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(40)the study of the vibration diagnosis method for GIS
The study of vibration diagnosis method for GIS
Ding Pei 1,a , Yan Zhenhua 1,b , Ma Feiyue 1,c , Zhang Liang 2,d ,Li Junhao 2,e , and Li Yanming 2,f
1Electric Power Research Institute of Ningxia Grid Corporation. Yinchuan, 750002, China 2School of Electrical Engineering , Xi ′ an Jiaotong University , Xi ′ an, 710049, China
Keywords:GIS, vibration, acceleration
Abstract. Gas insulated switchgear (GIS)will generate vibration during normal operation for the electromagnetic force. There will be generate abnormal vibration when the contacts are undesirable, the guide rod stressed unevenness. Therefore, it can be effective in fault diagnosis of this machineries through the vibration test of GIS in field. The vibration detection method of GIS equipment in field is studied in this paper, the composition of the vibration detection system is described. The field test has been done using vibration detection system and the test results show that through the vibration signal detected from the GIS equipment, the vibration characteristics of GIS can be clarified and make the fault diagnosis effectively.
Introduction
The gas insulated switchgear (GIS)have been used in power grid more and more widely for its high operating reliability and small floor space. As the voltage level of the power grid has continuously improved, it requires electrical devices small, reliable operation and easy maintenance. GIS welcomed by the majority of users just attributed to these advantages[1~3].In order to ensure the safe operation of GIS and as much as possible to extend its maintenance cycle, the study of the approach to predict the internal latent faults is necessary.
As to the discharge fault detection of GIS, the main methods include electrical method, acoustic measurement method, chemical analysis, optical measurement method and so on. Electrical method use pulse current method in the factory test and the UHF detection method is a wider used application of online monitoring, acoustic measurement method mainly use ultrasonic detection method, Chemical analysis is analyzing the decomposition composition changes of the gas which is caused by discharge. In addition, there are optical measurement method which used the optical sensor detection buried inside the device to detect the light intensity of the arc and so on. UHF detection method and acoustic detection method used more often in the field at present, chemical analysis has also been taken seriously and studied by many research institutions, while optical measurement method is still in the stage of laboratory research.
There will be one or more of the inherent vibration frequency in the course of normal operation of GIS, and when GIS has mechanical failure, there will be a different vibration frequencies. The so-called mechanical failure refers when GIS has some defects such as abnormal contact of the switch contacts, uneven shell butt, the guide rods are slightly bent and so on. Then the discharge failure does not occur at this time, however, due to the alternating power in the conductor generated by alternating current, the electromagnetic force generated by the transformer core and so on will lead to GIS products mechanical movement, due to the presence of the mechanical defect, in addition to normal vibration, it will generate abnormal vibration signals and this signals can be detected on GIS shell. Abnormal vibration of GIS has great harm to GIS body. The bolts will loose for long-term vibration and lead to the gas leakage, reduction of pressure and then caused insulation accident. It will caused damage to insulators and affect the stability of the ground contact point for abnormal vibration. Therefore, the strengthening of GIS mechanical failure detection is important to ensure the safe
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The following method is usually used. During the load operation, overall ...line vibration diagnosis of rotating machinery in power plants. This system ...Method Equipment Round/Surveillance etc Vibration Diagnosis Vibration Diagnosis Vibration Diagnosis Equipment Round/Surveillance etc Equipment Round/Surveillance etc ... Vibration-based fault diagnosis of spur bevel gear box using fuzzy ...vibration signals is the most commonly used method for detecting gear ... Journal of Vibration,Measurement & Diagnosis_专业资料。维普资讯
289 Junlo bain.esrmet&Digoi ora fVirtoMauenan ... A roller bearing fault diagnosis method based_机械/仪表_工程科技_专业资料。学习资料ARTICLE IN PRESS JOURNAL OF SOUND AND VIBRATION Journal of Sound and ...diagnosis of GIS through vibration method ,this paper classifies and analyzes...( 4 ): 1316. Zhang Yalin, Qian Jiali. Experimental study of vibration ...Based on GIS equipment as the center, this paper mainly studies the ...4. The diagnosis method based on vibration are analyzed in detail, put ... Partial Discharge Diagnosis Method Using ...GIS SHAPES To study on the propagation of the ...Output TEM 0.74 0.40 Less than 0.01 Input TEM... vibration fault diagnosis of mine__ ventilator based on intelligent method ...0.40~0.49 0.50 0.51~0.99 1 2 high-order odd number extremely high ...A future possibility of vibration based condition ...method for the fault diagnosis in a machine [21...Hammond, Experimental study of the vibrational ...Analysis on the Vibration of GIS--《Huatong Technology》2001年02期
Analysis on the Vibration of GIS
Yang Rui Tang (Zhong Nan Survey Design Institute 410014)
A study mainly on the vibration of phaseisolated GIS, also on the inherent vibration characteristics of the conductors and case of GIS, a discussion on the distance choice of the basin style insulators to get better technical performance and economic effect.
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【References】
Chinese Journal Full-text Database
CHENG Lin (State Grid Electric Power Research Institute,Wuhan 430074,China);[J];Electric Power C2009-07
【Co-references】
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Wang Zhiyi
(Anhui Provincial Electric Power Design Institute, Hefei City, 230022);[J];Electric Power C2004-04
Wang Chixin,Ma Zhihong(Guangdong Provincial Electric Power Design and Research Institute,Guangzhou City,510600);[J];Electric Power C2005-11
Chen Fei,Wu Guozhong(Electrical Engineering College of Zhejiang University,Hangzhou City,310027);[J];Electric Power C2006-01
Guo Bihong, Zhang H[J];Power System T1989-02
WANG Feng, QIU Yu-chang (School of Electrical Engineering, Xi抋n Jiaotong University, Xi抋n 710049, Shaanxi Province, China);[J];Power System T2003-02
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CHEN Xue(Xuancheng Power Supply Company,Xuancheng 242000,China);[J];Journal of Anhui Electrical Engineering Professional Technique C2010-03
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(C)2006 Tsinghua Tongfang Knowledge Network Technology Co., Ltd.(Beijing)(TTKN) All rights reservedMethod for the decomposition of N2O, catalyst therefor and preparation of this catalyst
United States Patent 7704474
The invention relates to a method for the catalytic decomposition of N2O in a gas containing N2O in the presence of a catalyst, wherein the catalyst comprises a zeolite that has been loaded with a first metal selected from the group of noble metals consisting of ruthenium, rhodium, silver, rhenium, osmium, iridium, platinum and gold, and with a second metal selected from the group of transition metals consisting of chromium, manganese, iron cobalt, nickel and copper, and wherein the loading of the zeolite with metals has been obtained by first loading the zeolite with the noble metal and then with the transition metal, as well as a catalyst for this method and a method for the preparation of this catalyst.
Inventors:
Pieterse, Johannis Alouisius Zacharias (Alkmaar, NL)
Van Den, Brink Rudolf Willem (Schagen, NL)
Application Number:
Publication Date:
04/27/2010
Filing Date:
05/17/2005
Export Citation:
Stichting Energieonderzoek Centrum Nederland (Petten, NL)
Primary Class:
Other Classes:
International Classes:
B01D53/56; B01D53/86; B01J23/38; B01J23/54; B01J23/72; B01J23/74; B01J29/06; B01J29/064; B01J29/072; B01J29/076; B01J29/24; B01J29/46; B01J29/68; B01J29/76
Field of Search:
502/305, 502/353, 502/74, 502/326, 502/344, 502/324, 502/325, 502/300, 423/239.2
View Patent Images:
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US Patent References:
McMinn et al.502/64Hamon et al.502/606274107Yavuz et al.423/213.55968466Kharas423/239.25908806Kharas502/645536687Ward502/675171553Li et al.423/239.25160033Vassilakis et al.208/111.155149512Li et al.5041272Tamura et al.4902392Aufdembrink et al.208/110
Foreign References:
JP6142517May, 1994JP6154603June, 1994JP6154604June, 1994JPJune, 1994CATALYST FOR DECOMPOSITION OF NITROUS OXIDEJP6198187July, 1994WOA1CATALYST BASED ON FERRIERITE/IRON FOR CATALYTIC REDUCTION OF NITROUS OXIDE CONTENT IN GASES, METHOD FOR OBTAINING SAME AND APPLICATIONWOA1METHOD FOR THE REMOVAL OF NOX AND CATALYST THEREFORJPHAJPHAJPHAJPHAJPHA
Other References:
IZA Structure Commission, Database of Zeolite Structures, BEA, www.zeolites.ethz.ch/zeolites, Dated Mar. 18, 2004.
IZA Structure Commission, Database of Zeolite Structures, MOR, www.zeolites.ethz.ch/zeolites, Dated Mar. 18, 2004.
IZA Structure Commission, Database of Zeolite Structures, FER, www.zeolites.ethz.ch/zeolites, Dated Mar. 18, 2004.
IZA Structure Commission, Database of Zeolite Structures, CHA, www.zeolites.ethz.ch/zeolites, Dated Mar. 18, 2004.
Primary Examiner:
Vanoy, Timothy C.
Attorney, Agent or Firm:
The Webb Law Firm
The invention claimed is:
1. A method for the catalytic decomposition of N2O in a gas containing N2O in the presence of a catalyst, wherein the catalyst comprises a zeolite that has been loaded with a first metal selected from the group of noble metals consisting of ruthenium, rhodium, silver, rhenium, osmium, iridium, platinum and gold, and with a second metal selected from the group of transition metals consisting of vanadium, chromium, manganese, iron, cobalt, nickel and copper, wherein the loading of the zeolite with metals has been obtained by first loading the zeolite with the noble metal and then with the transition metal, and wherein the zeolite is selected from the group consisting of FER, CHA and BEA.
2. The method according to claim 1, wherein the zeolite has been loaded with the first metal by means of ion exchange.
3. The method according to claim 1, wherein the first metal has been selected from the group consisting of ruthenium, rhodium, osmium and iridium.
4. The method according to claim 1, wherein the second metal has been selected from the group consisting of iron, cobalt and nickel.
5. The method according to claim 1, wherein the zeolite loaded with metals has been selected from the group consisting of Fe—Rh-FER, Fe—Ir-FER, Fe—Ru-FER, Fe—Ru-MOR, Co—Rh-FER, Co—Ir-FER, Co—Ru-FER, Fe—Rh-BEA, Fe—Ir-BEA, Fe—Ru-BEA, Co—Rh-BEA, Co—Ir-BEA and Co—Ru-BEA.
6. The method according to claim 1, wherein the zeolite contains 0.00001-4% (m/m) of the first metal and 0.1-10% (m/m) of the second metal.
7. The method according to claim 1, wherein the zeolite contains 0.1-0.5% (m/m) of the first metal and 1-4% (m/m) of the second metal.
8. The method according to claim 1, wherein the gas containing N2O also contains oxygen or water.
9. The method according to claim 1, wherein the gas containing N2O essentially contains no hydrocarbon.
10. The method according to claim 1, wherein the gas containing N2O contains less than 50 ppm hydrocarbon.
11. The method according to claim 1, wherein the gas containing N2O also contains NOx, where x is equal to or greater than 1.
12. The method according to claim 11, wherein a catalyst is also used for the removal of NOx.
13. The method according to claim 1, wherein the gas containing N2O is fed through a chamber that contains the catalyst, wherein the chamber, the gas or both are heated if required.
14. A method for the preparation of a catalyst for the catalytic decomposition of N2O in a gas containing N2O, wherein the catalyst comprises a zeolite and the zeolite is first loaded with a first metal selected from the group of noble metals consisting of ruthenium, rhodium, silver, osmium and iridium, and then loaded with a second metal selected from the group of transition metals consisting of vanadium, chromium, manganese, iron, cobalt, nickel and copper.
15. The method according to claim 14, wherein the zeolite is loaded with the first metal by means of ion exchange.
16. The method according to claim 14, wherein the second metal is selected from the group consisting of iron, cobalt and nickel.
17. The method according to claim 14, wherein the zeolite is selected from the group consisting of FAU, FER, CHA, MOR, MFI, BEA, EMT, CON, BOG and ITQ-7.
18. A catalyst obtained according to the method of claim 14, wherein the zeolite is selected from the group consisting of FER, CHA and BEA.
19. The catalyst according to claim 18, wherein the zeolite contains 0.00001-4% (m/m) of the first metal and 0.1-10% (m/m) of the second metal.
20. The catalyst according to claim 18, wherein the catalyst comprises a zeolite based on Si and Al and wherein 2-50% of the Al has been coordinated by the first metal.
21. The catalyst according to claim 18, wherein the zeolite has a mean first metal concentration, and wherein any local first metal concentration may have a concentration deviation of not larger than 50% of the mean first metal concentration.
22. A catalyst, comprising a zeolite, wherein the zeolite is loaded with a first metal selected from the group of noble metals consisting of ruthenium, rhodium, rhenium, osmium, iridium and gold, and with a second metal selected from the group of transition metals consisting of vanadium, chromium, manganese, iron, cobalt, nickel and copper, wherein the zeolite is selected from the group consisting of FER, CHA and BEA.
23. A catalyst for the catalytic decomposition of N2O in a gas containing N2O comprising a zeolite, wherein the zeolite is first loaded with a first metal selected from the group consisting of ruthenium, rhodium, osmium, and iridium, and wherein the zeolite is loaded with a second metal selected from the group of transition metals consisting of vanadium, chromium, manganese, iron, cobalt, nickel and copper.
24. A catalyst for the catalytic decomposition of N2O in a gas containing N2O comprising a zeolite, the zeolite is first loaded with a first metal selected from the group of noble metals consisting of ruthenium, rhodium, silver, rhenium, osmium, iridium, platinum and gold, and then loaded with a second metal selected from the group of transition metals consisting of vanadium, chromium, manganese, iron, cobalt, wherein the zeolite is selected from the group consisting of FER, CHA and BEA; and wherein the zeolite loaded with metals is selected from the group consisting of Fe—Rh-FER, Fe—Ir-FER, Fe—Ru-FER, Co—Rh-FER, Co—Ir-FER, Co—Ru-FER, Fe—Rh-BEA, Fe—Ir-BEA, Fe—Ru-BEA, Co—Rh-BEA, Co—Ir-BEA and Co—Ru-BEA.
Description:
FIELD OF THE INVENTIONThe invention relates to a method for the catalytic decomposition of N2O in a gas containing N2O. The invention also relates to a catalyst therefor, as well as the preparation of this catalyst.STATE OF THE ARTDinitrogen oxide or laughing gas (N2O) contributes substantially to the greenhouse effect and has a high global warming potential (the degree to which a molecule contributes to the greenhouse effect relative to a molecule of CO2). Over the past few years a policy has been developed for reducing the emission of greenhouse gases. Various significant sources of N2O emissions have been identified: agriculture, the industrial production of precursors for nylon (adipic acid and caprolactam), the production of nitric acid and motor vehicles equipped with a three-way catalyst.Various catalytic and non-catalytic techniques can be used to render laughing gas harmless. Various catalysts are known for, for example, the catalytic decomposition or conversion of N2O into N2 and O2 (for example JP Patent Application no. Hei-06-154611, in which catalysts based on supports with transition metals and noble metals are described). However, this reaction with catalysts according to the state of the art is severely impeded by the presence of oxygen and water, which occur in the off-gases from virtually all the abovementioned sources of N2O.A promising alternative is selective catalytic reduction. Various catalysts are known from the literature for the conversion of N2O with the aid of reducing agents such as alkenes (CnH2n), alcohols or ammonia. On technical and economic grounds, additions of saturated hydrocarbons (CnH2n+2) would be preferred to the said reducing agents. In particular natural gas (CH4) and LPG (mixture of C3H8 and C4H10) are attractive in this context.A disadvantage of the method using catalysts that are able to reduce N2O with the aid of hydrocarbons is that additional facilities for hydrocarbons have to be put in place and hydrocarbons and/or CO can be emitted. From the environmental standpoint, an additional catalyst is often used to avoid the emission of hydrocarbons.WO describes the catalytic reduction of NOx, but this disclosure does not provide a method for the catalytic decomposition of N2O.A disadvantage of many known catalysts for decomposition of N2O is that these catalysts are often unstable and/or are deactivated by the presence of gases such as NOx (NO, NO2, N2O3 (x=3/2), etc.), O2 and H2O. However these gases are virtually always present in practical situations, such as for the decomposition of N2O from flue gases.SUMMARY OF THE INVENTIONThe aim of the invention is, therefore, to provide a method for the catalytic decomposition of N2O where the abovementioned disadvantages are completely or partially eliminated. A further aim of the invention is to provide a catalyst for use in this method, as well as a method for the preparation of this catalyst.Surprisingly it is found that the catalysts according to the invention give good conversion of N2O, even at low temperatures, are stable during the decomposition reaction (of N2O into N2 and O2) and also give good conversion and have good stability if other gases (such as NO, NO2, N2O3, etc., O2 and H2O) are also present in the gas containing N2O. In addition, advantageously no hydrocarbon has to be added to the gas containing N2O. Therefore these catalysts are exceptionally suitable for the decomposition of N2O.The invention relates to a method for the catalytic decomposition of N2O in a gas containing N2O in the presence of a catalyst, wherein the catalyst comprises a zeolite that has been loaded with a first metal selected from the group of noble metals consisting of ruthenium, rhodium, silver, rhenium, osmium, iridium, platinum and gold, preferably ruthenium, rhodium, osmium and iridium, and with a second metal selected from the group of transition metals consisting of vanadium, chromium, manganese, iron, cobalt, nickel and copper, and wherein the loading of the zeolite with metals has been obtained by first loading the zeolite with the noble metal and then with the transition metal.The invention also provides a method for the preparation of a catalyst for the catalytic decomposition of N2O in a gas containing N2O, wherein the catalyst comprises a zeolite and the zeolite is first loaded with a first metal selected from the group of noble metals consisting of ruthenium, rhodium, silver, rhenium, osmium, iridium, platinum and gold and then loaded with a second metal selected from the group of transition metals consisting of vanadium, chromium, manganese, iron, cobalt, nickel and copper.The invention furthermore also provides a catalyst that can be obtained according to this method and, for example, contains 0.00001-4% (m/m) of the first metal and 0.110% (m/m) of the second metal, as well as the use of this catalyst for the decomposition of N2O.DESCRIPTION OF THE INVENTIONThe gas containing N2O can be, for example, off-gas from the synthesis of nitric acid or, for example, off-gas that is liberated during the production of nylon precursors. The gas can also contain oxygen and/or water. In contrast to the majority of catalysts according to the state of the art, the catalyst according to the invention loses little or no activity in the presence of oxygen, water or both. This applies in particular if the water is present in amounts of up to approx. 5-10% (V/V) ( percent by volume relates to the volume of the gas containing N2O, including any NOx, O2 and H2O, etc. present). Up to approx. 20%, for example 0.5-20% (V/V), oxygen can be present, for example. NOx can also be present, for example from approx. 10 ppm-5% NOx, for example 10 ppm-1% (V/V) NOx. Therefore, in one embodiment the invention is aimed at a method where the gas containing N2O also contains oxygen and/or water, as well as a method where the gas containing N2O also contains one or more gasses selected from the group consisting of oxygen, water and NOx (for example all three gases are present alongside N2O). Therefore, in the context of the invention, gas containing N2O means that the gas in any event contains N2O and in addition can contain other gases such as N2, NOx, H2O, O2, etc. This gas (or gas mixture) can, as is known to those skilled in the art, be brought into contact with a catalyst. “Decomposition of N2O in a gas containing N2O” means that N2O that is present in the gas is in any event partially decomposed (with the aid of the catalyst according to the invention) to give N2 and O2.More particularly, the invention is aimed at a method for the catalytic decomposition of N2O in a gas containing N2O, comprising:
the provision of a catalyst, wherein the catalyst comprises a zeolite that has been loaded with a first metal selected from the group of noble metals consisting of ruthenium, rhodium, silver, rhenium, osmium, iridium, platinum and gold and with a second metal selected from the group of transition metals consisting of vanadium, chromium, manganese, iron, cobalt,the provision of a gas containing N2O and feeding the gas containing N2O through a chamber that contains the catalyst, wherein the chamber, the gas containing N2O or both are heated if required.
The gas containing N2O is contacted with the catalyst according to the invention and N2O is at least partially decomposed in a composition reaction. During the reaction it is possible, if required, to heat up to a temperature at which (complete or partial) decomposition of N2O however, the gas containing N2O can, as off-gas, already have the desired temperature or be cooled to the desired temperature. The chamber is, for example, a reactor (chamber), a reaction tube, or any other space where the N2O-containing gas can be brought into contact with the catalyst of the invention, as is known to those skilled in the art. Preferably, the chamber is a reactor, designed to decompose N2O, as known to the person skilled in the art.In the description of the invention NOx is defined as nitrogen oxides where x is greater than or equal to 1, such as NO, NO2, N2O3, etc. Thus, N2O, laughing gas, is not understood as falling under this term. NO is usually in equilibrium with other nitrogen oxides, where x is greater than 1. The catalyst according to the invention is found to be exceptionally suitable for the decomposition of N2O from a gas containing N2O, without the stability suffering from the possible presence of NO, NO2, etc. (NOx). Therefore, in one embodiment the invention also provides a method where the gas containing N2O also contains NOx, where x is equal to or greater than 1, for example x=1, 3/2, 2, etc. Of course, the gas can also contain combinations of such NOx compounds. Hence, in an embodiment the N2O-containing gas contains at least N2O and NOx.In particular the present invention is aimed at the decomposition of N2O where the gas containing N2O essentially does not contain any hydrocarbon. The gas containing N2O preferably contains less than 200 ppm, more preferably less than 50 ppm, even more preferably less than 20 ppm hydrocarbon, based on the total amount of gas containing N2O, or, for example, less than 5% (V/V), preferably less than 3% (V/V), more preferably less than 1% (V/V) hydrocarbon, based on the amount of N2O in the gas containing N2O. More particularly, the gas essentially contains no CnH2n+2 (where n is preferably selected from 1-4, including all isomers).The process conditions for the method for the catalytic decomposition of N2O in a gas containing N2O will depend on the applications. Those skilled in the art will in general choose the catalyst volume, the gas velocity, the temperature, the pressure, etc. such that the best conversion results are achieved. Good results are achieved with, for example, an N2O content of approx. 100 ppm or more, for example approx. 100-100,000 ppm of the gas containing N2O. Under practical conditions the quantity of N2O will in general be between approx. 100 and 3000 ppm of the gas containing N2O. The gas containing N2O is preferably fed at gas space velocities (GHSV; gas hourly space velocity) of approx. 200-200,000 h-1, preferably
h-1, where this value relates to the catalyst volume used. The pressure of the gas containing N2O will depend on the application and can be, for example, between approx. 1-50 bara (bar atmosphere: bara), preferably between approx. 1-25 bara. The method can be used at relatively low temperatures. The conversion of N2O takes place from approx. 300° C. Virtually complete conversion can already take place at approx. 375° C., depending on the conditions, such as, for example, the gas space velocity, volume and catalyst loading, etc. Preferably a method where the reaction temperature is between 300° C. and 600° C., more preferentially between 350° C. and 500° C., and even more preferably between about 375 and 475° C., is used. In yet a further embodiment, the reaction temperature is between about 300° C. and 450° C., more preferably between about 350° C. and 425° C., and even more preferably below 400° C., and the gas containing N2O is fed at gas space velocities (GHSV; gas hourly space velocity) of approx. 200-20,000 h-1, preferably
h-1, even more preferably about
h-1, where this value relates to the catalyst volume used.The method according to the invention can be used, inter alia, for the catalytic reduction of N2O that is emitted, for example, by emergency power generators, gas engines, installations for nitric acid production, N2O that is emitted during caprolactam production, during coal combustion in a fluidized bed, etc. Therefore, the invention is also aimed at the use of the catalyst according to the invention for, for example, the catalytic decomposition of N2O. The method according to the invention can also be used in combination with a catalyst for the removal of NOx, which, for example, is also emitted during the industrial production of nitric acid.Zeolites that are used in the method according to the invention are, for example, the following zeolites, as are known to those skilled in the art by their abbreviations (for example Atlas or zeolite framework types, Ch. Baerlocher, W. M. Meier, D. H. Olson, 2001, Elsevier Science, ISBN: 0-444-50701-9): ABW, ACO, AEI, AEL, AEN, AET, AFG, AFI, AFN, AFO, AFR, AFS, AFT, AFX, AFY, AHT, ANA, APC, APD, AST, ASV, ATN, ATO, ATS, ATT, ATV, AWO, AWW, BCT, BEA, BEC, BIK, BOG, BPH, BRE, CAN, CAS, CFI, CGF, CGS, CHA, -CHI, -CLO, CON, CZP, DAC, DDR, DFO, DFT, DOH, DON, EAB, EDI, EMT, EPI, ERI, ESV, ETR, EUO, FAU, FER, FRA, GIS, GME, GON, GOO, HEU, IFR, ISV, ITE, ITH, ITW, IWR, IWW, JBW, KFI, LAU, LEV, LIO, LOS, LOV, LTA, LTL, LTN, MAZ, MEI, MEL, MEP, MER, MFI, MFS, MON, MOR, MSO, MTF, MTN, MTT, MTW, MWW, NAB, NAT, NES, NON, NPO, OFF, OSI, OSO, -PAR, PAU, PHI, PON, RHO, -RON, RSN, RTE, RTH, RUT, RWY, SAO, SAS, SAT, SAV, SBE, SBS, SBT, SFE, SFF, SFG, SFH, SFN, SGT, SOD, SSY, STF, STI, STT, TER, THO, TON, TSC, UEI, UFI, UOZ, USI, VET, VFI, VNI, VSV, WEI, -WEN, YUG, ZON. Combinations of (loaded) zeolites can also be used.Preferably zeolites based on silicon and aluminium, with an Si/Al ratio of 2-60, preferably 2.5-30, are used. For example, good results are obtained where the zeolite is selected from the group consisting of FAU, FER, CHA, MOR, MFI, BEA, EMT, CON BOG and ITQ-7. In a preferred embodiment the invention is aimed at a method where the zeolite is selected from the group consisting of FER, CHA, MOR and BEA. Especially preferred are FER, CHA and BEA and even more preferred are FER and BEA. Especially BEA shows a surprising high stability in the N2O-decomposition method of the invention.Part of the zeolite framework ions may have been replaced with other ions like Fe, Ti etc., as known to the person skilled in the art. For example, up to about 5 mol % of Si or Al may have been replaced by Fe or Ti or other ions, like Ga or Ge, or combinations of two or more of such ions. Such a replacement of framework ions may be effected by replacing part of the “framework ions to be” in the starting materials by Fe or Ti (or other ions), as is known to the person skilled in the art. If desired, the zeolite may be subjected to a steam treatment, after synthesis of the zeolite or after the subsequent loading with the first and second metal, such that part of this framework metal may become available within the pores as catalytically active sites. In such a way, Co—Rh-BEA or Ni—Ru-MFI having Fe as framework ion may for example be converted to Fe,Co—Rh-BEA or Fe,Ni—Ru-MFI, respectively.In yet another preferred embodiment zeolites such as FER, CHA and MFI (ZSM-5) are used, which zeolites have relatively small channels and do not have excessively large rings such as 12-membered rings. Zeolites in this embodiment can have 4, 5, 6, 8 or 10-membered rings (or combinations thereof). In a variant embodiment the invention is aimed at a method and a catalyst where the second metal is a trivalent metal such as iron (FeIII) and where the zeolite is selected from the group consisting of zeolites that have 4, 5, 6, 8 or 10-membered rings (or combinations thereof) but no rings contain more than 10 members. In another variant embodiment the invention is aimed at a method and a catalyst where the second metal is a divalent metal such as cobalt (CoII) and where the zeolite is selected from the group consisting of zeolites that have 4, 5, 6, 8, 10 or 12-membered rings (or combinations thereof) and where the zeolite contains at least 10- or 12-membered rings (or both).There are various ways of preparing the catalyst according to the invention. The zeolite can be loaded with the aid of methods such as are known to those skilled in the art, for example with the aid of wet impregnation (volume of liquid with (dissolved) salt is greater than pore volume of zeolite) and pore volume impregnation (“dry impregnation” or “incipient wetness”: volume of liquid with (partially dissolved) salt is equal to pore volume of zeolite) or via ion exchange (exchange in the liquid phase, where the metals to be exchanged in any event are at least partially dissolved in the liquid phase as ions (or complexed ions); and where the zeolite is stirred in the liquid containing ions to be exchanged, as is known to those skilled in the art) or with the aid of chemical vapour deposition (CVD). Preferably a method for the catalytic decomposition of N2O in a gas containing N2O is used where the zeolite that is used for this composition has been loaded with the first metal by means of ion exchange or impregnation and a subsequent loading with the second metal and is used as such, or after possible further steps such as drying, sieving and/or calcination, applying to a support, etc., for the catalytic decomposition of N2O in a gas containing N2O. In a preferred embodiment a method is used where the zeolite has been loaded with the first metal by means of ion exchange.The same applies for the second metal. Therefore, preferably a method is used where the zeolite has been loaded with the second metal by means of ion exch in an embodiment a method is used where the zeolite has been loaded with the second metal by means of ion exchange. In a specific embodiment a method for the catalytic decomposition of N2O in a gas containing N2O is used where the zeolite has been loaded with the first metal and the second metal by means of ion exchange (sequential). This yields good decomposition values.In this invention metal is used to mean that an element that is known to those skilled in the art as a metal (for example the metals from groups 3-12 of the periodic table of the elements (IUPAC notation) is used in the invention. In the invention transition metals are metals from groups 3-12 of the periodic table of the elements (IUPAC notation), also known as the groups Ib, IIb-VIIb and VIII. The second metal is used to refer to those transition metals that are not at the same time also a noble metal. Noble metals are the metals Ru, Rh, Pd, Ag, Re, Os, Ir, Pt and Au. In the invention, Ru, Rh, Ag, Re, Os, Ir, Pt and Au, and preferably, Ru, Rh, Os and Ir (group 8 and 9 noble metals) are used. When loading the zeolite, in general salts in solution (ion exchange), where the metal is present in ion form (usually in water), or solutions (wet or pore volume impregnation (incipient wetness)), where the metal is present as ion in solution and/or as ion in a salt compound, will be used. Because ion exchange (in the liquid phase) or pore volume impregnation is preferably used, after preparation and before calcination the catalyst will generally comprise a zeolite in which the metal is present in ion form (and coordinated with Al). After calcination and/or while carrying out the method according to the invention some of the metal in ion form can be converted to oxide and/or to metal at the exchange locations, for example by clustering to give particles. This behaviour of zeolites exchanged with metals is known to those skilled in the art. In this invention, metal is therefore also used to refer to metal ion and, for example after loading of (the application of the metals to) the zeolite, metal can further also comprise metal oxide or metal salt (for example chloride, oxycloride, nitrate, sulphate, etc.).In one embodiment a method is used where the zeolite has been loaded with the first metal by means of ion exchange. This can lead to a zeolite where 2-50% of the Al has been coordinate more preferentially approx. 5-40% of the Al has been coordinated by the first metal. This can be determined with the aid of, for example, IR techniques, etc. Thus, for example, the integral intensity of the bridged OH stretch vibration (approx. 3600 cm-1, depending on the type of zeolite and the measurement temperature) of an activated zeolite can be compared with the same zeolite loaded with the metal of choice. This integral intensity correlates with the concentration of aluminium in the zeolite. As a result of exchanging with the metal of choice the integral intensity decreases and the difference in intensity (before/after exchange) is the amount of metal that coordinates with aluminium.After loading the zeolite, the zeolite is generally dried. It can then be calcined. Instead of calcination (heating in air, oxygen) it is also possible to reduce (heating in a reducing atmosphere) or activate in an inert atmosphere (heating in an inert atmosphere). Such procedures are known to those skilled in the art as ‘post-modification’ procedures. Calcination is generally carried out in air at, for example, 400-550° C. Reduction can be effected with hydrogen at, for example, 300-500° C. Inert activation can be done with the aid of nitrogen, argon, helium, etc., at, for example, approx. 300-550° C. These procedures usually take a few hours.Good decomposition results are obtained if a method is used where the first metal has been selected from the group consisting of ruthenium, rhodium, osmium and iridium. In another embodiment a zeolite is used where the second metal is selected from the group consisting of iron, cobalt and nickel. Preferably, a method for the catalytic decomposition of N2O in a gas containing N2O is used where the first metal has been selected from the group consisting of ruthenium, rhodium, osmium and iridium and where the second metal has been selected from the group consisting of iron, cobalt and nickel. In a preferred embodiment, a method and a catalyst for decomposition of N2O are provided, wherein the catalyst comprises a zeolite and wherein the zeolite is selected from the group consisting of FAU, FER, CHA, MOR, MFI, BEA, EMT, CON, BOG and ITQ-7. Preferred first metals are selected from the group consisting of ruthenium, rhodium, osmium and iridium.Specific preferred embodiments comprise methods according to the invention and catalysts according to the invention where the second metal is Fe and the zeolite is FER, or where the second metal is Co and the zeolite is MOR. In another preferred embodiment the invention comprises a method and catalyst where the second metal is Co and the zeolite is FER, for example Co—Rh-FER, or where the second metal is Fe and the zeolite is MOR, for example Fe—Rh-MOR. Therefore, the invention is also aimed at a method and a catalyst where the zeolite loaded with metals has been selected from the group consisting of Fe—Rh-FER, Fe—Ir-FER, Fe—Ru-FER, Co—Rh-MOR, Co—Ir-MOR, Co—Ru-MOR, Fe—Rh-MOR, Fe—Ir-MOR, Fe—Ru-MOR, Co—Rh-FER, Co—Ir-FER and Co—Ru-FER. Further preferred catalysts are Fe—Rh-BEA, Fe—Ir-BEA, Fe—Ru-BEA, Co—Rh-BEA, Co—Ir-BEA and Co—Ru-BEAThe catalyst according to the invention preferably comprises a zeolite that contains approx. 0.00001-4% (m/m) of the first metal (0.00001% (m/m) is 10 ppm) and approx. 0.1-10% (m/m) of the second metal. More preferentially, the zeolite contains approx. 0.01 to 0.5% (m/m), more preferably 0.1-0.5% (m/m), of the first metal and approx. 0.5 to 4% (m/m), more preferably 1-4%(m/m), of the second metal. Of course, combinations of “first” metals can also be used, as well as combinations of “second” metals, etc., for example: Fe—Ir,Ru-FER, Co,Ni—Ir-MOR and Co,Ni—Rh,Os-MOR etc. Likewise, a first and a second loading do not preclude one or more subsequent loadings.The catalyst according to the invention preferably comprises the zeolite only. In another embodiment the catalyst comprises zeolite and a quantity of support, for example 0.1-50% (m/m) of boehmite, for example in the form of pellets or applied to a monolite, as is known to those skilled in the art. The amounts of metal (first metal and second metal) are related to t the metals are present on and in the zeolite.Known salts, such as, for example, readily soluble nitrates are used for the ion exchange. The zeolite used can be, for example, the H, Na, K or NH4 form of the zeolite, such as, for example, NH4-MOR or H-FAU, etc. Exchange is continued for such a length of time (or so often) that approx. 0.00001-4% (m/m) of the first metal is present in the zeolite. The zeolite can also be loaded in other ways (pore volume impregnation, etc.). The zeolite is then preferably filtered off, washed and optionally dried. The zeolite is then loaded with 0.1-10% (m/m) of the second metal. This can be done by ion exchange (in the liquid phase) or by pore volume impregnation (incipient wetness technique), etc. (see above). The zeolite is then dried and calcined if required.In addition to the abovementioned IR techniques that are able to demonstrate that the preferably desired percentage exchange with regard to the first metal has been achieved, the advantage of the method for the application according to the invention can also be determined in other ways, using, for example, electron microscopy or CO chemisorption. By this means it is possible to map what the final dispersion of noble metal has become as a function of the sequence. In the case of CO chemisorption, for example, the amount of CO to be bound is a measure of the dispersion of the noble metal.The catalyst of the invention, obtainable by the method for preparation according to the invention, comprises a zeolite being loaded with a first metal selected from the group of noble metals consisting of ruthenium, rhodium, silver, rhenium, osmium, iridium, platinum and gold, and with a second metal selected from the group of transition metals consisting of vanadium, chromium, manganese, iron, cobalt, nickel and copper. In a preferred embodiment, the catalyst of the invention consists of the zeolite, i.e. the catalyst of the invention is the zeolite as prepared according to the invention (optionally provided to a support). Preferred zeolites are selected from the group consisting of FAU, FER, CHA, MOR, MFI, BEA, EMT, CON, BOG and ITQ-7, especially FER, CHA and BEA. Preferred first metals are selected from the group consisting of ruthenium, rhodium, osmium and iridium, even more preferred are Ru, Rh and Ir. In another embodiment, the catalyst of the invention may further comprise other catalysts, e.g. other catalysts suitable for the decomposition of N2O and/or catalysts suitable for the decomposition of NOx.In contrast to prior art catalysts (wherein e.g. first the transition metal ion has been introduced in the zeolite and then the noble metal) the catalyst of the invention comprises a zeolite wherein about 2-50% of the Al is coordinated by the first metal. Another important distinction of the catalyst (i.e. zeolite) of the invention is that the zeolite has a relatively constant concentration of first metal through the bulk of the zeolite particles and an even concentration over the different zeolite particles. The concentration of the first metal in a zeolite particle (for example a pressed zeolite particle of about 0.1-5 mm diameter) can be measured at different positions (local concentrations) within the particle, (e.g. by SEM/EDX) thereby providing a mean first metal concentration. Hence, herein the term “local” concentration refers to a concentration measured by SEM/EDX at one spot of a zeolite particle, preferably with a scan resolution of about 0.5-5 μm2, preferably a scan resolution of about 0.1-1 μm2. Herein, a zeolite having a mean (first) metal concentration refers to the bulk (or mean) concentration of e.g. a zeolite crystallite (e.g. about 0.1-10 μm), a zeolite (bulk) powder (e.g. consisting of such crystallites), a pressed particle, etc. A number of measurements of local concentrations may be used to calculate a mean metal concentration. For example, determining the concentration at one spot of about 0.1-1 μm2, moving to another spot in the zeolite powder or another spot in the zeolite crystallite, e.g. at a distance of a few μm's from the first spot, and determining a second local concentration, etc. Averaging the local (first) metal concentrations measured provides the mean (first) metal concentration. It appears that the zeolite catalyst provided according to the method of preparation of the invention is a zeolite, wherein local first metal concentrations advantageously appear to have concentration deviations of not larger than 50%, preferably not larger than 30%, and more preferably not larger than 20%, of the mean first metal concentration. Hence, there is provided a zeolite having a mean first metal concentration, and wherein any local first metal concentration may have a concentration deviation of not larger than 50% of the mean first metal concentration. The surprisingly even distribution of the first metal may provide the good N2O-decomposition results of t in case the opposite order of loading was chosen, lower N2O conversions are obtained.EXAMPLESTest EquipmentThe catalytic decomposition of N2O (and any NOx) was studied in a semi-automatic test set-up. Gases are supplied using so-called mass flow controllers (MFC) and water is added by means of a saturator that is set to the correct temperature. Lines are heated to 130° C. to counteract condensation. For the experiments a quartz reactor with an internal diameter of 0.6 to 1 cm was placed in an oven. The catalyst sieve fraction (0.25-0.5 mm) was placed on a quartz gauze. Quantitative analysis of the gas phase is possible by the use of a calibrated Bomen MB100 Fourier transform infrared (FTIR) spectrometer equipped with a model 9100 gas analyser or with the aid of a Perkin Elmer GC-TCD. The carrier gas (balance) in the examples is N2.Example 1Preparation of Loaded ZeolitesCatalysts Prepared:CatalystDescriptionCat 1Rh-MORCat 2Rh-alumina (Al2O3)Cat 3Cu—Rh-MORCat 4Rh—Cu-MORCat 5Co—Rh-MORCat 6Fe-FERCat 7Fe—Ru-FERCat 8Fe—Ir-FERCat 9Fe—Rh-FERCat 10Fe—Ru-MORCat 11Ru-FERCat 12Co-MORCat 13Co—Rh-FERCat 14Fe-ZSM-5Cat 15Ru-ZSM-5Cat 16Fe—Ru-ZSM-5Cat 17Fe-BEACat 18Fe—Ru-BEA
Cat 1: Rh-MOR In a first step Rh-MOR was prepared with the aid of ion exchange. NH4-MOR powder (Zeolyst, CBV21a) in 1.5% rhodium nitrate (Johnsson & Matthey) was stirred together with 0.1 M NH4NO3 for 16 h at 80° C. The zeolite was then filtered off, washed thoroughly with demineralised water and dried for 16 h at 80° C. The zeolite is loaded with 0.35% (m/m) Rh (chemical analysis: digestion of metals (everything is dissolved in concentrated acid) and components are determined using ICP/AAS).Cat 2: Rh-alumina (Al2O3)Rh-alumina was prepared with the aid of wet impregnation. A concentration of rhodium nitrate corresponding to 1% (m/m) rhodium was applied to the alumina in a volume that was approx. twice the volume of the pores.Cat 3: Cu—Rh-MORIn a first step Rh-MOR was prepared with the aid of ion exchange. NH4-MOR powder (Zeolyst, CBV21a) in 1.5% rhodium nitrate (Johnsson & Matthey) was stirred together with 0.1 M NH4NO3 for 16 h at 80° C. The zeolite was then filtered off, washed thoroughly with demineralised water and dried for 16 h at 80° C. The zeolite is loaded with 0.35% (m/m) Rh (chemical analysis). In a second step a volume of copper nitrate was added to the rhodium-MOR equal to the pore volume of rhodium MOR and with a concentration resulting in 4.9% (m/m) copper. The zeolite was then filtered off, washed thoroughly with demineralised water and dried for 16 h at 120° C.Cat 4: Rh—Cu-MORThe same method of preparation as above was followed except that exchange with copper was first carried out, as described in the second step above. The zeolite is loaded with 5% (m/m) Cu and 0.35% (m/m) Rh (chemical analysis). This catalyst was prepared analogously to JP patent application Hei-06 154611 (first Cu, then Rh; percentages by weight 5% (m/m) Cu and 0.35% (m/m) Rh).Cat 5: Co—Rh-MORIn a first step Rh-MOR was prepared with the aid of ion exchange. NH4-MOR powder (Zeolyst, CBV21a) in 1.5% rhodium nitrate (J&M) was stirred together with 0.1 M NH4NO3 for 16 h at 80° C. The zeolite was then filtered off, washed thoroughly with demineralised water and dried for 16 h at 80° C. The zeolite is loaded with 0.35% (m/m) Rh (chemical analysis). In a second step a volume of cobalt nitrate was added to rhodium-MOR equal to the pore volume of rhodium MOR and with a concentration resulting in 2.8% (m/m) cobalt. The zeolite was then filtered off, washed thoroughly with demineralised water and dried for 16 h at 120° C.Cat 6: Fe-FERFe-FER was prepared prepared using pore volume impregnation: a volume of iron nitrate was added to NH4-FER (T Si/Al 9)) equal to the pore volume of FER and with a concentration resulting in 2.5% (m/m) iron. The zeolite was then filtered off, washed thoroughly with demineralised water and dried for 16 h at 120° C.Cat 7: Fe—Ru-FER2.3 gram Ru(NH3)6Cl3 (J&M) was dissolved in 100 ml demineralised water and stirred with Na-FER (Tosoh) for 16 hours at 80° C. The zeolite was then filtered off, washed thoroughly and dried at 80° C. It was then stirred for 24 hours at room temperature with 0.1 M NH4NO3. The zeolite was then filtered off, washed thoroughly and dried at 80° C. A volume of iron nitrate was then added to Ru—NH4-FER equal to the pore volume of Ru-FER and with a concentration resulting in 2.5% (m/m) iron. Loading 0.41% (m/m) Ru and 2.5% (m/m) Fe.Cat 8: Fe—Ir-FER400 mg IrCl3 was dissolved in 300 ml conc. HCl. A volume of IrCl3 was then added to NH4-FER equal to the pore volume of FER, according to the pore volume impregnation method, filtered off, washed thoroughly with demineralised water and dried at 80° C.: loading 0.2% (m/m) Ir. A volume of iron nitrate was then added to Ir—NH4-FER equal to the pore volume of Ir-FER and with a concentration resulting in 2.5% (m/m) iron.Cat 9: Fe—Rh-FERRh-FER was stirred in 1.5% (m/m) rhodium nitrate (J&M) together with 0.1 M NH4NO3, analogously to the methods described above for iron exchange. A volume of iron nitrate was then added to rhodium-NH4-FER equal to the pore volume of rhodium-FER and with a concentration resulting in 2.5% (m/m) iron and 0.3% (m/m) Rh.Cat 10: Fe—Ru-MOR2.3 g Ru(NH3)6Cl3 (J&M) was dissolved in 100 ml demineralised water and stirred with Na-MOR (Zeolyst CBV10a) for 16 hours at 80° C. The zeolite was then filtered off, washed thoroughly and dried at 80° C. It was then stirred for 24 hours at room temperature with 0.1 M NH4NO3. The zeolite was then filtered off, washed thoroughly and dried at 80° C. A volume of iron nitrate was then added to Ru—NH4-FER equal to the pore volume of Ru-FER and with a concentration resulting in 2.5% (m/m) iron. Loading 0.41% (m/m) Ru and 2.5% (m/m) Fe.Cat 11: Ru-FER2.3 g Ru(NH3)6Cl3 (J&M) was dissolved in 100 ml demineralised water and stirred with Na-FER (Tosoh) for 16 hours at 80° C. The zeolite was then filtered off, washed thoroughly and dried at 80° C. It was then stirred for 24 hours at room temperature with 0.1 M NH4NO3. The zeolite was then filtered off, washed thoroughly and dried at 80° C. Loading is 0.4% (m/m) Ru.Cat 12: Co-MORCo-MOR was prepared by adding a volume of cobalt nitrate to NH4-MOR (Zeolyst CBV21a) equal to the pore volume of MOR and with a concentration resulting in 2.8% (m/m) cobalt.Cat 13: Co—Rh-FERRh-FER was stirred in 1.5% (m/m) rhodium nitrate (J&M) together with 0.1 M NH4NO3, analogously to the methods described above for ion exchange. In a second step a volume of cobalt nitrate was then added to rhodium MOR (0.3% (m/m) Rh) equal to the pore volume of rhodium MOR and with a concentration resulting in 2.5% (m/m) cobalt. The zeolite was then filtered off, washed thoroughly with demineralised water and dried for 16 h at 120° C.Cat 14: Fe-ZSM-5The catalyst was prepared with the aid of ion exchange of Alsi-penta SN27 zeolite ZSM-5 in the liquid phase with FeCl2.4H2O (which ought to lead to a loading of 2.5% (m/m) Fe) at 16 hours 80° C., as also described above. The zeolite was then filtered off, washed thoroughly and dried at 80° C. Before the reaction the catalyst was calcined in situ for 5 h at 550° C.Cat 15: Ru-ZSM-5The catalyst was prepared with the aid of ion exchange of Alsi-penta SN27 zeolite ZSM-5 in the liquid phase with Ru(NH3)6Cl3 (which ought to lead to a loading of 0.3% (m/m) Ru) at 16 hours 80° C., as also described above. The zeolite was then filtered off, washed thoroughly and dried at 80° C. Before the reaction the catalyst was calcined in situ for 5 h at 550° C.Cat 16: Fe—Ru-ZSM-5The catalyst was prepared with the aid of co-ion exchange of Alsi-Penta SN27 zeolite ZSM-5 in the liquid phase with FeCl2.4H2O, Ru(NH3)6Cl3 (which ought to lead to a loading of 0.3% (m/m) Ru and 2.5% (m/m) Fe) at 16 hours 80° C., as also described above. The zeolite was then filtered off, washed thoroughly and dried at 80° C. Before the reaction the catalyst was calcined in situ for 5 h at 550° C.Cat 17: Fe-BEAThe catalyst was prepared with the aid of ion exchange of Zeolyst BEA CP814e. The NH4-BEA was exchanged with an amount of FeSO4.7H2O that equals 2.5% (m/m) Fe. The zeolite was then filtered off, washed thoroughly and dried at 80° C. The catalysts was calcined before reaction at 550° C.Cat 18: Fe—Ru-BEAThe catalyst was prepared with the aid of ion exchange of Zeolyst BEA CP814e. The NH4-BEA was first exchanged with 1M NaNO3 to obtain the sodium form BEA. Subsequently, the Na-BEA was exchanged with Ru(NH4)2Cl6 (J&M) resulting in a loading of 0.3% (m/m) Ru. The zeolite was then filtered off and washed thoroughly to obtain Ru-BEA. Fe—Ru-BEA was obtained by ion-exchange of Ru-BEA with FeCl2 resulting in a loading of 2.3% (m/m) Fe. The zeolite was then filtered off, washed thoroughly and dried at 80° C. The catalyst was calcined before reaction at 550° C.Example 2Decomposition of N2O with the Aid of Rh-alumina and Rh-MORN2O was decomposed with the aid of Cat 1 and Cat 2 under the following conditions with the following results:TABLE 1Reaction conditions Example 2Volume0.3mlGas flow velocity150ml/minGHSV30000h-1T400°C.P1baraN2O1500ppmNO200ppmH2O0.5%O22.5%N2bal. TABLE 2Results of N2O conversion in Example 2TimeConversion (%) of N2O withConversion (%) of N2O with(hours)rhodium-MOR (Cat 1)rhodium-Al2O3 (Cat 2)260654586485964106063126163145862166062186062205961226061246060266160285860306059326058345860365957386157405856426055446054465954486053506053 It can be seen from this table that zeolites are more suitable supports than alumina. Rh-alumina is less stable and deactivates as a function of time.Example 3Decomposition of N2O with the Aid of Cu—Rh-alumina and Rh—Cu-MORN2O was decomposed with the aid of Cat 3, Cat 4 and Cat 5 from Example 1 under the conditions as described in Example 2, Table 1, except that instead of 400° C. 430° C. was now used and instead of 0.5% there was now 5% H2O present. The following results were obtained here:TABLE 3Results Example 3:Conversion (%) ofConversion (%) ofConversion (%) ofN2O withN2O withN2O withTimecopper-rhodium-rhodium-copper-cobalt-rhodium-(hours)MOR (Cat 3)MOR (Cat 4)MOR (Cat 5)1343779548487710595677156460772168607725696277317061773571617841706077457060785070607755695879606958776669577770695777756856778068557785685477906777956777976778 It can be seen from these results that the method according to the invention where a catalyst is used that has been prepared according to the invention (Cat 3; first a noble metal, then a transition metal) has better properties than a catalyst prepared according to the state of the art (Cat 4; first transition metal, then noble metal). Cobalt-rhodium-MOR (Cat 5), according to the invention, is also found to have even better properties than Cu-rhodium-MOR (Cat 3), likewise according to the invention.Example 4Decomposition of N2O with the Aid of FER Exchanged with Fe, Fe/Ru, Re/Ir and Fe/RhN2O was decomposed with the aid of Catalysts 6-9 from Example 1 under the conditions as described in Example 2, Table 1, except that the temperature was varied, with the following results:TABLE 4Results Example 4:ConversionConversionConversionConversion(%) of N2O(%) of N2O(%) of N2O(%) of N2Owith iron-with iron-with iron-Temper-with iron-ruthenium-iridium-rhodium-atureferrieriteferrieriteferrieriteferrierite(° C.)(Cat 6)(Cat 7)(Cat 8)(Cat 9)3671215161637714222023387193426323962447354540630594560415407156744254884688443459928093444739789984548299951004639010099100473951001001004829810010010049199100100100 It can be seen from these results that the combinations according to the invention of Fe as second metal and a first metal such as Ru, Ir and Rh produce a clearly improved conversion.Example 5Decomposition of N2O with the Aid of Fe—Ru-FER and Fe—Ru-MORN2O was decomposed with the aid of Catalysts 7 and 10 from Example 1 under the conditions as described in Example 2, Table 1, except that the temperature was varied, with the following results:TABLE 5Results Example 5:Conversion (%) ofConversion (%) ofTemper-N2O with iron-N2O with iron-atureruthenium-FERruthenium-MOR(° C.)(Cat 7)(Cat 10)3681753782763873893975214406672041679304258942435955544410068454100804631009147310096483100100492100100 Both catalysts according to the invention have good properties, but the combination of a first metal such as Ru, Ir and Rh with Fe as second metal provides even better properties (conversions) with zeolites such as FER than MOR.Example 6Decomposition of N2O with the Aid of a) Fe—Ru-FER and a Combination of Fe-FER and Ru-FER and b) Co—Rh-MOR and a Combination of Co-MOR and Rh-MORN2O was decomposed with the aid of Catalysts 6, 7 and 11 from Example 1 under the conditions as described in Example 2, Table 1, except that the temperature was varied. Catalyst 7 was compared with a physical mixture of Catalyst 6 and 11 (a: Fe—Ru-FER and a combination of Fe-FER and Ru-FER). This mixture consisted of a physical mixture of 0.3 ml Cat 6 and 0.3 ml Cat 11 (total 0.6 ml).N2O was decomposed with the aid of Catalysts 5, 1 and 12 from Example 1 under the conditions as described in Example 2, Table 1, except that the temperature was varied. Catalyst 5 was compared with a physical mixture of Catalyst 1 and 12 (b: Co—Rh-MOR and a combination of Co-MOR and Rh-MOR). This mixture consisted of a physical mixture of 0.3 ml Cat 1 and 0.3 ml Cat 12 (physical mixture: combine and homogenise for some time).The following results were obtained:TABLE 6Results Example 6:ConversionConversion(%) of N2OConversionConversion(%) of N2Owith iron-(%) of N2O(%) of N2OTemper-with iron-FER + ruthe-with cobalt-with rhodium-atureruthenium-nium-FERrhodium-MOR + Co-MOR(° C.)FER (Cat 7)(Cat 6 + 11)MOR (Cat 5)(Cat 1 + 12)36817131243782717201038738243015397523345244066744623441679597855425897990864359510098100444100100100100454100100100100463100100100100473100100100100483100100100100492100100100100 It can be seen from this experiment that a physical mixture does not have the good properties such as the catalyst according to the invention. If the catalyst according to the invention is prepared, the presence of a first metal, such as Ru, Ir and Rh, and a second metal, such as Fe and Co, apparently produces a synergistic effect on the decomposition of N2O. This synergistic effect is visible in particular at lower temperatures, such as between approx. 350-430° C., in particular 370-430° C.Cat 5 was also tested in a CH4-SCR setup as described in WO under the conditions of table 3 of WO, but it appeared that this catalyst was not suitable for NOx-conversion by CH4 (NOx-conversion ≦1% between 280-433° C.).Example 7Decomposition of N2O with the Aid of Co—Rh-MOR and Co—Rh-FERN2O was decomposed with the aid of Cat 5 and Cat 13 from Example 1 under the conditions as described in Example 2, Table 1, except that the temperature was varied.TABLE 7Results Example 7:Temper-atureConversion (%) of N2OConversion (%) of N2O(° C.)with Co—Rh-MOR (Cat 5)with Co—Rh-FER (Cat 13)36712133772022387303439645504066268415788442590954349899444100100454100100463100100473100100482100100491100100 It can be seen from these results that Co—Rh-FER also gives excellent results.Example 8Decomposition of N2O with the Aid of Co—Rh-MORN2O was decomposed with the aid of Cat 5 from Example 1 under the conditions as described in Table 8a. The results are given in Table 8b.TALE 8aReaction conditions Example 8Volume38mlGas flow velocity5ml/minGHSV7900h-1T400°C.P1baraN2O1500ppmNO200ppmH2O0.5%O22.5%N2bal. TABLE 8bResults Example 8:TemperatureConversion (%) of N2O with(° C.)Co—Rh-MOR (Cat 5)3092326734317360413757439596412100429100446100463100480100498100 It can be seen from these results that a removal efficiency of approx. 75% is possible at 375° C. with a long contact time.Example 9Decomposition of N2O with the Aid of ZSM-5 Exchanged with Fe, Fe/Ru and RuN2O was decomposed with the aid of Catalysts 14-16 from Example 1 under the conditions as described in Example 2, Table 1, except that the temperature was varied.The following results were obtained here:TABLE 9Results Example 9:Conversion (%)Conversion (%)Conversion (%)of N2O withof N2O withof N2O withTemperatureFe—Ru-ZSM-5Fe-ZSM-5Ru-ZSM-5(° C.)(Cat 16)(Cat 14)(Cat 15)36768937710911387161415396232217406333225415454532425595641434736848444857960454938875463979483473100989348210010098491100100100 It can be seen from these results that co-ion exchange (simultaneous exchange of first and second metal) in the liquid phase, that is to say simultaneous loading with Fe and Ru, also gives an improved catalyst compared with the analogous Ru-ZSM-5 and Fe-ZSM-5 loaded with a single metal.Example 10Decomposition of N2O with the Aid of BEA Exchanged with Fe or Fe and RuN2O was decomposed with the aid of Catalysts 17 and 18 from Example 1 under the conditions as described in Table 10a, and that the temperature was varied (see Table 10b).TABLE 10aReaction conditions Example 10Volume0.3mlGas flow velocity150ml/minGHSV30000h-1P1baraN2O1500ppmNO200ppmH2O0.5%O22.5%N2bal. The following results were obtained here:TABLE 10bResults Example 10:Temper-Conversion (%) ofTemper-Conversion (%) ofatureN2O with Fe-BEAatureN2O with Fe—Ru-BEA(° C.)(Cat 17)(° C.)(Cat 18)3090307032003171329132723382337434833484358535853677368937710378133871138819396183982940623408394152841855425374286943447438824445944891454734589646387468994739747810048299488100491100489100 It can be seen from these results that the combination of Ru—Fe provides a significant higher N2O-conversion, especially in the temperature range of about 385-470° C. Further, it red that the Fe—Ru-BEA catalyst is also very stable in the conversion of N2O.Example 11Variation in Concentration of First MetalThe weight percentage of Rh was measured at different spots of samples of zeolites first loaded with Rh or first loaded with Cu. SEM/EDX (scanning electron microscopy/energy dispersive X-ray spectroscopy) measurements were performed with a JEOL-JSM-6330F microscope. Such measurements are known to the person skilled in the art. The samples are subjected to irradiation by a focused electron beam, which results in imaging of secondary or back-scattered electrons and energy analysis of x-rays for view and cross-section surface imaging and composition analysis. With the SEM/EDX analysis technique, particles can be imaged by SEM, providing information on the physical properties of particles including size, shape, and surface morphology, while EDX provides information on the elemental composition of particles.TABLE 11EDX results of Rhodium-Copper-MORand Copper-Rhodium-MOR.First Cu, then Rh (Cat 4)First Rh, then Cu (Cat 3)ScanWt. % RhodiumScanWt. % Rhodiumscan 12.29 +/- 0.35scan 11.21 +/- 0.4scan 20.06 +/- 0.3 scan 20.94 +/- 0.3scan 31.62 +/- 0.35scan 31.11 +/- 0.3scan 41.06 +/- 0.35scan 4 1.02 +/- 0.35Mean1.26Mean1.07concentrationconcentrationLargest95% (0.06/1.26)Largest13% (1.21/1.07)deviation ofdeviation ofmeanmeanconcentrationconcentration The four scans for each sample were taken with different particles with a scan resolution of 0.1-1 μm2. It follows from the table that the rhodium concentration is highly heterogeneous when copper was loaded first, but that the largest deviation for the first Rh and then Cu loaded sample (according to the invention) is smaller than 20%.
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