CN111097498B - CH 4 -SCR denitration catalyst, preparation method thereof and exhaust gas denitration method - Google Patents

CH 4 -SCR denitration catalyst, preparation method thereof and exhaust gas denitration method Download PDF

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CN111097498B
CN111097498B CN201911400365.2A CN201911400365A CN111097498B CN 111097498 B CN111097498 B CN 111097498B CN 201911400365 A CN201911400365 A CN 201911400365A CN 111097498 B CN111097498 B CN 111097498B
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catalyst
beta
metal oxide
scr denitration
sulfur
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CN111097498A (en
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朱荣淑
丁然
朱满玉
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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
    • B01J29/7049—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65 containing rare earth elements, titanium, zirconium, hafnium, zinc, cadmium, mercury, gallium, indium, thallium, tin or lead
    • B01J29/7057—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
    • 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
    • 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
    • B01J29/78—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65 containing arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J29/7815—Zeolite Beta
    • 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
    • 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
    • Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
    • Y02C20/00—Capture or disposal of greenhouse gases
    • Y02C20/20—Capture or disposal of greenhouse gases of methane

Abstract

The invention discloses a CH 4 -SCR denitration catalyst, method for preparing same, and exhaust gas denitration method, CH 4 -the component of the SCR denitration catalyst comprises an H-Beta molecular sieve carrier, indium and a metal oxide, wherein the indium is loaded on the H-Beta molecular sieve carrier, and the metal oxide is selected from Ga 2 O 3 、Fe 2 O 3 、NiO、CeO 2 With Co 3 O 4 Combinations of (a) and (b). From above by Ga 2 O 3 、Fe 2 O 3 、NiO、CeO 2 With Co 3 O 4 The addition of the metal oxide can obviously improve the sulfur resistance and water resistance of the catalyst and improve the denitration rate of the catalyst.

Description

CH 4 -SCR denitration catalyst, preparation method thereof and exhaust gas denitration method
Technical Field
The invention relates to the technical field of catalysts, in particular to CH 4 An SCR denitration catalyst, a preparation method thereof and an exhaust gas denitration method.
Background
The nitrogen oxide is one of main pollutants in the atmosphere, and the nitrogen oxide can not only cause damage to the respiratory organs of human bodies, but also cause the environmental problems of serious harm such as optical smoke, acid rain, ozone cavities and the like. The method mainly comes from the combustion of fossil fuels, and the manufacturing industry, the power production and the transportation are main nitrogen oxide emission sources, and in order to achieve the expected nitrogen oxide emission reduction target and optimize the atmospheric quality, besides strictly controlling the emission, the method is very important to develop a practical and efficient denitrification technology.
By NH 3 The Selective Catalytic Reduction (SCR) method which is a reducing agent is a mature technology with wide application and higher removal efficiency at present. But NH 3 The paint is toxic and corrosive, and has the problems of leakage, secondary pollution and the like in the transportation and use processes; conventional NH 3 The vanadium oxide contained in the-SCR denitration catalyst V-W/Ti catalyst has high toxicity and is healthy to human bodies and environmentHealth presents a great hazard; and the ammonium salt generated in the denitration reaction process can block the pipeline, even can cause explosion, and has potential safety hazard. Therefore, new reducing agents are always sought to replace NH 3 And an environment-friendly catalyst is developed.
CH 4 Has the advantages of abundant resources, wide sources, low price, convenient transportation and storage, and the like, has very excellent economic value in Selective Catalytic Reduction (SCR), and is CH 4 To replace NH 3 The method brings possibility as a reducing agent of a Selective Catalytic Reduction (SCR) method. At present, CH 4 The SCR technology has become a research hotspot for scholars at home and abroad. Among them, H-Beta molecular sieve supported indium catalysts (i.e., in/H-Beta catalysts) are attracting much attention due to their high denitration efficiency, but In/H-Beta catalysts have poor sulfur and water resistance and are severely deactivated under the condition of containing sulfur and water; in practical application, the flue gas often contains water and sulfur dioxide with certain concentration, so that the key for applying the catalyst to the practical application is to improve the sulfur resistance and water resistance of the In/H-Beta catalyst.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a CH 4 The SCR denitration catalyst, the preparation method thereof and the waste gas denitration method can improve the sulfur-resistant and water-resistant performance and the denitration rate of the In/H-Beta catalyst, and have high denitration efficiency.
The technical scheme adopted by the invention is as follows:
in a first aspect of the present invention, a CH is provided 4 -SCR denitration catalyst, said CH 4 The components of the SCR denitration catalyst comprise an H-Beta molecular sieve carrier, indium and metal oxide, wherein the indium is loaded on the H-Beta molecular sieve carrier;
the metal oxide is selected from Ga 2 O 3 、Fe 2 O 3 、NiO、CeO 2 With Co 3 O 4 Combinations of (a) and (b).
According to some embodiments of the invention, the metal oxide is selected from Ga 2 O 3 、Fe 2 O 3 At least one ofCo 3 O 4 A combination of (a) and (b).
According to some embodiments of the invention, the metal oxide is selected from Ga 2 O 3 And Co 3 O 4 Combinations of (a) and (b).
According to some embodiments of the invention, the metal oxide is selected from the group consisting of (1 to 4) by mass: 1 Co 3 O 4 And Ga 2 O 3 . Preferably, the metal oxide is selected from the group consisting of 4:1 Co 3 O 4 And Ga 2 O 3 。
According to some embodiments of the invention, the mass ratio of the metal oxide to the H-Beta molecular sieve support is 1: (2-8). Preferably, the mass ratio of the metal oxide to the H-Beta molecular sieve carrier is 1:4. according to some embodiments of the invention, the indium is loaded on the H-Beta molecular sieve support by an ion exchange method.
In a second aspect of the invention, there is provided any one of the CHs provided in the first aspect of the invention 4 -a method for preparing an SCR denitration catalyst, comprising the steps of:
s1, uniformly mixing an H-Beta molecular sieve carrier, metal oxide and an indium-containing ion exchange solution, stirring for reaction at 75-95 ℃, and then carrying out solid-liquid separation;
and S2, washing, drying and grinding the solid obtained by solid-liquid separation in the step S1, and then calcining at the temperature of 400-550 ℃.
According to some embodiments of the invention, in the step S1, the concentration of the indium ions in the indium-containing ion exchange solution is (0.025 to 0.07) mol/L. Preferably, the concentration of indium ions in the indium-containing ion exchange solution is 0.033mol/L. In step S1, the stirring reaction time is generally 2 to 10 hours.
According to some embodiments of the invention, in step S2, the calcination temperature is 500 ℃. In addition, in step S2, the supernatant is generally washed with water until it is neutral; after calcination is completed, the mixture is generally tabletted, ground and sieved.
In a third aspect of the present invention, a method for denitrating exhaust gas is provided, specifically, a selective catalytic reduction method is used for waste gas denitrationGas treatment with CH 4 The catalyst is any CH provided by the first aspect of the invention as a reducing agent 4 -an SCR denitration catalyst.
The embodiment of the invention has the beneficial effects that:
the embodiment of the invention provides a CH 4 SCR denitration catalyst consisting of Ga 2 O 3 、Fe 2 O 3 、NiO、CeO 2 With Co 3 O 4 The metal oxide is mixed with an indium-loaded H-Beta molecular sieve carrier to form the metal oxide; by Ga In comparison to H-Beta molecular sieve supported indium catalyst (i.e., in/H-Beta catalyst) 2 O 3 、Fe 2 O 3 、NiO、CeO 2 With Co 3 O 4 The addition of the metal oxide can obviously improve the sulfur resistance and water resistance of the catalyst and improve the denitration rate of the catalyst.
Drawings
FIG. 1 is a schematic view of an evaluation apparatus used in an activity evaluation experiment of a catalyst;
FIG. 2a, FIG. 2b and FIG. 2c show the In/H-Beta catalyst without modification treatment and the single metal oxide modified In/H-Beta catalyst, respectively, for CH under sulfur-containing aqueous conditions 4 Conversion rate, NO x Removal Rate and CH 4 A graph of selectivity test results;
FIG. 3a, FIG. 3b and FIG. 3c are In-Co 3 O 4 catalyst/H-Beta and metal oxide modified In-Co 3 O 4 Catalyst of H-Beta for NO under the condition of containing sulfur and water x Removal rate, CH 4 Conversion and CH 4 A graph of selectivity test results;
FIG. 4a, FIG. 4b and FIG. 4c are In-Fe, respectively 2 O 3 catalyst/H-Beta and metal oxide modified In-Fe 2 O 3 Catalyst of H-Beta for NO under the condition of containing sulfur and water x Removal rate, CH 4 Conversion and CH 4 A graph of selectivity test results;
FIG. 5a, FIG. 5b and FIG. 5c are the In-NiO/H-Beta catalyst and the metal oxide modified In-NiO/H-Beta catalyst In the presence of sulfur-containing aqueous solution, respectivelyUnder the condition of NO x Removal rate, CH 4 Conversion and CH 4 A graph of selectivity test results;
FIG. 6a, FIG. 6b and FIG. 6c are In-Co 3 O 4 -Fe 2 O 3 catalyst/H-Beta and modified In-Co 3 O 4 -Fe 2 O 3 Catalyst of H-Beta for NO under the condition of containing sulfur and water x Removal rate, CH 4 Conversion and CH 4 A graph of selectivity test results;
FIG. 7a, FIG. 7b and FIG. 7c are In-Co 3 O 4 -Ga 2 O 3 catalyst/H-Beta and modified In-Co 3 O 4 -Ga 2 O 3 Catalyst of H-Beta for NO under the condition of sulfur-containing and water-containing x Removal rate, CH 4 Conversion and CH 4 A graph of selectivity test results;
FIGS. 8a, 8b and 8c are graphs showing the influence of In ion concentration on NO In the presence of sulfur-containing water In each of the catalysts x Removal rate, CH 4 Conversion and CH 4 A graph of selectivity test results;
FIG. 9a, FIG. 9b and FIG. 9c are graphs showing the effect of mass ratio of metal oxide to molecular sieve on NO in sulfur-containing and water-containing conditions for each of the catalysts x Removal rate, CH 4 Conversion and CH 4 A graph of selectivity test results;
FIG. 10a, FIG. 10b and FIG. 10c are each Co 3 O 4 And Ga 2 O 3 Influence of mass ratio on NO in the presence of sulfur and water x Removal rate, CH 4 Conversion and CH 4 A graph of selectivity test results;
FIG. 11a, FIG. 11b and FIG. 11c are graphs showing the influence of calcination temperature on NO in the presence of sulfur and water x Removal rate, CH 4 Conversion and CH 4 And (4) a selective test result chart.
Detailed Description
The idea of the invention and the resulting technical effects will be clearly and completely described below in connection with the embodiments, so that the objects, features and effects of the invention can be fully understood. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and those skilled in the art can obtain other embodiments without inventive effort based on the embodiments of the present invention, and all embodiments are within the protection scope of the present invention.
(one) CH 4 Preparation of SCR denitration catalyst
100mL of indium-containing ion exchange solution (indium nitrate) with indium ion concentration of 0.033mol/L is prepared, and then 4g of H-Beta molecular sieve carrier (SiO) is added into the indium-containing ion exchange solution 2 /Al 2 O 3 = 25) and 1g of metal oxide, then placing the mixture on a magnetic stirrer, and magnetically stirring the mixture in a thermostatic water bath at the temperature of 85 ℃ for 8 hours; placing the stirred solution on a Buchner funnel, performing suction filtration by using a vacuum pump, and washing with water until the pH of the lower clear liquid is = 7; pouring out the filtrate, taking out the filter cake on the filter paper, putting the filter cake into a drying oven, and drying for 12 hours at the temperature of 80 ℃; and then taking out the dried catalyst, grinding, calcining in a tubular furnace at 500 ℃ for 3h in an air atmosphere, tabletting and grinding the calcined catalyst, and screening by using a 40-60-mesh screen.
By the method, indium ions in indium nitrate containing indium ion exchange solution are loaded on an H-Beta molecular sieve carrier by an ion exchange method and mixed with metal oxide to form CH 4 -SCR denitration catalyst, which can be considered as metal oxide modified In/H-Beta catalyst. Specifically, the single metal oxide modified In/H-Beta catalyst, the double metal oxide modified In/H-Beta catalyst and the triple metal oxide modified In/H-Beta catalyst were prepared according to the above methods, respectively. The metal oxides selected are mainly concentrated on transition metal oxides and group IIIA metal oxides, including Sb 2 O 5 、La 2 O 3 、CdO、BiO 2 、MoO 3 、WO 3 、 Zr 2 O 5 、In 2 O 3 、SnO 2 、Ga 2 O 3 、Ta 2 O 5 、Co 3 O 4 、Fe 2 O 3 、NiO、MnO 2 、CeO 2 . In addition, inCH prepared by adding metal oxide and adopting the preparation method 4 SCR denitration catalyst (In/H-Beta catalyst) as control.
Evaluation of catalyst Activity
The catalyst activity was evaluated by the Temperature Programmed Surface Reaction (TPSR) technique. The evaluation system mainly comprises a gas circuit control system, a catalytic reaction device system and an online analysis and test system, and the schematic diagram of the evaluation device is shown in figure 1.
The experimental process adopts simulated sulfur-containing water-containing flue gas, the gas is provided by gas cylinders, and the gas in each cylinder is NO and CH respectively 4 、 O 2 、SO 2 And Ar as an equilibrium gas. The water vapor was added by bubbling argon. The gas in the steel cylinder enters the gas circuit control system through a gas pressure reducing valve, and the gas pressure is regulated through a pressure stabilizing valve after the gas is controlled to be switched on and off through a switch valve, so that the gas pressure is 0.1MPa; and then the flow of each gas path is adjusted through a flow stabilizing valve and a mass flow meter, and different gases enter a gas mixing pipe to be uniformly mixed and then enter a reaction pipe to react. 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. The on-line analysis test system comprises a nitrogen oxide analyzer (42 i) and a gas chromatograph (GC-2014C), and the gas passes through a drying device to remove water in the gas before entering a detection instrument.
The concentrations of the reaction gases of the components in the experiment are as follows: NO is 400ppm, CH 4 400ppm of oxygen 2 At 10vol%, SO 2 100ppm, 5vol% of water vapor and Ar as an equilibrium gas. The total flow of gas is 100mL/min, the dosage of the catalyst is 100mg, and the space velocity is 23600h -1 . And introducing the mixed gas into a quartz reaction tube at normal temperature until the catalyst adsorbs and saturates the nitrogen oxide to reach adsorption balance (the indication of a nitrogen oxide analyzer is not changed basically). Regulating the temperature controller to maintain the programmed heating rate at 4 deg.C/min and the temperatureFrom 100 ℃ to 600 ℃.
Three indexes, namely nitrogen oxide removal rate, methane conversion rate and methane selectivity, are adopted to evaluate the denitration activity of the catalyst. Removal rate of nitrogen oxide with NO x (de) as shown in formula (1), the higher the removal rate of nitrogen oxide, the higher the NO x The higher the (de) value, the higher the denitration activity of the catalyst under the sulfur-containing water condition. In the selective catalytic reduction reaction process, methane is used as the reducing gas of the reaction, the conversion rate of the methane can also directly reflect the activity of the catalyst in the reaction with the methane, and further the activity of the nitrogen oxide catalyst in the reaction with the methane can be indirectly explained, and further the removal condition of nitrogen oxides, CH, can be indirectly explained 4 Conversion of from CH 4 (c) Expressed as shown in equation (2). CH (CH) 4 Can directly reflect the utilization of CH by the catalyst 4 Reduction of NO x Ability of CH 4 For NO x Is selected from CH 4 (s) as shown in equation (3).
Figure GDA0003916950550000051
Figure GDA0003916950550000052
Figure GDA0003916950550000053
In the formula, c (NO) x-in ) -Prior to reaction NO x Initial concentration (ppm);
c(NO x-out ) After reaction NO x Concentration (ppm);
c(CH 4-in ) -Prior to reaction CH 4 Initial concentration (ppm);
c(CH 4-out ) After reaction CH 4 Concentration (ppm).
Sulfur-resistant and water-resistant performance of (III) single metal oxide modified In/H-Beta catalyst
By usingThe above activity evaluation method was carried out on the above single metal oxide (Sb) 2 O 5 、La 2 O 3 、CdO、BiO 2 、MoO 3 、 WO 3 、Zr 2 O 5 、In 2 O 3 、SnO 2 、Ga 2 O 3 、Ta 2 O 5 、Co 3 O 4 、Fe 2 O 3 、NiO、MnO 2 、CeO 2 ) The modified In/H-Beta catalyst and the unmodified In/H-Beta catalyst are subjected to activity evaluation to obtain the SO content of each catalyst 2 And H 2 Nitrogen Oxide (NO) in O gas atmosphere x ) Removal rate, CH 4 Conversion and CH 4 The results of the selectivity test are shown in fig. 2a, fig. 2b and fig. 2c, respectively. Due to the addition of Sb 2 O 5 、La 2 O 3 、CdO、BiO 2 、MoO 3 、WO 3 The In/H-Beta catalysts subjected to modification were completely deactivated under sulfur-containing aqueous conditions, and therefore their NO was not shown In FIGS. 2a, 2b and 2c x Removal rate, CH 4 Conversion and CH 4 And (4) selecting a test result.
As can be seen from FIG. 2b, zr was added 2 O 5 、In 2 O 3 、SnO 2 Although the modified In/H-Beta catalyst can maintain certain denitration activity under the condition of containing sulfur and water, the modified catalyst has NO activity x The removal rate of (b) is reduced to a certain extent compared with that of the In/H-Beta catalyst, therefore, zr is added 2 O 5 、In 2 O 3 、SnO 2 The sulfur resistance and water resistance of the In/H-Beta catalyst can not be improved. Adding Ga 2 O 3 、Ta 2 O 5 、Co 3 O 4 、Fe 2 O 3 、NiO、MnO 2 、CeO 2 Compared with an In/H-Beta catalyst, the denitration rate of the modified catalyst under the condition of sulfur and water is improved to a certain extent. In-CeO 2 The denitration rate of the/H-Beta catalyst is not obviously improved at 600 ℃, but the active temperature window is widened, and when the temperature is higher than 600 ℃, ceO 2 Can keep the denitration rate of the catalyst at the bestAnd (4) denitration rate. Adding Ta 2 O 5 The sulfur-resistant and water-resistant performance of the modified In/H-Beta catalyst is improved, and NO is treated at 625 DEG C x The removal rate of (3) was 37.2%. In/H-Beta addition of Ga 2 O 3 、NiO、MnO 2 The denitration activity In the whole reaction temperature range under the condition of containing sulfur and water is similar, and the In-Ga temperature is 625 DEG C 2 O 3 /H-Beta、In-NiO/H-Beta、 In-MnO 2 H-Beta vs. NO x The removal rates of (a) were 40.7%, 43.1% and 41.9%, respectively; adding Co 3 O 4 And Fe 2 O 3 The sulfur-resistant and water-resistant performance of the modified In/H-Beta catalyst is improved most obviously, and the In-Co catalyst is In-Co at 625 DEG C 3 O 4 /H-Beta、 In-Fe 2 O 3 H-Beta vs. NO x The removal rates of (a) and (b) were 65.1% and 55.3%, respectively.
As can be seen from FIG. 2a, the addition of each of the above metal oxides increases the CH content of the catalyst to some extent in both the high-temperature stage and the low-temperature stage 4 The conversion rate shows that the addition of the metal oxide can improve the catalyst and CH 4 And (3) activity of the reaction. In the low temperature region, in-Ga 2 O 3 /H-Beta、In-In 2 O 3 CH of/H-Beta 4 The conversion rate is obviously better than that of other catalysts, so that Ga is known to be in a low-temperature region 2 O 3 And In 2 O 3 Has a better and CH 4 Activity of the reaction. In the high temperature section, in-Ga 2 O 3 /H-Beta、 In-Ta 2 O 5 /H-Beta、In-Co 3 O 4 CH of/H-Beta 4 The conversion rate can reach about 90 percent. Bound to NO x Removal efficiency can be predicted for Ta 2 O 5 Promote CH at high temperature 4 The non-selective reaction proceeds, but the denitration reaction is not facilitated.
FIG. 2c shows that In/H-Beta is poor In denitration activity under the condition of containing sulfur and water, and is specific to CH 4 Also the conversion of (A) was low, but the In/H-Beta catalyst CH at 550 ℃ and 600 ℃ was low 4 The selectivity is much higher than for the modified catalyst. At 550 ℃, in-NiO/H-Beta, in-Fe 2 O 3 H-Beta and In-Co 3 O 4 CH of/H-Beta 4 Excellent selectivityCatalysts modified with other monometallic oxides, CH thereof 4 The selectivities were 76.2%, 60.9% and 60.2%, respectively. When the temperature rises to 600 ℃, in-NiO/H-Beta, in-Fe 2 O 3 H-Beta and In-Co 3 O 4 CH of/H-Beta 4 The selectivity is still better than other modified catalysts, in-Fe 2 O 3 H-Beta and In-Co 3 O 4 CH of/H-Beta 4 The selectivity is relatively close (54.1 percent and 53.9 percent respectively) and is better than the CH of the In-NiO/H-Beta 4 Selectivity (48.9%). CH of In/H-Beta catalyst at 650 deg.C 4 The selectivity is sharply reduced from 77.8% at 600 ℃ to 10.0%. The modified catalyst has better CH at 650 DEG C 4 Selectivity of In-Ta 2 O 5 The temperature at which the/H-Beta has the highest CH 4 The selectivity was 58.9%. In-Ga 2 O 3 /H-Beta、In-In 2 O 3 CH of/H-Beta 4 The selectivities are relatively similar and are respectively 56.6 percent and 56.1 percent. And CH at 550 ℃ and 600 ℃ 4 In-Fe with high selectivity 2 O 3 /H-Beta、In-Co 3 O 4 The CH of the/H-Beta and In-NiO/H-Beta increases when the temperature rises to 650 DEG C 4 The selectivity dropped to 52.5%, 53.1% and 42.7%, respectively. The rest catalyst also keeps better CH under high temperature condition 4 The selectivity can reach more than 40 percent.
As can be seen from the above, zr was added 2 O 5 、In 2 O 3 、SnO 2 The In/H-Beta catalyst is modified to deteriorate the sulfur resistance and water resistance of the In/H-Beta. Addition of metal oxide Ga 2 O 3 、Ta 2 O 5 、Co 3 O 4 、Fe 2 O 3 、NiO、MnO 2 、CeO 2 The In/H-Beta catalyst has improved sulfur water resistance, wherein the In-NiO/H-Beta and the In-Fe 2 O 3 H-Beta and In-Co 3 O 4 the/H-Beta is either for NO under the condition of containing sulfur and water x Removal rate of (2), CH 4 Conversion and CH 4 The selectivity is obviously superior to that of the catalysis modified by other single metal oxidesAnd (3) preparing.
Sulfur-resistant and water-resistant performance of (IV) bimetallic oxide modified In/H-Beta catalyst
Based on the research results of the sulfur resistance and water resistance of the single metal oxide modified In/H-Beta catalyst, three single metal modified In/H-Beta catalyst systems (In-Co) with excellent sulfur resistance and water resistance are further investigated 3 O 4 /H-Beta、In-Fe 2 O 3 the/H-Beta and the In-NiO/H-Beta) are respectively oxidized by NiO and Co 3 O 4 、Fe 2 O 3 、Ga 2 O 3 、MnO 2 、CeO 2 The sulfur-resistant and water-resistant performance of the formed bimetallic oxide modified In/H-Beta catalyst is further modified to carry out research experiments. That is, specifically Co is used 3 O 4 、Fe 2 O 3 One of NiO, niO and Co 3 O 4 、Fe 2 O 3 、Ga 2 O 3 、MnO 2 、CeO 2 The In/H-Beta catalyst is modified to form the bimetallic oxide modified In/H-Beta catalyst; and then according to the above catalyst activity evaluation method, carrying out research experiment on the sulfur-resistant and water-resistant performances of each bimetallic oxide modified In/H-Beta catalyst, wherein the obtained results comprise:
1. metal oxide modified In-Co 3 O 4 Sulfur-resistant and water-resistant performance of/H-Beta catalyst
NiO and Fe were treated by the above method 2 O 3 、Ga 2 O 3 、MnO 2 、CeO 2 Are respectively reacted with Co 3 O 4 Bimetallic oxide modified In/H-Beta catalyst prepared by combined modification of In/H-Beta and In-Co 3 O 4 The research experiment of the sulfur-resistant and water-resistant performance of the/H-Beta catalyst is carried out to obtain the SO content of each catalyst 2 And H 2 Nitrogen Oxide (NO) in O gas atmosphere x ) Removal rate, CH 4 Conversion and CH 4 The results of the selectivity test are shown in fig. 3a, fig. 3b and fig. 3c, respectively.
As can be seen from FIG. 3a, the metal oxides NiO and Fe 2 O 3 、Ga 2 O 3 、CeO 2 Can improve In-Co 3 O 4 Sulfur-and water-resistance of/H-Beta, in which 3 O 4 -Fe 2 O 3 /H-Beta、In-Co 3 O 4 -Ga 2 O 3 The denitration activity of the/H-Beta is highest under the condition of containing sulfur and water, and the denitration activity is to NO at 625 DEG C x The removal rates were 71.5% and 74.6%, respectively. Adding NiO and CeO 2 Compared with Co-doped catalyst, the sulfur-resistant and water-resistant performance of the catalyst modified by doping is improved 3 O 4 、Ga 2 O 3 Weaker, NO at 625 ℃ x The removal rates of (a) and (b) were 68.9% and 69.7%, respectively. And In-Co 3 O 4 -MnO 2 The denitration activity of the/H-Beta is basically not obviously changed from the activity before the modification in the whole temperature range, which shows that MnO is not obviously changed 2 Addition of (2) does not improve In-Co 3 O 4 The sulfur resistance and water resistance of the/H-Beta catalyst.
As can be seen from FIG. 3b, CH 4 Trend of conversion with NO x The trend of the removal rate was almost the same. The addition of the above metal oxide can further improve the catalyst and CH 4 The reactivity of (A) is CH of the modified catalyst in both the low temperature stage and the high temperature stage 4 The conversion rate is improved.
From FIG. 3c, the CH of the catalyst 4 The selectivity decreases with increasing temperature, in-Co being present at a temperature In the range from 550 ℃ to 600 ℃ 3 O 4 -NiO/H-Beta、In-Co 3 O 4 -Fe 2 O 3 /H-Beta、In-Co 3 O 4 -Ga 2 O 3 CH of/H-Beta 4 The selectivity is relatively close and is obviously superior to CH of other catalysts at the same temperature 4 And (4) selectivity. In-Co at 650 deg.C 3 O 4 -Fe 2 O 3 CH of/H-Beta 4 The selectivity was the highest, 40.3%.
2. Metal oxide modified In-Fe 2 O 3 Sulfur-resistant and water-resistant performance of/H-Beta catalyst
NiO and Co are treated by the above method 3 O 4 、Ga 2 O 3 、MnO 2 、CeO 2 Respectively with Fe 2 O 3 Bimetallic oxide modified In/H-Beta catalyst prepared by combined modification of In/H-Beta and In-Fe 2 O 3 The sulfur-resistant and water-resistant performance of the/H-Beta catalyst is researched and tested to obtain the SO content of each catalyst 2 And H 2 Nitrogen Oxide (NO) in O gas atmosphere x ) Removal rate, CH 4 Conversion and CH 4 The selectivity test results are shown in fig. 4a, 4b and 4c, respectively.
As can be seen from FIGS. 4a to 4c, co is added 3 O 4 In-Fe of 2 O 3 The sulfur resistance and water resistance of the/H-Beta are improved, and the NO resistance is improved at 625 DEG C x The removal rate of (a) was 61.8%; while the addition of other metal oxides will reduce In-Fe 2 O 3 The sulfur-resistant and water-resistant performance of the/H-Beta is especially doped with NiO and Ga 2 O 3 Catalyst NO of x The removal rate of the CeO is reduced to 45.1 percent and 45.8 percent from 55.3 percent respectively, and the CeO is doped 2 、MnO 2 The sulfur-resistant and water-resistant performance of the modified catalyst is similar, and the modified catalyst is used for NO at 625 DEG C x The removal rates of (a) and (b) were 48.8% and 49.6%, respectively. For CH 4 Conversion rate except for In-Fe 2 O 3 -CeO 2 The H-Beta is for CH over the entire temperature range 4 In addition to not increasing the conversion, the addition of the remaining metal oxide increases the CH 4 And (4) conversion rate. For CH 4 Selectivity, co 3 O 4 The addition of (A) improves the selectivity of the catalyst in the whole active temperature range, and CeO 2 The addition of (2) increases the CH of the catalyst at 550 ℃ 4 Selectivity, the selectivity at this point was 65.1%. The addition of other metal oxides does not improve In-Fe 2 O 3 CH of/H-Beta 4 And (4) selectivity.
3. Sulfur-resistant and water-resistant performance of metal oxide modified In-NiO/H-Beta catalyst
For Fe by the above method 2 O 3 、Co 3 O 4 、Ga 2 O 3 、MnO 2 、CeO 2 Bi-metal oxide modified In/H-Beta catalyst prepared by modifying In/H-Beta through combination with NiO and In-NiO/H-Beta catalystCarrying out sulfur-resistant and water-resistant performance research experiments to obtain the catalyst containing SO 2 And H 2 Nitrogen Oxide (NO) in O gas atmosphere x ) Removal rate, CH 4 Conversion and CH 4 The selectivity test results are shown in fig. 5a, fig. 5b and fig. 5c, respectively.
As can be seen from FIGS. 5a to 5c, co is selected 3 O 4 、Ga 2 O 3 The sulfur-resistant and water-resistant performance of the catalyst subjected to doping modification is improved, wherein Co is added 3 O 4 The sulfur resistance and water resistance of the modified catalyst are improved most, and NO is treated at 625 DEG C x The removal rate of (b) was 65.3%, in-NiO-Ga 2 O 3 H-Beta vs. NO x The removal rate of (3) was 49.6%. To be doped with CeO 2 、Fe 2 O 3 And MnO 2 The sulfur-resistant and water-resistant properties of the catalyst may be decreased, wherein the modified catalyst having the worst sulfur-resistant and water-resistant properties is In-NiO-Fe 2 O 3 H-Beta, NOx removal 38.2% at 625 ℃. The CH can be improved by adding metal oxide to modify an In-NiO/H-Beta system 4 Conversion, modified catalyst CH 4 Trend of conversion with NO x The change trend of the removal rate is basically consistent.
To sum up, in-Co 3 O 4 /H-Beta、In-Fe 2 O 3 Further modification based on the/H-Beta and In-NiO/H-Beta systems is found In the In-Co 3 O 4 The modification effect is obviously better than that of other two systems on the basis of the/H-Beta system, wherein In-Co 3 O 4 -Fe 2 O 3 /H-Beta、In-Co 3 O 4 -Ga 2 O 3 The sulfur resistance and water resistance of the/H-Beta are obviously better than those of other catalysts. At 625 deg.C, for NO x The removal rates of (a) and (b) were 71.5% and 74.6%, respectively, and In-Co 3 O 4 H-Beta vs. NO x The removal rate is obviously improved; to CH 4 The conversion of (A) was 73.2% and 75.8%, respectively, for CH 4 The selectivity of the catalyst is respectively 50.2 percent and 48.8 percent, and is obviously improved compared with a single metal oxide modified system.
Sulfur-resistant and water-resistant performance of (V) trimetal oxide modified In/H-Beta catalyst
Based on the research results of the sulfur resistance and water resistance of the bimetallic oxide modified In/H-Beta catalyst, two bimetallic modified In/H-Beta catalyst systems (In-Co) with better sulfur resistance and water resistance are further investigated 3 O 4 -Fe 2 O 3 H-Beta and In-Co 3 O 4 -Ga 2 O 3 /H-Beta) is respectively processed by NiO and Fe 2 O 3 、Ga 2 O 3 、MnO 2 、CeO 2 The sulfur-resistant and water-resistant performance of the formed bimetallic oxide modified In/H-Beta catalyst is further modified to carry out research experiments. That is, niO and Fe are used specifically 2 O 3 、 Ga 2 O 3 、MnO 2 、CeO 2 And (Co) 3 O 4 +Fe 2 O 3 ) Or (Co) 3 O 4 +Ga 2 O 3 ) Combining to form metal oxide, and modifying the In/H-Beta catalyst to form a tri-metal oxide modified In/H-Beta catalyst; and then according to the above catalyst activity evaluation method, carrying out research experiments on the sulfur-resistant and water-resistant performances of each trimetal oxide modified In/H-Beta catalyst, and obtaining the results comprising:
1. modified In-Co 3 O 4 -Fe 2 O 3 Sulfur-resistant and water-resistant performance of/H-Beta catalyst
NiO and Ga are treated by the above method 2 O 3 、MnO 2 、CeO 2 Are respectively connected with (Co) 3 O 4 +Fe 2 O 3 ) Trimetal oxide modified In/H-Beta catalyst prepared by combined modification of In/H-Beta, and In-Co 3 O 4 -Fe 2 O 3 The sulfur-resistant and water-resistant performance of the/H-Beta catalyst is researched and tested to obtain the SO content of each catalyst 2 And H 2 Nitrogen Oxide (NO) in O gas atmosphere x ) Removal rate, CH 4 Conversion and CH 4 The selectivity test results are shown in fig. 6a, fig. 6b and fig. 6c, respectively.
As is clear from FIGS. 6a and 6b, ga is added 2 O 3 In-Co of 3 O 4 -Fe 2 O 3 The sulfur-resistant and water-resistant performance of the/H-Beta is improved to a certain extent at 625 DEG CWhen to NO x The removal rate of the catalyst can reach 76.9 percent compared with In-Co 3 O 4 -Fe 2 O 3 The improvement of the/H-Beta is 3.5 percent. In-Co 3 O 4 -Fe 2 O 3 -Ga 2 O 3 the/H-Beta pairs CH in both the low temperature section and the high temperature section 4 The conversion rate is improved, and CH is obtained when the temperature reaches 650 DEG C 4 The highest conversion rate can reach 91.6 percent. Adding CeO 2 In-Co of 3 O 4 -Fe 2 O 3 The sulfur resistance and water resistance of the/H-Beta are compared with those of In-Co In a low temperature region 3 O 4 -Fe 2 O 3 the/H-Beta is greatly improved, but In a high-temperature region, the denitration activity of the catalyst is combined with that of In-Co 3 O 4 -Fe 2 O 3 The denitration activity of the/H-Beta is basically the same. And for CH 4 In terms of conversion, in-Co is present In both the low temperature stage and the high temperature stage 3 O 4 -Fe 2 O 3 -CeO 2 CH of/H-Beta 4 Trend of conversion and In-Co 3 O 4 -Fe 2 O 3 the/H-Beta is almost the same. In-Co 3 O 4 -Fe 2 O 3 -MnO 2 the/H-Beta catalyst is used for NO in a low-temperature region x The removal rate of the catalyst is better than that of other catalysts, the high activity of other catalysts can not be achieved in a high-temperature section, and NO is not removed at 625 DEG C x The removal rate was 66.8%. In-Co over the whole temperature range 3 O 4 -Fe 2 O 3 -MnO 2 CH of/H-Beta 4 The conversion rate is higher than that of In-Co 3 O 4 -Fe 2 O 3 /H-Beta。
As can be seen from FIG. 6c, ceO was added at 550 deg.C 2 NiO and MnO 2 Catalyst modified relative to unmodified pre-CH 4 The selectivity is improved, wherein In-Co 3 O 4 -Fe 2 O 3 CH of-NiO/H-Beta 4 The selectivity was the highest, 92.9%. CH of each catalyst at 600 deg.C 4 The selectivities are very close. When the temperature reaches 650 ℃, in-Co 3 O 4 -Fe 2 O 3 -Ga 2 O 3 CH of/H-Beta 4 SelectingThe highest performance was 41.4%. It can be seen that In-Co is present over the entire active temperature range 3 O 4 -Fe 2 O 3 -Ga 2 O 3 the/H-Beta can always keep higher CH 4 And (4) selectivity.
2. Modified In-Co 3 O 4 -Ga 2 O 3 Sulfur-resistant and water-resistant performance of/H-Beta catalyst
NiO and Fe were treated by the above method 2 O 3 、MnO 2 、CeO 2 Are respectively connected with (Co) 3 O 4 +Ga 2 O 3 ) Tri-metal oxide modified In/H-Beta catalyst prepared by combined modification of In/H-Beta and In-Co 3 O 4 -Ga 2 O 3 The sulfur-resistant and water-resistant performance of the/H-Beta catalyst is researched and tested to obtain the SO content of each catalyst 2 And H 2 Nitrogen Oxide (NO) in O gas atmosphere x ) Removal rate, CH 4 Conversion and CH 4 The selectivity test results are shown in fig. 7a, fig. 7b and fig. 7c, respectively.
As can be seen from FIGS. 7a to 7c, in-Co 3 O 4 -Ga 2 O 3 After other metal oxides are added into the/H-Beta system for modification, the sulfur resistance and the water resistance are not improved, but are reduced. CH of all catalysts modified with trimetallic oxide 4 The conversion of (2) is decreased in both the high temperature stage and the low temperature stage. CH for catalyst 4 Optionally, adding Fe 2 O 3 NiO and CeO 2 The catalyst to be modified has CH at 550 DEG C 4 The selectivity was improved, but as the temperature continued to rise, the modified catalyst was compared to CH before modification 4 The selectivity is reduced.
To sum up, in-Co 3 O 4 -Fe 2 O 3 H-Beta and In-Co 3 O 4 -Ga 2 O 3 Further metal oxide modification is carried out on the basis of the catalytic system of the/H-Beta. The experimental result shows that the sulfur-resistant and water-resistant performance of the catalyst is not improved along with the increase of the types of the metal oxides, most of the further modified catalysts have slightly reduced sulfur-resistant and water-resistant performance compared with the original catalytic system, and only In-Co 3 O 4 -Fe 2 O 3 -Ga 2 O 3 The sulfur resistance and water resistance of the catalyst/H-Beta are slightly improved, and NO is generated at 625 DEG C x The removal rate is improved from the original 74.6 percent to 76.9 percent.
(VI) Experimental study on influence of preparation conditions on sulfur resistance and water resistance of catalyst
Although the sulfur resistance and water resistance of the catalyst modified by adding the three metal oxides are superior to those of the catalyst modified by the double metal oxides, the sulfur resistance and water resistance are not obviously improved, and the catalyst system is more complicated by adding the three metal oxides, so that the In-Co is selected 3 O 4 -Ga 2 O 3 The H-Beta is further subjected to an experiment on the influence of the preparation conditions on the sulfur-resistant and water-resistant performances of the catalyst.
In CH 4 In SCR, the preparation conditions directly influence the denitration activity of the catalyst, and the conditions that can be controlled and influence the activity of the catalyst in the ion exchange process include: ion exchange solution concentration, ion exchange time, ion exchange temperature and calcination temperature. The preparation conditions studied in the present invention include: in ion exchange solution, mass ratio of metal oxide to molecular sieve, and Co 3 O 4 And Ga 2 O 3 The mass ratio of (a) and the calcination temperature. The specific method and results are as follows:
1. experimental study on influence of In ion concentration
CH was prepared according to the preparation method described In the first paragraph using ion-exchange solutions containing no In ion and having In ion concentrations of 0.01M (i.e., 0.01 mol/L), 0.02M, 0.033M, 0.05M and 0.066M, respectively 4 -an SCR denitration catalyst. Other preparation conditions were as follows: the mass ratio of the metal oxide to the carrier is 1:4,Co 3 O 4 And Ga 2 O 3 The mass ratio of (A) to (B) is 4:1, the calcination temperature is 500 ℃. Then, the denitration activity evaluation is carried out on each catalyst according to the activity evaluation method of the catalyst described in the second part to obtain the SO content of each catalyst 2 And H 2 Nitrogen Oxide (NO) in O gas atmosphere x ) Removal rate, CH 4 Conversion and CH 4 Results of the selectivity test are as followsFig. 8a, 8b and 8c.
As can be seen from FIG. 8a, if In is not added during the preparation of the catalyst, the catalyst will not have denitration activity under the sulfur-containing aqueous condition, demonstrating that In is present throughout CH 4 -important denitration active components in SCR reactions. With the increase of the In ion concentration, the optimum denitration activity of the catalyst shows a tendency of increasing first and then decreasing. Catalyst vs NO at 625 ℃ when In ion concentration is 0.01M x The removal rate of (2) was only 29.8%. When the In ion concentration was increased to 0.02M, the low temperature activity of the catalyst also showed a tendency to increase for NO x The removal rate of the catalyst can reach 41.1 percent at most, when the concentration of In ions is 0.033M, the denitration activity of the prepared catalyst is highest, and when the temperature is 625 ℃, NO is generated x The removal rate of (2) was 74.6%. As the In ion concentration continues to increase, in-Co 3 O 4 -Ga 2 O 3 H-Beta vs. NO x The maximum removal rate of (2) also decreased, and NO was observed at In ion concentrations of 0.05M and 0.066M x The maximum removal rates were 65.7% and 64.5%, respectively. It is noted that when the In ion concentration is 0.05M, the low-temperature denitration activity of the catalyst under the sulfur-containing and water-containing condition is obviously improved, the optimal activity temperature is 600 ℃, and the denitration activity of the catalyst prepared under the temperature of 550 ℃ is optimal compared with that of the catalyst prepared under other conditions.
FIG. 8b shows that the catalyst produced at different In ion concentrations is paired with CH 4 All increases with increasing temperature and the CH between different catalysts 4 Law of change of conversion and its action on NO x The conversion of (A) is substantially in accordance with the law that the catalyst is on NO x The higher the removal rate of (A), its CH 4 The higher the conversion.
As can be seen from FIG. 8c, the catalyst without In had no denitration activity and thus it was able to react with CH 4 The selectivity of (a) is also almost zero. The remaining catalyst pairs CH 4 The change law of the selectivity is increased and then reduced along with the temperature rise. In the high-temperature stage, CH of catalyst 4 The selectivity shows a decreasing trend with increasing temperature. In ion concentrations of 0.05M and 0.066M at 550 ℃ for the CH of the catalyst prepared 4 The selectivity is obviously higher than that of other catalystsThe selectivity of the reagent is 98.4 percent and 97.3 percent respectively. CH of the catalyst at an In ion concentration of 0.05M when the temperature was raised to 600 deg.C 4 The highest selectivity, about 72.5%, in ion concentrations of 0.033M and 0.066M, resulted In a catalyst having CH 4 Selectivity was comparable, 57.2% and 56.2%, respectively, with an In ion concentration of 0.01M CH 4 The selectivity was the worst, only 35.4%. At a temperature of 650 ℃ CH 4 In-Co with high selectivity of 0.033M, 0.066M, 0.05M, 0.02M and 0.01M, and In ion concentration of 0.033M 3 O 4 -Ga 2 O 3 the/H-Beta shows good CH under high temperature condition 4 And (4) selectivity. According to the experimental result, the catalysts prepared by high In ion concentration all have higher CH 4 Alternatively, an increase In the In ion concentration may limit CH 4 Carrying out non-selective oxidation reaction.
2. Experimental study on influence of mass ratio of metal oxide to molecular sieve
Respectively adopting the mass ratio of metal oxide to molecular sieve as 2: 40. 5: 40. 10: 40. 20:40 and 40:40 according to the preparation process described in the first paragraph. Other preparation conditions were as follows: the In ion concentration was 0.033M 3 O 4 And Ga 2 O 3 4:1, the calcining temperature is 500 ℃. Then, the denitration activity evaluation is carried out on each catalyst according to the activity evaluation method of the catalyst described in the second part to obtain the SO content of each catalyst 2 And H 2 Nitrogen Oxide (NO) in O gas atmosphere x ) Removal rate, CH 4 Conversion and CH 4 The selectivity test results are shown in fig. 9a, 9b and 9 c.
As can be seen from FIG. 9a, as the mass ratio of metal oxide to molecular sieve increases, in-Co 3 O 4 -Ga 2 O 3 H-Beta on NO under Sulfur-containing and Water-containing conditions x The maximum removal rate of (a) is increased and then decreased, wherein the optimal mass ratio is 10:40 to NO at 625 ℃ x The removal rate of the catalyst can reach 74.6 percent; for NO x The lowest removal rate equivalent mass ratio is 40:40, only 29.6% at 625 ℃.
From FIG. 9b, it can be seen that CH of the catalyst 4 Change in conversion with NO x The change in conversion rate is identical, i.e. CH over the entire temperature range 4 The conversion increases and then decreases with increasing mass ratio.
From FIG. 9c, it can be seen that CH of each catalyst 4 The selectivity decreases with increasing temperature, and the mass ratio of 2:40 showed good CH at 550 deg.C 4 The selectivity, in this case 94.5%. CH at 600 ℃ and 650 ℃ 4 The mass ratio of the highest selectivity is 10:40, CH 4 The selectivity was 57.2% and 37.3%, respectively.
In summary, when the mass ratio of the metal oxide to the molecular sieve is 10: at 40 f, the catalyst has the best denitration activity under the sulfur-containing and water-containing conditions, and the catalyst prepared at the mass ratio has CH 4 The conversion rate is higher than that of other catalysts, and the mass ratio of proper metal oxide to molecular sieve can properly improve CH 4 Selectivity, mass ratio at optimum activation temperature of 10: CH of catalyst at 40- 4 The selectivity is the highest.
3、Co 3 O 4 And Ga 2 O 3 Experimental study on influence of mass ratio
Respectively using Co 3 O 4 And Ga 2 O 3 The mass ratio is 1: 1. 2: 1. 3: 1. 4:1 and 5:1 ratio In-Co preparation according to the preparation method of the first part 3 O 4 -Ga 2 O 3 a/H-Beta catalyst. Other preparation conditions were as follows: the In ion concentration is 0.033M, and the mass ratio of the metal oxide to the molecular sieve is 4:1, the calcination temperature is 500 ℃. Then, the denitration activity evaluation is carried out on each catalyst according to the activity evaluation method of the catalyst described in the second part (second part), and the SO content of each catalyst is obtained 2 And H 2 Nitrogen Oxide (NO) in O gas atmosphere x ) Removal rate, CH 4 Conversion and CH 4 The results of the selectivity tests are shown in fig. 10a, 10b and 10 c.
As can be seen from FIG. 10a, with Co 3 O 4 And Ga 2 O 3 Is prepared from 1:1 liter to 4:1, in-Co 3 O 4 -Ga 2 O 3 H-Beta vs. NO x The maximum removal rate of (2) also increases, and NO is removed at 625 DEG C x The removal rate of (a) increased from 63.4% to 74.6%, but as the mass ratio continued to increase to 5:1, in-Co 3 O 4 -Ga 2 O 3 H-Beta vs. NO x The removal rate of (2) is greatly reduced, and NO is removed at 625 DEG C x The removal rate of (2) was only 39.1%.
As can be seen from FIGS. 10b and 10c, the results of the experiments show that different Co conversions can be obtained for CH4 3 O 4 And Ga 2 O 3 CH of catalyst prepared at mass ratio 4 Tendency of conversion to change and to NO x The removal rate variation trend of (A) is basically consistent, and CH is distributed in the whole temperature range 4 Highest conversion and NO x The mass ratio of the highest removal rate is 4:1, and CH 4 Lowest conversion and NO x The mass ratio of the lowest removal rate is 5:1. for CH 4 Selectivity, CH of each catalyst 4 The selectivity decreases with increasing temperature. Although Co is present 3 O 4 And Ga 2 O 3 The mass ratio is 4:1 hour to NO x Has a high removal rate, but is directed to CH over the entire temperature range 4 Has a very low selectivity, and it has been found that the catalyst prepared at this mass ratio promotes CH 4 Non-selective oxidation reaction of (2). At 550 ℃, co 3 O 4 And Ga 2 O 3 The mass ratio is 1: catalyst prepared at 1 has maximum CH 4 Selectivity of 91.8%, co at 600 deg.C 3 O 4 And Ga 2 O 3 The mass ratio is 3:1 catalyst has the highest CH 4 The selectivity was 65.7%. When the temperature continued to rise to 650 ℃, except for a mass ratio of 5:1, CH of the catalyst prepared at each mass ratio 4 The selectivity is comparable. 4. Experimental study on Effect of calcination temperature
Preparing In-Co according to the preparation method In the first part at the calcining temperature of 400 ℃, 450 ℃,500 ℃, 550 ℃ and 600 ℃ respectively 3 O 4 -Ga 2 O 3 A/H-Beta catalyst. Other preparation conditions were as follows: the In ion concentration is 0.033M, and the mass ratio of the metal oxide to the molecular sieve is 4:1,Co 3 O 4 And Ga 2 O 3 The mass ratio of (A) to (B) is 4:1. then, the denitration activity evaluation is carried out on each catalyst according to the activity evaluation method of the catalyst described in the second part (second part), and the SO content of each catalyst is obtained 2 And H 2 Nitrogen Oxide (NO) in O gas atmosphere x ) Removal rate, CH 4 Conversion and CH 4 The selectivity test results are shown in fig. 11a, 11b and 11 c.
As can be seen from FIG. 11a, the catalyst is used for NO under the condition of sulfur and water x The removal rate of (a) is increased and then decreased with the increase of the calcination temperature, wherein the calcination temperature is 500 ℃ to prepare In-Co 3 O 4 -Ga 2 O 3 The best denitration activity of/H-Beta is NO at 625 DEG C x The removal rate is the highest and can reach 74.6 percent. And the catalyst prepared by selecting the calcination temperature of 600 ℃ has NO reaction in the whole temperature range x The removal of (a) is inactive, presumably because the metal oxide is sintered on the surface of the molecular sieve due to the too high firing temperature, and active sites on the surface of the catalyst are damaged; on the other hand, too high a temperature may cause collapse of the framework of the molecular sieve, which in turn leads to catalyst deactivation.
As can be seen from FIGS. 11b and 11c, catalyst CH 4 Tendency of conversion to change over the entire temperature range and NO x The change trend of the removal rate is basically consistent, namely the catalyst is matched with NO x Higher removal rate of (A), its CH 4 The higher the conversion. For CH 4 Selectivity, CH of catalyst 4 The selectivity decreases with increasing temperature and the calcination temperature of the catalyst is relative to CH 4 The selectivity impact is small. Since the catalyst prepared at 600 ℃ is almost inactive under sulfur-containing aqueous conditions, its CH 4 Selectivity is not of practical reference. The catalyst prepared at a calcination temperature of 400 ℃ exhibited the highest CH at 550 ℃ 4 The selectivity, in this case, was 70.1%. Catalyst prepared under each condition at 600 ℃ for CH 4 The selectivity is almost the same when the temperature is raised to 650 DEG COf catalyst CH 4 The selectivity is greatly reduced, and the catalyst prepared at the calcination temperature of 500 ℃ shows high CH compared with other catalysts 4 Selectivity, in this case CH 4 The selectivity was 37.3%.
In conclusion, the catalyst prepared at the calcination temperature of 500 ℃ has higher NO under the condition of sulfur and water x Removal Rate and CH 4 Conversion while on CH in the high temperature range 4 The selectivity is also superior.

Claims (10)

1. CH (physical channel) 4 -SCR denitration catalyst, characterized in that the CH 4 -the components of the SCR denitration catalyst comprise an H-Beta molecular sieve support, indium and a metal oxide, the indium being supported on the H-Beta molecular sieve support;
the metal oxide is selected from Ga 2 O 3 、Fe 2 O 3 、NiO、CeO 2 With Co 3 O 4 Combinations of (a) and (b).
2. The CH of claim 1 4 -SCR denitration catalyst, characterized in that said metal oxide is selected from Ga 2 O 3 、Fe 2 O 3 With Co 3 O 4 A combination of (a) and (b).
3. The CH of claim 2 4 -SCR denitration catalyst, characterized in that said metal oxide is selected from Ga 2 O 3 And Co 3 O 4 A combination of (a) and (b).
4. The CH of claim 2 4 -an SCR denitration catalyst, characterized in that the metal oxide is selected from the group consisting of (1 to 4) by mass: 1 Co 3 O 4 And Ga 2 O 3 。
5. The CH of any one of claims 1-4 4 -an SCR denitration catalyst, characterized in that said metal oxide is separated from said H-Beta fractionThe mass ratio of the sub-sieve carrier is 1: (2-8).
6. The CH of any one of claims 1-4 4 -SCR denitration catalyst, characterized in that said indium accounts for said CH 4 The mass percent of the-SCR denitration catalyst is 2-7 wt%.
7. The CH of any one of claims 1 to 4 4 -an SCR denitration catalyst, characterized in that the indium is supported on the H-Beta molecular sieve support by an ion exchange method.
8. CH according to any one of claims 1 to 7 4 The preparation method of the SCR denitration catalyst is characterized by comprising the following steps of:
s1, uniformly mixing an H-Beta molecular sieve carrier, metal oxide and an indium-containing ion exchange solution, stirring for reaction at 75-95 ℃, and then carrying out solid-liquid separation;
and S2, washing, drying and grinding the solid obtained by solid-liquid separation in the step S1, and then calcining at the temperature of 400-550 ℃.
9. The CH of claim 8 4 The method for producing an SCR denitration catalyst is characterized in that, in step S1, the concentration of indium ions in the indium-containing ion exchange liquid is (0.025 to 0.07) mol/L.
10. The method for denitration of waste gas is characterized in that the waste gas is treated by a selective catalytic reduction method, and CH is used 4 The catalyst is the CH as defined in any one of claims 1 to 7 as a reducing agent 4 -an SCR denitration catalyst.
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