueous sulfur has a CH4For NOxThe selectivity is the best.
Therefore, the ionic Co is adopted to modify the In-H-Beta catalyst, so that the water resistance and sulfur resistance of the catalyst can be improved, the modification effect of other ionic metals on the In-H-Beta catalyst is general, but the highest denitration rate of the Co-In-H-Beta catalyst is only 49%.
Example 2
The denitration performance of the metal oxide modified In-H-Beta catalyst.
With Co3O4The In-H-Beta is modified, the loading method adopts an ion exchange method, and the preparation method comprises the following specific steps:
SiO of H-Beta molecular sieve2/Al2O325 (southern university catalyst works). The active phase precursor of the modified H-Beta is indium nitrate, and a certain amount of metal is added. 100mL of In ion solution with a certain concentration is prepared, 3g of molecular sieve raw powder and a certain amount of metal are added into the solution and mixed uniformly, then the solution is placed on a magnetic stirrer and is stirred for 8 hours In a thermostatic water bath at the temperature of 85 ℃. The stirred solution was placed on a buchner funnel, filtered with a vacuum pump, and washed with water until the pH of the supernatant became 7. Pouring out the filtrate, taking out the filter cake on the filter paper, putting the filter cake into an oven, and drying the filter cake at 80 ℃ for 12 DEG CAnd (4) hours. And taking out the dried catalyst, grinding, putting the catalyst into a tubular furnace, calcining for 3 hours at a certain temperature in an air atmosphere. And tabletting and grinding the calcined catalyst, and screening by using a screen of 40-60 meshes. And (4) placing the screened catalyst particles into a sample tube for sealed storage.
At the same time, Cr is selected2O3、MnO2、Fe2O3In-H-Beta was used as a control example of metal oxides such as NiO, CuO and ZnO, and the supporting method was the same as above.
The catalytic activity of the obtained different second metal oxide In-H-Beta catalysts was evaluated according to the above method, and the experimental results are shown In FIG. 2. As can be seen from FIG. 2(a), of the seven catalysts, In-ZnO/H-Beta and In-CuO/H-Beta were completely deactivated In the presence of sulfur water, but the remaining five catalysts had some water-and sulfur-resistance. In-Co therein3O4The best catalytic effect is achieved by the catalyst/H-Beta. In-Co3O4The highest denitration rate of-H-Beta can reach 83 percent. In-NiO/H-Beta, In-Fe2O3/H-Beta、In-MnO2H-Beta and In-Cr2O3Compared with In-H-Beta, the/H-Beta also has better water resistance and sulfur resistance, and the highest denitration rates are respectively 72%, 70%, 64% and 44%.
FIG. 2(b) is CH at different temperatures for the catalyst4And (4) conversion rate. As can be seen from FIG. 2(b), the seven metal ions of Co, Cr, Mn, Fe, Ni, Cu and Zn are supported to promote CH4The conversion rate increases. FIG. 2(c) illustrates CH for various types of catalysts4For NOxAnd (4) selectivity. In-ZnO/H-Beta and In-CuO/H-Beta do not have denitration performance In the presence of water sulfur, and CH4Are all reacted with O2The reaction takes place. In the rest of the catalyst, In-Cr2O3CH of/H-Beta4The conversion is highest in the high temperature section, CH4Lowest selectivity, Cr2O3May promote CH4React with oxygen to affect CH4Selectivity of (2). In-Fe2O3/H-Beta、In-Co3O4CH for/H-Beta, In-NiO/H-Beta and In-Mn/H-Beta4Difference in conversion rateNot much, CH4The selectivity of (A) was slightly inferior compared to that of In-H-Beta, but the CH of these four catalysts4The selectivity is stable in a high-temperature section, and CH participating in the reaction is at 652 DEG C4About 40% of the total are NOxA reaction takes place.
As can be seen, In-ZnO/H-Beta and In-CuO/H-Beta do not have denitration properties In the presence of water sulfur, while Cr does not have denitration properties In the presence of water sulfur2O3、MnO2、Fe2O3、Co3O4The doping of NiO improves the sulfur resistance and water resistance of In/H-Beta, wherein In-Co3O4The catalytic effect of the/H-Beta under the condition of water sulfur is best.
Example 2 is compared with comparative example 1, Co3O4The highest denitration rate of the doped modified In/H-Beta can reach 83 percent, and CH4The selectivity can reach 57 percent, and Co3+The highest denitration rate of the doped modified In/H-Beta is only 49 percent, and CH4The selectivity is only 44%. It can be seen that, with Co3O4The doping modification is better than Co3+And (5) doping modification.
Comparative example 2
Anti-sulfur and water-resistant CH4SCR denitration catalyst, In this example, In-Co was prepared separately by different preparation methods3O4The In-Co is prepared by adopting an ion exchange method and an impregnation method respectively3O4The ratio of the Beta to the Beta is/H-Beta. The procedure of the ion exchange process was the same as in example 2. The impregnation method comprises the following steps:
with H-Beta molecular Sieve (SiO)2/Al2O325, catalyst works of southern kayaku university) as a carrier, indium nitrate as a precursor, and Co was added3O4. Firstly, weighing a certain mass of indium nitrate, and dissolving the indium nitrate and the indium nitrate into a proper amount of deionized water, wherein the dosage of the deionized water is based on that the indium nitrate is completely adsorbed by the H-Beta molecular sieve and the cobaltosic oxide with the target mass. Nitrate solutions with different active components are stirred uniformly, then a proper amount of H-Beta molecular sieve and cobaltosic oxide are added, mixed and stirred for one hour, and then aged for 24 hours at room temperature. Drying in oven at 80 deg.C for 12 hr, taking out catalyst, grinding, and air dryingCalcining at 500 ℃ for 3 hours. And finally, screening the catalyst to obtain fine particles of 40-60 meshes. And placing the prepared catalyst particles into a sample tube for sealed storage.
The remaining experimental preparation conditions for the two different preparation methods were: the Si/Al ratio of the H-Beta molecular sieve is 25, Co3O4The mass ratio of the ion exchange solution to the H-Beta is 1:4, the concentration of the ion exchange solution is 0.033M, and the calcining temperature is 500 ℃. The In content In the impregnation liquid is kept consistent with the In loading capacity of the catalyst prepared by the ion exchange method. The In loading of the catalyst was measured by ICP experiment. The results of In loadings obtained for both methods are shown In Table 1, In-Co prepared by ion exchange3O4The mass fraction of In the/H-Beta was 3.38%. In-Co prepared by dipping method3O4The mass fraction of In the/H-Beta was 3.55%.
For both CH4SCR denitration Performance experiments were carried out. The catalyst prepared by the ion exchange method is named as In-Co3O4the/H-Beta-E, rule of impregnation is designated In-Co3O4H-Beta-I. The results of the experiment are shown in FIG. 3. As can be seen from FIG. 3, the impregnation method for preparing In-Co3O4The highest denitration rate of the/H-Beta-I is only 36 percent, and In-Co is prepared by an ion exchange method3O4The catalytic effect of the/H-Beta-E is obviously better than that of the impregnation method. Furthermore, methane to NOxThe selectivity of (A) is significantly different. It can be seen that the ion exchange method for preparing In-Co is superior to the dipping method3O4the/H-Beta has higher CH4-SCR denitration activity.
TABLE 1 In-Co prepared by different preparation methods3O4In loading on/H-Beta
Figure BDA0001504395080000091
Example 3
On the basis of the ion exchange method of comparative example 2, the H-Beta molecular sieves with the Si/Al ratios of 25, 40 and 60 are adopted to respectively prepare In-Co3O4H-Beta, other experimental preparation conditions: co3O4The ratio of the/H-Beta is 1:4, the calcining temperature is 500 ℃, and the concentration of the ion exchange liquid indium nitrate is 0.033M. And for CH of catalyst under the condition of sulfur-containing and water-containing4SCR denitration Performance experiments were carried out. The catalyst prepared by different silicon-aluminum ratios is named as In-Co3O4H-Beta-x, wherein x is the ratio of silicon to aluminum; such as In-Co3O4The ratio of Si to Al of the molecular sieve in the catalyst was 25 as indicated by/H-Beta-25. The results of the experiment are shown in FIG. 4.
As shown In FIG. 4, In-Co In the presence of aqueous sulfur3O4H-Beta-40 and In-Co3O4the/H-Beta-60 has almost no denitration performance, but still oxidizes the methane. For this phenomenon, we supplemented the denitration performance test of the catalyst under the sulfur-free and water-free condition, and the test result is shown in fig. 5. As can be seen from FIG. 5, In-Co3O4The denitration rate of the/H-Beta-25 reaches 90.8 percent at 524 ℃, and In-Co3O4The denitration rate of the/H-Beta-40 reaches 34.4 percent at 524 ℃, and In-Co3O4the/H-Beta-60 has no denitration performance. It can be seen that the high Si/Al ratio is not favorable for In-Co3O4And selective catalytic denitration by H-Beta.
Example 4
On the basis of the ion exchange method of comparative example 2, different Co was used3O4Respectively preparing In-Co by the mass ratio of/H-Beta3O4The mass ratio of the Beta to the H-Beta is respectively as follows: co3O4H-Beta 2:40, 5:40, 10:40, 20:40, 40:0 and CH to catalyst4SCR denitration Performance experiments were carried out. For different Co3O4The catalyst prepared by doping amount is named as In-Co3O4H-beta (y). y is Co3O4The ratio of/H-Beta. The results of the experiment are shown in FIG. 6.
As is clear from the experimental results of FIG. 6(a), In-Co3O4The denitration performance of the/H-Beta (2:40) is relatively common, and the denitration rate does not exceed 60 percent. In-Co3O4The catalytic effect of the/H-Beta (5:40) is optimal, and the denitration rate can reach 88 percent at most. With Co3O4The mass ratio of the/H-Beta is continuously increased, and the catalytic effect activity of the catalyst is improvedA gradual decrease occurs. In-Co3O4The highest denitration rate of/H-Beta (10:40) is 83%, In-Co3O4The highest denitration rate of/H-Beta (20:40) was 76.2%, In-Co3O4The highest denitration rate of the/H-Beta (40:40) is only 34%. In-Co3O4the/H-Beta (40:0) indicates no H-Beta, at which point the catalyst had no denitration performance, indicating Co alone3O4No catalytic effect, Co3O4And acts as a promoter in the catalyst.
Fig. 6(b) and 6(c) show the methane conversion rate and the selectivity of methane to nitrogen oxides of the catalyst. With Co3O4The methane conversion of the catalyst decreases with increasing mass ratio/H-Beta. The selectivity of methane to nitrogen oxide is in Co3O4The overall best ratio of the mass/H-Beta is 5: 40. As described above, the catalyst Co3O4Co of/H-Beta3O4The optimum ratio of the ratio to the best ratio is 5: 40.
Example 5
On the basis of the ion exchange method of comparative example 2, In-Co with different In loading amounts were prepared by using ion exchange solutions with different In concentrations3O4The In concentrations are 0.0066M, 0.01M, 0.033M and 0.066M respectively. CH for catalysts of different In concentrations4SCR denitration Performance experiments were carried out. The catalyst prepared by different ion exchange solution concentrations is named as In-Co3O4The experimental results are shown In FIG. 7, wherein z is the In concentration In the ion-exchange liquid. An ICP experiment was further performed to measure the In content of each catalyst, and the experimental results are shown In table 2.
TABLE 2 In-Co prepared at different In concentrations3O4In loading of/H-Beta
Figure BDA0001504395080000101
As can be seen from the experimental results of FIG. 7, the denitration activity of the catalyst increases first and then decreases as the concentration of the ion exchange solution increasesLow. In-Co3O4The denitration efficiency of the/H-Beta-0.033 is highest. Further increase the concentration of the ion exchange solution, In-Co3O4The highest denitration rate of the H-Beta-0.066 is 86 percent. While the methane conversion rate of the fourth graph is not very different, the methane selectivity is obviously increased along with the increase of the In concentration, and In-Co3O4The value of/H-Beta-0.033 is most preferable. Further, when the concentration of the ion-exchange liquid was 0.033M, the loading amount of In the catalyst tended to be saturated. Therefore, when the concentration of the ion exchange solution, namely the In concentration, is 0.033M, the catalytic performance of the catalyst is optimal.
Example 6
Based on the ion exchange method of comparative example 2, In-Co was prepared at different calcination temperatures of 400 deg.C, 450 deg.C, 500 deg.C, 550 deg.C and 600 deg.C for the experiment of this example3O4H-Beta and CH for catalyst4-SCR denitration performance. The catalyst prepared at different calcination temperatures is named as In-Co3O4In which a is the calcination temperature, e.g. In-Co3O4The term,/H-Beta-400, denotes the catalyst prepared at a calcination temperature of 400 ℃. The results of the experiment are shown in FIG. 8.
As can be seen from FIG. 8, as the calcination temperature was increased, the CH of the catalyst4SCR denitration activity increases first and then decreases. The catalyst has the best CH when calcined at the calcination temperature of 500 DEG C4-SCR denitration activity.
As can be seen from the above experiment, the molecular sieve prepared by the ion exchange method has the H-Beta silicon-aluminum ratio of 25 and the In ion exchange solution concentration of 0.033M, Co3O4The In-Co obtained by calcination at a calcination temperature of 500 ℃ and a/H-Beta of 5:403O4The catalyst effect of the/H-Beta is the best, and the denitration rate can reach 88 percent at most.
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.

Claims (9)

1. Anti-sulfur and water-resistant CH4-an SCR denitration catalyst, characterized in that: the active components are indium and Co3O4Said Co3O4Mixing with an H-Beta molecular sieve, and loading the indium on the H-Beta molecular sieve by an ion exchange method; the weight percentage of the indium in the catalyst is 2.48-4.68 wt%.
2. The sulfur-and water-resistant CH of claim 14-an SCR denitration catalyst, characterized in that: the Co3O4The mixing mass ratio of the H-Beta to the H-Beta is (2-20): 40.
3. the sulfur-and water-resistant CH of claim 14-an SCR denitration catalyst, characterized in that: the silicon-aluminum ratio of the H-Beta molecular sieve is 25-40.
4. The sulfur-and water-resistant CH according to any one of claims 1 to 34-an SCR denitration catalyst, characterized in that: the preparation method comprises the following steps:
step S1: preparing an indium nitrate solution;
step S2: adding H-Beta molecular sieve raw powder and Co into the indium nitrate solution prepared in the step S13O4Uniformly mixing, stirring at a constant temperature of 75-95 ℃ for 2-10 h, then carrying out suction filtration, and washing with water until the pH of the lower clear liquid is 7;
step S3: drying and grinding the filtered filter cake, and calcining to obtain the CH4-SCR denitration catalyst, wherein the calcination temperature is 400-600 ℃, and the calcination time is 2-6 h.
5. The sulfur-and water-resistant CH of claim 44-an SCR denitration catalyst, characterized in that: in the step S1, the concentration of the indium nitrate solution is 0.0066-0.066 mol/L; in step S2, uniformly mixing, and stirring at constant temperature of 85 ℃ for 8 h; in step S3, the calcination temperature is 500 ℃.
6. The sulfur-resistant and water-resistant CH as claimed in any one of claims 1 to 34-a method for preparing an SCR denitration catalyst, characterized in that: which comprises the following steps:
step S1: preparing an indium nitrate solution;
step S2: adding H-Beta molecular sieve raw powder and Co into the indium nitrate solution prepared in the step S13O4Uniformly mixing, stirring at a constant temperature of 75-95 ℃ for 2-10 h, then carrying out suction filtration and washing;
step S3: drying and grinding the filtered filter cake, and calcining to obtain the CH4-SCR denitration catalyst, wherein the calcination temperature is 400-600 ℃, and the calcination time is 2-6 h.
7. The sulfur-and water-resistant CH of claim 64-a method for preparing an SCR denitration catalyst, characterized in that:
in the step S1, the concentration of the indium nitrate solution is 0.0066-0.066 mol/L.
8. The sulfur-and water-resistant CH of claim 64-a method for preparing an SCR denitration catalyst, characterized in that:
in the step S1, the concentration of the indium nitrate solution is 0.033 mol/L; in step S2, uniformly mixing, and stirring at constant temperature of 85 ℃ for 8 h; in step S3, the calcination temperature is 500 ℃.
9. The sulfur-and water-resistant CH of claim 64-a method for preparing an SCR denitration catalyst, characterized in that: in step S2, the Co3O4The mass ratio of H-Beta to H-Beta is (2-20) to 40; the silicon-aluminum ratio of the H-Beta molecular sieve is 25-40.
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