DK201600583A1

DK201600583A1 - Monolithic honeycomb oxidation catalyst and method of preparation thereof

Info

Publication number: DK201600583A1
Application number: DKPA201600583A
Authority: DK
Inventors: Kim Hougaard Pedersen; Francesco Castellino; Viggo Lucassen Hansen
Original assignee: Haldor Topsoe As
Priority date: 2016-10-03
Filing date: 2016-10-03
Publication date: 2018-04-23
Also published as: DK180289B1

Abstract

A monolithic honeycomb oxidation catalyst and a method of preparation thereof, the honeycomb oxidation catalyst has a plurality of flow through channels confined by walls, the walls consisting of an inert material coated with a core layer comprising an inert clay material, the core layer is coated with a top layer comprising at least one metal selected from the group of platinum group metals and vanadium pentoxide.

Description

<¹θ> DANMARK <¹°> DK 2016 00583 A1

<¹²> PATENTANSØGNING

Patent- og

Varemærkestyrelsen (51) lnt.CI.: B 01 J 37/02(2006.01)

B 01 J 23/40 (2006.01)

B 01 J 23/22 (2006.01) B 01 J 35/04 (2006.01)

B 01 J 23/30 (2006.01) (21) Ansøgningsnummer: PA 2016 00583 (22) Indleveringsdato: 2016-10-03 (24) Løbedag: 2016-10-03 (41) Aim. tilgængelig: 2018-04-04 (71) Ansøger: HALDOR TOPSØE A/S, Haldor Topsøes Allé 1,2800 Kongens Lyngby, Danmark (72) Opfinder: Kim Hougaard Pedersen, Virumstræde 11 C, 2830 Virum, Danmark Francesco Castellino, Rolighedsvej 31,3460 Birkerød, Danmark

Viggo Lucassen Hansen, Botoftevej 12, 2700 Brønshøj, Danmark (54) Benævnelse: Monolithic honeycomb oxidation catalyst and method of preparation thereof (56) Fremdragne publikationer:

WO 2017072138 A1 US 2006035780 A1 US 2015375207 A1 US 2007209350 A1 EP 0734756 A2 (57) Sammendrag:

DK 2016 00583 A1

DK 2016 00583 A1 i

Monolithic honeycomb oxidation catalyst and method of preparation thereof

The invention relates to a monolithic honeycomb catalyst for the oxidation of carbon monoxide and volatile organic compounds (VOCs) in exhaust gases and flue gases from stationary flue gas sources including gas turbines and power plants .

The invention is in particular directed to a monolithic honeycomb shaped oxidation catalyst with a core layer comprising inert clay material and a top layer comprising one or more platinum group metals (PGM)coated on a monolithic honeycomb shaped substrate for use in the removal of carbon monoxide and VOCs in flue gas formed in stationary sources in the combustion of fossil fuel like natural gas, coal or oil.

The invention is additionally directed a method for the preparation of an oxidation catalyst with a core layer of inert clay material coated on a monolithic honeycomb substrate and a top layer of catalytic material active in the oxidation of CO and VOCs.

Methods for removing CO and VOCs by catalytic oxidation are well-known in the art.

The most typical oxidation catalyst compositions employed in flue gas cleaning from stationary sources are based on platinum supported on alumina for applications such as CO and VOC oxidation.

DK 2016 00583 A1

It is also known that palladium promoted vanadium oxide catalysts offer a very high CO and VOC oxidation activity in combination with a high sulfur resistance.

Those catalysts are in particular preferred where there is a risk of exposure to high sulfur containing flue gases and where high sulfate emissions and fouling of downstream equipment and/or risk of catalyst deactivation has to be minimized.

The advantage of palladium based oxidation catalysts is that these catalysts have a relatively low sulfur oxidation activity, which is particularly important when employed in the cleaning of sulfur oxide containing flue gas.

For use in gas cleaning from stationary sources, the catalyst is washcoated on a monolithic honeycomb substrate, typically consisting of stacked up corrugated sheets of ceramic material or non-woven glass fibers forming a monolithic honeycomb structure with a plurality of parallel flow through channels.

Monolithic honeycomb shaped catalysts of the above type are typically prepared by coating the monolithic honeycomb substrate with a washcoat containing a catalyst carrier material and impregnating the coated substrate with a solution of precursors of the catalytic active metal oxides. Alternatively, the washcoat can also contain the precursors.

Washcoating of a monolithic honeycomb substrate is usually performed by slurry pickup in the substrate by pouring the slurry into the channels of the substrate, by dipping the

DK 2016 00583 A1 substrate at one side into the washcoat slurry and optionally applying vacuum at the opposite side or by pumping the washcoat slurry into the channels and optionally applying vacuum.

After having been coated with the washcoat, the substrate is dried and finally calcined for activation of the catalytic components in the coat.

It is well known that the oxidation reaction is much faster than diffusion of CO and some VOCs into the catalyst wall at typical oxidation reaction conditions and it would therefore be an advantage in terms of cost saving, when reducing or limiting distribution of the expensive PGM catalyst material only to the outer surface of the walls or the wall coat of the monolithic honeycomb substrate.

In the known oxidation catalysts as prepared by the above mentioned coating methods, the PGM catalyst is distributed throughout the whole wall cross section. Thus, the PGM catalyst distributed beneath surface of the walls does not participate in the catalytic CO and reactive VOC oxidation.

The problem is solved by the present invention, when providing the walls of the substrate with a core layer of inert clay materials and applying a washcoat comprising PGM on the surface of the core layer.

We have further found that diffusion of PGM can be eliminated or substantially diminished when decreasing the rate of diffusion of PGM on the substrate. Instead of having precursor compounds of PGM dissolved in an aqueous impregDK 2016 00583 A1 nation liquid, the precursor compounds are added to an aqueous slurry containing vanadium compounds, which act as a carrier for PGM and which is used for the coating of the inert clay core layer on the substrate. In this aqueous slurry, the PGM compounds are adsorbed on the supported vanadium compound particles and are thereby not dissolved in the aqueous phase of the aqueous slurry, which otherwise would result in undesired diffusion into the walls of the substrate and/or clay core layer.

Pursuant to the above findings, this invention provides a monolithic honeycomb oxidation catalyst with a plurality of flow through channels confined by walls, the walls consisting of one or more corrugated sheets of inert material, optionally provided with flat liners, coated with a core layer comprising an inert clay material, the core layer is coated with a top layer comprising at least one metal selected from the group of platinum group metals and vanadium pentoxide.

The catalyst according to the invention has the advantage that it shows at least as good structure stability as conventional monoliths since the overall thickness of the monolith wall is preserved due to the inert clay core layer. The present invention reduces additionally the catalyst load per unit volume of monolith leading to a reduced SO2 oxidation .

Specific features of the catalyst according to the invention are alone or in combination thereof that

DK 2016 00583 A1 the top layer further comprises an oxide of tungsten and titania;

the at least one metal selected from the group of platinum group metals is palladium;

the one or more corrugated sheets of inert material, and the optional flat liners comprise entangled non-woven fibers ;

the entangled non-woven fibers comprise glass fibers; the inert clay material is selected from the kaolin group, hydrous alumina silicates, the chlorite group, the pyrophillite group, bentonite or mixtures thereof;

the top layer comprises 0.1 to 10 % by weight vanadium pentoxide;

the top layer comprises 100 to 30000 ppm by weight palladium;

A further aspect of the present invention is a method of preparing a monolithic honeycomb oxidation catalyst comprising the steps of (a) providing an inert monolithic honeycomb substrate with a plurality of flow through channels confined by walls by stacking or rolling up one or more corrugated sheets of inert material, optionally provided with flat liners;

(b) coating the monolithic honeycomb substrate with a core layer comprising an inert clay material;

(c) providing a washcoat comprising at least one metal selected from the group of platinum group metals and vanadium pentoxide;

(d) coating the core layer with a top layer by applying the washcoat prepared in step (c); and (e) calcining the coated monolithic honeycomb substrate.

DK 2016 00583 A1

Specific features of the method according to the invention are alone or in combination thereof that the washcoat of step(c) is prepared by (i) pulverising a finished SCR catalyst product comprising vanadium pentoxide;

(ii) dispersing the pulverized catalyst product in water and forming a slurry;

(iii) adding a water soluble precursor of the at least one metal selected from the group of platinum group metals; the washcoat further comprises titania and an oxide of tungsten;

the finished SCR catalyst product comprising vanadium pentoxide further comprises titania and an oxide of tungsten; the platinum group metal is palladium;

the one or more corrugated sheets of inert material and the optional flat liners, comprise entangled non-woven fibers; the entangled non-woven fibers are glass fibers;

the inert clay material is selected from the kaolin group, hydrous alumina silicates, the chlorite group, the pyrophillite group, bentonite or mixtures thereof; the top layer comprises 0.1 to 10 % by weight vanadium pentoxide;

the top layer comprises 100 to 30000 ppm by weight palladium.

By the terms inert material and inert clay material as used hereinbefore or in the following description and claims it should be understood that the material is not catalytically active.

DK 2016 00583 A1

Example

An Pd-V2O5-WO3-TiC>2 based oxidation catalyst on an inert clay core was prepared as follows.

A monolithic honeycomb substrate made of a number of corrugated sheets made of glass fibers and provide each with a flat liner were coated with a core layer of kaolin by dipping the substrate into a slurry of kaolin and butanol until the wall thickness of the coated substrate was 0.4 mm. The thus prepared monolithic honeycomb substrate was then allowed to drain for 10 minutes, dried for three days and fired for two hours at 550°C in N2 atmosphere.

The substrate with the kaolin core layer was coated with a wash coat prepared as follows:

200 grams of crushed and milled l^Os-WCy-TiCk SCR catalyst in water (25 % by mass) was adjusted to a pH value of 8.5 by adding an aqueous ammonia solution. To the resulting slurry was added a Pd nitrate solution of 100 ppmw by metal until 1000 ppmw Pd by dry matter in the slurry was achieved. The resulting slurry was sufficiently mixed while adjusting pH to 8.5 using an aqueous ammonia solution followed by addition of polysaccharide to a concentration of 0.1 % by mass.

The monolithic honeycomb substrate with an inert core layer of kaolin as prepared above was dipped into the slurry for 1.5 minutes and the slurry was afterwards allowed to drain from the substrate for 15 minutes. The resulting monolithic honeycomb catalyst was then calcined for two hours at 400°C.

DK 2016 00583 A1

Claims

1. A monolithic honeycomb oxidation catalyst with a plurality of flow through channels confined by walls, the walls consisting of one or more corrugated sheets of inert material, optionally provided with flat liners, coated with a core layer comprising an inert clay material, the core layer is coated with a top layer comprising at least one metal selected from the group of platinum group metals and vanadium pentoxide.

2. The monolithic honeycomb oxidation catalyst of claim 1, wherein the top layer further comprises titania and an oxide of tungsten.

3. The monolithic honeycomb oxidation catalyst of claim 1 or 2, wherein the at least one metal selected from the group of platinum group metals is palladium.

4. The monolithic honeycomb oxidation catalyst of any one of claims 1 to 3, wherein the one or more corrugated sheets of inert material, and the optional flat liners comprise entangled non-woven fibers.

5. The monolithic honeycomb oxidation catalyst of claim 4, wherein the entangled non-woven fibers comprise glass fibers .

6. The monolithic honeycomb oxidation catalyst of any one of claims 1 to 5, wherein the inert clay material is selected from the kaolin group, hydrous alumina silicates,

DK 2016 00583 A1 the chlorite group, the pyrophillite group, bentonite or mixtures thereof.

7. The monolithic honeycomb oxidation catalyst according to any one of claims 1 to 6, wherein the top layer comprises 0.1 to 10 % by weight vanadium pentoxide.

8. The monolithic honeycomb oxidation catalyst according to any one of claims 1 to 7, wherein the top layer comprises 100 to 30000 ppm by weight palladium.

9. Method of preparing a monolithic honeycomb oxidation catalyst comprising the steps of (a) providing an inert monolithic honeycomb substrate with a plurality of flow through channels confined by walls by stacking or rolling up one or more corrugated sheets of inert material, optionally provided with flat liners;

10. The method of claim 9, wherein the washcoat of step(c) is prepared by (i) pulverising a finished SCR catalyst product comprising vanadium pentoxide;

(ii) dispersing the pulverized catalyst product in water and forming a slurry;

DK 2016 00583 A1 (iii) adding a water soluble precursor of the at least one metal selected from the group of platinum group metals.

11. The method of claim 9, wherein the washcoat further comprises an oxide of tungsten and titania.

12. The method of claim 10, wherein the finished SCR catalyst product comprising vanadium pentoxide further comprises titania and an oxide of tungsten.

13. The method of any one of claims 9 to 12, wherein the platinum group metal is palladium.

14. The method of any one of claims 9 to 13, wherein the one or more corrugated sheets of inert material and the optional flat liners, comprise entangled non-woven fibers.

15. The method of claim 14, wherein the entangled nonwoven fibers are glass fibers.

16. The method of any one of claims 9 to 15, wherein the inert clay material is selected from the kaolin group, hydrous alumina silicates, the chlorite group, the pyrophillite group, bentonite or mixtures thereof.

17. The method of any one top layer comprises 0.1 to ide .

18. The method of any one top layer comprises 100 to of claims 9 to 16, wherein the 10 % by weight vanadium pentox of claims 7 to 15, wherein the 30000 ppm by weight palladium.

öANm/ Fäto? asö TfeARSMAAK Oma

SEARCH REPORT - PATENT Application No. PA 2016 00583 1. 1 1 Certain claims were found unsearchable (See Box No. I). 2. 1 1 Unity of invention is lacking prior to search (See Box No. II). A. CLASSIFICATION OF SUBJECT MATTER B 01 J 37/02 (2006.01); B 01 J 23/22 (2006.01); B 01 J 23/30 (2006.01); B 01 J 23/40 (2006.01); B 01 J 35/04 (2006.01) According to International Patent Classification (IPC) or to both national classification and IPC B. FIELDS SEARCHED PCT-minimum documentation searched (classification system followed by classification symbols) IPC/CPC: B01J Documentation searched other than PCT-minimum documentation Electronic database consulted during the search (name of database and, where practicable, search terms used) EPODOC, WPI, FULL TEXT: ENGLISH C. DOCUMENTS CONSIDERED TO BE RELEVANT Category* Citation of document, with indication, where appropriate, of the relevant passages Relevant for claim No. X, E WO 2017072138 Al (HALDOR TOPS0E A/S) 4 May 2017, see claims. 1-18 A US 2006035780 Al (XU et al.) 16 February 2006, see sections [0009]-[0011] and 1-18 [0014]-[0017], A US 2015375207 Al (CASTELLINO et al.) 31 December 2015, see section 1-18 [0019] - [0021], [0029] and claims. A US 2007209350 Al (JOHANSEN) 13 September 2007, see section [0023] and - example. A EP 0734756 A2 (TOYOTA JIDOSHA KABUSHIKIKAISHA) 2 October 1996, see claims. 1 1 Further documents are listed in the continuation of Box C. * Special categories of cited documents: P Document published prior to the filing date but later than the A Document defining the general state of the art which is not priority date claimed. considered to be of particular relevance. T Document not in conflict with the application but cited to D Document cited in the application. understand the principle or theory underlying the invention. Έ Earlier application or patent but published on or after the filing date. ^X Document of particular relevance; the claimed invention cannot be considered novel or cannot be considered to involve an inventive L Document which may throw doubt on priority claim(s) or which is _{when ώ document is taken alone}. cited to establish the publication date of another citation or other special reason fas specified⁵! Y Document of particular relevance; the claimed invention cannot be considered to involve an inventive step when the document is ”°” Document referring to an oral disclosure, use, exhibition or other combined with one or more other such documents, such ^means' combination being obvious to a person skilled in the art. Document member of the same patent family. Danish Patent and Trademark Office Date of completion of the search report Helgeshøj Allé 81 30 May 2017 DK-2630 Taastrap Denmark Authorized officer Vemer Holm Telephone No.+45 4350 8000 _Λ „„„ _Λ Facsimile No. +45 4350 8001 ^{1 ele}P^{hone No}· +^{45 4350 8354}

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SEARCH REPORT - PATENT Application No. PA 2016 00583 C (Continuation). DOCUMENTS CONSIDERED TO BE RELEVANT Category* Citation of document, with indication, where appropriate, of the relevant passages Relevant for claim No.

Search Report

SEARCH REPORT - PATENT Application No. PA 2016 00583 Box No. I Observations where certain claims were found unsearchable

This search report has not been established in respect of certain claims for the foiiowing reasons: !·□ Claims Nos.:

because they relate io subject matter not required to be searched, namely:

2. I I Claims Nos.:

because they relate to parts of the patent application that do not comply with the prescribed requirements to such an extent that no meaningful search can be carried out, specifically:

3. I I Claims Nos.: because of other matters.

Box No. II Observations where unity of invention is lacking prior to the search

The Danish Patent and Trademark Office found multiple inventions in this patent application, as follows:

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SEARCH REPORT - PATENT Application No. PA 2016 00583 SUPPLEMENTAL BOX Continuation of Box [.]

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