CN110560056B - Universal small gasoline engine tail gas catalyst and preparation method thereof - Google Patents
Universal small gasoline engine tail gas catalyst and preparation method thereof Download PDFInfo
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- CN110560056B CN110560056B CN201910814632.4A CN201910814632A CN110560056B CN 110560056 B CN110560056 B CN 110560056B CN 201910814632 A CN201910814632 A CN 201910814632A CN 110560056 B CN110560056 B CN 110560056B
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- 239000003054 catalyst Substances 0.000 title claims abstract description 120
- 238000002360 preparation method Methods 0.000 title claims abstract description 19
- 239000002002 slurry Substances 0.000 claims abstract description 83
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 54
- 239000011248 coating agent Substances 0.000 claims abstract description 53
- 238000000576 coating method Methods 0.000 claims abstract description 53
- RCFVMJKOEJFGTM-UHFFFAOYSA-N cerium zirconium Chemical compound [Zr].[Ce] RCFVMJKOEJFGTM-UHFFFAOYSA-N 0.000 claims abstract description 38
- 239000002131 composite material Substances 0.000 claims abstract description 38
- 238000002156 mixing Methods 0.000 claims abstract description 21
- 239000000463 material Substances 0.000 claims abstract description 19
- 229910000510 noble metal Inorganic materials 0.000 claims abstract description 14
- 238000001035 drying Methods 0.000 claims abstract description 13
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims abstract description 8
- 238000003756 stirring Methods 0.000 claims description 34
- 229910052751 metal Inorganic materials 0.000 claims description 33
- 239000002184 metal Substances 0.000 claims description 33
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 25
- 238000000498 ball milling Methods 0.000 claims description 20
- 239000008367 deionised water Substances 0.000 claims description 20
- 229910021641 deionized water Inorganic materials 0.000 claims description 20
- 229910052593 corundum Inorganic materials 0.000 claims description 17
- 229910001845 yogo sapphire Inorganic materials 0.000 claims description 17
- VXAUWWUXCIMFIM-UHFFFAOYSA-M aluminum;oxygen(2-);hydroxide Chemical compound [OH-].[O-2].[Al+3] VXAUWWUXCIMFIM-UHFFFAOYSA-M 0.000 claims description 12
- 229910003158 γ-Al2O3 Inorganic materials 0.000 claims description 12
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 8
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 8
- 239000002245 particle Substances 0.000 claims description 5
- MRELNEQAGSRDBK-UHFFFAOYSA-N lanthanum oxide Inorganic materials [O-2].[O-2].[O-2].[La+3].[La+3] MRELNEQAGSRDBK-UHFFFAOYSA-N 0.000 claims description 4
- MCMNRKCIXSYSNV-UHFFFAOYSA-N ZrO2 Inorganic materials O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 claims description 3
- 229910002651 NO3 Inorganic materials 0.000 claims description 2
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims description 2
- 229910002637 Pr6O11 Inorganic materials 0.000 claims description 2
- 239000011230 binding agent Substances 0.000 claims description 2
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 claims description 2
- PLDDOISOJJCEMH-UHFFFAOYSA-N neodymium oxide Inorganic materials [O-2].[O-2].[O-2].[Nd+3].[Nd+3] PLDDOISOJJCEMH-UHFFFAOYSA-N 0.000 claims description 2
- KTUFCUMIWABKDW-UHFFFAOYSA-N oxo(oxolanthaniooxy)lanthanum Chemical compound O=[La]O[La]=O KTUFCUMIWABKDW-UHFFFAOYSA-N 0.000 claims description 2
- 229910052697 platinum Inorganic materials 0.000 claims description 2
- 229910052703 rhodium Inorganic materials 0.000 claims description 2
- 229910006415 θ-Al2O3 Inorganic materials 0.000 claims description 2
- 229910000838 Al alloy Inorganic materials 0.000 claims 1
- 150000001875 compounds Chemical class 0.000 claims 1
- 230000032683 aging Effects 0.000 abstract description 13
- 230000015556 catabolic process Effects 0.000 abstract description 2
- 238000006731 degradation reaction Methods 0.000 abstract description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 abstract 1
- 229910017604 nitric acid Inorganic materials 0.000 abstract 1
- 239000007789 gas Substances 0.000 description 56
- KDLHZDBZIXYQEI-UHFFFAOYSA-N palladium Substances [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 18
- 238000000034 method Methods 0.000 description 10
- GPNDARIEYHPYAY-UHFFFAOYSA-N palladium(ii) nitrate Chemical compound [Pd+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O GPNDARIEYHPYAY-UHFFFAOYSA-N 0.000 description 10
- 239000011148 porous material Substances 0.000 description 10
- 238000006243 chemical reaction Methods 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 7
- 239000000203 mixture Substances 0.000 description 7
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Natural products N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 6
- 239000011268 mixed slurry Substances 0.000 description 4
- 230000006866 deterioration Effects 0.000 description 3
- 239000010970 precious metal Substances 0.000 description 3
- 238000000746 purification Methods 0.000 description 3
- 239000000446 fuel Substances 0.000 description 2
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 230000003584 silencer Effects 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
Classifications
-
- 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
- B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
- B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
- B01D53/9445—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC]
- B01D53/945—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC] characterised by a specific catalyst
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/002—Mixed oxides other than spinels, e.g. perovskite
-
- 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
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
- B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/56—Platinum group metals
- B01J23/63—Platinum group metals with rare earths or actinides
-
- B01J35/56—
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2258/00—Sources of waste gases
- B01D2258/01—Engine exhaust gases
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2523/00—Constitutive chemical elements of heterogeneous catalysts
Abstract
The invention relates to a universal small gasoline engine tail gas catalyst and a preparation method thereof, and the universal small gasoline engine tail gas catalyst comprises a catalyst carrier and a catalyst coating coated on the catalyst carrier, wherein the catalyst coating consists of an alumina material containing noble metal and a cerium-zirconium composite oxide; the total coating amount of the catalyst coating is 20 to 100g/L, wherein the weight of the cerium-zirconium composite oxide is 5 to 30 percent of the coating weight, and the usage amount of the noble metal is 20 to 80g/ft3And the balance of alumina material. The preparation method comprises the steps of preparing aluminum oxide material slurry, adding a noble metal nitric acid solution and adjusting pH, preparing cerium-zirconium composite oxide slurry, mixing the slurry, coating, drying and roasting. The catalyst has the advantages of good high-temperature aging resistance, low degradation coefficient and the like.
Description
Technical Field
The invention discloses a universal small gasoline engine tail gas catalyst, and also discloses a preparation method of the universal small gasoline engine tail gas catalyst, belonging to the technical field of catalyst preparation.
Background
The general small gasoline engine is a power machine using gasoline as fuel, CO, HC and NOxIs the main tail gas pollutant of the general small gasoline engine. The purification outside the engine for the general small gasoline engine mainly means that a tail gas purification catalyst is added in a silencer. Due to the self-emission characteristics of the general small gasoline engine, the tail gas purification catalyst needs to meet the following requirements:
1)HC+NOxis the key point of the emission control of the general small gasoline engine, but NOxThe emission is low, and the occupied proportion is small, so HC is a key to be treated;
2) The muffler space of the general small gasoline engine is small, so that the catalyst has smaller volume and high conversion efficiency;
3) The exhaust temperature of the general small gasoline engine is 350-600 ℃, the exhaust temperature exceeds the light-off temperature of the catalyst, the normal use of the catalyst can be ensured, but the oxidation reaction of HC and CO releases a large amount of heat, so the temperature of a catalyst bed layer is close to or even exceeds 800 ℃, and the catalyst is required to have good high temperature resistance.
Aiming at the characteristics of emission and regulations of a general small gasoline engine, noble metal Pd is mainly used as an active component of a catalyst in the tail gas catalysis of the general small gasoline engine at the present stage, the discharge regulations in North America and Europe have requirements on the durability of the catalyst, although the domestic demand for the general small gasoline engine is gradually increased along with the continuous increase of economy in China, the international market export is still the main at present, and the European and American market accounts for more than half of the share of the export market. On the other hand, pd is easily sintered at a high temperature to lower the catalyst activity and improve the deterioration coefficient, and therefore, higher demands are made on the durability of a general-purpose small gasoline catalyst.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide the universal small gasoline engine tail gas catalyst with good high-temperature aging resistance and low degradation coefficient.
The invention also aims to provide a preparation method of the universal small gasoline engine tail gas catalyst.
According to the technical scheme provided by the invention, the universal small gasoline engine tail gas catalyst comprises a catalyst carrier and a catalyst coating coated on the catalyst carrier, wherein the catalyst coating consists of an alumina material containing noble metal and a cerium-zirconium composite oxide;
the total coating amount of the catalyst coating is 20-100 g/L, wherein the weight of the cerium-zirconium composite oxide is 5-30% of the coating weight, and the use amount of the noble metal is 20-80 g/ft3And the balance of alumina material.
Preferably, the catalyst support is a wire mesh or metal honeycomb support.
Preferably, the alumina material is gamma-Al2O3、θ-Al2O3、δ-Al2O3、La2O3-Al2O3、BaO-Al2O3、SiO2-Al2O3、ZrO2-Al2O3One or more of them.
Preferably, the La is2O3-Al2O3Middle La2O3The mass content of the alloy is 1 to 5 percent, and the BaO-Al2O3The mass content of the medium BaO is 1 to 5 percent, and the SiO is2-Al2O3SiO 22The mass content of (a) is 1-5%, zrO2-Al2O3Medium ZrO of2The mass content of (A) is 1-5%.
Preferably, the cerium-zirconium composite oxide contains 5 to 70 weight percent of CeO220 to 90 percent of ZrO2And 5 to 10 percent of other oxides,and the other oxide is La2O3、Pr6O11、Y2O3、Nd2O3One or more of them.
Preferably, the noble metal comprises at least Pd.
Preferably, the noble metal further comprises one or both of Pt and Rh.
The preparation method of the tail gas catalyst of the universal small gasoline engine comprises the following steps:
(1) Mixing and stirring an aluminum oxide material and deionized water, and performing ball milling to obtain aluminum oxide slurry;
(2) Dripping the noble metal nitrate solution into the aluminum oxide material slurry, fully stirring, adding ammonia water, and adjusting the pH value to 4-6;
(3) Mixing and stirring cerium-zirconium composite oxide and deionized water, and performing ball milling to obtain cerium-zirconium composite oxide slurry;
(4) Adding the slurry obtained in the step (3) into the slurry obtained in the step (2), fully stirring, and adding pseudo-boehmite accounting for 1% -5% of the weight of the catalyst coating as a binder to obtain a finished slurry;
(5) Coating the finished slurry on a catalyst carrier according to the coating amount of 20-100 g/L, drying at 80-200 ℃ for 0.5-20 h, and roasting the dried carrier at 400-600 ℃ for 0.5-20 h to obtain the small gasoline general engine tail gas catalyst.
Preferably, the alumina material slurry has a particle size D90＝5～20μm。
Preferably, the cerium-zirconium composite oxide slurry has a particle size D90＝5～40μm。
The invention has the advantages that:
(1) The precious metals are all loaded on the alumina material with high specific surface area, so that the dispersity of the precious metals is improved, and the alumina material also has high specific surface area at high temperature, and the sintering of the precious metals can be effectively prevented. Not only has better HC conversion efficiency in a fresh state, but also can keep good conversion efficiency after high-temperature durability.
(2) A small amount of cerium-zirconium composite oxide is added, so that a larger air-fuel ratio window is provided while a higher HC conversion rate is maintained, and the influence of the fluctuation of the oxygen concentration in the exhaust emission on HC conversion is prevented.
(3) The addition of the large-particle cerium-zirconium composite oxide (relative to alumina particles) increases the porosity of the catalyst coating, is beneficial to the diffusion of harmful gases in tail gas, enables the harmful gases to contact with more active components, and improves the conversion efficiency of the harmful gases.
Detailed Description
The present invention is further illustrated by the following examples.
Example 1
The tail gas catalyst for the universal small gasoline engine comprises a honeycomb metal carrier, wherein the specification of the honeycomb metal carrier is phi 16 × 25, and the pore density is as follows: 400CPSI, volume of 0.005L; the coating amount of the catalyst is 60g/L, and the usage amount of Pd is 40g/ft3。
The preparation method of the universal small gasoline engine tail gas catalyst adopts the following process steps:
(1) 85g of gamma-Al2O3Mixing with 160g of deionized water, stirring, and ball-milling to obtain the granularity D90Alumina slurry of =10.6 μm.
(2) 12.858g of a palladium nitrate (18.31 wt%) solution was slowly added dropwise to the alumina slurry, and after completion of the dropwise addition, stirring was carried out for 1 hour, and then aqueous ammonia was added dropwise to adjust the pH of the slurry to =5.03.
(3) 10g of a cerium-zirconium composite oxide (20%)2、70％wtZrO2、5％La2O3、5％Pr2O5) Mixing with 15g of deionized water, stirring, and ball-milling to obtain a granularity D90Slurry of cerium-zirconium composite oxide of =18.3 μm.
(4) The cerium-zirconium composite oxide slurry and the alumina slurry containing Pd are mixed and stirred for 0.5h, 2.65g of pseudo-boehmite is added, and the mixture is stirred for 1h to obtain the finished slurry.
(5) Coating the obtained finished product slurry on a metal honeycomb carrier according to the coating amount of 60g/L, drying at 120 ℃ for 2h, and roasting the dried catalyst at 480 ℃ for 5h to obtain the small gasoline engine tail gas catalyst.
Example 2
The tail gas catalyst for the universal small gasoline engine comprises a honeycomb metal carrier, wherein the specification of the honeycomb metal carrier is phi 16 × 25, and the pore density is as follows: 400CPSI, volume of 0.005L; the coating amount of the catalyst is 60g/L, and the using amount of Pd is 40g/ft3。
The preparation method of the universal small gasoline engine tail gas catalyst adopts the following process steps:
(1) 85g of gamma-Al2O3Mixing with 160g of deionized water, stirring, and ball-milling to obtain the granularity D90Alumina slurry of =10.6 μm.
(2) 12.858g of a palladium nitrate (18.31 wt%) solution was slowly added dropwise to the alumina slurry, and after completion of the dropwise addition, stirring was carried out for 1 hour, and aqueous ammonia was added dropwise to adjust the pH of the slurry =5.03.
(3) 10g of a cerium-zirconium composite oxide (20%)2、70％wtZrO2、5％La2O3、5％Pr2O5) Mixing with 15g of deionized water, stirring, and ball-milling to obtain granularity D90Slurry of cerium-zirconium composite oxide of =18.3 μm.
(4) The cerium-zirconium composite oxide slurry and the alumina slurry containing Pd are mixed and stirred for 0.5h, 2.65g of pseudo-boehmite is added, and the mixture is stirred for 1h to obtain the finished slurry.
(5) Coating the obtained finished product slurry on a metal honeycomb carrier according to the coating amount of 60g/L, drying at 120 ℃ for 2h, and roasting the dried catalyst at 480 ℃ for 5h to obtain the small gasoline engine tail gas catalyst.
And (3) aging the obtained small gasoline general gasoline engine tail gas catalyst for 20 hours in an aging furnace containing 10% of water vapor at 850 ℃ to obtain the aged small gasoline engine general engine tail gas catalyst.
Example 3
The tail gas catalyst for the universal small gasoline engine comprises a honeycomb metal carrier, wherein the specification of the honeycomb metal carrier is phi 16 × 25, and the pore density is as follows: 400CPSI, volume of 0.005L; the coating amount of the catalyst is 60g/L, and the usage amount of Pd is 40g/ft3。
The preparation method of the universal small gasoline engine tail gas catalyst adopts the following process steps:
(1) 90g of gamma-Al2O3Mixing with 165g of deionized water, stirring, and ball-milling to obtain the granularity D90Alumina slurry of =9.7 μm.
(2) 12.858g of a palladium nitrate (18.31 wt%) solution was slowly added dropwise to the alumina slurry, and after completion of the dropwise addition, stirring was carried out for 1 hour, and then aqueous ammonia was added dropwise to adjust the pH of the slurry to =5.2.
(3) 5g of a cerium-zirconium composite oxide (40%)2、50％wtZrO2、5％La2O3、5％Pr2O5) Mixing with 7.5g of deionized water, stirring, and ball-milling to obtain the granularity D90Slurry of cerium-zirconium composite oxide of =22.5 μm.
(4) The cerium-zirconium composite oxide slurry and the alumina slurry containing Pd are mixed and stirred for 0.5h, 2.65g of pseudo-boehmite is added, and the mixture is stirred for 1h to obtain the finished slurry.
(5) Coating the obtained finished product slurry on a metal honeycomb carrier according to the coating amount of 60g/L, drying at 120 ℃ for 2h, and roasting the dried catalyst at 480 ℃ for 5h to obtain the small gasoline engine-through tail gas catalyst.
Example 4
The tail gas catalyst for the universal small gasoline engine comprises a honeycomb metal carrier, wherein the specification of the honeycomb metal carrier is phi 16 × 25, and the pore density is as follows: 400CPSI, volume of 0.005L; the coating amount of the catalyst is 60g/L, and the usage amount of Pd is 40g/ft3。
The preparation method of the universal small gasoline engine tail gas catalyst adopts the following process steps:
(1) 90g of gamma-Al2O3Mixing with 165g of deionized water, stirring, and ball-milling to obtain the granularity D90Alumina slurry of =9.7 μm.
(2) 12.858g of a palladium nitrate (18.31 wt%) solution was slowly added dropwise to the alumina slurry, and after completion of the dropwise addition, stirring was carried out for 1 hour, and then aqueous ammonia was added dropwise to adjust the pH of the slurry to =5.2.
(3) 5g of a cerium-zirconium composite oxide (40%)2、50％wtZrO2、5％La2O3、5％Pr2O5) Mixing with 7.5g of deionized water, stirring, and ball-milling to obtain the granularity D90Slurry of cerium-zirconium composite oxide of =22.5 μm.
(4) The cerium-zirconium composite oxide slurry and the alumina slurry containing Pd are mixed and stirred for 0.5h, 2.65g of pseudo-boehmite is added, and the mixture is stirred for 1h to obtain the finished slurry.
(5) Coating the obtained finished product slurry on a metal honeycomb carrier according to the coating amount of 60g/L, drying at 120 ℃ for 2h, roasting the dried catalyst at 480 ℃ for 5h to obtain the small gasoline engine-starter tail gas catalyst
And (3) aging the obtained small gasoline general gasoline engine tail gas catalyst for 20 hours in an aging furnace containing 10% of water vapor at 850 ℃ to obtain the aged small gasoline engine general engine tail gas catalyst.
Example 5
The tail gas catalyst for the universal small gasoline engine comprises a honeycomb metal carrier, wherein the specification of the honeycomb metal carrier is phi 16 × 25, and the pore density is as follows: 400CPSI, volume of 0.005L; the coating amount of the catalyst is 60g/L, and the using amount of Pd is 40g/ft3。
The preparation method of the universal small gasoline engine tail gas catalyst adopts the following process steps:
(1) 80g of gamma-Al2O3Mixing with 150g of deionized water, stirring, and ball-milling to obtain granularity D90Alumina slurry of =8.3 μm.
(2) 12.858g of a palladium nitrate (18.31 wt%) solution was slowly added dropwise to the alumina slurry, and after completion of the dropwise addition, stirring was carried out for 1 hour, and then aqueous ammonia was added dropwise to adjust the pH of the slurry =4.92.
(3) 15g of a cerium-zirconium composite oxide (15%)2、75％wtZrO2、5％La2O3、5％Pr2O5) Mixing with 22.5g of deionized water, stirring, and ball-milling to obtain the granularity D90Slurry of cerium-zirconium composite oxide of =21.8 μm.
(4) The cerium-zirconium composite oxide slurry and the alumina slurry containing Pd are mixed and stirred for 0.5h, 2.65g of pseudo-boehmite is added, and the mixture is stirred for 1h to obtain the finished slurry.
(5) Coating the obtained finished product slurry on a metal honeycomb carrier according to the coating amount of 60g/L, drying at 120 ℃ for 2h, and roasting the dried catalyst at 480 ℃ for 5h to obtain the small gasoline engine tail gas catalyst.
Example 6
The tail gas catalyst for the universal small gasoline engine comprises a honeycomb metal carrier, wherein the specification of the honeycomb metal carrier is phi 16 × 25, and the pore density is as follows: 400CPSI, volume of 0.005L; the coating amount of the catalyst is 60g/L, and the using amount of Pd is 40g/ft3。
The preparation method of the universal small gasoline engine tail gas catalyst adopts the following process steps:
(1) 80g of gamma-Al2O3Mixing with 150g of deionized water, stirring, and ball-milling to obtain granularity D90Alumina slurry of =8.3 μm.
(2) 12.858g of a palladium nitrate (18.31 wt%) solution was slowly added dropwise to the alumina slurry, and after completion of the dropwise addition, stirring was carried out for 1 hour, and then aqueous ammonia was added dropwise to adjust the pH of the slurry =4.92.
(3) 15g of a cerium-zirconium composite oxide (15%)2、75％wtZrO2、5％La2O3、5％Pr2O5) Mixing with 22.5g of deionized water, stirring, and ball-milling to obtain the granularity D90Slurry of cerium-zirconium composite oxide of =21.8 μm.
(4) The cerium-zirconium composite oxide slurry and the alumina slurry containing Pd are mixed and stirred for 0.5h, 2.65g of pseudo-boehmite is added, and the mixture is stirred for 1h to obtain the finished slurry.
(5) Coating the obtained finished product slurry on a metal honeycomb carrier according to the coating amount of 60g/L, drying at 120 ℃ for 2h, and roasting the dried catalyst at 480 ℃ for 5h to obtain the small gasoline engine tail gas catalyst.
And (3) aging the obtained small gasoline on-line tail gas catalyst for 20 hours in an aging furnace containing 10% of water vapor at 850 ℃ to obtain the aged small gasoline on-line tail gas catalyst.
Comparative example 1
The tail gas catalyst for the universal small gasoline engine comprises a honeycomb metal carrier, wherein the specification of the honeycomb metal carrier is phi 16 × 25, and the pore density is as follows: 400CPSI, volume of 0.005L; the coating amount of the catalyst is 60g/L, and the usage amount of Pd is 40g/ft3。
The preparation method of the universal small gasoline engine tail gas catalyst adopts the following process steps:
(1) 95g of gamma-Al2O3Mixing with 180g of deionized water, stirring, and ball-milling to obtain the granularity D90Alumina slurry of =11.2 μm.
(2) 12.858g of a palladium nitrate (18.31% strength by weight) solution were slowly added dropwise to the alumina slurry and stirred for 1h after the addition.
(3) Adding 2.65g of pseudo-boehmite, and stirring for 1h to obtain the finished slurry.
(4) Coating the obtained finished product slurry on a metal honeycomb carrier according to the coating amount of 60g/L, drying at 120 ℃ for 2h, and roasting the dried catalyst at 480 ℃ for 5h to obtain the small gasoline engine tail gas catalyst.
Comparative example 2
The tail gas catalyst for the universal small gasoline engine comprises a honeycomb metal carrier, wherein the specification of the honeycomb metal carrier is phi 16 × 25, and the pore density is as follows: 400CPSI, volume of 0.005L; the coating amount of the catalyst is 60g/L, and the usage amount of Pd is 40g/ft3。
The preparation method of the universal small gasoline engine tail gas catalyst adopts the following process steps:
(1) 95g of gamma-Al2O3Mixing with 180g of deionized water, stirring, and ball-milling to obtain the granularity D90Alumina slurry of =11.2 μm.
(2) 12.858g of a palladium nitrate (18.31% by weight) solution were slowly added dropwise to the alumina slurry, and stirred for 1 hour after completion of the dropwise addition.
(3) Adding 2.65g of pseudo-boehmite, and stirring for 1h to obtain the finished slurry.
(4) Coating the obtained finished product slurry on a metal honeycomb carrier according to the coating amount of 60g/L, drying at 120 ℃ for 2h, and roasting the dried catalyst at 480 ℃ for 5h to obtain the small gasoline engine tail gas catalyst.
And (3) aging the obtained small gasoline general gasoline engine tail gas catalyst for 20 hours in an aging furnace containing 10% of water vapor at 850 ℃ to obtain the aged small gasoline engine general engine tail gas catalyst.
Comparative example 3
The tail gas catalyst for the universal small gasoline engine comprises a honeycomb metal carrier, wherein the specification of the honeycomb metal carrier is phi 16 × 25, and the pore density is as follows: 400CPSI, volume of 0.005L; the coating amount of the catalyst is 60g/L, and the usage amount of Pd is 40g/ft3。
The preparation method of the universal small gasoline engine tail gas catalyst adopts the following process steps:
(1) 50g of gamma-Al2O340g of cerium-zirconium composite oxide (60%2、30％wtZrO2、5％La2O3、5％Pr2O5) Mixing with 210g of deionized water, stirring, and ball-milling to obtain the granularity D90Mixed slurry of =15.6 μm.
(2) 12.858g of a palladium nitrate (18.31% strength by weight) solution were slowly added dropwise to the mixed slurry, and the mixture was stirred for 1 hour after completion of the dropwise addition.
(3) Adding 2.65g of pseudo-boehmite, and stirring for 1h to obtain the finished slurry.
(4) Coating the obtained finished product slurry on a metal honeycomb carrier according to the coating amount of 60g/L, drying at 120 ℃ for 2h, and roasting the dried catalyst at 480 ℃ for 5h to obtain the small gasoline engine-through tail gas catalyst.
Comparative example 4
The tail gas catalyst for the universal small gasoline engine comprises a honeycomb metal carrier, wherein the specification of the honeycomb metal carrier is phi 16 × 25, and the pore density is as follows: 400CPSI, volume of 0.005L; the coating amount of the catalyst is 60g/L, and the usage amount of Pd is 40g/ft3。
The preparation method of the universal small gasoline engine tail gas catalyst adopts the following process steps:
(1) 50g of gamma-Al2O340g of a cerium-zirconium composite oxide (50%; wtCeO)2、40％wtZrO2、5％La2O3、5％Pr2O5) Mixing with 210g of deionized water, stirring, and ball-milling to obtain granularity D90Mixed slurry of =15.6 μm.
(2) 12.858g of a palladium nitrate (18.31% by weight) solution was slowly added dropwise to the mixed slurry, and stirred for 1 hour after completion of the dropwise addition.
(3) Adding 2.65g of pseudo-boehmite, and stirring for 1h to obtain the finished slurry.
(4) Coating the obtained finished product slurry on a metal honeycomb carrier according to the coating amount of 60g/L, drying at 120 ℃ for 2h, and roasting the dried catalyst at 480 ℃ for 5h to obtain the small gasoline engine tail gas catalyst.
And (3) aging the obtained small gasoline on-line tail gas catalyst for 20 hours in an aging furnace containing 10% of water vapor at 850 ℃ to obtain the aged small gasoline on-line tail gas catalyst.
The catalysts prepared in examples 1 to 6 and comparative examples 1 to 4 were subjected to catalyst performance evaluation in a simulated atmosphere (C)3H8＝800ppm、C3H6＝1600ppm、CO2=15% and the remainder is N2Lambda =0.96, space velocity 2L/min, test temperature 500 ℃). The experimental data obtained are shown in table 1:
TABLE 1
As shown in table 1, examples 1, 3 and 5 have HC conversion efficiency better than that of example 3, and although the conversion rate is not much different from that of comparative example 1, examples 2, 4 and 6 have lower deterioration coefficients than those of comparative example 2 and 4, which indicates that the present invention not only has better conversion efficiency in a fresh state, but also can improve catalyst aging performance and reduce the deterioration coefficient of the catalyst.
Claims (7)
1. A universal small gasoline engine tail gas catalyst is characterized in that: the catalyst comprises a catalyst carrier and a catalyst coating coated on the catalyst carrier, wherein the catalyst coating consists of a cerium-zirconium composite oxide and an alumina material containing noble metal;
the total coating amount of the catalyst coating is 20 to 100g/L, wherein the weight of the cerium-zirconium composite oxide is 5 to 30 percent of the coating weight, and the usage amount of the noble metal is 20 to 80g/ft3The balance of alumina material;
the preparation method of the universal small gasoline engine tail gas catalyst comprises the following steps:
(1) Mixing and stirring aluminum oxide material and deionized water, and performing ball milling to obtain aluminum oxide material slurry, wherein the granularity D of the aluminum oxide material slurry90=5~20μm；
(2) Dropwise adding a noble metal nitrate solution into the aluminum oxide material slurry, fully stirring, adding ammonia water, and adjusting the pH to 4-6;
(3) Mixing and stirring cerium-zirconium composite oxide and deionized water, and performing ball milling to obtain cerium-zirconium composite oxide slurry, wherein the granularity D of the cerium-zirconium composite oxide slurry90A particle size D of the cerium-zirconium composite oxide slurry of =5 to 40 mu m90Granularity D larger than that of aluminium oxide material slurry90；
(4) Adding the slurry obtained in the step (3) into the slurry obtained in the step (2), fully stirring, and adding pseudo-boehmite accounting for 1% -5% of the weight of the catalyst coating as a binder to obtain a finished slurry;
(5) And (3) coating the finished product slurry on a catalyst carrier according to the coating amount of 20-100g/L, drying at 80-200 ℃ for 0.5-20h, and roasting the dried carrier at 400-600 ℃ for 0.5-20h to obtain the small gasoline engine exhaust catalyst.
2. The exhaust catalyst for the universal small gasoline engine as set forth in claim 1, wherein: the catalyst carrier is a metal wire mesh or metal honeycomb carrier.
3. The exhaust catalyst for the universal small gasoline engine as set forth in claim 1, wherein: the alumina material is gamma-Al2O3、θ-Al2O3、δ-Al2O3、La2O3-Al2O3、BaO-Al2O3、SiO2-Al2O3、ZrO2-Al2O3One or more of them.
4. The exhaust catalyst for the universal small gasoline engine as set forth in claim 3, wherein: the La2O3-Al2O3Middle La2O3The mass content of the BaO-Al alloy is 1-5 percent2O3The mass content of the medium BaO is 1-5%, and the SiO2-Al2O3SiO 22The mass content of the ZrO 2 is 1-5 percent2-Al2O3Medium ZrO2The mass content of the compound is 1% -5%.
5. The universal small gasoline engine exhaust catalyst according to claim 1, characterized in that: the cerium-zirconium composite oxide contains 5-70 wt% of CeO220% -90% of ZrO2And 5% -10% of other oxides, wherein the other oxides are La2O3、Pr6O11、Y2O3、Nd2O3One or more of them.
6. The universal small gasoline engine exhaust catalyst according to claim 1, characterized in that: the noble metal comprises at least Pd.
7. The universal small gasoline engine exhaust catalyst according to claim 6, characterized in that: the noble metal also comprises one or two of Pt and Rh.
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| CN113600188B (en) * | 2021-08-10 | 2023-05-30 | 无锡威孚环保催化剂有限公司 | Catalyst for purifying tail gas of gasoline car and preparation method thereof |
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