CN111036241B - Catalyst with regular structure, preparation method and application thereof, and catalytic oxidation treatment method for ammonia-containing waste gas - Google Patents

Catalyst with regular structure, preparation method and application thereof, and catalytic oxidation treatment method for ammonia-containing waste gas Download PDF

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CN111036241B
CN111036241B CN201811189250.9A CN201811189250A CN111036241B CN 111036241 B CN111036241 B CN 111036241B CN 201811189250 A CN201811189250 A CN 201811189250A CN 111036241 B CN111036241 B CN 111036241B
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catalyst
noble metal
transition metal
active component
slurry
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CN111036241A (en
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孙言
宋海涛
王鹏
朱玉霞
田辉平
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Sinopec Research Institute of Petroleum Processing
China Petroleum and Chemical Corp
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Sinopec Research Institute of Petroleum Processing
China Petroleum and Chemical Corp
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
    • B01J27/14—Phosphorus; Compounds thereof
    • B01J27/185—Phosphorus; Compounds thereof with iron group metals or platinum group metals
    • B01J27/1853—Phosphorus; Compounds thereof with iron group metals or platinum group metals with iron, cobalt or nickel
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
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    • 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
    • B01D53/8634—Ammonia
    • 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
    • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
    • B01J27/02—Sulfur, selenium or tellurium; Compounds thereof
    • B01J27/053—Sulfates
    • B01J27/055—Sulfates with alkali metals, copper, gold or silver
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    • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
    • B01J27/06—Halogens; Compounds thereof
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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Abstract

The invention relates to the field of catalyst preparation, and discloses a catalyst with a regular structure, a preparation method and application thereof, and a catalytic oxidation treatment method for ammonia-containing waste gas, wherein the catalyst comprises the following components in parts by weight: the catalyst comprises a regular structure carrier and an active component coating distributed on the inner surface and/or the outer surface of the regular structure carrier, wherein the active component coating comprises 1-20 wt% of an active component, 60-98 wt% of a matrix and 1-20 wt% of titanium dioxide based on the total weight of the active component coating, the content of the active component coating is 5-50 wt% based on the total weight of the catalyst, and the active component comprises a transition metal carbide and a noble metal. The catalyst provided by the invention has better stability and stronger water and gas scouring resistance, and is beneficial to the dispersion of noble metal and transition metal carbide. When the catalyst provided by the invention is used for treating the waste gas containing ammonia gas, 100% conversion of the ammonia gas at the waste gas outlet can be realized.

Description

Catalyst with regular structure, preparation method and application thereof, and catalytic oxidation treatment method for ammonia-containing waste gas
Technical Field
The invention relates to the field of catalyst preparation, and particularly relates to a catalyst with a regular structure, a preparation method and application thereof, and a catalytic oxidation treatment method for ammonia-containing waste gas.
Background
With the increasing strictness of environmental regulations, the requirement on the discharge amount of nitrogen-containing waste gas is higher and higher, nitrogen oxides are generated in the petroleum refining process, the coal burning process and the automobile exhaust emission process, and in order to treat the nitrogen oxide emission, a plurality of existing technologies can achieve a very good effect. However, ammonia is often used in the treatment of nitrogen oxides, and ammonia escape is a further source of atmospheric pollution in cities.
NH 3 Easily cause the ammonia nitrogen of the waste water of the washing tower to exceed the standard or the SO in the flue gas x The ammonium salt generated by the reaction is separated out, so that salt deposition is caused in a waste boiler or other flue gas post-treatment equipment (such as SCR), and the long-period operation of the device is influenced. At the same time, ammonia gas causes irritation to eyes and skin and can cause severe chemical burns, so that it is necessary to remove ammonia gas from exhaust gas.
Catalysts for the catalytic oxidation treatment of ammonia in exhaust gases are commonly used as noble metals, and US7393511 discloses an ammonia oxidation catalyst comprising a noble metal (e.g. platinum, palladium, rhodium, or gold) on a substrate of titania, alumina, silica, zirconia, or the like. Other ammonia oxidation catalysts include a first layer of vanadium pentoxide, tungsten oxide and molybdenum oxide on a titania support, and a second layer of platinum on a titania support (see US8202481 and US 7410626). However, the above catalysts have limited conversion efficiency in ammonia conversion, especially at relatively low temperatures.
Therefore, the development of the ammonia oxidation catalyst with high efficiency, low price, environmental friendliness, lasting strength and high conversion efficiency becomes a research hotspot and application trend of the catalytic oxidation catalyst at home and abroad at present.
Disclosure of Invention
The invention aims to overcome the defects of low conversion efficiency, short service cycle and poor antitoxic performance of an ammoxidation catalyst existing in the prior art, and provides a regular structure catalyst, a preparation method and application thereof and a catalytic oxidation treatment method of ammonia-containing waste gas. The catalyst provided by the invention has the advantages of high catalytic efficiency, strong antitoxic capability, long service cycle, good strength and the like, and waste gas reaching safe, nontoxic and pollution-free emission standards can be obtained by using the catalyst provided by the invention to treat ammonia-containing waste gas.
In order to achieve the above object, one aspect of the present invention provides a structured catalyst comprising: the catalyst comprises a regular structure carrier and an active component coating distributed on the inner surface and/or the outer surface of the regular structure carrier, wherein the active component coating comprises 1-20 wt% of an active component, 60-98 wt% of a matrix and 1-20 wt% of titanium dioxide based on the total weight of the active component coating, the content of the active component coating is 5-50 wt% based on the total weight of the catalyst, and the active component comprises a transition metal carbide and a noble metal.
In a second aspect, the present invention provides a process for the preparation of a structured catalyst, the process comprising:
(1) Pulping and grinding a substrate and water to obtain substrate slurry, mixing the substrate slurry with silane coupling agent modified nano titanium sol, transition metal oxide and noble metal, and grinding to obtain first slurry;
(2) Coating the first slurry on a regular structure carrier, and then drying to obtain a semi-finished catalyst;
(3) The semi-finished catalyst is added into a catalyst containing CH 4 And/or reduction treatment is carried out under a CO atmosphere so as to reduce the transition metal oxide in the semi-finished catalyst to form transition metal carbide.
In a third aspect, the present invention provides a structured catalyst prepared by the above process.
In a fourth aspect, the present invention provides the use of the above structured catalyst in the treatment of exhaust gas.
In a fifth aspect, the present invention provides a catalytic oxidation treatment method for ammonia-containing exhaust gas, comprising: under the condition of catalytic oxidation, contacting the waste gas containing ammonia gas with a catalyst to convert the ammonia gas into nitrogen and water, wherein the catalyst is the regular structure catalyst provided by the invention.
Compared with the prior art, the invention takes the transition metal carbide and the noble metal as the active components in the catalyst with the regular structure, thereby not only reducing the consumption of the noble metal, but also improving the conversion efficiency of the catalyst. In addition, it is preferable to use at least one of a strong acid salt of a group IIA metal, a strong acid salt of a group IIIA metal, a strong acid salt of a group IB metal, and a strong acid salt of a group IIB metal as a substrate, which is more advantageous in improving the conversion efficiency and stability of the catalyst. According to the preparation method of the regular structure catalyst, the nano titanium sol modified by the silane coupling agent is used as the binder, so that the prepared catalyst is better in stability and stronger in water-gas scouring resistance, and the dispersion of noble metal and transition metal carbide is facilitated. Preferably, when the catalyst provided by the invention is used for treating the waste gas containing ammonia gas, 100% conversion of the ammonia gas at the waste gas outlet can be realized.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For numerical ranges, each range between its endpoints and individual point values, and each individual point value can be combined with each other to give one or more new numerical ranges, and such numerical ranges should be construed as specifically disclosed herein.
In the present invention, the term "structured catalyst" is used to refer to a catalyst comprising a structured carrier and a coating of active component distributed on the inner and/or outer surface of the carrier; the regular structure carrier is a carrier with a regular structure; the regular structure reactor is a fixed bed reactor filled with a regular structure catalyst as a catalyst bed layer.
The invention provides a structured catalyst, which comprises: the catalyst comprises a regular structure carrier and an active component coating distributed on the inner surface and/or the outer surface of the regular structure carrier, wherein the active component coating comprises 1-20 wt% of an active component, 60-98 wt% of a matrix and 1-20 wt% of titanium dioxide based on the total weight of the active component coating, the content of the active component coating is 5-50 wt% based on the total weight of the catalyst, and the active component comprises a transition metal carbide and a noble metal.
In the invention, the active component containing the transition metal carbide and the noble metal with specific content is introduced into the active component coating, so that the conversion efficiency of the catalyst can be improved, the consumption of the noble metal can be reduced, and the production cost of the catalyst can be reduced. In addition, the catalyst provided by the invention has higher stability and water and gas scouring resistance.
According to a preferred embodiment of the present invention, the substrate is selected from at least one of a group IIA metal strong acid salt, a group IIIA metal strong acid salt, a group IB metal strong acid salt and a group IIB metal strong acid salt.
In the present invention, the strong acid salt is preferably at least one of a sulfate, a phosphate and a fluoride.
According to a preferred embodiment of the invention, the substrate is selected from at least one of the group consisting of sulfates, phosphates and fluorides of group IIA metals, group IIIA metals, group IB metals and group IIB metals.
According to the invention, preferably the group IIA metal is Mg and/or Ca.
According to the present invention, the group IIIA metal is preferably at least one of Al, ga and In, and more preferably Al.
According to the present invention, preferably, the group IB metal is Cu.
According to the present invention, preferably the group IIB metal is Zn.
According to a most preferred aspect of the invention, the substrate is selected from at least one of magnesium phosphate, calcium sulfate and magnesium fluoride.
According to a specific embodiment of the present invention, the transition metal is selected from at least one of Ti, V, fe, co, ni, zr, mn, cu, mo and W.
According to the structured catalyst of the present invention, the transition metal in the transition metal carbide is preferably selected fromTi (corresponding carbide is mainly TiC), V (corresponding carbide is mainly VC), fe (corresponding carbide is mainly Fe) 3 C) Co (the corresponding carbide is mainly Co) 2 C) Ni (the corresponding carbide is mainly Ni) 2 C) Zr (corresponding carbide is mainly ZrC), mn (corresponding carbide is mainly Mn) 3 C) Cu (the corresponding carbide is mainly Cu) 2 C) Mo (the carbide corresponding to Mo is mainly 2 C) And W (the corresponding carbide is mainly WC).
It should be noted that, in the active component of the present invention, the transition metal oxide is not excluded in addition to the transition metal carbide and the noble metal, and when the active component contains only the transition metal carbide, the transition metal oxide and the noble metal, the sum of the contents of the transition metal carbide, the transition metal oxide and the noble metal is necessarily 100% by weight based on the total amount of the active component.
According to a preferred embodiment of the present invention, the transition metal is at least one selected from Fe, co and Ni.
The noble metal in the present invention includes at least one of gold, silver, and platinum group metals (ruthenium, rhodium, palladium, osmium, iridium, platinum). According to a preferred embodiment of the present invention, the noble metal is selected from at least one of Au, pt, pd, rh, ru and Ag, and more preferably from at least one of Au, pt and Ag.
The invention adopts the combination of the noble metal and the transition metal carbide, the dosage of the noble metal is selected widely, preferably, the content of the noble metal in the active component is 50-800 mug/g, more preferably 90-400 mug/g, and even more preferably 90-200 mug/g.
The structured catalyst according to the invention, wherein the structured carrier can be used in a catalyst bed provided in a fixed bed reactor. The regular structure carrier can be a whole carrier block, a hollow pore channel structure is formed inside the regular structure carrier, a catalyst coating can be distributed on the inner wall of a pore channel, and the pore channel space can be used as a flowing space of fluid. Preferably, the structured carrier is selected from a monolithic carrier having a parallel channel structure with two open ends. The structured carrier can be a honeycomb structured carrier (honeycomb carrier for short) with honeycomb open pores on the cross section.
According to the structured catalyst of the present invention, the cross section of the structured carrier preferably has a pore density of 6 to 140 pores/cm, preferably 10 to 40 pores/cm; the cross-sectional area of each hole in the regular structure carrier is 0.1-5 square millimeters, preferably 0.1-2 square millimeters, and the aperture ratio of the carrier surface of the regular structure carrier is 20-85%, preferably 50-85%. The holes can be regular or irregular, and the holes can be the same or different in shape and can be independent of each other and can be one of square, regular triangle, regular hexagon, circle and ripple.
In the present invention, the open cell ratio means a ratio of a total cross-sectional area of the cells to a cross-sectional area of the carrier of the regular structure.
According to the structured catalyst of the present invention, preferably, the structured carrier may be at least one selected from the group consisting of cordierite honeycomb carrier, mullite honeycomb carrier, diamond honeycomb carrier, corundum honeycomb carrier, zircon corundum honeycomb carrier, quartz honeycomb carrier, nepheline honeycomb carrier, feldspar honeycomb carrier, alumina honeycomb carrier and metal alloy honeycomb carrier.
According to the structured catalyst of the present invention, preferably, the active component coating layer contains 5 to 15 wt% of the active component, 75 to 94 wt% of the matrix and 1 to 10 wt% of titanium dioxide, based on the total weight of the active component coating layer; further preferably, the active ingredient coating contains 5 to 12 wt% of the active ingredient, 84 to 90 wt% of the matrix, and 3 to 6 wt% of titanium dioxide, based on the total weight of the active ingredient coating.
According to a preferred embodiment of the present invention, the active component coating is present in an amount of 10 to 40 wt.%, more preferably 10 to 20 wt.%, based on the total weight of the catalyst.
The catalyst provided by the invention adopts the active component coating with a specific composition, so that the activity of the catalyst can be ensured, and the stability and the water and gas scouring resistance of the catalyst can be kept.
Meanwhile, the invention also provides a preparation method of the regular structure catalyst, which comprises the following steps:
(1) Pulping and grinding a substrate and water to obtain substrate slurry, mixing the substrate slurry with silane coupling agent modified nano titanium sol, transition metal oxide and noble metal, and grinding to obtain first slurry;
(2) Coating the first slurry on a regular structure carrier, and then drying to obtain a semi-finished catalyst;
(3) Subjecting the semi-finished catalyst to a reaction with CH 4 And/or performing reduction treatment under a CO atmosphere to reduce the transition metal oxide in the semi-finished catalyst to form transition metal carbide.
The kind and preparation of the matrix according to the present invention are as described above and will not be described herein.
The conditions for the grinding in step (1) are not particularly limited in the present invention, and the substrate is preferably ground to the specified particles. According to a preferred embodiment of the invention, the particle diameter d of the matrix in the matrix slurry 90 Is 1 to 10 micrometers, more preferably 7 to 10 micrometers.
According to a preferred embodiment of the present invention, the solid content of the matrix in the matrix slurry is 15 to 50% by weight, more preferably 30 to 45% by weight.
According to a preferred embodiment of the present invention, the method for preparing the silane coupling agent modified nano titanium sol comprises: adding water into the nano titanium sol for pulping to obtain slurry, and mixing the slurry with a silane coupling agent. In the present invention, the mixing method is not particularly limited, but in order to further enhance the dispersion of the silane coupling agent and the nano titanium sol, the mixing method preferably includes: adding a silane coupling agent into the slurry under the stirring condition, and then standing for 1-10 hours at the temperature of 40-90 ℃; most preferably, the manner of mixing comprises: the silane coupling agent is added (e.g., dropped) to the slurry with stirring, and then left at 60 to 80 ℃ for 2 to 7 hours. The selection range of the stirring speed is wide, and the stirring speed can be properly selected by a person skilled in the art according to the actual situation, for example, the stirring speed can be 800-4000r/min, and preferably 1200-1600r/min.
According to a preferred embodiment of the present invention, the silane coupling agent may be added at a rate of 0.5 to 1 part by weight per minute with respect to 100 parts by weight of the slurry. The adoption of the preferred embodiment is more beneficial to enhancing the dispersion of the silane coupling agent and the nano titanium sol.
In the present invention, it is preferable that the silane coupling agent is at least one of organosilicon compounds having a hydrophilic group and a hydrophobic group.
According to the invention, the silane coupling agent may be YSiX 3 Wherein Y is a non-hydrolyzable group including an alkenyl group (mainly vinyl group), and a terminal group having Cl, NH 2 SH, epoxy, N 3 A hydrocarbon group having a functional group such as a (meth) acryloyloxy group or an isocyanate group, i.e., a carbon functional group; x is a hydrolyzable group including Cl, OMe, OEt, OC 2 H 4 OCH 3 、OSiMe 3 And OAc.
According to a preferred embodiment of the present invention, the silane coupling agent is selected from at least one of γ -aminopropyltriethoxysilane (KH-550), γ - (2, 3-epoxypropoxy) propyltrimethoxysilane (KH-560) and γ -methacryloxypropyltrimethoxysilane (KH-570). The preferred embodiment of the invention is more beneficial to the modification of the nano titanium sol by the silane coupling agent and the synergistic effect of the silane coupling agent and the nano titanium sol.
In the present invention, the nano titanium sol may be obtained by commercial production or preparation, and the present invention is not particularly limited thereto.
In the present invention, the solvent of the nano titanium sol may be water.
In the present invention, the nano titanium sol has a solid content of 10 to 50% by weight, preferably 20 to 30% by weight.
According to a preferred embodiment of the present invention, tiO in the nano titanium sol 2 The average particle diameter of the particles is 1 to 200nm, preferably 50 to 100nm, and more preferably 50 to 80nm.
According to a preferred embodiment of the present invention, the slurry obtained by pulping the nano titanium sol with water has a solid content of 5 to 40% by weight, more preferably 10 to 35% by weight, and still more preferably 10 to 20% by weight.
According to a preferred embodiment of the present invention, the weight ratio of the silane coupling agent to the nano titanium sol as titanium dioxide is (10-50): 100, more preferably (10-35): 100. the inventor of the invention finds that when a specific amount of silane coupling agent is used in combination with the nano titanium sol, the synergistic effect of the silane coupling agent and the nano titanium sol can be better played, and the stability and the water-gas scouring resistance of the prepared catalyst can be better improved.
The invention has wide selection range of the dosage of the substrate and the nano titanium sol modified by the silane coupling agent, and preferably, the mass ratio of the nano titanium sol modified by the silane coupling agent to the substrate on a dry basis is (0.5-8): 100, preferably (1-7): 100, more preferably (3-7): 100.
according to the present invention, the conditions for the polishing after the mixing of the matrix slurry with the silane coupling agent-modified nano titanium sol, the transition metal oxide and the noble metal in the step (1) are not particularly limited, and preferably, the particle diameter d of the transition metal oxide in the first slurry obtained by the polishing in the step (1) is the particle diameter 90 1-10 μm, particle diameter d of noble metal 90 Is 0.05-1 μm.
According to the present invention, in order to further disperse the transition metal oxide and the noble metal, it is preferable that the matrix slurry is mixed with the silane coupling agent-modified nano titanium sol, the transition metal oxide and the noble metal in a manner including: mixing the matrix slurry, the silane coupling agent modified nano titanium sol and a mixture containing transition metal oxide and noble metal.
According to a preferred embodiment of the present invention, the method for preparing the mixture containing the transition metal oxide and the noble metal comprises: mixing noble metal, organic solvent and surfactant, ultrasonic treating for 1-4 hr, separating to obtain slurry containing noble metal, adding transition metal oxide, stirring and drying. The organic solvent may be at least one of butanediol, pentanediol, hexanediol, and ethylene glycol. The purpose of the surfactant is to enhance dispersion of the noble metal in the organic solvent, and the surfactant may be selected from at least one of polyvinyl alcohol, polyvinylpyrrolidone, ethyl acetate, and sodium dodecylbenzenesulfonate. The selection range of the use amount of the organic solvent and the surfactant is wide, and preferably, the use amount of the organic solvent may be 100 to 1000mL, and more preferably 150 to 500mL, relative to 1g of the noble metal. Preferably, the surfactant is used in an amount of 0.1 to 2g, more preferably 0.5 to 2g, relative to 1g of the noble metal. According to the present invention, it is preferable that the transition metal oxide is ground and then added to the slurry containing the noble metal. In the present invention, the method of drying in the production process of the mixture containing the transition metal oxide and the noble metal is not particularly limited, and for example, freeze drying may be used.
According to the preparation method provided by the invention, preferably, the content of the noble metal in the mixture containing the transition metal oxide and the noble metal is 50-800 μ g/g, preferably 90-400 μ g/g, and more preferably 90-200 μ g/g.
According to the production method provided by the present invention, the amount of the mixture containing the transition metal oxide and the noble metal is preferably 1 to 20% by weight, preferably 1 to 15% by weight, and more preferably 5 to 12% by weight, based on the total amount of the mixture containing the transition metal oxide and the noble metal, the matrix slurry on a dry basis, and the silane coupling agent-modified nano titanium sol on a dry basis.
The method and conditions for drying the structured carrier coated with the first slurry in step (2) according to the method provided by the present invention are well known to those skilled in the art. For example, the drying method may be air drying, oven drying, forced air drying; the method of calcination may also be a method known in the art. Preferably, in step (2), the drying temperature is between room temperature and 300 ℃, preferably between 100 and 200 ℃, and the drying time is more than 0.5h, preferably between 1 and 10h.
According to the invention, in step (3), the semi-finished catalyst obtained in step (2) is added to a catalyst containing CH 4 And/or performing reduction treatment under a CO atmosphere to reduce the transition metal oxide in the semi-finished catalyst to form transition metal carbide. The reduction treatment may be carried out immediately after the production of the semi-finished catalyst, or may be carried out before the use of the catalyst (i.e., before the use for the treatment of exhaust gas).
According to a preferred embodiment of the present invention, the conditions of the reduction treatment include: at a temperature of 250-700 deg.C, preferably 500-650 deg.C, for 0.5-6 hours, preferably 1-4 hours, containing CH 4 And/or the volume space velocity of the CO atmosphere is 25-100h -1 Preferably 25-75h -1 The pressure is 0.1 to 3MPa, preferably 0.1 to 1MPa. The pressure refers to gauge pressure.
Preferably, it contains CH 4 And/or the CO atmosphere contains 5-25 vol.% CH based on the total volume 4 And/or CO and 75-95% by volume of an inert gas; preferably 10-20% by volume of CH 4 And/or CO and 80-90% by volume of an inert gas. The inert gas may be any gas that does not participate in the reaction, and may be, for example, at least one of helium, argon, and nitrogen, and is preferably nitrogen.
According to the preparation method, the chemical element analysis method and the X-ray small angle diffraction measurement method show that when the transition metal is Ti, the formed carbide is mainly TiC; when the transition metal is V, the carbide formed is mainly VC; when the transition metal is Fe, the carbide formed is mainly Fe 3 C; when the transition metal is Co, the carbide formed is mainly Co 2 C; when the transition metal is Ni, the carbide formed is mainly Ni 2 C; when the transition metal is Zr, the carbide mainly comprises ZrC; when the transition metal is Mn, the carbide formed is mainly Mn 3 C; when the transition metal is Cu, the carbide formed is mainly Cu 2 C; when the transition metal is Mo, the carbide formed is mainly Mo 2 C; when the transition metal is W, the carbide formed is mainly WC.
The preparation process according to the invention, in which the carriers of structured structure used have been described in the foregoing, is described in detail with reference to the foregoing description.
The invention also provides the regular structure catalyst prepared by the preparation method. The catalyst comprises a regular structure carrier and an active component coating distributed on the inner surface and/or the outer surface of the regular structure carrier, wherein the active component coating comprises 1-20 wt% of an active component, 60-98 wt% of a matrix and 1-20 wt% of titanium dioxide based on the total weight of the active component coating, the content of the active component coating is 5-50 wt% based on the total weight of the catalyst, and the active component comprises a transition metal carbide and a noble metal. The structured catalyst prepared by the above preparation method has the same technical characteristics as the structured catalyst claimed in the present invention, and the specific contents refer to the previous description of the structured catalyst in the present invention.
The catalyst with the regular structure provided by the invention is suitable for various working conditions, and has the advantages of high catalytic efficiency, strong antitoxic capability, long service cycle, good strength and the like. The catalyst can meet the requirements of safe, nontoxic and pollution-free emission standards when used for treating waste gas (industrial waste gas).
The invention therefore also provides the use of the structured catalyst described above in the treatment of exhaust gases.
The invention also provides a catalytic oxidation treatment method of ammonia-containing waste gas, which comprises the following steps: under the condition of catalytic oxidation, the waste gas containing ammonia is contacted with a catalyst to convert the ammonia into nitrogen and water, wherein the catalyst is the regular structure catalyst provided by the invention. Preferably, the structured catalyst is present in the form of a catalyst bed.
According to the ammonia-containing waste gas catalytic oxidation treatment method provided by the invention, the regular structure catalyst can be used as a fixed catalyst bed layer in a waste gas catalytic oxidation reactor, and flowing waste gas can flow through the regular structure catalyst bed layer, namely can flow through the pore channels in the regular structure carrier and react with the active component coating distributed on the pore channel wall under the catalytic oxidation condition to convert ammonia gas in the waste gas into nitrogen gas and water. The catalytic oxidation reactor for exhaust gas may be a conventional reactor, and for example, may be a fixed bed reactor in which the structured catalyst of the present invention is packed when a fixed bed reactor is used as the reactor.
According to the catalytic oxidation treatment method of the ammonia-containing exhaust gas provided by the invention, the content of ammonia in the ammonia-containing exhaust gas is not particularly limited, and the catalyst provided by the invention can be used for treating the exhaust gas with high ammonia concentration. However, in general, ammonia gas is industrially appropriately recovered and used when its concentration is large. Therefore, according to one embodiment of the present invention, preferably, the concentration of ammonia in the exhaust gas containing ammonia is 80 to 2000ppm, for example, 80 to 200ppm.
According to the method provided by the invention, in order to provide oxygen required by ammonia oxidation, when the waste gas contains oxygen, additional oxygen-containing gas can be not required to be provided. When the exhaust gas does not contain oxygen, an oxygen-containing gas may be additionally provided, and those skilled in the art may appropriately select it according to the actual situation.
The oxygen-containing gas is oxygen required for combustion of the non-collinear gases and may be air.
The catalytic oxidation conditions are selected from a wide range, and preferably, the catalytic oxidation conditions comprise: the temperature is 300-650 ℃, the pressure is 90-120kPa, and the volume space velocity of the waste gas is 3000-40000h -1 。
Theoretically, the higher the temperature is, the more beneficial the conversion of ammonia gas is, but in order to save energy consumption, the catalytic oxidation needs to be controlled at a lower temperature, and the catalyst provided by the invention can completely convert the ammonia gas even at a lower temperature.
According to one embodiment of the invention, the conditions of the catalytic oxidation includeComprises the following steps: the temperature is 500-550 ℃, the pressure is normal pressure, and the volume space velocity of the waste gas is 20000-30000h -1 。
In the present invention, the pressures involved are all expressed as gauge pressures.
The present invention will be described in detail below by way of examples. The transition metal carbide and titanium dioxide in the catalyst are measured by an X-ray fluorescence spectrum analysis method. The content of the active component coating is calculated by adopting the feeding.
The coating method in the following examples and comparative examples is a water coating method, and the specific process method comprises the following steps: in each coating process, one end of the regular structure carrier (or the semi-finished catalyst) is immersed in the first slurry, and the other end of the regular structure carrier (or the semi-finished catalyst) is vacuumized so that the slurry continuously passes through the pore channel of the carrier; the vacuum pressure applied was-0.03 MPa (MPa) and the coating temperature was 35 ℃.
Example 1
(1) Preparation of modified nano titanium sol
Nano titanium sol (from new material of Xuancheng crystal material, ltd., tiO) with 20 wt% solid content was added 2 Average particle diameter of 50 nm) was added with water and beaten to obtain a slurry having a solid content of 10% by weight, to the slurry was added (at a speed of 0.5g part by weight/min per 100 parts by weight of the slurry) KH-550 (AR, dow Corning, USA) in an amount of 20% by weight of the nano-titanium sol in terms of titanium dioxide, and the mixture was stirred continuously (at a speed of 1200 r/min) for 30min, and the resulting mixture was transferred to a four-necked flask and reacted at 80 ℃ for 2 hours to obtain a silane coupling agent-modified nano-titanium sol.
(2) Preparation of the first slurry
a) Preparation of slurry containing noble metal
Putting 3g of Ag powder into 500mL of butanediol, adding 0.5g of surfactant polyvinyl alcohol (purity: 3N, shanghai Aladdin Biotechnology Co., ltd.), performing ultrasonic treatment for 4h in an ultrasonic instrument, and performing centrifugal separation to obtain slurry containing noble metals;
b) 6g of Fe 2 O 3 Grinding, adding into the slurry containing noble metal, stirring (at 800 r/min) for 1 hr, and freeze drying to obtain the final productTo a mixture containing transition metal oxide and noble metal, wherein the noble metal content is 200 mug/g;
c) 50g of magnesium phosphate (AR, national chemical group, pharmaceutical industry Co., ltd.) was mixed with 92 g of deionized water, and wet ball milling was carried out to obtain a matrix slurry in which the particle diameter d of the matrix 90 10 μm and a solid content of 30% by weight, and then 35.5g of the above silane coupling agent-modified nano titanium sol and 6g of the mixture containing the transition metal oxide and the noble metal obtained in step b) were added to the base slurry to continue wet ball milling for 60 minutes to obtain a first slurry in which the transition metal oxide has a particle diameter d 90 Is 10 μm, particle diameter d of noble metal 90 0.05 micron;
(3) Preparation of semi-finished catalyst
Coating an alumina honeycomb carrier (with the weight of 100g, the pore density of the carrier being 10 pores/square centimeter, the cross section area of each pore being 0.1 square millimeter, the aperture ratio being 85 percent and the shape of the pore being square) with the first slurry obtained in the step (2), and drying at 120 ℃ for 5 hours to obtain a semi-finished catalyst with the coating content being 10 percent by weight;
(4) The semi-finished catalyst obtained in the step (3) is added into the mixture at 10 vol% CO/90 vol% N 2 Under atmosphere (space velocity of 50 h) -1 ) And reducing the mixture at the temperature of 600 ℃ for 1.5h under the pressure of 0.11MPa to obtain the catalyst S-1 with the regular structure, wherein the composition of the catalyst S-1 is shown in the table 1. Analyzing the regular structure catalyst S-1 by an X-ray small angle diffraction method, wherein Fe in the regular structure catalyst S-1 2 O 3 Partial conversion to Fe 3 C；
(5) Catalytic oxidation treatment of exhaust gas
Taking the catalyst prepared in the step (4) as a catalyst bed layer to form a reactor with a regular structure, wherein the total weight of an active component coating is 10.02 g, introducing simulated waste gas (containing 105ppm of ammonia gas and the balance of air) preheated to 350 ℃ into a fixed bed reactor, and the volume space velocity (relative to the active component coating) of the waste gas is 40000h -1 The reaction temperature was 500 ℃ and the reaction pressure was atmospheric pressure (101.325 kPa), and the gas obtained after the reaction was analyzed by chromatography, as a result of the reaction: conversion of ammonia toWater and nitrogen, ammonia conversion was 100 vol%.
Comparative example 1
The procedure of example 1 was followed except that, in step (1), the nano-titanium sol was not modified, and in step (2), 30g of the slurry having a solid content of 10% by weight as described in step (1) of example 1 was directly added to the matrix slurry to obtain a structured catalyst D-1, the composition of which is shown in Table 1. Catalytic oxidation treatment of exhaust gas was carried out according to the step (5) of example 1, and the gas obtained after the reaction was analyzed by chromatography, as a result: the ammonia gas was converted to water and nitrogen gas with 100% conversion by volume. When the nano titanium sol is not modified, ammonia can be converted, but the catalyst is proved to have poor stability through a scouring experiment, and the data of the scouring experiment are shown in tables 2 to 4.
Comparative example 2
The procedure of example 1 was followed except that no noble metal was introduced into the first slurry, that is, in step c), silane coupling agent-modified nano-titanium sol and 6g of Fe were added to the base slurry 2 O 3 And then the grinding is performed. The compositions of the catalysts D-2 and D-2 which gave a structured structure are given in Table 1. The gas obtained after the reaction was analyzed by chromatography, the reaction results were: the ammonia was converted to water and nitrogen with a conversion of 66 vol%.
Example 2
(1) Preparation of modified nano titanium sol
Mixing nano titanium sol (from Xuancheng Crystal Rui New Material Co., ltd., tiO) with solid content of 30 wt% 2 Average particle size of 70 nm) was added with water and slurried to obtain a slurry having a solid content of 10 wt%, to the slurry was added dropwise (at a rate of 0.8g parts by weight/min, relative to 100 parts by weight of the slurry) KH-560 (AR, dow corning, usa) in an amount of 15% by weight of the nano-titanium sol in terms of titanium dioxide, and the mixture was stirred continuously (at a rate of 1600 r/min) for 30min, transferred to a four-neck flask and reacted at 60 ℃ for 7 hours to obtain a silane coupling agent-modified nano-titanium sol.
(2) Preparation of the first slurry
a) Preparation of noble metal-containing slurries
Putting 2g of Au powder into 500mL of pentanediol, adding 1g of surfactant ethyl acetate (purity: 3N, national medicine group chemical reagent Co., ltd.), carrying out ultrasonic treatment for 2h in an ultrasonic instrument, and then carrying out centrifugal separation to obtain slurry containing precious metals;
b) 5.7g of Co 2 O 3 Grinding, adding into the slurry containing noble metal, stirring (speed of 800 r/min) for 1h, and freeze drying to obtain a mixture containing transition metal oxide and noble metal, wherein the content of noble metal is 96 μ g/g;
c) 50g of calcium sulfate (AR, national drug group, pharmaceutical industry Co., ltd.) was mixed with 92 g of deionized water, and wet ball milling was carried out to obtain a matrix slurry, wherein the particle diameter d of the matrix was 90 10 μm and a solid content of 35% by weight, and then 17.2g of the above silane coupling agent-modified nano titanium sol and 5.7g of the mixture containing the transition metal oxide and the noble metal obtained in step b) were added to the base slurry to continue wet ball milling for 60 minutes to obtain a first slurry in which the transition metal oxide has a particle diameter d 90 Is 10 μm, particle diameter d of noble metal 90 Is 0.05 micron;
(3) Preparation of semi-finished catalyst
Coating a mullite honeycomb carrier (the weight of the carrier is 100g, the pore density of the carrier is 10 pores/square centimeter, the sectional area of each pore is 0.1 square millimeter, the aperture ratio is 85 percent, and the shape of the pore is square) with the first slurry obtained in the step (2), and drying at 120 ℃ for 5 hours to obtain a semi-finished catalyst, wherein the content of the coating is 20 percent by weight;
(4) The semi-finished catalyst obtained in the step (3) is added into the mixture of 9 volume percent CO and 4 volume percent CH 4 /87 vol% N 2 Under the atmosphere (space velocity of 25 h) -1 ) And reducing the mixture at 650 ℃ under a pressure of 0.12MPa for 1 hour to obtain the catalyst S-2 with the regular structure, wherein the composition of the catalyst S-2 is shown in Table 1.
(5) Catalytic oxidation treatment of exhaust gas
Taking the catalyst prepared in the step (4) as a catalyst bed layer to form a reactor with a regular structure, wherein the total weight of the active component coating is 11.2 gIntroducing simulated waste gas (containing 97ppm of ammonia gas and the balance of air) preheated to 350 ℃ into the fixed bed reactor, wherein the volume space velocity (relative to the active component coating) of the waste gas is 25000h -1 The reaction temperature was 510 ℃ and the reaction pressure was atmospheric pressure (101.325 kPa), and the gas obtained after the reaction was analyzed by chromatography, as a result of the reaction: the ammonia gas was converted to water and nitrogen gas with 100% conversion by volume.
Example 3
(1) Preparation of modified nano titanium sol
Nano titanium sol (from new material of Xuancheng crystal material, ltd., tiO) with 20 wt% solid content was added 2 Particle average diameter of 80 nm) was added with water and beaten to obtain a slurry having a solid content of 10% by weight, to the slurry was added dropwise (at a rate of 1 part by weight/min per 100 parts by weight of the slurry) KH-570 (AR, dow Corning, USA) in an amount of 35% by weight of the nano-titanium sol in terms of titanium dioxide, and the mixture was stirred continuously (at a rate of 1500 r/min) for 30min, and the mixture was transferred to a four-necked flask and reacted at 70 ℃ for 4 hours to obtain a silane coupling agent-modified nano-titanium sol.
(2) Preparation of the first slurry
a) Preparation of slurry containing noble metal
Putting 1g of Pt powder into 500mL of butanediol, adding 2g of surfactant polyvinyl pyrrolidone (purity: 3N) into the butanediol, carrying out ultrasonic treatment for 4h in an ultrasonic instrument, and then carrying out centrifugal separation to obtain slurry containing noble metals;
b) Grinding 2.8g of NiO, adding into the slurry containing the noble metal, stirring (the speed is 600 r/min) for 1h, and freeze-drying to obtain a mixture containing transition metal oxide and noble metal, wherein the content of the noble metal is 150 mu g/g;
c) 50g of MgF 2 (AR, national drug group pharmaceutical products Co., ltd.) was mixed with 96 g of deionized water and subjected to wet ball milling to obtain a matrix slurry, wherein the particle diameter d of the matrix was 90 10 μm, and a solid content of 34 wt%, and then 28g of the above silane coupling agent-modified nano titanium sol and 2 were added to the base slurry8g of the mixture obtained in step b) containing the transition metal oxide and the noble metal are further wet ball-milled for 60 minutes to obtain a first slurry in which the transition metal oxide has a particle diameter d 90 Is 10 μm, particle diameter d of noble metal 90 0.05 micron;
(3) Preparation of semi-finished catalyst
Coating a cordierite honeycomb carrier (with the weight of 100g, the carrier pore density of 40 pores/square centimeter, the cross section area of each pore of 0.4 square millimeter, the opening rate of 85 percent and the shape of the pore of circular) with the first slurry obtained in the step (2), and drying at 120 ℃ for 5 hours to obtain a semi-finished catalyst with the coating content of 15 weight percent;
(4) The semi-finished catalyst obtained in the step (3) is added into the mixture of 3 volume percent CO and 7 volume percent CH 4 90% by volume of N 2 Under the atmosphere (space velocity of 75 h) -1 ) And reducing the mixture at 500 ℃ for 4 hours under the pressure of 0.12MPa to obtain the catalyst S-3 with the regular structure, wherein the composition of the catalyst S-3 is shown in Table 1.
(5) Catalytic oxidation treatment of exhaust gas
Taking the catalyst prepared in the step (4) as a catalyst bed layer to form a reactor with a regular structure, wherein the total weight of an active component coating is 11.12 g, introducing simulated waste gas (containing 97ppm of ammonia gas and the balance being air) preheated to 350 ℃ into a fixed bed reactor, wherein the volume space velocity (relative to the active component coating) of the waste gas is 25000h -1 The reaction temperature was 500 ℃ and the reaction pressure was atmospheric pressure (101.325 kPa), and the gas obtained after the reaction was analyzed by chromatography, as a result of the reaction: the ammonia gas was converted to water and nitrogen gas with 100% conversion by volume.
Example 4
The process of example 1 is followed except that during step b) of step (2), fe 2 O 3 The addition amount of (a) is 7.3g, in the process of step c), the addition amount of the silane coupling agent modified nano titanium sol is 37g, and the addition amount of the mixture containing the transition metal oxide and the noble metal is 7.3g; in the preparation process of the semi-finished catalyst in the step (3), the first slurry obtained in the step (2) is adopted to coat an alumina honeycomb carrier, and the alumina honeycomb carrier is dried for 5 hours at 120 ℃ to obtain the catalystSemi-finished catalyst, coating content 5 wt%. The compositions of the catalysts S-4 and S-4 obtained are shown in Table 1.
The catalytic oxidation treatment of the exhaust gas was carried out according to the method described in example 1, with the following results: the ammonia gas was converted to water and nitrogen gas with a conversion of 93 vol%.
Example 5
The procedure of example 1 was followed, except that the silane coupling agent-modified nano titanium sol in step (2) was added in an amount of 5.6 g. The compositions of the catalysts S-5 and S-5 obtained are shown in Table 1.
The catalytic oxidation treatment of the exhaust gas was carried out according to the method described in example 1, with the following results: the ammonia gas was converted to water and nitrogen gas with 100% conversion by volume.
When the addition amount of the silane coupling agent modified nano titanium sol is small, ammonia gas can be converted, but the stability of the catalyst is proved to be worse than that of the catalyst in the example 1 through a scouring experiment, and the data of the scouring experiment are shown in tables 2 to 4.
Example 6
The procedure is as in example 1, except that Fe is added as the metal element 2 O 3 Replacement by equal mass MoO 3 The compositions of the catalysts S-6 and S-6 obtained are shown in Table 1. The gas obtained after the reaction was analyzed by chromatography, and the reaction results were: the ammonia was converted to water and nitrogen with an ammonia conversion of 89 vol%.
Example 7
The procedure is as in example 1, except that 50g of magnesium phosphate are replaced by 50g of ZrO on a dry basis 2 (national drug group, AR). The compositions of the catalysts S-7, S-7 having a regular structure are shown in Table 1. The gas obtained after the reaction was analyzed by chromatography, the reaction results were: the ammonia was converted to water and nitrogen with 88 volume% conversion of ammonia.
In table 1, the contents of the active component coating layer are based on the total weight of the catalyst, and the contents of the active component, the matrix and the titanium dioxide are based on the total weight of the active component coating layer.
TABLE 1
Figure BDA0001827047440000201
Test example 1
The test example is used for testing the water and gas scouring resistance of the catalyst provided by the invention.
According to the method of the comparative example 1, nano titanium sol with 20 wt% of solid content is respectively replaced by silica sol and aluminum sol with 20 wt% of solid content and equal mass, the obtained catalyst is used as a comparative example 3 and a comparative example 4, the test is divided into three groups, the first group adopts pure air to wash the catalyst, and the air flow rate is 80L/min; the second group uses pure steam to wash the catalyst, and the steam flow rate is 80L/min; and the third group flushes the catalyst by adopting mixed gas of air and water vapor, and the air flow rate and the water vapor flow rate are both 40L/min. The washing test is carried out for 100h, 200h and 300h at the temperature of 450 ℃.
The results are shown in tables 2,3 and 4, respectively. Table 2 shows the evaluation results of the air scouring alone; table 3 shows the evaluation results of the simple steam scouring; table 4 shows the results of the steam and air flush evaluations.
In tables 2,3 and 4, the retention rate of active ingredient r = (1- (m 0-m 2)/m 1) × 100%
Wherein, the weight of the catalyst before the scouring experiment is marked as m0, the weight of the active component coating is marked as m1, and the weight of the catalyst after the scouring experiment is marked as m2.
TABLE 2 evaluation of active ingredient retention results by air washout alone
Figure BDA0001827047440000211
TABLE 3 evaluation of active ingredient retention results by simple steam flush
Figure BDA0001827047440000212
Figure BDA0001827047440000221
Table 4 water vapor and air scouring evaluation of active ingredient retention results
Figure BDA0001827047440000222
Test example 2
This test example was used to evaluate the stability of the catalysts provided in the examples and comparative examples. Specifically, the catalysts obtained in examples and comparative examples were subjected to the above-mentioned steam and air scouring for 300 hours, and then subjected to the catalytic oxidation treatment of exhaust gas by the method of step (5) of example 1, and the conversion of ammonia gas at the time of carrying out the reactions for 10 hours, 20 hours, 50 hours, 100 hours, and 200 hours is shown in Table 5.
TABLE 5
Figure BDA0001827047440000231
As can be seen from the results of the above examples and comparative examples, the catalyst provided by the present invention comprises a regular structure carrier and an active component coating layer distributed on the inner surface and/or the outer surface of the regular structure carrier, the active component coating layer comprising an active component comprising a transition metal carbide and a noble metal, titanium dioxide and a matrix. The catalyst provided by the invention can be used for converting ammonia gas in waste gas into nitrogen and water. As can be seen from the results in tables 2 to 4, the catalyst provided by the invention has good strength and strong water and gas scouring resistance, and the retention rate r of the active component is kept at about 90% when a scouring experiment is carried out for 300 hours under the optimal condition. In addition, as can be seen from the data in table 5, after 300h of steam and air washing, the catalyst provided by the invention still has good conversion performance, and the catalyst provided by the invention has good stability.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims (53)

1. A structured catalyst, comprising: the catalyst comprises a regular structure carrier and an active component coating distributed on the inner surface and/or the outer surface of the regular structure carrier, wherein the active component coating comprises 1-20 wt% of an active component, 60-98 wt% of a matrix and 1-20 wt% of titanium dioxide based on the total weight of the active component coating, the content of the active component coating is 5-50 wt% based on the total weight of the catalyst, and the active component comprises a transition metal carbide and a noble metal;
the titanium dioxide is from a silane coupling agent modified nano titanium sol.
2. The catalyst of claim 1, wherein the substrate is selected from at least one of a group IIA metal strong acid salt, a group IIIA metal strong acid salt, a group IB metal strong acid salt, and a group IIB metal strong acid salt.
3. The catalyst of claim 2, wherein the substrate is selected from at least one of sulfates, phosphates, and fluorides of group IIA metals, group IIIA metals, group IB metals, and group IIB metals.
4. The catalyst of claim 3, wherein the group IIA metal is Mg and/or Ca; the IIIA group metal is at least one of Al, ga and In; the group IB metal is Cu; the group IIB metal is Zn.
5. The catalyst of claim 4, wherein the substrate is selected from at least one of magnesium phosphate, calcium sulfate, and magnesium fluoride.
6. The catalyst according to any one of claims 1 to 5,
the transition metal is selected from at least one of Ti, V, fe, co, ni, zr, mn, cu, mo and W;
the noble metal is at least one of Au, pt, pd, rh, ru and Ag;
the regular structure carrier is selected from a monolithic carrier with a parallel pore channel structure with two open ends.
7. The catalyst according to claim 6, wherein the transition metal is selected from at least one of Fe, co and Ni;
the noble metal is at least one of Au, pt and Ag;
the pore density of the section of the regular structure carrier is 6-140 pores/square centimeter, and the cross section area of each pore in the regular structure carrier is 0.4-10 square millimeter.
8. The catalyst of claim 7, wherein the structured carrier is selected from at least one of a cordierite honeycomb carrier, a mullite honeycomb carrier, a diamond honeycomb carrier, a corundum honeycomb carrier, a zirconia corundum honeycomb carrier, a quartz honeycomb carrier, a nepheline honeycomb carrier, a feldspar honeycomb carrier, an alumina honeycomb carrier, and a metal alloy honeycomb carrier.
9. The catalyst of any of claims 1-5, 7-8, wherein the active component coating comprises 5-15 wt% active component, 75-94 wt% matrix, and 1-10 wt% titanium dioxide, based on the total weight of the active component coating.
10. The catalyst according to claim 9, wherein the content of the noble metal in the active component is 50 to 800 μ g/g.
11. The catalyst according to claim 10, wherein the content of the noble metal in the active component is 90-400 μ g/g.
12. The catalyst according to claim 11, wherein the content of the noble metal in the active component is 90-200 μ g/g.
13. The catalyst according to claim 9, wherein the active component coating layer is contained in an amount of 10 to 40 wt% based on the total weight of the catalyst.
14. The catalyst of claim 13, wherein the active component coating is present in an amount of 10 to 20 wt.%, based on the total weight of the catalyst.
15. A method for preparing a structured catalyst, the method comprising:
(1) Pulping and grinding a substrate and water to obtain substrate slurry, mixing the substrate slurry with silane coupling agent modified nano titanium sol, transition metal oxide and noble metal, and grinding to obtain first slurry;
(2) Coating the first slurry on a regular structure carrier, and then drying to obtain a semi-finished catalyst;
(3) The semi-finished catalyst is added into a catalyst containing CH 4 And/or reduction treatment is carried out under a CO atmosphere so as to reduce the transition metal oxide in the semi-finished catalyst to form transition metal carbide.
16. The method of claim 15, wherein the substrate is selected from at least one of a group IIA metal strong acid salt, a group IIIA metal strong acid salt, a group IB metal strong acid salt, and a group IIB metal strong acid salt.
17. The method of claim 16, wherein the substrate is selected from at least one of sulfates, phosphates, and fluorides of group IIA metals, group IIIA metals, group IB metals, and group IIB metals.
18. The method of claim 17, wherein the group IIA metal is Mg and/or Ca; the IIIA group metal is at least one of Al, ga and In; the group IB metal is Cu; the group IIB metal is Zn.
19. The production method according to claim 18, wherein the substrate is selected from at least one of magnesium phosphate, calcium sulfate, and magnesium fluoride.
20. The production method according to claim 19, wherein the particle diameter d of the matrix in the matrix slurry 90 1-10 microns and a matrix having a solids content of 15-50% by weight.
21. The method for preparing the nano titanium sol according to any one of claims 15 to 20, wherein the silane coupling agent modified nano titanium sol is prepared by: adding water into the nano titanium sol for pulping to obtain slurry, and mixing the slurry with a silane coupling agent.
22. The method of claim 21, wherein the mixing comprises: adding a silane coupling agent to the slurry under stirring, and then standing at 40-90 ℃ for 1-10 hours.
23. The method according to claim 21, wherein the silane coupling agent is at least one selected from the group consisting of γ -aminopropyltriethoxysilane, γ - (2, 3-glycidoxy) propyltrimethoxysilane and γ -methacryloxypropyltrimethoxysilane.
24. The production method according to claim 21, wherein the nano titanium sol has a solid content of 10 to 50% by weight.
25. The method of claim 24, wherein the nano titanium sol contains TiO 2 The average particle diameter of the particles is 1-200nm.
26. The method of claim 25The preparation method of (1), wherein, tiO in the nano titanium sol 2 The average particle diameter of the particles is 50-100nm.
27. The production method according to claim 21, wherein the slurry has a solid content of 5 to 40% by weight.
28. The production method according to claim 27, wherein the slurry has a solid content of 10 to 35% by weight.
29. The production method according to claim 21, wherein the weight ratio of the silane coupling agent to the nano titanium sol as titanium dioxide is (10-50): 100.
30. the production method according to claim 29, wherein the weight ratio of the silane coupling agent to the nano titanium sol as titanium dioxide is (10-35): 100.
31. the production method according to any one of claims 15 to 20 and 22 to 30, wherein the mass ratio of the silane coupling agent-modified nano titanium sol to the matrix on a dry basis is (0.5 to 8): 100.
32. the preparation method of claim 31, wherein the mass ratio of the silane coupling agent modified nano titanium sol to the matrix on a dry basis is (1-7): 100.
33. the production method according to claim 32, wherein the mass ratio of the silane coupling agent-modified nano titanium sol to the matrix on a dry basis is (3-7): 100.
34. the production method according to any one of claims 15 to 20, 22 to 30, and 32 to 33, wherein the manner of mixing the matrix slurry with the silane coupling agent-modified nano titanium sol, the transition metal oxide, and the noble metal includes: mixing the matrix slurry, the silane coupling agent modified nano titanium sol and a mixture containing transition metal oxide and noble metal.
35. The production method according to claim 34, wherein the mixture containing the transition metal oxide and the noble metal is produced by a method comprising: noble metal, organic solvent and surfactant are mixed, treated by ultrasonic treatment and then separated to obtain slurry containing noble metal, transition metal oxide is added into the slurry, and then stirring and drying are carried out.
36. The production method according to claim 35, wherein the mixture containing the transition metal oxide and the noble metal has a noble metal content of 50 to 800 μ g/g.
37. The production method according to claim 36, wherein the mixture containing the transition metal oxide and the noble metal has a noble metal content of 90 to 400 μ g/g.
38. The production method according to claim 37, wherein the mixture containing the transition metal oxide and the noble metal has a noble metal content of 90 to 200 μ g/g.
39. The production method according to claim 35, wherein the mixture containing the transition metal oxide and the noble metal is used in an amount of 1 to 20% by weight based on the total amount of the mixture containing the transition metal oxide and the noble metal, the matrix slurry on a dry basis, and the silane coupling agent-modified nano titanium sol on a dry basis.
40. The production method according to claim 39, wherein the mixture containing the transition metal oxide and the noble metal is used in an amount of 1 to 15% by weight based on the total amount of the mixture containing the transition metal oxide and the noble metal, the matrix slurry on a dry basis, and the silane coupling agent-modified nano titanium sol on a dry basis.
41. The production method according to claim 40, wherein the mixture containing the transition metal oxide and the noble metal is used in an amount of 5 to 12% by weight based on the total amount of the mixture containing the transition metal oxide and the noble metal, the matrix slurry on a dry basis, and the silane coupling agent-modified nano titanium sol on a dry basis.
42. The production method according to any one of claims 15 to 20, 22 to 30, 32 to 33, and 35 to 41,
the noble metal is at least one of Au, pt, pd, rh, ru and Ag;
the transition metal is selected from at least one of Ti, V, fe, co, ni, zr, mn, cu, mo and W;
the regular structure carrier is selected from an integral carrier with a parallel pore channel structure with openings at two ends.
43. The production method according to claim 42,
the noble metal is at least one selected from Au, pt and Ag;
the transition metal is selected from at least one of Fe, co and Ni;
the pore density of the section of the regular structure carrier is 6-140 pores/square centimeter, and the cross section area of each pore in the regular structure carrier is 0.4-10 square millimeter.
44. The production method according to claim 43, wherein the carrier of a structured structure is selected from at least one of a cordierite honeycomb carrier, a mullite honeycomb carrier, a diamond honeycomb carrier, a corundum honeycomb carrier, a zirconia corundum honeycomb carrier, a quartz honeycomb carrier, a nepheline honeycomb carrier, a feldspar honeycomb carrier, an alumina honeycomb carrier, and a metal alloy honeycomb carrier.
45. The production method according to any one of claims 15 to 20, 22 to 30, 32 to 33, 35 to 41, and 43 to 44, wherein the conditions of the reduction treatment in the step (3) include: at 250-700 deg.C for 0.5-6 hr, and containing CH 4 And/or the volume space velocity of the CO atmosphere is 25-100h -1 The pressure is 0.1-3MPa.
46. The production method according to claim 45, wherein in the step (3), the conditions of the reduction treatment include: the temperature is 500-650 deg.C, the time is 1-4 hours, and the product contains CH 4 And/or the volume space velocity of the CO atmosphere is 25-75h -1 The pressure is 0.1-1MPa.
47. The method of claim 45, containing CH 4 And/or the CO atmosphere contains 5-25 vol.% CH based on the total volume thereof 4 And/or CO and 75-95% by volume of an inert gas.
48. The method of claim 47, containing CH 4 And/or the CO atmosphere contains 10-20 vol% of CH based on the total volume of the atmosphere 4 And/or CO and 80-90% by volume of an inert gas.
49. A structured catalyst obtained by the production method according to any one of claims 15 to 48.
50. Use of a structured catalyst according to any one of claims 1 to 14, 49 in the treatment of exhaust gases.
51. A catalytic oxidation treatment method for ammonia-containing exhaust gas comprises the following steps: contacting the exhaust gas containing ammonia gas with a catalyst under catalytic oxidation conditions to convert the ammonia gas to nitrogen and water, wherein the catalyst is a structured catalyst as claimed in any one of claims 1 to 14 and 49.
52. The method of claim 51, wherein the conditions of the catalytic oxidation comprise: the temperature is 300-650 ℃; the pressure is 90-120kPa, and the volume space velocity of the waste gas is 3000-40000h -1 。
53. The method of claim 52, wherein the conditions of the catalytic oxidation comprise: the pressure is normal pressure.
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