CN1160599A - Preparation process of catalyst for waste gas purification - Google Patents
Preparation process of catalyst for waste gas purification Download PDFInfo
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- CN1160599A CN1160599A CN 96102488 CN96102488A CN1160599A CN 1160599 A CN1160599 A CN 1160599A CN 96102488 CN96102488 CN 96102488 CN 96102488 A CN96102488 A CN 96102488A CN 1160599 A CN1160599 A CN 1160599A
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Abstract
During the preparation, part of pre-determined amount of thin diaspore is prepared into size, the size is then acidified with hydrochloric acid, mixed with the rest thin diaspore and aluminium sol, aged, mixed witht he aqueous solution of iron-chromium lignin sulphonate in the amount of 2.5-15.0 wt% of dry alumina, and painted onto the surface of cellular cordierite carrier, and after drying, roasting and loading noble metal, Re metal and transition metal, the catalyst is prepared. With great specific surface area and excellent thermal stability, the catalyst is used in purifying harmful gas, including automobile tail gas, containing CO, HC and NOx.
Description
The present invention relates to a method for preparing a catalyst for exhaust gas purification, and more particularly, to a catalyst for exhaust gas purification including automobile exhaust gas containing carbon monoxide (CO), Hydrocarbon (HC), and Nitrogen Oxide (NO)x) And the preparation method of the catalyst for purifying harmful gases.
The common purification process is to make the automobile exhaust pass through a catalyst bed layerto make the harmful components in the exhaust such as CO, HC and NOxThe same into CO which is harmless to human body or less harmful2、H2O、N2And the like. In order to adapt to the running conditions of automobile engines at different temperatures, the catalyst carrier mostly adopts high temperature resistance and heat shock resistanceA shock-resistant and corrosion-resistant honeycomb ceramic body. Most of common honeycomb ceramic bodies are made of cordierite, and the specific surface area of the cordierite is extremely small, so that the loading and the dispersion of the metal active components are not facilitated. Therefore, alumina having a large specific surface area is coated on the surface of the honeycomb ceramic body, and then a metal active component is supported on the surface of the alumina to prepare a catalyst. For example, CN1055302A describes an exhaust gas purifying catalyst, which is prepared by depositing noble metal active components on alumina or zirconia in a proportion of 5-30 wt%, then mixing the alumina or zirconia containing noble metals with alumina and cerium oxide not containing noble metals, grinding the mixture by a ball mill to obtain aqueous slurry, coating the aqueous slurry on the surface of a honeycomb ceramic body, drying, and roasting at 600 ℃ at 100-. The alumina used in this patent is activated alumina having a surface area of 5-200 meters2Per gram.
It is known that, with increasing temperature, alumina undergoes the following phase changes:
with the change of the crystal phase, the specific surface area of the alumina is also reduced, thereby causing the catalyst active components, particularly the noble metal active components, to be aggregated and encapsulated, with the result that the catalyst activity is reduced and the lifetime is shortened.
Therefore, it has been attempted to modify alumina so as to have a large specific surface area at high temperatures, and then use this modified alumina as a catalyst support coating material to adapt a purification catalyst to the operation of an automobile engine at high and low temperatures, thereby maintaining the activity of the catalyst. For example, in U.S. Pat. No. 5,260,241, AlPO with a large specific surface area is obtained by modifying alumina with a phosphate, such as ammonium phosphate4phosphate-Al with a content of 3-12 wt%2O3As an example, 10% by weight of AlPO was contained4The alumina still has 162 m after being roasted at 850 DEG C2The specific surface area per gram, the patent directly coats the precursor slurry of the modified alumina on the surface of a honeycomb ceramic body and then loads active metal to prepare the exhaust gas purification catalyst, and better results are obtained. However, the phosphorus used in this patent is susceptible to catalysisThe noble metal poisoning in the catalyst, which sees pore canals, especially small pores, causes a change in the average pore size, limits the diffusion of the active component, and finally results in a significant decrease in the catalyst activity.
In addition, CN1097351A also discloses a method for preparing microspherical gamma-Al2O3The method is that after part of pseudo-boehmite in a preset amount is acidified, the rest of pseudo-boehmite and alumina sol are added, and the microspherical gamma-Al is prepared through the steps of spray forming, roasting and the like2O3The alumina prepared by the method has the characteristics of high strength, large specific surface area and the like.
The object of the present invention is to provide a method for preparing an exhaust gas purifying catalyst, which has good activity and thermal stability, based on the above prior art.
The preparation method of the catalyst provided by the invention comprises the following steps: preparing alumina slurry modified by iron-chromium lignosulfonate (FCLS for short), coating the slurry on the surface of a cordierite honeycomb carrier to prepare a composite carrier with an alumina coating, and then loading noble metal, rare earth metal and transition metal active components to prepare the catalyst.
The preparation method of the composite carrier comprises the following steps:
(1) preparing the pseudoboehmite with the weight percent of 25-75% in the preset amount and the decationized water into slurry with the solid content of 10-15% by weight, adding hydrochloric acid to adjust the pH value to be 1.5-4.0, adding the rest pseudoboehmite, and stirring until the slurry is in a uniform colloid state. The weight ratio of the pseudo-boehmite added in the two times is preferably 1: 1.
(2) Adding Al2O3The alumina sol with the content of 21.5-23.5 wt% and the weight ratio of Al/Cl of 1.15-1.25 is continuously stirred for 30-60 minutes.
(3) Aging for 1-3 hours at 50-70 ℃.
(4) Adding an aqueous solution of iron-chromium lignosulfonate accounting for 2.5-15.0% of the weight of the dry-based alumina, and uniformly stirring.
(5) The cordierite honeycomb carrier is immersed in the slurry, taken out, blown off by compressed air to remove the excess slurry in the channels, dried at room temperature to 120 ℃, preferably 40-60 ℃ for 2-4 hours, and calcined at 500-600 ℃ for 2-4 hours.
In the above preparation process, pseudo-boehmite Al is used2O3The content of the pseudo-boehmite is 20-60 wt%, and the weight ratio of the pseudo-boehmite to the alumina sol is (calculated as Al)2O3The ignition base is taken as a calculation reference) is 90-95: 5-10.
The iron-chromium lignosulfonate comprises not less than 85 wt% of effective substances, 2.5-3.8 wt% of total iron and 3.0-3.8 wt% of total chromium.
The active metal composition in the catalyst prepared by the method provided by the invention is as follows (based on the weight of the catalyst):
(1) at least one noble metal selected from Rh, Pt and Pd. When the noble metal is selected from Rh, the content of the noble metal is 0.03-0.5%; when the noble metal is selected from Pt or Pd, the content is 0.1-2.0%; when the noble metal is selected from Rh and Pt, the weight ratio of Pt/Rh is 3-10: 1, preferably 3-5: 1.
(2) The rare earth metal is selected from any one or a mixture of more of La, Ce and Pr, and the content of the rare earth metal is 1.2-12.0%.
(3) The transition metal is selected from one or more of Cr, Fe, Mn, Co, Ni and Cu, and the content of the transition metal is 1.2-8.5%.
The catalyst is prepared by a step impregnation method: taking a proper amount of cordierite carrier coated with an alumina coating, soaking and flowing a predetermined amount of nitrate or hydrochloride of cerium or lanthanum or a cerium-rich rare earth chloride aqueous solution, blowing the soaked carrier by compressed air to remove redundant liquid in the pore channel of the honeycomb carrier, drying at the temperature of 110 ℃ for 2-4 hours, and roasting at the temperature of 500-600 ℃ for 2-4 hours. And then carrying out secondary impregnation by using a Pt or Pd containing solution or a transition metal salt solution, and then carrying out tertiary impregnation by using a rhodium containing solution, wherein the carrier after each impregnation is treated according to the drying and roasting steps in the primary impregnation. Finally, the temperature is continuously raised to 500 ℃ from room temperature by using reducing gas for treatment, the temperature raising rate is 11 ℃/min, and then the temperature is cooled to room temperature. The process is repeated once more. The reducing gas comprises hydrogen, carbon monoxide, hydrocarbon or synthesis gas formed by mixing the three gases and carbon dioxide in any proportion in nitrogen.
The modifier of iron-chromium lignosulfonate (FCLS) is added into the alumina coating slurry, so that the modifier can inhibit the phase change of alumina at high temperature, adjust the viscosity of the slurry, ensure that the slurry has strong adhesiveness and ensure that the slurry can be more uniformly coated on the surface of a honeycomb carrier, and the prepared alumina still has large specific surface area at high temperature, and still has 200 m after being roasted at 850 DEG C2The surface area per gram, thus enabling the active components of the catalyst, particularly the noble metal, to be uniformly distributed on the carrier, thereby enhancing the activity and stability of the catalyst.
FIG. 1 is an X-ray diffraction phase diagram of alumina calcined at 900 deg.C for 6 hours after FCLS addition.
FIG. 2 is an X-ray diffraction phase diagram of alumina without modifier FCLS calcined at 900 deg.C for 6 hours.
FIG. 3 is a differential thermogram of alumina after FCLS addition.
FIG. 4 is a differential thermogram of alumina without modifier FCLS.
FIG. 5 is a graph showing the change in specific surface area of alumina added with FCLS and commercial alumina at high-temperature calcination.
The invention is further illustrated by the following examples.
Example 1
This example illustrates the preparation of an alumina coating according to the invention.
250 g of pseudo-boehmite (Al) is taken2O322 percent of the content, produced by Zhou village catalyst factory), adding 360 grams of decationized water, stirring for 30 minutes, controlling the solid content of the slurry to be 10-15 percent, adding 19 milliliters of 1: 1 hydrochloric acid (chemical purity, produced by Beijing chemical plant), adjusting the pH value of the slurry to be 3.45, adding 250 grams of pseudo-boehmite, stirring for 30 minutes to make the slurry be in a uniform colloid shape, aging for hours at 60 ℃, taking the slurry100 g of the slurry was added with 10 ml of an aqueous solution containing 10 wt% FCLS (Industrial pure, produced by Tanshiki chemical Co., Ltd.) and stirred well. An aqueous slurry for coating is prepared.
A commercially available cordierite honeycomb carrier (produced by Beijing Dahua ceramics works, phi 100X 50 cm, pore density of 26 pores/cm)2Specific gravity of 0.64 g/cm3) Cutting into 16.7 mm thick pieces, immersing in the aqueous slurry for coating, taking out, blowing off excessive slurry in the pore channels with compressed air, drying at 110 deg.C for 2 hr, and calcining at 550 deg.C for 2 hr to obtain composite carrier AL-A, wherein the content of alumina is 52 g per liter of carrier. The specific surface area is 252 meters by using a low-temperature nitrogen adsorption method2Per gram.
A composite carrier AL-B was prepared as described above except that the drying temperature was 50 ℃ and the drying time was 24 hours, and the specific surface area was 288 m2Per gram.
Example 2
This example illustrates the effect of the modifier FCLS added in the process of the present invention to inhibit phase change in alumina.
The aqueous slurry for coating prepared in example 1 and the slurry prepared in the same manner without the modifier FCLS were dried at 110 ℃ for 2 hours and calcined at 550 ℃ for 2 hours to obtain γ -Al2O3Powders A and B (comparative).
A, B two kinds of gamma-Al2O3The powder was calcined at 900 ℃ for 6 hours, and then an X-ray diffraction phase diagram (shown in FIGS. 1 and 2) was obtained using a DfMAX-IIIA type X-ray diffractometer of Japan. Comparing fig. 1 and fig. 2, it can be seen that the alumina in fig. 1 has no distinct phase transition peak, which indicates that the phase transition of the alumina is suppressed after adding the modifier FCLS.
Example 3
This example demonstrates the better thermal stability of the alumina made according to the invention.
gamma-Al prepared in example 22O3Powder A, B was subjected to differential thermal analysis using a thermal analyzer model USA Dupout Instrument 990 at a temperature rise rate of 10 deg.C/min, as indicated byAs shown in FIGS. 3 and 4, it can be seen that the alumina powder A to which FCLS was added still showed no destruction peak at 1100 deg.C, while the alumina powder B to which FCLS was not added showed a destruction peak at 966 deg.C. The alumina prepared by the invention has better thermal stability.
Example 4
This example illustrates the large specific surface area of the alumina produced according to the invention.
The BET specific surface area of the alumina powder A prepared in example 2 and the commercially available alumina powder C after calcination at different temperatures were measured, and the results are shown in FIG. 5, which shows that the alumina prepared according to the present invention has a large specific surface area even at high temperature calcination, e.g., 200 m at 850 deg.C2Per gram, even when calcined at a high temperature of 950 ℃, the specific surface area is higher than that of commercial alumina, which is up to 150 m2Per gram.
Examples 5 to 9
The following examples describe the preparation of the catalyst.
A certain amount of the carrier AL-A prepared in the example 1 is taken, impregnated with 40 ml of lanthanum chloride (chemical purity, produced by Beijing chemical plant) solution or cerous chloride (chemical purity, produced by Beijing chemical plant) solution, then blown by compressed air, redundant liquid in the pore channels of the honeycomb-shaped carrier is removed, the volume of the redundant liquid is measured, the carrier is dried at 110-120 ℃ for 2 hours, and the carrier is roasted at 550 ℃ for 2 hours. Then using 40 ml of chloroplatinic acid (chemical purity, Changling catalyst factory) or chromium chloride (chemical purity, produced by Beijing chemical plant) to make secondary impregnation, using 40 ml of rhodium chloride (chemical purity, produced by Beijing chemical plant) or palladium chloride (chemical purity, produced by Beijing chemical plant) to make tertiary impregnation, after every impregnation the carrier is treated according to the drying and roasting steps of primary impregnation, finally using synthetic gas (containing H) similar to tail gas of automobile22500ppm, HC60ppm, CO10000ppm, and the balance of N2) The temperature was continuously raised from room temperature to 500 ℃ at a temperature raisingrate of 11 ℃/min, and then cooled again to room temperature. And repeating the treatment once again to obtain the catalysts A-E.
The amount of carrier AL-A used and the active metal content of the impregnation solution in each example are shown in Table 1Wherein the catalyst D, E is impregnated with only one noble metal active component, and the composition of each active metal is shown in Table 2, and the value is calculated by the following formula
Comparative example 1
Comparative catalyst N was prepared as in examples 5-9 using the same impregnation solution and active metal content as catalyst C and the same support preparation method as in example 1 except that no modifier FCLS was added to the alumina coating slurry used to prepare the support.
Comparative example 2
Comparative catalyst M was prepared using commercially available alumina.
100 g of alumina (microsphere gamma-Al manufactured by Beijing chemical research institute)2O3) Placing the mixture in a ball mill, adding decationized water (the solid content is 50%), wet-milling for 4 hours to obtain aqueous slurry for coating, preparing a carrier according to the coating method of example 1, and then preparing a catalyst according to the methods of examples 5-9, wherein the active metal composition is the same as that of catalyst C.
Example 10
This example demonstrates that the catalyst provided by the process of the invention has better low temperature purification performance.
The evaluation was carried out by the following method: crushing a catalyst, taking 5 ml of 5-20-mesh particles, loading the particles into a quartz reactor with the inner diameter of 14 mm, putting the reactor into a heating furnace, heating to 550 ℃ at the speed of 11 ℃/min, and preparing synthesis gas by using a gas distribution device to simulate automobile exhaust to form synthesis gas, wherein the synthesis gas is N2Based on CO 9000ppm and H22000ppm、HC 240ppm、CO210800ppm、NOx700ppm、O220000ppm, 24000 hours of the synthesis gas-1The volume space velocity of (A) is measured by passing through a quartz reactor at a temperature of 20 ℃ per liter, and measuring CO, HC and NO in the gas generated at the outlet of the reactorxAnd then the harmful gas purification rate is calculated according to the following formula.
The purification rate was plotted against the reaction temperature to obtain the reaction temperature T at which the purification rate was 50%50This value, which can be used as a criterion for evaluating the low-temperature purification performance of the catalyst, is now shown in Table 3 together with the low-temperature purification performance of the inventive catalyst and the comparative agent, and the results show that the inventive catalyst C has a lower T50Temperature, and NOxThe highest purification rate value is the largest.
The compositions of the simulated synthesis gas and the generated gas at the outlet of the reactor are measured by the following instruments; carbon monoxide (CO): QGS-08 model CO Analyzer, Beijing Analyzer Mill; carbon dioxide (CO)2): QGS-08 type CO2Analyzer, beijing analytical instruments factory;
oxygen (O)2): GXH-500 model oxygen analyzer, Beijing Analyzer Mill; hydrocarbon (HC): model 31100RES Hydrocarbon Analyzer, manufactured by Japan; nitrogen Oxides (NO)x): model-10 type chemiluminescent NOxAnalyzer, usa thermionic company.
Example 11
This example demonstrates that the process of the invention provides catalysts with better stability.
The catalyst C of the present invention and the comparative catalyst N were calcined at a high temperature of 600 to 900 ℃ for 6 hours, and then evaluated by the method of example 10 to determine the T of CO and HC50Value and NOxThe highest conversion results are shown in Table 4. As can be seen from Table 4, after more severe high temperature treatment, catalyst C of the present invention still had lower T of CO and HC than the comparative catalyst N50Especially the T of the catalyst to CO after high-temperature roasting at 900 DEG C50The values are still lower, showing that the catalyst of the invention has better stability.
Example 12
This example illustrates the activity and selectivity of catalysts loaded with different metal active components.
The catalyst A, B, D, E of the present invention was evaluated by the method of example 10, and the results are shown in Table 5. As can be seen from Table 5, the platinum-carrying catalyst COT of50Lower value, palladium on catalyst for NOxThe removal rate of the catalyst B is higher, but the comprehensive consideration shows that the purification effect of the catalyst B is better.
TABLE 1
| Example number | 1 | 2 | 3 | 4 | 5 | |
| Catalyst numbering | A | B | C | D | E | |
| Amount of carrier, g | 11.56 | 11.61 | 8.57 | 8.52 | 8.90 | |
| First, the A Next time Dipping in water Stain | Impregnation liquid | Lanthanum chloride | Cerous chloride | Cerous chloride | Chloroplatinic acid | Palladium chloride |
| Metal content, g/ml | 0.165 | 0.33 | 0.33 | 0.04 | 0.019 | |
| Difference value*Ml of | 3.5 | 3.5 | 3.0 | 3.0 | 3.0 | |
| First, the II Next time Dipping in water Stain | Impregnation liquid | Chromium chloride | Chloroplatinic acid | Chloroplatinic acid | - | - |
| Metal content, g/ml | 0.19 | 0.04 | 0.01 | - | - | |
| Difference value*Ml of | 3.5 | 3.5 | 3.0 | - | - | |
| First, the II Next time Dipping in water Stain | Impregnation liquid | Palladium chloride | Rhodium chloride | Rhodium chloride | - | - |
| Metal content, g/ml | 0.019 | 0.0113 | 0.00283 | - | - | |
| Difference value*Ml of | 3.5 | 3.5 | 3.0 | - | - | |
*This value is the volume difference of the impregnation solution before and after impregnation.
TABLE 2
| Catalyst numbering | Metal composition, weight% |
| A | La 4.4 Cr 5.2 Pd 0.51 |
| B | Ce 8.9 Pt 1.08 Rh 0.31 |
| C | Ce 103 Pt 0.31 Rh 0.09 |
| D | Pt 1.4 |
| E | Pd 0.6 |
TABLE 3
| Catalyst numbering | T50，℃ | NOxHighest point of the design Conversion rate% | |
| CO | HC | ||
| C | 210 | 343 | 17.0 |
| N | 265 | 360 | 10.0 |
| M | 242 | 445 | 8.5 |
TABLE 4
| Roasting Temperature, C | Catalyst and process for preparing same Numbering | T50，℃ | NOxHighest point of the design Conversion rate% | |
| CO | HC | |||
| 600 | C | 210 | 343 | 17 |
| N | 265 | 362 | 10 | |
| 800 | C | 230 | 370 | 25 |
| N | 240 | 378 | 27 | |
| 900 | C | 252 | 550 | 34 |
| N | 290 | 580 | 32 | |
TABLE 5
| Catalyst and process for preparing same Numbering | Metal component | T50，℃ | NOxHighest point of the design Conversion rate% | |
| CO | HC | |||
| A | Pd-Cr-La | 211 | 289 | 9.0 |
| B | Ph-Pt-Ce | 199 | 284 | 32.9 |
| D | Pt | 146 | 365 | 24.6 |
| E | Pd | 235 | 395 | 42.3 |
Claims (10)
1. A preparation method of exhaust gas purification catalyst is to use a honeycomb ceramic body with a monolithic structure coated with an alumina coating as a composite carrier, and load noble metal, rare earth metal and transition metal active components to prepare the catalyst, and is characterized in that the composite carrier is prepared by the following steps:
(1) preparing 25-75 wt% of pseudoboehmite in a predetermined amount and decationized water into slurry with the solid content of 10-15 wt%, adding hydrochloric acid to adjust the pH value to be 1.5-4.0, adding the rest pseudoboehmite, and stirring until the slurry is in a uniform colloid state;
(2) adding the alumina sol and continuously stirring for 30-60 minutes;
(3) aging for 1-3 hours at 50-70 ℃;
(4) adding an aqueous solution of iron-chromium lignosulfonate accounting for 2.5-15.0% of the weight of the dry-based alumina, and uniformly stirring;
(5) and soaking the cordierite honeycomb carrier into the slurry, taking out the cordierite honeycomb carrier, blowing off redundant slurry in the pore channel by using compressed air, drying and roasting.
2. A method according to claim 1, characterized in that the weight ratio of pseudoboehmite to aluminium sol in the slurry (in terms of Al)2O3The burning base is taken as a calculation reference) is 90-95: 5-10.
3. A method according to claim 1, wherein the coated alumina is present in the composite support in an amount of from 40 to 60 grams per liter of support.
4. The method according to claim 1, wherein the weight ratio of the diasporite added twice in (1) is 1: 1.
5. The method of claim 1, wherein the pseudoboehmite contains Al2O320-60 wt% of aluminum sol containing Al2O321.5-23.5 wt%, and Al/Cl weight ratio of the aluminum sol is 1.15-1.25.
6. The method of claim 1 wherein the iron chromium lignosulfonate has an active content of not less than 85 wt%, a total iron content of 2.5-3.8 wt% and a total chromium content of 3.0-3.8 wt%.
7. The method according to claim 1, wherein the drying temperature in (5) is from room temperature to 120 ℃, preferably from 40 ℃ to 60 ℃, and the calcination temperature is 500 ℃ to 600 ℃.
8. A process according to claim 1, wherein the metal active components are loaded by a stepwise impregnation process, each impregnation being followed by drying, calcination and impregnation of the other component, the active metals comprising (based on catalyst weight):
(1) at least one noble metal selected from Rh and/or Pt and Pd, wherein when the noble metal is selected from Rh, the content of the noble metal is 0.03-0.5%, and when the noble metal is selected from Pt or Pd, the content of the noble metal is 0.1-2.0%;
(2) 1.2-12.0% of any one or several mixed rare earth metals selected from La, Ce and Pr;
(3) 1.2-8.5% of one or more mixed transition metals selected from Cr, Fe, Mn, Co, Ni and Cu.
9. The method according to claim 8, wherein the noble metal in (1) is 0.1 to 0.9% when it is selected from Pt and Pd.
10. The process according to claim 8, wherein in the case where the noble metal of (1) is selected from Rh and Pt, the weight ratio of Pt/Rh is 3-10: 1, preferably 3-5: 1.
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN100371072C (en) * | 2005-09-30 | 2008-02-27 | 清华大学 | Preparation process of selective reduction catalyst for lean-burn gasoline motor car exhausted gas nitrogen oxide |
| CN1872409B (en) * | 2005-05-31 | 2010-12-01 | 中国石油化工股份有限公司 | Cleaning catalyst for tail gas of automobile, and preparation method |
| CN102580733A (en) * | 2011-12-15 | 2012-07-18 | 无锡威孚环保催化剂有限公司 | Method for preparing Pd-only catalyst used for tail gas purification of universal minitype petrol engines |
| CN101495423B (en) * | 2006-06-30 | 2012-11-07 | 康宁股份有限公司 | Low-microcracked, porous ceramic honeycombs and methods of manufacturing same |
| CN102888242A (en) * | 2012-10-20 | 2013-01-23 | 东北石油大学 | Method for decreasing FCC regenerative process NOx by DeNOx additive |
| CN105396543A (en) * | 2015-12-17 | 2016-03-16 | 广州南枢电子科技有限公司 | Fuel oil catalytic reactor |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1021412C (en) * | 1988-10-26 | 1993-06-30 | 中国科学院生态环境研究中心 | Complex rare-earth oxidate containing valuable metal type honeycomb catalyst and its preparation |
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1996
- 1996-03-21 CN CN96102488A patent/CN1048650C/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1872409B (en) * | 2005-05-31 | 2010-12-01 | 中国石油化工股份有限公司 | Cleaning catalyst for tail gas of automobile, and preparation method |
| CN100371072C (en) * | 2005-09-30 | 2008-02-27 | 清华大学 | Preparation process of selective reduction catalyst for lean-burn gasoline motor car exhausted gas nitrogen oxide |
| CN101495423B (en) * | 2006-06-30 | 2012-11-07 | 康宁股份有限公司 | Low-microcracked, porous ceramic honeycombs and methods of manufacturing same |
| CN102580733A (en) * | 2011-12-15 | 2012-07-18 | 无锡威孚环保催化剂有限公司 | Method for preparing Pd-only catalyst used for tail gas purification of universal minitype petrol engines |
| CN102888242A (en) * | 2012-10-20 | 2013-01-23 | 东北石油大学 | Method for decreasing FCC regenerative process NOx by DeNOx additive |
| CN105396543A (en) * | 2015-12-17 | 2016-03-16 | 广州南枢电子科技有限公司 | Fuel oil catalytic reactor |
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| CN1048650C (en) | 2000-01-26 |
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