JPH09501348A - Base metal catalysts and catalyst supports for automobile exhaust gas purification and a further two-step process. - Google Patents

Abstract

  (57) [Summary] (A) a copper component containing cuprous oxide and cupric oxide, and (B) one or more kinds of lanthanoid oxides, (2) one kind of an oxide of a group II element of the Mendeleev periodic table As described above, (3) a mixed carrier containing one or more kinds of Group IIIb oxides and (4) one or more kinds of Group IV element oxides, wherein the copper component of (A) is (B) A catalyst for treating automobile exhaust gas dispersed on a carrier.

Description

Detailed Description of the Invention   Base metal catalysts and catalyst supports for automobile exhaust gas purification and a further two-step process.   The present invention relates to a catalyst for treating gas, in particular for automobile exhaust. The present invention relates to a catalyst for treating exhaust gas which is a combustion product such as gas.   Air pollution from exhaust gas from internal combustion engines is of great public concern. Of unburned hydrocarbons, nitrogen oxides and carbon monoxide from such exhaust gases. Many studies have been conducted to remove such pollutants.   One common solution is to make the pollutants relatively poisonous before releasing the exhaust gas into the atmosphere. Passing the exhaust gas through the catalyst bed to promote conversion to less aggressive materials. Current The catalyst component of such exhaust gas catalysts used is platinum, and other platinum compounds in combination. It consists of group metals. Platinum group metals are in low supply, their prices are already high, and Increased widespread use of exhaust gas catalysts due to legal regulation of Increase the cost of platinum group metals until they account for a significant proportion of the total cost of the vehicle. There is concern about doing so.   Accordingly, it is an object of the present invention to provide a rare and expensive material such as platinum or other platinum group metals. The object is to provide an effective exhaust gas catalyst that does not depend on the substance.   Exhaust gas purification catalysts utilizing certain base metals, especially copper, have also been investigated. Only However, the catalytic activity declines during use, and long-term service life of automobile exhaust gas is essential. It has the drawback of being unsuitable for use in purification. This point will be explained further See Figures 1a and 1b Then, γ-Al₂O_ThreeCopper oxide, which is a typical base metal oxide supported on, is CO Has a light off temperature of 250 ° C. for the reduction of NO by After feeding gas at 0 ° C. for 8 hours, its activity is dramatically reduced (FIG. 1b).   Moreover, the base metal catalyst system exhibits a variable resistance to sulfur poisoning, It has been found to have a lower specific activity than group metal systems.   The present invention solves the above problems.   According to the invention,   A. Copper composition,   B. (1) One or more lanthanide oxides       (2) One or more oxides of Group II elements of the Mendeleev Periodic Table       (3) One or more oxides of group IIIb elements       (4) One or more oxides of group IV elements     Mixed carrier containing A catalyst having a copper component dispersed on a carrier B is provided.   What is a "copper component"?   A (1) Cuprous oxide and cupric oxide, a simple substance of these, a mixture with metallic copper, or Is a mixture of cuprous oxide and cupric oxide, and   A (2) transition metal, preferably selected from cobalt, manganese, nickel, and iron Oxides of one or more metals Means a mixture containing.   The presence of transition metal oxides causes NO due to carbon monoxide by a synergistic mechanism.₁of It has been found to result in increased activity of the copper catalyst in the reduction.   Alternatively, the transition metal may provide the active site of the bidentate reaction, NO₁Of oxygen, transfer of oxygen to other loci, occurs at the first locus Recombination of nitrogen (N + N = N₂) From other CO to CO₂Including oxidation to.   Advantageously, the component B (1) of the lanthanoid oxide is cerium, lanthanum and Selected from thorium. Preferably, component B (1) is cerium dioxide alone or Is a mixture with one or more other lanthanoid oxides.   Preferably, Group II component B (2) is magnesium, calcium, strontium. And one or more oxides of barium.   Preferably, the Group IV component B (4) comprises zirconium, titanium, and hafnium. It is selected from one or more oxides.   Component B (3) of group IIIb is preferably alumina (Al_ThreeO₂).   The components of the mixed carrier B are 0.005 to 99.0 weight based on the total weight (W) of the carrier. %, Each of which can be present, where the sum of components B (1) to B (4) is always It is 100% by weight or less in total.   The base component of the copper component distributed or carried on the carrier is based on the total weight (W) of the carrier. Each can be present in an amount of 0.005 to 25% by weight.   Carbon monoxide (CO), nitric oxide (NO), propane (C_ThreeH₈) (Actual exhaust gas Carbon dioxide (representing all hydrocarbons present in CO)₂), Water (H₂O), oxygen (O₂), Hydrogen (H₂), And nitrogen (N₂Experiments with synthetic exhaust gas mixtures containing In, the catalyst of the present invention is equivalent to or better than the commercially available platinum group metal catalyst. It exhibited stability and catalytic activity.   The catalyst of the present invention is prepared by a variety of different methods within the purview of those skilled in the art. be able to.   Suitably, but not exclusively, the method of preparing the carrier includes urine. Elementary hydrolysis, Propoxide hydrolysis, Ammonium hydroxide (NH_FourOH) or Ammonium oxalate ((NH_Four)₂C₂O_Four・ H₂O) coprecipitation, carbonate As co-precipitation, mechanical mixing and decomposition of acetate, decomposition of nitrate, etc.   Appropriately, but not exclusively, the method of dispersing the copper compound on the carrier includes vinegar. There are deposits with acid copper, copper formate, copper amine complexes, copper carbonate, and copper nitrate.   Efficient NO at high space velocity_xTo facilitate removal, the catalyst is_xRemoval reaction     2CO + 2NO → CO₂+ N₂ The next "shift reaction" is relatively fast     CO + H₂O → CO₂+ H₂ Should be prepared to compete with.   In another aspect, the present invention provides the following two-stage process for exhaust gas purification. ,   (1) The exhaust gas is introduced onto the first catalyst containing the copper component A on the mixed carrier B, and Removes carbon monoxide and hydrocarbons in one step,   (2) Direct the exhaust gas onto the second catalyst arranged in series with the first catalyst, and At NO_xAnd residual hydrocarbons are removed, and the second catalyst is a copper component on a strongly acidic carrier. Including A.   Strong acidic carriers,   (a) one or more zeolites, or   (b) Zirconium oxide preferably present in an amount of 3-15%, more preferably 7%. Um (ZrO₂), Tungsten oxide (WO_Three), Molybdenum oxide (MoO_Three), Alumina (Al₂O_Three) Is a solid solution containing two or more of l₂O_ThreeHigh surface area carriers such as), preferably stabilized with magnesium oxide Of) Supported on, or   (c) Alumina (Al₂O_Three) And silicon oxide (SiO₂), Titanium oxide (TiO)₂ ), And zirconium oxide (ZrO₂) Obtained by co-gelling with one or more of Strong acidic compounds Can be included.   Generally, the air / combustion ratio (λ) of the exhaust gas changes from the stoichiometry (λ = 1) to the oxidation condition. When it fluctuates between (λ ≧ 1), the catalyst activity decreases and NO_xThe conversion rate decreases. However, using the two-step process described above, NO under oxidizing conditions_xConversion The rate is from the stoichiometric conversion achieved at a GHSV of 500000 / h. Is also improved by 20% or more.   In another embodiment, the first catalyst comprises cuprous oxide and cupric oxide on the mixed carrier B. Any metal, which may include copper, and which includes a platinum group metal dispersed on the mixed carrier B. Two catalysts can be used in combination.   Preferably, the platinum group metal comprises palladium, the metal palladium and palladium oxide. Especially preferred is a mixture of gums.   According to the above embodiment, it contains less than 10% of the noble metal loading known in commercial catalysts. When the palladium catalyst is stoichiometric, that is, when the ratio of air to combustion is 14.67 ( NO obtained at λ = 1)_xA conversion of about 40% of the conversion was achieved. This value Corresponds to the amount of air required for complete oxidation.   In another aspect, the present invention relates to a base metal or platinum group metal used for exhaust gas purification. A mixed oxide support B for the catalyst is provided.   Reference will now be made to the accompanying drawings for examples of catalysts employed in the present invention (merely by way of example) While explaining.   1a and 1b show γ-Al₂O_ThreeIncluding copper oxide supported on, outside the scope of the present invention. The results obtained using a base metal catalyst are shown.   FIG. 2 shows that the GHSV space velocity of 5000 / h was measured at λ = 1 using the catalyst of the present invention. The catalytic conversion of the corresponding synthesis exhaust gas mixture is shown with respect to temperature.   Carrier B-Mg_0.935Zr_0.03Ce_0.03La_0.005Al₂O_FourPreparation of ± δ-   Coprecipitation with NH ₄ OH   The required amount of nitrate was added to 400 ml of distilled water and heated to 60 ° C. this Approximately 35 ml of (1: 1) NH while stirring the solution_FourOH was added in a short time. Profit The pH obtained was 9. The slurry was aged at 70-80 ° C for 4 hours, filtered and , Wash 4 times with 200 ml cold water each and dry overnight at 110 ° C. Dried and then powdered.   191.0m in 6 hours at 550 ° C²/ G, 57.8m for 24 hours at 1000 ° C² / G   Preparation of carrier   While stirring 500 ml of distilled water at 50 ° C., Al (NO_Three)_Three・ 9H₂ O (246 mmol), Mg (NO_Three)₂・ 6H₂O (123 mmol), Ce ( NO_Three)_Three・ 6H₂O (6.2 mmol), ZrO (NO_Three)₂(6.2 mmol) , And La (NO_Three)_Three・ 6H₂O (1 mmol) was dissolved. Then NH_FourOH 10% solution of was added slowly to adjust pH to 9. The precipitate obtained is then 8 The mixture was aged at 0 ° C. for 5 hours, filtered, and washed with 300 ml of water three times. After drying, this mixture The mixture was calcined at 1 ° C./min at 550 ° C. for 6 hours and then passed through a 100 μm sieve. This gives a nominal composition of Mg_0.935Ce_0.03Zr_0.03La_0.005Al₂O_Fourso, Surface area is 137m²/ G of carrier (B) was obtained.   Metal deposition   In the subsequent deposition process, carrier B calcined at 500 ° C. and calcined at 1000 ° C. The solution was added to both Carrier B (heated at 1000C for 2 hours at 10C / min). A total of 5% by weight of copper was supported on the carrier.   Deposition with copper amine complex   While stirring 19 ml of water at 50 ° C., Cu (NO_Three)₂・ 5 / 2H₂O (11.6 mmol) was added. Then 5 ml of 33% NH with stirring_FourO H was added to produce a deep purple copper ammonium nitrate solution. Then stir However, 1.2 ml of this solution was added to 1.5 g of carrier B. This mixture Allow to dry and repeat the same procedure. Same as above, at 550 ° C for 6 hours and 10 Both calcinations were carried out at 00 ° C. for 2 hours.   FIG. 2 shows CO (1.0%), NO (1500 ppm), O₂(0.85%), H₂(0.33%), CH_Four(500ppm), C_ThreeH₈(167ppm), H₂O (10%), CO₂(15%), SO₂(20ppm), N₂Λ including (residual) The catalyst conversion rate of the synthetic exhaust gas of = 1 using the catalyst of the present invention is GHS of 5000 / h. Shown against temperature in V space velocity.   As shown, the catalyst of the present invention has greater than 90% NO at 525 ° C. A conversion rate can be achieved.   In addition, the supply gas is 0.05% SO₂By introducing the above The effect of sulfur poisoning on the catalyst was examined. Surprisingly, such processing It was found to have no effect on the catalytic activity.   FIG. 3 is a GHSV space velocity of 15000 / h in the two-step process of the present invention. 2 shows the catalyst conversion rate of the synthetic exhaust gas composition in which the first stage catalyst includes the catalyst of FIG. , The second stage catalyst is on a zeolite support 2 containing the copper component of the catalyst of FIG. As shown, the two stages of the present invention A 100% NO conversion was obtained at 225 ° C by using the double layer process. Can be   FIG. 4 shows the space velocity of 15000 / hGHSV in the two-step process of the present invention. 2 shows the catalyst conversion rate of the synthetic exhaust gas composition in FIG. , The second stage catalyst is based on the total weight of the support dispersed on the mixed oxide support B. It contains mixed oxide support B of the catalyst of FIG. 2 with 1% by weight of palladium. Shown Thus, by using a palladium loading of only 1% by weight, Excellent NO conversion can be obtained by performing a two-step process.

[Procedure of Amendment] Article 184-8 of the Patent Act [Submission date] September 6, 1995 [Correction contents]                                The scope of the claims   1. A. Copper component containing cuprous oxide and cupric oxide, and       B. (1) Yttrium oxide or one or more lanthanoid oxides           (2) One or more IIA group element oxides           (3) One or more oxides of group IIIA elements           (4) One or more kinds of oxides of elements selected from Zr, Ti, and Hf         A mixed carrier containing A catalyst comprising the components of A dispersed on a carrier of B.   2. The catalyst according to claim 1, wherein the copper catalyst component A (1) further contains metallic copper.   3. The copper catalyst component further comprises one or more transition metal oxides of A (2). The catalyst according to item 1 or 2.   4. Claims where A (2) is selected from cobalt, manganese, nickel, and iron. The catalyst according to item 3 above.   5. Component B (1) is selected from oxides of cerium, lanthanum, and yttrium. The catalyst according to any one of claims 1 to 4, wherein   6. Component B (1) is cerium dioxide alone or cerium dioxide and one or more other The mixture according to any one of claims 1 to 5, which is a mixture with a lanthanoid oxide. The listed catalyst.   7. B (2) is one or more of manganese, calcium, strontium, and barium 7. A catalyst according to any one of claims 1 to 6 selected from the above oxides.   8. Any one of claims 1 to 7 in which B (3) is alumina The catalyst according to the item.   9. The carrier B is magnesium (Mg), zirconium (Zr), cerium (Ce). ), Lanthanum (La) oxide, and alumina (Al₂O_Four) Claims including The catalyst according to any one of items 1 to 8.   10. Each component of the mixed carrier B is 0.005 to 99., based on the total weight of the carrier. A catalyst according to any one of claims 1 to 10 present in an amount of 0% by weight.   11. Each element of the copper component is 0.005 to 25 times the total weight of the carrier B. A catalyst according to any one of claims 1 to 10 which is present in an amount of% by weight.   12. The component of carrier B is Mg_0.935, Zr_0.03, Ce_0.03, La_0.005, Al₂O_Four ± δ (25.42% MgO, 2.49% ZrO₂3.48% CeO₂, 0 . 55% La₂O_ThreeThe catalyst according to claim 9, which is present in the ratio of).   13. The exhaust gas is introduced onto the catalyst according to any one of claims 1 to 12. A method for purifying vehicle exhaust gas, including:   14． (1) On the mixed carrier B according to any one of claims 1 to 12. The exhaust gas is guided to the first catalyst containing the copper component A, and carbon monoxide and hydrocarbon Remove the element,         (2) The first component containing copper component A on a strongly acidic carrier arranged in series with the first catalyst. Directs exhaust gas to the two catalysts, NO in the second stage₁And remove hydrocarbons present A two-stage method for purification of exhaust gas including:   15. The strong acidic carrier of the second catalyst   (a) Theolite, or   (b) Zirconium oxide (ZrO₂), Tungsten oxide (WO_Three), Molybdenum oxide Den (MoO_Three), Alumina (Al₂O_Three) Two or more A solid solution containing   (c) Alumina (Al₂O_Three) And silicon oxide (SiO₂), Titanium oxide (TiO)₂ ), And zirconium oxide (ZrO₂) Obtained by co-gelling with one or more of Strong acidic compounds 15. The method of claim 14 including.   16. Zirconium oxide is present in the second catalyst in an amount of 3 to 15%. The method according to paragraph 15.   17． Claims wherein the second catalyst comprises a platinum group metal dispersed on mixed support B. The method according to Item 14.   18. Mixture according to any one of claims 1, 5, 6-10 and 12. Contains the oxide carrier B and is used as a base metal of a platinum group metal catalyst used for purification of exhaust gas. body.

Claims (1)

[Claims]     1. A. Copper component containing cuprous oxide and cupric oxide, and         B. (1) One or more lanthanide oxides             (2) One or more oxides of Group II elements of the Mendeleev Periodic Table             (3) One or more oxides of group IIIb elements             (4) One or more oxides of group IV elements           A mixed carrier containing A catalyst in which the copper component of A is dispersed on the carrier of B.     2. The catalyst according to claim 1, wherein the copper catalyst component A (1) further contains metallic copper. .     3. Claims including copper catalyst components or one or more transition metal oxides of A (1) The catalyst according to item 1 or 2.     4. Claims in which A (1) is selected from cobalt, manganese, nickel, and iron A catalyst according to claim 3.     5. Component B (1) is selected from oxides of cerium, lanthanum and yttrium The catalyst according to any one of claims 1 to 4, which is provided.     6. Component B (1) is cerium dioxide alone, or cerium dioxide and at least one other 6. A mixture with the lanthanoid oxide according to any one of claims 1 to 5. The described catalyst.     7. B (2) is one of manganese, calcium, strontium, and barium The catalyst according to any one of claims 1 to 6 selected from the above oxides. .     8. Whether B (4) is one or more oxides of zirconium, titanium, and hafnium The statement according to any one of claims 1 to 8 selected from The listed catalyst.     9. The B (3) is alumina, according to any one of claims 1 to 8. catalyst.     10. The carrier B is magnesium (Mg), zirconium (Zr), cerium ( Ce), oxides of lanthanum (La), and alumina (Al)₂O_Four) Including claims The catalyst according to any one of items 1 to 10.     11. Each component of the mixed carrier B is 0.005 to 99 based on the total weight of the carrier. . Catalyst according to any one of claims 1 to 10 present in an amount of 0% by weight. .     12. Each of the copper components has an amount of 0.005 to 25 based on the total weight of the carrier B. The catalyst according to any one of claims 1 to 11, which is present in an amount of% by weight.     13. The component of carrier B is Mg_0.935, Zr_0.03, Ce_0.03, La_0.005, Al₂ O_Four± δ (25.42% MgO, 2.49% ZrO₂3.48% CeO₂ , 0.55% La₂O_ThreeThe catalyst according to claim 10, which is present in a ratio of).     14． A gas is introduced onto the catalyst according to any one of claims 1 to 13. A method for purifying vehicle exhaust gas, including:     15. (1) On the mixed carrier B according to any one of claims 1 to 13. The exhaust gas is led to the first catalyst containing copper component A in the first step, and carbon monoxide and carbon are added in the first step. Remove hydrogen fluoride,           (2) Guide the exhaust gas to the second catalyst that is placed in series with the first catalyst, and By the way, NO₁And residual hydrocarbons are removed, and the second catalyst is a copper component on a strongly acidic carrier. Including A,   A two-stage method for purification of exhaust gas including:     16. Strong acidic carrier     (a) Zeolite or     (b) Zirconium oxide (ZrO₂), Tungsten oxide (WO_Three), Molybdenum oxide Buden (MoO_Three), Alumina (Al₂O_Three) A solid solution containing two or more of     (c) Alumina (Al₂O_Three) And silicon oxide (SiO₂), Titanium oxide (Ti O₂), And zirconium oxide (ZrO₂) Obtained by co-gelling with one or more of Strong acidic compounds   A second catalyst comprising: and for use in the method of claim 15.     17． The method according to claim 16, wherein zirconium oxide is present in an amount of 3 to 15%. The second catalyst described.     18. 15. The method according to claim 14, comprising a platinum group metal dispersed on the mixed carrier B. A second catalyst for use in the method described in.     19. The mixture according to any one of claims 1, 5, 6 to 11, and 13. A base metal or platinum group metal catalyst containing a mixed oxide carrier B and used for purification of exhaust gas Carrier.