CN112536061B - Exhaust gas treatment catalyst and preparation method thereof - Google Patents
Exhaust gas treatment catalyst and preparation method thereof Download PDFInfo
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- CN112536061B CN112536061B CN201910900922.0A CN201910900922A CN112536061B CN 112536061 B CN112536061 B CN 112536061B CN 201910900922 A CN201910900922 A CN 201910900922A CN 112536061 B CN112536061 B CN 112536061B
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- 239000003054 catalyst Substances 0.000 title claims abstract description 70
- 238000002360 preparation method Methods 0.000 title claims description 11
- 239000000758 substrate Substances 0.000 claims abstract description 59
- 239000011248 coating agent Substances 0.000 claims abstract description 29
- 238000000576 coating method Methods 0.000 claims abstract description 29
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims abstract description 24
- 229910000510 noble metal Inorganic materials 0.000 claims abstract description 24
- 239000002808 molecular sieve Substances 0.000 claims abstract description 10
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 claims abstract description 10
- 239000004408 titanium dioxide Substances 0.000 claims abstract description 10
- 229910044991 metal oxide Inorganic materials 0.000 claims abstract description 9
- 150000004706 metal oxides Chemical class 0.000 claims abstract description 9
- 150000002430 hydrocarbons Chemical class 0.000 claims abstract description 5
- 238000000034 method Methods 0.000 claims description 20
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 16
- QPLDLSVMHZLSFG-UHFFFAOYSA-N Copper oxide Chemical compound [Cu]=O QPLDLSVMHZLSFG-UHFFFAOYSA-N 0.000 claims description 9
- 239000005751 Copper oxide Substances 0.000 claims description 9
- 229910000431 copper oxide Inorganic materials 0.000 claims description 9
- 229910000420 cerium oxide Inorganic materials 0.000 claims description 8
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 claims description 8
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 6
- 238000011068 loading method Methods 0.000 claims description 6
- 238000002156 mixing Methods 0.000 claims description 5
- 239000011148 porous material Substances 0.000 claims description 5
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 4
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 claims description 4
- 229910052802 copper Inorganic materials 0.000 claims description 4
- 239000010949 copper Substances 0.000 claims description 4
- 238000001035 drying Methods 0.000 claims description 4
- 229910052742 iron Inorganic materials 0.000 claims description 3
- 239000002243 precursor Substances 0.000 claims description 3
- 239000000654 additive Substances 0.000 claims description 2
- 230000000996 additive effect Effects 0.000 claims description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 2
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 claims description 2
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 claims description 2
- 229910052751 metal Inorganic materials 0.000 claims description 2
- 239000002184 metal Substances 0.000 claims description 2
- 150000002736 metal compounds Chemical class 0.000 claims description 2
- 239000000377 silicon dioxide Substances 0.000 claims description 2
- 229910052684 Cerium Inorganic materials 0.000 claims 2
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 claims 2
- 239000011247 coating layer Substances 0.000 claims 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 16
- 239000007789 gas Substances 0.000 description 14
- 239000002002 slurry Substances 0.000 description 13
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 9
- 229910021529 ammonia Inorganic materials 0.000 description 8
- 239000000843 powder Substances 0.000 description 8
- 238000006243 chemical reaction Methods 0.000 description 6
- 239000003638 chemical reducing agent Substances 0.000 description 4
- 239000002912 waste gas Substances 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 241000219782 Sesbania Species 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- HSJPMRKMPBAUAU-UHFFFAOYSA-N cerium(3+);trinitrate Chemical compound [Ce+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O HSJPMRKMPBAUAU-UHFFFAOYSA-N 0.000 description 2
- 239000003344 environmental pollutant Substances 0.000 description 2
- HQKMJHAJHXVSDF-UHFFFAOYSA-L magnesium stearate Chemical compound [Mg+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O HQKMJHAJHXVSDF-UHFFFAOYSA-L 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229920000609 methyl cellulose Polymers 0.000 description 2
- 239000001923 methylcellulose Substances 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 231100000719 pollutant Toxicity 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- 229920002472 Starch Polymers 0.000 description 1
- 229910010413 TiO 2 Inorganic materials 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000012752 auxiliary agent Substances 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000007580 dry-mixing Methods 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 239000003546 flue gas Substances 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 239000002440 industrial waste Substances 0.000 description 1
- 235000019359 magnesium stearate Nutrition 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000008107 starch Substances 0.000 description 1
- 235000019698 starch Nutrition 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 239000012855 volatile organic compound Substances 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
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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
- B01J29/08—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the faujasite type, e.g. type X or Y
- B01J29/10—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the faujasite type, e.g. type X or Y containing iron group metals, noble metals or copper
- B01J29/14—Iron group metals or copper
- B01J29/146—Y-type faujasite
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/8621—Removing nitrogen compounds
- B01D53/8625—Nitrogen oxides
- B01D53/8628—Processes characterised by a specific catalyst
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/8668—Removing organic compounds not provided for in B01D53/8603 - B01D53/8665
-
- 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
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
-
- 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
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
- B01J35/61—Surface area
- B01J35/617—500-1000 m2/g
-
- 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
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
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- Health & Medical Sciences (AREA)
- Biomedical Technology (AREA)
- Analytical Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Crystallography & Structural Chemistry (AREA)
- Catalysts (AREA)
Abstract
The invention discloses an exhaust gas treatment catalyst, comprising: a porous substrate comprising a molecular sieve, titanium dioxide, and a metal oxide; a coating for the surface of the porous substrate comprising a noble metal catalyst. The porous substrate is provided with a plurality of parallel airflow channels, and the channels are separated by porous substrate walls; the ratio of the thickness of the coating to the thickness of the porous base wall is 1: (5-50). The catalyst disclosed by the invention can be used for reducing hydrocarbon compounds in exhaust gas and simultaneously efficiently removing NOx, and a corresponding exhaust gas treatment system.
Description
Technical Field
The invention relates to an exhaust gas treatment catalyst, a preparation method thereof and an exhaust gas treatment method using the catalyst, and belongs to the field of exhaust gas treatment.
Background
To remove nitrogen oxides from exhaust gases of various sources, ammonia (NH 3 ) Are generally used to convert nitrogen oxides to N 2 And H 2 Reducing agent of O. In using NH 3 In the denitration process as the reducing agent, NH is added to further improve the reaction efficiency of the denitration catalyst 3 There may be some excess. This part of the excess ammonia not involved in the reaction is discharged to the atmosphere and may cause secondary pollution.
For this case, CN 105555403B discloses an ammonia slip catalyst. The catalyst integrates an ammonia oxidation catalyst and an SCR catalyst, and can effectively reduce the escape of excessive ammonia.
The ammonia oxidation catalysts described above do not solve the problem from the source, i.e. ammonia is still used as a reducing agent for the reduction of nitrogen oxides. Further, for certain classes of industrial waste gases, if some hydrocarbons in the waste gas can be directly utilized as a reducing agent for reducing NO x The problem of ammonia slip described above can be better solved. CN 103752331B discloses a multi-effect catalyst for synergistic purification of flue gas and a preparation method thereof. The catalyst can utilize VOCs to selectively convert NO x Reduction to N 2 And H 2 O, NO of x The purification efficiency of (2) is higher than 95%. However, the particulate catalyst of this patent causes an increase in pressure drop and is not suitable for industrial use.
Disclosure of Invention
The invention aims at solving the problems in the prior art and provides an exhaust gas treatment catalyst and a preparation method thereof. The catalyst can reduce hydrocarbon compounds in waste gas and simultaneously remove NO efficiently x The catalyst comprises a porous substrate and a catalyst coating, wherein the thickness of the coating and the thickness of the wall of the porous substrate have proper proportion ranges, so that the catalyst can meet the requirement of pollutant removal and reduce the reaction pressure drop.
According to an aspect of the present invention, there is provided an exhaust gas treatment catalyst comprising:
a porous substrate comprising a molecular sieve, titanium dioxide, and a metal oxide;
a coating on the surface of the porous substrate comprising a noble metal catalyst.
According to a preferred embodiment of the invention, the porous substrate is provided with a plurality of parallel air flow channels, and the channels are separated by porous substrate walls; preferably, the ratio of the thickness of the coating to the thickness of the porous base wall is 1: (5-50).
According to a preferred embodiment of the present invention, the porous substrate comprises 50 to 70 parts of molecular sieve, 2 to 40 parts of titanium dioxide and 1 to 10 parts of metal oxide.
According to a preferred embodiment of the present invention, the metal oxide includes at least one of copper oxide, iron oxide, and cerium oxide; preferably copper oxide and iron oxide, or preferably copper oxide and cerium oxide, more preferably copper oxide, iron oxide and cerium oxide.
According to a preferred embodiment of the present invention, the mass ratio of copper oxide, iron oxide and cerium oxide is (1 to 10): (1-5): (1-5).
According to a preferred embodiment of the present invention, the noble metal catalyst comprises a carrier and a noble metal supported on the carrier; preferably the support comprises an oxide support, preferably the oxide comprises at least one of alumina, zirconia, silica, titania, ceria; preferably the noble metal comprises Pt and/or Pd; preferably, the weight ratio of the noble metal element to the carrier is (0.05-5): 100.
According to a preferred embodiment of the present invention, the porous substrate has a pore density of 100 to 600cpsi.
The copper oxide, iron oxide and cerium oxide applied thereto are not present on the same carrier at the same time as the noble metal mixture.
According to another aspect of the present invention, there is provided a method for preparing the above catalyst, comprising the steps of:
s1, respectively preparing a porous substrate and a noble metal catalyst;
s2, preparing a coating medium containing a noble metal catalyst and a porous substrate;
s3, coating the coating medium on the surface of the porous substrate.
9. The method according to claim 8, wherein the step S1 comprises:
1A, loading a noble metal compound on an oxide carrier, and roasting to obtain a noble metal catalyst;
and 1B, mixing the molecular sieve, titanium dioxide and necessary forming auxiliary agents, adding a metal precursor solution, mixing, extruding, drying and roasting to obtain the porous substrate.
According to a preferred embodiment of the present invention, after the molecular sieve, titanium dioxide and the necessary molding aid are mixed in step 1B, a preform having plasticity is obtained, and the preform is extruded through a specific die (for example, a die having a honeycomb-shaped cross section), so that a porous substrate having the same cross section as the die can be obtained. And then drying and roasting to obtain the porous substrate.
The coating of the invention also comprises a porous substrate, which has the following advantages: 1) The coating medium comprising the porous substrate component facilitates the coating of the slurry and the stability of the coating; 2) The noble metal catalyst and the porous substrate coating medium are coated together to facilitate the dispersion of the noble metal catalyst, and particularly, the noble metal catalyst and the porous substrate with catalytic performance are mixed, so that the exhaust gas can be fully contacted with the noble metal catalyst in the process of contacting catalyst diffusion.
According to a preferred embodiment of the invention, the shaping aid comprises an inorganic aid and an organic aid. The inorganic aids include, but are not limited to: aluminum sol, silica sol, clay, etc.; the organic aids include, but are not limited to: sesbania powder, starch, polyvinyl alcohol, cellulose, methylcellulose, and the like.
According to another aspect of the present invention, there is provided an exhaust gas treatment method comprising: and (3) contacting the waste gas to be treated with the catalyst. Preferably, the exhaust gas stream is passed through channels of the catalyst.
The invention is thatThe catalyst can reduce hydrocarbon compounds in the waste gas and simultaneously remove NO efficiently x The catalyst comprises a porous substrate and a catalyst coating, wherein the thickness of the coating and the thickness of the wall of the porous substrate have proper proportion ranges, so that the catalyst can meet the requirement of pollutant removal and reduce the reaction pressure drop.
Drawings
FIG. 1 shows a schematic diagram of a porous substrate structure:
FIG. 2 shows a bottom view of a porous substrate according to example 1 of the present invention;
FIG. 3 shows an SEM image of a porous substrate according to example 1 of the invention;
fig. 4 shows an SEM image of a porous substrate according to example 1 of the present invention.
Reference numerals illustrate: a is the side length of the end face of the porous substrate; d is the pore diameter on the end face of the porous substrate; w is the wall thickness of the porous substrate; l is the length of the porous substrate.
Detailed Description
The present invention is further illustrated by, but not limited to, the following examples.
1. Geometric specific surface area A of porous substrate p
Geometric specific surface area A of porous substrate p The values are expressed in square meters per cubic meter (m 2 /m 3 ) The expression is calculated according to the following formula (1):
wherein:
d-the numerical aperture on the end face of the porous substrate in millimeters (mm);
n-the number of a row of holes on the end face of the porous substrate;
a-the value of the side length of the end face of the porous substrate, in millimeters (mm).
2. Theoretical average coating thickness ε
Theoretical average coating thickness epsilon, the values expressed in millimeters (mm), is calculated by the following equation (2):
wherein:
m-the loading of the coating in grams (g);
ρ coat density of the coating material in kg/m 3 ；
A p The geometric specific surface area of the porous substrate is expressed as m 2 /m 3 ；
V C The volume of the porous substrate is expressed in cubic meters (m 3 )。
Example 1 preparation of exhaust gas treatment catalyst
Preparation of a porous substrate: weighing Y-type molecular sieve powder, titanium dioxide powder, forming additive methylcellulose, sesbania powder and magnesium stearate, dry-mixing, then dropwise adding an aqueous solution containing copper, iron and cerium nitrate precursors and aluminum sol under stirring, mixing for minutes under the condition of stirring speed of 40 r/min, and then extruding the mixed mixture by adopting a porous honeycomb die. The extrudate was dried at 60℃for 24 hours and then calcined at 600℃for 2 hours to give a porous substrate. The porous substrate has an end face pore density of 200cpsi and a geometric specific surface area of 768m 2 /m 3 . The weight portions of the components are as follows: 63 parts of a Y-type molecular sieve, 31 parts of titanium dioxide, 3 parts of copper oxide, 2 parts of iron oxide and 1 part of cerium oxide.
The preparation process of the coating medium comprises the following steps: gamma-Al 2 O 3 The powder was immersed in an aqueous solution of chloroplatinic acid, dried and calcined at 500 ℃ to obtain a powder catalyst 1 in which the Pt loading was 0.1% by weight. Water was added to the obtained powder catalyst 1, and ball-milled in a ball mill to obtain a catalyst slurry 1. Similarly, the powder of the porous substrate described above was ball-milled with water in a ball mill to obtain catalyst slurry 2.
30 parts by weight of catalyst slurry 1 and 70 parts by weight of catalyst slurry 2 were mixed to obtain coated catalyst slurry 3. The porous substrate described above is immersed in the coated catalyst slurry 3. The catalyst obtained after drying at 60℃for 24 hours was calcined at 550℃for 4 hours. The loading of the coated catalyst slurry was 20g/L, and the ratio of the thickness of the coating to the wall thickness of the porous substrate was 1:15.
example 2
An exhaust gas-treating catalyst 2 was obtained in a similar manner to example 1, except that the ratio of the coating thickness to the porous substrate wall thickness was 1:10.
example 3
An exhaust gas-treating catalyst 3 was obtained in a similar manner to example 1, except that the ratio of the coating thickness to the porous substrate wall thickness was 1:6.
example 3
An exhaust gas treatment catalyst 4 was obtained in a similar manner to example 1, except that the weight ratio of the catalyst slurry 1 and the catalyst slurry 2 was 70:30, the ratio of coating thickness to porous substrate wall thickness remains 1:10.
comparative example 1
Integral extrusion porous denitration Deno x The catalyst was used as a substrate, and only the catalyst slurry 1 of example 1 was coated, and the loading was 20g/L. Porous denitration Deno x The catalyst is a relatively common catalyst for denitration of commercial fixed source, and also has a parallel pore canal structure, and has the composition of V-W-TiO 2 。
Comparative example 2
The preparation was the same as in example 1, but without the addition of catalyst slurry 1.
Comparative example 3
The preparation was the same as in example 1, but without the addition of catalyst slurry 2.
The catalyst performance test was performed under the following conditions:
reaction temperature: 420 DEG C
Reaction space velocity: 10,000h -1
Concentration of NO in intake: 300ppm; c (C) 3 H 6 Concentration: 1475mg/m 3 The method comprises the steps of carrying out a first treatment on the surface of the CO concentration: 2000ppm.
The results of the treated exhaust gas are shown in table 1 below;
TABLE 1
Any numerical value recited in this disclosure includes all values incremented by one unit from the lowest value to the highest value if there is only a two unit interval between any lowest value and any highest value. For example, if the amount of one component, or the value of a process variable such as temperature, pressure, time, etc., is stated to be 50-90, it is meant in this specification that values such as 51-89, 52-88 … …, and 69-71, and 70-71 are specifically recited. For non-integer values, 0.1, 0.01, 0.001 or 0.0001 units may be considered as appropriate. This is only a few examples of the specific designations. In a similar manner, all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be disclosed in this application.
It should be noted that the above-described embodiments are only for explaining the present invention and do not constitute any limitation of the present invention. The invention has been described with reference to exemplary embodiments, but it is understood that the words which have been used are words of description and illustration, rather than words of limitation. Modifications may be made to the invention as defined in the appended claims, and the invention may be modified without departing from the scope and spirit of the invention. Although the invention is described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein, as the invention extends to all other means and applications which perform the same function.
Claims (12)
1. An exhaust gas treatment method comprises contacting an exhaust gas to be treated with a catalyst while removing NO from the exhaust gas x And hydrocarbon compounds; the catalyst comprises:
a porous substrate comprising a molecular sieve, titanium dioxide, and a metal oxide; the metal oxide includes at least one of copper oxide, iron oxide, and cerium oxide;
a coating layer on the surface of the porous substrate, comprising a noble metal catalyst;
the ratio of the thickness of the coating to the thickness of the porous base wall is 1: (5-50);
the preparation method of the catalyst comprises the following steps:
s1, respectively preparing a porous substrate and a noble metal catalyst;
s2, preparing a coating medium comprising a noble metal catalyst and a porous substrate;
s3, coating a coating medium on the surface of the porous substrate;
the step S1 includes:
1A, loading a noble metal compound on an oxide carrier, and roasting to obtain a noble metal catalyst;
and 1B, mixing the molecular sieve, titanium dioxide and a forming additive, adding a metal precursor solution, mixing, extruding, drying and roasting to obtain the porous substrate.
2. The exhaust gas treatment method of claim 1, wherein the porous substrate has a plurality of parallel gas flow passages formed therein, the passages being separated by porous substrate walls.
3. The exhaust gas treatment method according to claim 1, wherein the porous substrate comprises 50 to 70 parts of molecular sieve, 2 to 40 parts of titanium dioxide and 1 to 10 parts of metal oxide.
4. A method of treating exhaust gas according to any one of claims 1 to 3, wherein the metal oxide is an oxide of copper and an oxide of iron, or an oxide of copper and an oxide of cerium.
5. A method of treating exhaust gas according to any one of claims 1 to 3, wherein the metal oxide is an oxide of copper, an oxide of iron and an oxide of cerium.
6. The exhaust gas treatment method according to claim 5, wherein the mass ratio of copper oxide, iron oxide and cerium oxide is (1 to 10): (1-5): (1-5).
7. A method of treating exhaust gas according to any one of claims 1 to 3, wherein the noble metal catalyst comprises a carrier and a noble metal supported on the carrier.
8. The exhaust gas treatment method of claim 7, wherein the support comprises an oxide support.
9. The exhaust gas treatment method according to claim 8, wherein the oxide includes at least one of alumina, zirconia, silica, titania, and ceria.
10. A method of treating exhaust gas according to any one of claims 1-3, characterized in that the noble metal comprises Pt and/or Pd.
11. The method according to claim 10, wherein the weight ratio of the noble metal element to the carrier is (0.05-5) 100.
12. The exhaust gas treatment method of any one of claims 1-3, wherein the porous substrate has a pore density of 100-600cpsi.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910900922.0A CN112536061B (en) | 2019-09-23 | 2019-09-23 | Exhaust gas treatment catalyst and preparation method thereof |
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