WO2008009454A2 - Method for doping zeolites with metals - Google Patents

Method for doping zeolites with metals Download PDF

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Publication number
WO2008009454A2
WO2008009454A2 PCT/EP2007/006443 EP2007006443W WO2008009454A2 WO 2008009454 A2 WO2008009454 A2 WO 2008009454A2 EP 2007006443 W EP2007006443 W EP 2007006443W WO 2008009454 A2 WO2008009454 A2 WO 2008009454A2
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Prior art keywords
zeolite
catalytically active
metal
zeolites
mixture
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PCT/EP2007/006443
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German (de)
French (fr)
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WO2008009454A3 (en
Inventor
Arno Tissler
Roderik Althoff
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Süd-Chemie AG
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/8621—Removing nitrogen compounds
    • B01D53/8625—Nitrogen oxides
    • B01D53/8628—Processes characterised by a specific catalyst
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/061—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof containing metallic elements added to the zeolite
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/064—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof containing iron group metals, noble metals or copper
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively
    • B01J29/42—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively containing iron group metals, noble metals or copper
    • B01J29/46—Iron group metals or copper
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
    • B01J37/0027—Powdering
    • B01J37/0036—Grinding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/04—Mixing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/50—Zeolites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/50—Zeolites
    • B01D2255/502—Beta zeolites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/50—Zeolites
    • B01D2255/504—ZSM 5 zeolites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
    • B01J2229/10—After treatment, characterised by the effect to be obtained
    • B01J2229/18—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
    • B01J2229/10—After treatment, characterised by the effect to be obtained
    • B01J2229/18—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself
    • B01J2229/183—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself in framework positions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
    • B01J2229/30—After treatment, characterised by the means used
    • B01J2229/40—Special temperature treatment, i.e. other than just for template removal

Definitions

  • the present invention relates to a method of doping zeolites with catalytically active metals and to a composition for use in the doping of zeolites with catalytically active metals.
  • Metal-doped zeolites are known from the prior art and are used, for example, as catalyst material for the purification of exhaust gases.
  • These metal-doped zeolitic catalysts comprise at least one metallic, catalytically active component.
  • the catalytically active metal component is a transition or noble metal, especially copper, cobalt, iron, rhodium, platinum, etc.
  • metal-doped zeolites are prepared by providing a mixture of preferably the ammonium and / or H-form of the zeolite with a metal salt by mechanical mixing in a ball mill at room temperature under inert gas.
  • this object is achieved by a method comprising the following steps:
  • solid urea or a solid urea derivative causes no further oxidation of the catalytically active species upon the occurrence of several oxidation stages of the metal, and thus more catalytically active centers for the catalytic reaction, for example in the reduction of NO x or N 2 O is available.
  • a direct exchange of solid particles in the zeolite skeleton can be achieved with the process according to the invention, which was hitherto only possible via the detour via ammonium ion exchange and exchange (US Pat. No. 4,346,067).
  • the catalyst obtained according to the invention has a significantly higher conversion in catalysis than when using a catalyst prepared, for example, according to EP 0 955 080 B1.
  • the catalytically active metal is selected from Cu, Co, Rh, Pd, Ir, Pt, Ru, Fe, Ni, V.
  • the metals are first in the form of their salts, such as their chlorides, sulfates, nitrates, acetates or their complex compounds used. It is understood that the zeolite according to the invention can also be doped with a plurality of different metals. It is advantageous if the urea in an amount of 0.1 to 10 wt .-% based on the total mixture, preferably 1 to 5 wt .-%, is present.
  • the dry mixture is heated to a temperature of from 300 0 C to 800 0 C, preferably 400 ° C to 600 0 C, heated. It can thus be used in the context of the inventive method and comparatively low temperatures.
  • this temperature is maintained for a period of 1 hour to 24 hours, preferably 8 hours to 24 hours.
  • the heating rate in step iii) is more than 3, preferably more than 10 K / min.
  • the compound of the catalytically active metal is preferably used in an amount of 0.5 to 10 wt .-% based on the total amount of the dry mixture. It has also been found that, in particular, 1.5 to 6.0% by weight of metal, based on the total weight of the zeolite, must be present in the zeolite in order to achieve optimum adsorption capacity and optimized hydrothermal stability, especially in a water vapor / sulfur dioxide-containing Atmosphere, over a longer period of time to get.
  • Zeolites of the ZSM-5 type (MFI), Y (FAU), BETA (BEA) and mordenite (MOR) are preferably used as the zeolite, which in other embodiments, in their entirety or in part in their ammonium Form present.
  • the ammonium form of the zeolite is particularly preferred in the synthesis, because in the calcination in addition ammonia is released, which prevents further oxidation of catalytically active metal centers.
  • several different zeolites can be used simultaneously in the context of the inventive method.
  • the zeolite preferably has a ring opening formed from 8, 10, or 12 tetrahedral atoms with a high proportion of silicon dioxide, so that the ratio of SiZ 2 to Al 2 O 3 in the zeolite, depending on the structure, is at least 2: 1, not more than 100 : 1 amount.
  • Non-limiting typical values for this ratio are at least 2: 1 for type Y zeolites, at least 6 to 12: 1 for mordenite-type zeolites, and at least for BETA-type zeolites and ZSM5-type zeolites 10: 1.
  • the present invention relates to a metal, preferably transition metal-doped zeolite, obtainable by the method according to the invention explained above.
  • Preferred metals are Fe, Co, Cu, V, Pf, Ru, Ni, ZA and RL, most preferably Fe, Co and Ni.
  • the object of the present invention will be further by a composition for doping the zeolite with metals ge ⁇ lost.
  • This composition contains:
  • the catalytically active metal is selected from Cu, Co, Rh, Pd, Ir, Pt, Ru, Fe, Ni, V.
  • the compound used is preferably a chloride, sulfate, nitrate, acetate or a complex of these metals.
  • the inventive composition contains the compound of the catalytically active metal in an amount of 0.1 to 20 wt .-%.
  • the solid urea or the solid urea derivative is contained in an amount of 0.1 to 10% by weight based on the composition.
  • Non-limiting examples of erfmdungsgeand usable solid urea derivatives are urea prills and urea granules from Jara or SKW.
  • Example 2 After cooling, the metal-doped zeolite according to the invention was obtained. The resulting catalyst is stable under oxidative conditions.
  • the catalysts were roganten with different levels of solid urea in the form
  • the optimum for the content of the solid urea in the mixture is iron sulfate, NHy-MFi, solid urea obtained during the grinding of 2 to 6% by weight, particularly preferably from 2 to 4% by weight.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Environmental & Geological Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Biomedical Technology (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Catalysts (AREA)
  • Silicates, Zeolites, And Molecular Sieves (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)

Abstract

The invention relates to a method for doping zeolites with metals, said method comprising the following steps: i) a dry mixture is produced from a) a zeolite, b) a compound of a catalytically active metal, and c) a solid urea or a urea derivative; ii) the mixture is intimately ground; iii) the mixture is heated; and iv) the mixture is cooled to room temperature and the metal-doped zeoolite obtained. The invention also relates to a composition for doping zeolites with metals.

Description

VERFAHREN ZUR DOTIERUNG VON ZEOLITHEN MIT METALLEN METHOD FOR DOTING ZEOLITHS WITH METALS
Die vorliegende Erfindung betrifft ein Verfahren zur Dotierung von Zeolithen mit katalytisch aktiven Metallen sowie eine Zusammensetzung zur Verwendung bei der Dotierung von Zeolithen mit katalytisch aktiven Metallen.The present invention relates to a method of doping zeolites with catalytically active metals and to a composition for use in the doping of zeolites with catalytically active metals.
Metalldotierte Zeolithe sind aus dem Stand der Technik bekannt und finden beispielsweise Verwendung als Katalysatormaterial für die Reinigung von Abgasen.Metal-doped zeolites are known from the prior art and are used, for example, as catalyst material for the purification of exhaust gases.
Diese metalldotierten zeolithischen Katalysatoren umfassen mindestens eine metallische, katalytisch aktive Komponente. Typischerweise ist die katalytisch aktive Metallkomponente ein Übergangs- oder Edelmetall, insbesondere Kupfer, Kobalt, Eisen, Rhodium, Platin etc.These metal-doped zeolitic catalysts comprise at least one metallic, catalytically active component. Typically, the catalytically active metal component is a transition or noble metal, especially copper, cobalt, iron, rhodium, platinum, etc.
Übliche Verfahren, Zeolithe mit Metallen zu dotieren, umfassen beispielsweise ein Ionenaustauschverfahren in wassriger Losung (US 5,171,553). Oftmals werden als Trager für die aktiven Kom¬ ponenten siliziumreiche Zeolithe mit Si-Al-Verhaltnissen von über 5 bis 50 verwendet.Conventional methods of doping zeolites with metals include, for example, an aqueous-solution ion-exchange process (US 5,171,553). Often be used as a carrier for the active components Kom ¬ Si-rich zeolites having Si-Al-ratios of over 5 to 50th
Probleme ergeben sich insbesondere beim Dotieren bzw. Einbringen von aktiven Komponenten, wie z.B. Eisen oder Vanadium, in den Zeolithen, da oftmals verschiedene Oxidationsstufen dieser katalytisch aktiven Metalle vorliegen und nicht immer die gewünschte katalytisch aktive Spezies (Oxidationsstufe) erhalten wird bzw. die katalytisch aktiven Spezies aufgrund der Parameter des Dotierungsverfahrens (Sauerstoff, Temperatur, Feuch- tigkeit etc.) sich zu einer katalytisch inaktiven Spezies umwandeln.Problems arise in particular when doping or introducing active components, such as iron or vanadium, in the zeolites, since often different oxidation states of these catalytically active metals are present and not always the desired catalytically active species (oxidation state) is obtained or the catalytically active Species due to the parameters of the doping process (oxygen, temperature, humidity, activity, etc.) transform into a catalytically inactive species.
Bekannt ist ebenfalls das Dotieren von Zeolithen mit Eisen uuiui FestKorpeπonenaustausch (Studies in Surface Chemistry and Catalysis, 1994, Seite 665-669, Seite 43-64 (1991)).Also known is the doping of zeolites with iron uuiui FestKorpeπonenaustausch (Studies in Surface Chemistry and Catalysis, 1994, page 665-669, page 43-64 (1991)).
Üblicherweise werden dabei metalldotierte Zeolithe durch die Bereitstellung einer Mischung aus vorzugsweise der Ammonium- und/oder der H-Form des Zeolithen mit einem Metallsalz durch mechanisches Mischen in einer Kugelmühle bei Raumtemperatur unter Schutzgas hergestellt.Usually, metal-doped zeolites are prepared by providing a mixture of preferably the ammonium and / or H-form of the zeolite with a metal salt by mechanical mixing in a ball mill at room temperature under inert gas.
Aus „Journal of Catalysis", 167, Seite 256-265 (1997) ist allerdings bekannt, dass die derart hergestellten metalldotier- ten Zeolithe insbesondere bei der Konversion von NOx und N2O bei Temperaturen von unter 650 K im Falle von Cobalt-, Kupfer- und Eisen-dotierten Zeolithen katalytisch praktisch inaktiv sind. Dies ist daher insbesondere für die simultane Reduktion von Stickstoffmonoxid in Abgasen aus industriellen Prozessen, bei Autoabgasen und bei Wirbelschichtbefeuerung von Nachteil.However, it is known from "Journal of Catalysis", 167, page 256-265 (1997), that the metal-doped zeolites produced in this way in particular in the conversion of NO x and N 2 O at temperatures of below 650 K in the case of cobalt Catalytically virtually inactive, which is therefore of particular disadvantage for the simultaneous reduction of nitrogen monoxide in exhaust gases from industrial processes, in automotive exhaust gases and in fluidized bed firing.
Außerdem ist es wichtig, dass derartige Katalysatoren eine er¬ höhte Langzeitstabilitat aufweisen, insbesondere in Umgebungen, die Wasserdampf und Schwefeldioxid enthalten („hydrother- male Bedingungen") .It is also important that such catalysts have a long-term stability he ¬ creased, particularly in environments containing water vapor and sulfur dioxide containing ( "hydrothermal conditions").
Um diese Langzeitstabilitat zu erhalten ist es unumgänglich, dass das Katalysatormaterial unter hydrothermalen Bedingungen stabil ist, was zur Zeit nur dadurch zumindest teilweise er- reicht werden kann, wenn es unter anaeroben Bedingungen hergestellt wurde. Dies liegt insbesondere daran, dass beispielsweise Fe2+ Kationen im wassrigen Medium oxidiert werden und da¬ bei Eisenhydroxide ausfallen. Die EP 0 955 080 Bl lost dieses Problem dadurch, dass eine Mischung aus dem gewünschten Zeolith, einer Metallverbindung und einer Ammoniumverbindung unter Schutzgasatmosphare, insbesondere reduktiver Schutzgasatmosphare, beispielsweise unter Zu- ydbe vuii Ammoniak bzw. SticKstoff gesintert wird, so dass an- schließend ein metalldotierter Katalysator mit erhöhter Lang- zeitstabilitat erhalten wurde.In order to obtain this long-term stability, it is imperative that the catalyst material is stable under hydrothermal conditions, which at present can only be at least partially achieved if it has been prepared under anaerobic conditions. This is mainly because, for example, Fe 2+ cations are oxidized in aqueous medium and there ¬ fail when iron hydroxides. EP 0 955 080 B1 solves this problem by sintering a mixture of the desired zeolite, a metal compound and an ammonium compound under a protective gas atmosphere, in particular a reductive protective gas atmosphere, for example with ammonia or nitrogen, and then adding a metal-doped catalyst with increased long-term stability was obtained.
Aufgabe der vorliegenden Erfindung war es daher, ein weiteres Verfahren zur Verfugung zu stellen, um mit katalytisch aktiven Metallen dotierte Zeolithe mit hoher Langzeitstabilitat , die auch bei niederen Temperaturen katalytisch aktiv sind, herzustellen.It was therefore an object of the present invention to provide a further process for preparing zeolites doped with catalytically active metals with high long-term stability, which are catalytically active even at low temperatures.
Insbesondere war es ein Anliegen der vorliegenden Erfindung, die aus dem Stand der Technik bekannten Verfahren weiter zu vereinfachen, damit diese auch im großmdustriellen Maßstab anwendbar sind.In particular, it was an object of the present invention to further simplify the methods known from the prior art so that they can also be used on a large-scale industrial scale.
Erfindungsgemaß wird diese Aufgabe durch ein Verfahren gelost, das die folgenden Schritte umfasst:According to the invention, this object is achieved by a method comprising the following steps:
i) des Hersteilens einer trockenen Mischung aus a) einem Zeolithen, b) einer Verbindung eines katalytisch aktiven Metalls und c) festem Harnstoff oder einem fes- ten Harnstoffdeπvat, ii) des innigen Vermahlens der Mischung, iii) des Aufheizens der Mischung, iv) des Abkuhlens auf Raumtemperatur und Gewinnung des metalldotierten Zeolithen.i) preparing a dry mixture of a) a zeolite, b) a compound of a catalytically active metal and c) solid urea or a solid urea derivative, ii) intimately grinding the mixture, iii) heating the mixture, iv) cooling to room temperature and recovering the metal-doped zeolite.
Es wurde überraschenderweise gefunden, dass die Zugabe von festem Harnstoff bzw. einem Harnstoffderivat dazu fuhrt, dass das Aufheizen und Sintern (bzw. Kalzinieren) der trockenen Mi- schung auch in Gegenwart von Sauerstoff ohne das Vorhandensein einer reduktiven Schutzgasatmosphare durchgeführt werden kann.It has surprisingly been found that the addition of solid urea or a urea derivative leads to the fact that the heating and sintering (or calcination) of the dry mi- can be carried out in the presence of oxygen without the presence of a reductive protective gas atmosphere.
Die Zugabe von festem Harnstoff bzw. einem festen Harnstoffde- rivat funrt αazu, αass bei Auttreten von mehreren Oxidations- stufen des Metalls die katalytisch aktive Spezies nicht weiter oxidiert und somit mehr katalytisch aktive Zentren für die ka- talytische Reaktion, beispielsweise bei der Reduktion von NOx oder N2O, zur Verfugung steht. Überraschenderweise kann mit dem erfindungsgemaßen Verfahren ein direkter Festkorperionenaus- tausch im Zeolithgerust erreicht werden, was bislang nur über den Umweg über Ammoniumein- und -austausch möglich war (US 4,346,067) .The addition of solid urea or a solid urea derivative causes no further oxidation of the catalytically active species upon the occurrence of several oxidation stages of the metal, and thus more catalytically active centers for the catalytic reaction, for example in the reduction of NO x or N 2 O is available. Surprisingly, a direct exchange of solid particles in the zeolite skeleton can be achieved with the process according to the invention, which was hitherto only possible via the detour via ammonium ion exchange and exchange (US Pat. No. 4,346,067).
Im Falle von Eisen wurde gefunden, dass die Gegenwart von Harnstoff bzw. Harnstoffderivaten dazu fuhrt, dass beispielsweise im Falle einer Dotierung mit Eisen circa 90% der katalytisch aktiven Eisen ( II ) -Cluster und Eisen-Eisen-Dimere bei der Temperung bzw. Kalzinierung erhalten bleiben. Der Festharnstoff vermittelte Austausch stabilisiert also gerade auch an sich weniger stabile, aber meist katalytisch aktive Ubergangs- metalloxidationsstufen .In the case of iron, it has been found that the presence of urea or urea derivatives leads, for example in the case of doping with iron, to approximately 90% of the catalytically active iron (II) clusters and iron-iron dimers during tempering or calcination remain. The solid-urea-mediated exchange thus stabilizes even less stable but mostly catalytically active transition metal oxidation states.
Dadurch weist der erfindungsgemaß erhaltene Katalysator in der Katalyse einen deutlich höheren Umsatz auf als bei Verwendung eines Katalysators, der beispielsweise gemäß der EP 0 955 080 Bl hergestellt wurde.As a result, the catalyst obtained according to the invention has a significantly higher conversion in catalysis than when using a catalyst prepared, for example, according to EP 0 955 080 B1.
Bevorzugt ist das katalytisch aktive Metall ausgewählt aus Cu, Co, Rh, Pd, Ir, Pt, Ru, Fe, Ni, V. Die Metalle werden zunächst in Form ihrer Salze, wie z.B. ihrer Chloride, Sulfate, Nitrate, Acetate oder ihrer Komplexverbindungen eingesetzt. Es versteht sich, dass der Zeolith erfindungsgemaß auch mit mehreren unterschiedlichen Metallen dotiert werden kann. Von Vorteil ist, wenn der Harnstoff in einer Menge von 0,1 bis 10 Gew.-% bezogen auf die gesamte Mischung, bevorzugt 1 bis 5 Gew.-%, vorhanden ist. Die Gegenwart von weniger als 0,1 Gew.- % Harnstoff bzw. Harnstoffdeπvat fuhrt in Gegenwart von Sauerstoff zur weitgehenden Oxidation bzw. Deaktivierung der ka- talytisch aktiven Spezies. Mehr als 10 Gew.-% fuhrt zu einer erhöhten Hygroskopizität der festen Mischung. Somit bleibt diese nicht mehr pulverformig sondern verändert ihre Konsistenz hin zu einer schwer mischbaren Paste, die nur aufwandig weiterverarbeitbar ist. Vorteilhafterweise wird die trockene Mischung bis zu einer Temperatur von von 3000C bis 8000C, bevorzugt 400°C bis 6000C, aufgeheizt. Es können somit auch vergleichsweise niedrige Temperaturen im Rahmen des erfindungsgemaßen Verfahrens eingesetzt werden.Preferably, the catalytically active metal is selected from Cu, Co, Rh, Pd, Ir, Pt, Ru, Fe, Ni, V. The metals are first in the form of their salts, such as their chlorides, sulfates, nitrates, acetates or their complex compounds used. It is understood that the zeolite according to the invention can also be doped with a plurality of different metals. It is advantageous if the urea in an amount of 0.1 to 10 wt .-% based on the total mixture, preferably 1 to 5 wt .-%, is present. The presence of less than 0.1% by weight of urea or urea derivative leads in the presence of oxygen to extensive oxidation or deactivation of the catalytically active species. More than 10% by weight leads to increased hygroscopicity of the solid mixture. Thus, this no longer remains powdery but changes its consistency towards a hard-to-mix paste, which can only be further processed. Advantageously, the dry mixture is heated to a temperature of from 300 0 C to 800 0 C, preferably 400 ° C to 600 0 C, heated. It can thus be used in the context of the inventive method and comparatively low temperatures.
Bevorzugt wird diese Temperatur wahrend eines Zeitraums von Ih bis zu 24h, bevorzugt 8h bis 24h, beibehalten.Preferably, this temperature is maintained for a period of 1 hour to 24 hours, preferably 8 hours to 24 hours.
Die Aufheizrate in Schritt iii) betragt mehr als 3, vorzugs- weise mehr als 10 K/min.The heating rate in step iii) is more than 3, preferably more than 10 K / min.
Die Verbindung des katalytisch aktiven Metalls wird bevorzugt in einer Menge von 0,5 bis 10 Gew.-% bezogen auf die Gesamtmenge der trockenen Mischung eingesetzt. Es wurde weiter ge- funden, dass insbesondere 1,5 bis 6,0 Gew.-% Metall bezogen auf das Gesamtgewicht des Zeolithen im Zeolithen enthalten sein müssen, um eine optimale Adsorptionsfahigkeit und optimierte hydrothermale Stabilität, insbesondere in einer Wasserdampf/Schwefeldioxid-haltigen Atmosphäre, über einen längeren Zeitraum zu erhalten.The compound of the catalytically active metal is preferably used in an amount of 0.5 to 10 wt .-% based on the total amount of the dry mixture. It has also been found that, in particular, 1.5 to 6.0% by weight of metal, based on the total weight of the zeolite, must be present in the zeolite in order to achieve optimum adsorption capacity and optimized hydrothermal stability, especially in a water vapor / sulfur dioxide-containing Atmosphere, over a longer period of time to get.
Vorzugsweise werden als Zeolith Zeolithe vom ZSM-5 Typ (MFI), Y (FAU), BETA (BEA) und Mordenit (MOR) eingesetzt, die in weiteren Ausfuhrungsformen ganz oder teilweise in ihrer Ammonium- Form vorliegen. Die Ammoniumform des Zeolithen ist bei der Synthese insbesondere deshalb bevorzugt, weil bei der Kalzinierung zusatzlich Ammoniak frei wird, welches eine weitere Oxidation von katalytisch aktiven Metallzentren verhindert. In weiteren Ausfuhrungsformen der vorliegenden Erfindung können auch mehrere verschiedene Zeolithe gleichzeitig im Rahmen des erfindungsgemaßen Verfahrens eingesetzt werden.Zeolites of the ZSM-5 type (MFI), Y (FAU), BETA (BEA) and mordenite (MOR) are preferably used as the zeolite, which in other embodiments, in their entirety or in part in their ammonium Form present. The ammonium form of the zeolite is particularly preferred in the synthesis, because in the calcination in addition ammonia is released, which prevents further oxidation of catalytically active metal centers. In further embodiments of the present invention, several different zeolites can be used simultaneously in the context of the inventive method.
Der Zeolith weist bevorzugt eine Ringoffnung gebildet aus 8, 10, oder 12 Tetraederatomen mit einem hohen Anteil an Silizi- umdioxid auf, so dass das Verhältnis von SiÜ2 zu Al2O3 in dem Zeolith je nach Struktur mindestens 2:1, maximal 100:1 betragt. Als nicht einschränkende, typische Werte für dieses Verhältnis seien genannt bei Zeolithen vom Typ Y ca. mindestens 2:1, bei Zeolithen vom Typ Mordenit im Bereich von circa 6 bis 12:1 und bei ZSM5-Typ Zeolithen und Zeolithen vom BETA- Typ mindestens 10:1.The zeolite preferably has a ring opening formed from 8, 10, or 12 tetrahedral atoms with a high proportion of silicon dioxide, so that the ratio of SiZ 2 to Al 2 O 3 in the zeolite, depending on the structure, is at least 2: 1, not more than 100 : 1 amount. Non-limiting typical values for this ratio are at least 2: 1 for type Y zeolites, at least 6 to 12: 1 for mordenite-type zeolites, and at least for BETA-type zeolites and ZSM5-type zeolites 10: 1.
Außerdem betrifft die vorliegende Erfindung einen metall-, bevorzugt ubergangsmetalldotierte Zeolithen, erhaltlich durch das vorstehend erläuterte erfindungsgemaße Verfahren. Bevorzugte Metalle sind dabei Fe, Co, Cu, V, Pf, Ru, Ni, ZA und RL, ganz besonders bevorzugt Fe, Co und Ni.In addition, the present invention relates to a metal, preferably transition metal-doped zeolite, obtainable by the method according to the invention explained above. Preferred metals are Fe, Co, Cu, V, Pf, Ru, Ni, ZA and RL, most preferably Fe, Co and Ni.
Die Aufgabe der vorliegenden Erfindung wird weiter durch eine Zusammensetzung zur Dotierung von Zeolithen mit Metallen ge¬ lost. Diese Zusammensetzung enthalt:The object of the present invention will be further by a composition for doping the zeolite with metals ge ¬ lost. This composition contains:
a) einen Zeolithen, b) eine Verbindung eines katalytisch aktiven Metalls, c) festen Harnstoff oder ein festes Harnstoffderivat .a) a zeolite, b) a compound of a catalytically active metal, c) solid urea or a solid urea derivative.
Das katalytisch aktive Metall ist ausgewählt aus Cu, Co, Rh, Pd, Ir, Pt, Ru, Fe, Ni, V. Die eingesetzte Verbindung ist be- vorzugt ein Chlorid, Sulfat, Nitrat, Acetat bzw. eine Komplexverbindung dieser Metalle.The catalytically active metal is selected from Cu, Co, Rh, Pd, Ir, Pt, Ru, Fe, Ni, V. The compound used is preferably a chloride, sulfate, nitrate, acetate or a complex of these metals.
Die erfindungsgemaße Zusammensetzung enthalt die Verbindung des katalytisch aktiven Metalls in einer Menge von 0,1 bis 20 Gew.-%.The inventive composition contains the compound of the catalytically active metal in an amount of 0.1 to 20 wt .-%.
Bevorzugt ist der feste Harnstoff oder das feste Harnstoffderivat in einer Menge von 0,1 bis 10 Gew.-% bezogen auf die Zusammensetzung enthalten.Preferably, the solid urea or the solid urea derivative is contained in an amount of 0.1 to 10% by weight based on the composition.
Nicht einschränkende Beispiele für erfmdungsgemaß verwendbare feste Harnstoffderivate sind Harnstoff-Prills und Harnstoff- Granulate der Firma Jara oder SKW.Non-limiting examples of erfmdungsgemaß usable solid urea derivatives are urea prills and urea granules from Jara or SKW.
Die vorliegende Erfindung ist nachfolgend anhand von Beispielen beschrieben, die jedoch nicht als einschränkend verstanden werden sollenThe present invention will now be described by way of example, but not by way of limitation
Beispiel 1example 1
0,9 g FeSO4 x 7H2O (Merck), 5g NH4 - MFI (SM27 Sud-Chemie) sowie0.9 g FeSO 4 .7H 2 O (Merck), 5 g NH 4 - MFI (SM27 Sud-Chemie) and
0,2 g fester Harnstoff in Form von „Prills" (Harnstoff- Granulat, Fa. SKW)0.2 g of solid urea in the form of "prills" (urea granules, SKW)
werden in einer Kugelmühle über 2h intensiv vermengt. Anschließend wird die erhaltene trockene Mischung bei einer Temperatur von 5000C kalziniert. Die Aufheiztemperatur von Raumtemperatur auf 5000C betrug >10 K/min.are mixed intensively in a ball mill for 2 hours. Subsequently, the resulting dry mixture is calcined at a temperature of 500 0 C. The heating temperature from room temperature to 500 0 C was> 10 K / min.
Beispiel 2 Nach Abkühlen wurde der erfindungsgemaße metalldotierte Zeo- lith erhalten. Der erhaltene Katalysator ist auch unter oxida- tiven Bedingungen stabil.Example 2 After cooling, the metal-doped zeolite according to the invention was obtained. The resulting catalyst is stable under oxidative conditions.
Mchj.ei.ti dndiog zu Beispiel i erhaltene Katalysatoren herge- stellt mit unterschiedlichen Mengen an Festharnstoff wurden bei der katalytischen Reduzierung von Lachgas mit Methan alsMchj.ei.ti dndiog to Example i obtained catalysts prepared with different amounts of solid urea were in the catalytic reduction of nitrous oxide with methane as
Reduktionsmittel getestet. Die Katalysatoren wurden dabei mit unterschiedlichen Anteilen an Festharnstoff in Form rogantenReducing agent tested. The catalysts were roganten with different levels of solid urea in the form
Harnstoffprills in der Kugelmühle gemahlen, um den Einfluss des zugegebenen Festharnstoffanteils zu bestimmen.Milled urea prills in the ball mill to determine the influence of added solid urea content.
Die Vergleichsversuche wurden bei 3600C und einem GHSV vonThe comparative experiments were conducted at 360 0 C and a GHSV of
10.000 h sowie mit einem Verhältnis von CH4/N2O von 0,25 durchgeführt .10,000 h and carried out with a ratio of CH 4 / N 2 O of 0.25.
Gemessen wurde der Umsatz von N2O zu N2 gegen den Anteil in Gew% Festharnstoff zu eingesetztem Ammoniumzeolithen NHy-MFiThe conversion of N 2 O to N 2 was measured against the proportion in% by weight of solid urea to ammonium zeolite NHy-MFi used
Tabelle 1Table 1
Anteil Festharnstoff zu Zeolith bei der Herstel10 lung des Katalysators (in Gew%)Proportion of solid urea to zeolite during the preparation of the catalyst (in% by weight)
Umsatz N2O 62% 75% 97% 98% 91! Sales N 2 O 62% 75% 97% 98% 91 !
Wie aus Tabelle 1 ersichtlich ist, betragt das Optimum für den Anteil des Festharnstoffes im Gemisch Eisensulfat, NHy-MFi, Festharnstoff wahrend der Mahlung von 2 bis 6 Gew% , besonders bevorzugt von 2 bis 4 Gew. % erhalten. As can be seen from Table 1, the optimum for the content of the solid urea in the mixture is iron sulfate, NHy-MFi, solid urea obtained during the grinding of 2 to 6% by weight, particularly preferably from 2 to 4% by weight.

Claims

Patentansprüche claims
1. Verfahren zur Dotierung von Zeolithen mit Metallen, umfassend die Schritte desA method of doping zeolites with metals, comprising the steps of
i) Hersteilens einer trockenen Mischung aus a) einem Zeolithen, b) einer Verbindung eines katalytisch aktiven Metalls und c) festem Harnstoff oder einem festen Harnstoffderivat, ii) innigen Vermahlens der Mischung, in) Aufheizens der Mischung, iv) Abkuhlens auf Raumtemperatur und Gewinnung des me- talldotierten Zeolithen.i) preparing a dry mixture of a) a zeolite, b) a compound of a catalytically active metal and c) solid urea or a solid urea derivative, ii) intimately grinding the mixture, heating the mixture, iv) cooling to room temperature and recovery of the metal-doped zeolite.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass das katalytisch aktive Metall ausgewählt ist aus Cu,2. The method according to claim 1, characterized in that the catalytically active metal is selected from Cu,
Co, Rh, Pd, Ir, Pt, Ru, Fe, Ni, V.Co, Rh, Pd, Ir, Pt, Ru, Fe, Ni, V.
3. Verfahren nach Anspruch 2, dadurch gekennzeichnet, dass Harnstoff in einer Menge von 0,1 bis 10 Gew.-% bezogen auf die gesamte Mischung, bevorzugt 1 bis 5 Gew.-%, eingesetzt wird.3. The method according to claim 2, characterized in that urea in an amount of 0.1 to 10 wt .-% based on the total mixture, preferably 1 to 5 wt .-%, is used.
4. Verfahren nach Anspruch 3, dadurch gekennzeichnet, dass die trockene Mischung bis zu einer Temperatur im Be- reich von 3000C bis 8000C, bevorzugt 4000C bis 6000C, aufgeheizt wird.4. The method according to claim 3, characterized in that the dry mixture is heated up to a temperature in the range of 300 0 C to 800 0 C, preferably 400 0 C to 600 0 C, heated.
5. Verfahren nach Anspruch 4, dadurch gekennzeichnet, dass die Aufheizrate in Schritt m) > 10 K/mm betragt.5. The method according to claim 4, characterized in that the heating rate in step m) amounts to> 10 K / mm.
6. Verfahren nach Anspruch 4 oder 5, dadurch gekennzeichnet, dass die in Schritt m) erreichte Temperatur über einen Zeitraum von Ih bis zu 24h, bevorzugt 8h bis 24h, beibehalten wird. 6. The method according to claim 4 or 5, characterized in that the temperature reached in step m) over a period of Ih up to 24h, preferably 8h to 24h, is maintained.
7. Verfahren nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die Verbindung des kataly- tisch aktiven Metalls in einer Menge von 0,5 bis 10 Gew.-% bezogen auf die Gesamtmenge der trockenen Mi- scnung eingesetzt wird.7. The method according to any one of the preceding claims, characterized in that the compound of the catalytically active metal is used in an amount of 0.5 to 10 wt .-% based on the total amount of the dry Mi- scnung.
8. Verfahren nach Anspruch 7, dadurch gekennzeichnet, dass das Verhältnis von SiO2 zu Al2O3 im Zeolithen >2, bevorzugt >10 ist.8. The method according to claim 7, characterized in that the ratio of SiO 2 to Al 2 O 3 in the zeolite> 2, preferably> 10.
9. Verfahren nach Anspruch 8, dadurch gekennzeichnet, dass als Zeolith Zeolithe vom Typ ZSM-5, Y, BETA und Morde- nit eingesetzt werden.9. Process according to claim 8, characterized in that zeolites of the type ZSM-5, Y, BETA and mordenite are used as the zeolite.
10. Verfahren nach Anspruch 9, dadurch gekennzeichnet, dass die Zeolithe teilweise oder vollständig in ihrer Ammonium-Form vorliegen.10. The method according to claim 9, characterized in that the zeolites are partially or completely present in their ammonium form.
11. Metalldotierter Zeolith, erhältlich durch das Verfahren gemäß einem der Ansprüche 1 bis 10.11. A metal-doped zeolite obtainable by the process according to any one of claims 1 to 10.
12. Zusammensetzung zur Dotierung von Zeolithen mit Metallen enthaltend12. Containing a composition for doping zeolites with metals
a) einen Zeolithen, b) eine Verbindung eines katalytisch aktiven Metalls, c) festen Harnstoff oder ein festen Harnstoffderivat .a) a zeolite, b) a compound of a catalytically active metal, c) solid urea or a solid urea derivative.
13. Zusammensetzung nach Anspruch 12, dadurch gekennzeichnet, dass das katalytisch aktive Metall ausgewählt ist aus Cu, Co, Rh, Pd, Ir, Pt, Ru, Fe, Ni, V.13. The composition according to claim 12, characterized in that the catalytically active metal is selected from Cu, Co, Rh, Pd, Ir, Pt, Ru, Fe, Ni, V.
14. Zusammensetzung nach Anspruch 13, dadurch gekennzeichnet, dass die Verbindung des katalytisch aktiven Me- talls in einer Menge von 0,5 bis 10 Gew.-I in der Zusammensetzung enthalten ist.14. The composition according to claim 13, characterized in that the compound of the catalytically active Me- Talls in an amount of 0.5 to 10 parts by weight in the composition.
15. Zusammensetzung nach Anspruch 14, dadurch gekennzeichnet, dass fester Harnstoff oder ein festes Harnstoffde- rivat in einer Menge von 0,1 bis 10 Gew.-I in der Zusammensetzung enthalten ist.15. A composition according to claim 14, characterized in that solid urea or a solid urea derivative in an amount of 0.1 to 10 wt. I is contained in the composition.
16. Verwendung eines metalldotierten Zeolithen, erhaltlich nach einem der Ansprüche 1 bis 10 bei der katalytischen Umsetzung von Stickoxiden. 16. Use of a metal-doped zeolite, obtainable according to one of claims 1 to 10 in the catalytic conversion of nitrogen oxides.
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