GB2078146A - An apparatus and a method for forming a substrate for a catalyst body, and a catalyst body formed from the substrate - Google Patents

Abstract

An apparatus for forming a substrate (30) for a catalyst body (10) comprises a slotted mandrel 21 into which the end of a metallic precursor 97 is inserted, a guide 50 through which the precursor 97 extends, and a shroud 28 about the mandrel 21 having a clearance slot 32 for the precursor 97. Rotation of the mandrel 21 winds the precursor 97 into a coil 30 inside the shroud 28. A ram assembly 75 of the apparatus may be used to push a split ring 14 about the coil 30 to prevent the coil 30 from unwinding. Alternatively, a circumferential weld (158) may be made around the coil 30 whilst the coil 30 is being rotated by the mandrel 21. The precursor may comprise separate plain and corrugated strips 11, 12 or may be a single strip plain for half its length and corrugated for the other half, the junction between the halves being located in the mandrel slot <IMAGE>

Description

SPECIFICATION An apparatus and a method for forming a substrate for a catalyst body, and a catalyst body formed from the substrate This invention relates to an apparatus and to a method for forming a substrate for a catalyst body for use in the catalysis of chemical reactions, and includes a catalyst body so formed and an application thereof.

In co-pending patent application No. 811 6839 there is described inter alia a device for use in the catalysis of a chemical reaction which comprises a container having a fluid inlet thereto and a fluid outlet therefrom; a plurality of discrete catalyst bodies randomly assembled within the container, each body having a plurality of internal channels of an ordered, pre-determined size and arrangement thereby to permit substantially unrestricted flow of fluid through the body, and each body carrying a surface coating comprising catalytically active material for the reaction.

The present invention therefore in a first aspect provides an apparatus for making a substrate for a catalyst body, the apparatus comprising, (a) a rotatable member having a longitudinally extending slot at one end thereof for locating therein a metallic elongate precursor for the substrate: (b) shroud means about said one end of the rotatable member and having at least one longitudinally extending slot for the passage therethrough of the precursor; (c) means for rotating the rotatable member so as to wind the precursor into a coiled body at least partially inside the shroud means; and (d) means for applying a securing means about the coiled body whilst the coiled body is restrained from unwinding by the shroud means.

The securing means may comprise a resilient clip or split ring, or may comprise a substantially circumferential weld around the coiled body.

Advantageously, the ram means includes a tubular mounting member co-axial with the shroud means and onto which mounting member the clip or split ring can be disposed, the mounting member being movable towards the shroud means so as to shroud a portion of the precursor at the other side thereof, and means for pushing the clip or split ring off the mounting member and on to the coiled body.

Feeding means may be provided for presenting a succession of the clips or split rings to the mounting member so that a said clip or split ring can be mounted on the mounting member by movement of the mounting member through the presented clip or split ring.

After removal of the coiled body from the apparatus of the invention, the surfaces of the body are arranged to be coated with a catalytically active material so as to provide a catalyst body.

The invention according to a second aspect includes a method of forming a substrate for a catalyst body, the method comprising, (a) forming an elongate precursor from a strip or strips of a metal adapted to carry a coating comprising a catalytically active material, at least a portion of the precursor having corrugations extending transverse to the length of the precursor; (b) introducing the precursor into a shroud means therefor, which shroud means extends at least partially across the width of the precursor, and winding the precursor into a tightly wound spirally coiled body, whereby the corrugations define in part a plurality of transverse channels through the coiled body, and (c) securing the outer end of the precursor to the coiled body whilst the coiled body is restrained from unwinding by the shroud means.

The precursor may be formed such as to provide a relatively plain portion thereof, and the precursor then wound so that the relatively plain portion and the corrugated portion are adjacent and substantially co-extensive in the coiled body so as to define the channels therebetween.

In one mode of said second aspect of the invention, the outer end may be secured by placing a resilient clip or split ring about the coiled body, but if desired other means of securing said outer end may be used, for example by welding a substantially circumferential weld around the coiled body whilst the body is rotated inside-the shroud means.

In a third aspect of the present invention, the invention provides a substrate for a catalyst body made by the method according to the second aspect of the invention, and further includes in a fourth aspect a catalyst body comprising a substrate of the third aspect of the invention to which a coating comprising a catalytically active material has been applied. The invention additionally includes an application of the catalyst body of the fourth aspect of the invention in the catalysis of a chemical reaction, the application comprising disposing a multiplicity of the catalyst bodies in a chamber, and passing a fluid comprising a reactant or reactants for the reaction through the chamber under conditions for the catalytically active material of the catalyst bodies to effect catalysis of the reaction.

The invention will now be further described by way of example only with reference to the accompanying drawings, in which~ Figure 1 shows a side enlarged view of a catalyst body; Figure 2 shows a view in the direction of arrow 'A' of Figure 1; Figures 3 to 6 show an apparatus at different stages of the operation thereof for forming a substrate for the catalyst body of Figures 1 and 2; Figure 7 shows a side view to an enlarged scale of a precursor for forming in the apparatus of Figures 3 to 6, and Figure 8 shows a perspective view of an alternative apparatus.

Referring now to Figure 1 and Figure 2, a catalyst body 10 is shown and comprises a plain strip 11 and a corrugated strip 12, which together provide an elongate precursor in the form of a composite member, spirally coiled together and restrained from unwinding by a resilient metal circular clip 14 about the coiled composite member. The strips 11, 12 define between them a plurality of channels 19 extending through the body 10.

The plain strip 11 and the corrugated strip 12 are each conveniently ~17 mm wide and 0.002 inch thick, and the body 10 I 7 cm diameter, and might comprise an aluminium bearing iron base alloy having a composition by weight of 10 to 30% Cr, 1 to 10% Al, O to 0.5% C, and the balance Fe, and sold under the UK Registered Trade Mark "Fecralloy". Where resistance to high temperature embrittlement is important, such a Fecralloy alloy may be made within the specification of a composition by weight of up to 20% Cr, 1 to 10% Al, 0.1 to 3.0% Y, and the balance Fe. However, where a degree of high temperature embrittlement can be tolerated, a higher chromium content of up to 25% by weight might be used.One particularly preferred Fecralloy alloy has a composition of 1 5.50 to 16.50% Cr, 4.6 to 5.6% Al. 0.3 to 1.0% Y, and the balance Fe.

The above-mentioned Fecralloy alloys may include additions of Co and/or Ni, and although these additions are usually limited to the range 0 to 3% by weight of each element, acceptable performance may still be achieved with the ranges extending to 5% of each element.

An example of an alternative alloy for the plain strip 11 and the corrugated strip 12 is that sold under the UK Registered Trade Mark "Kanthal DSD", a typical example having an approximate composition by weight of 22.5% Cr, 5%AI,2 2.0% Cho,0.1 C, and the balance Fe. For some applications, a plain strip 11 and a corrugated strip 12 of aluminium, stainless steel, or a high Ni content steel might be suitable.

The surface of the plain strip 11 and the corrugated strip 12 are provided with a catalytic coating (not shown), and this coating may comprise one or more transition metal elements or a compound thereof as the catalytically active material, for example Ni, a platinum group metal or V compounds, but the choice of catalytically active material is in practice determined to a large extent by the reaction to be treated by catalysis.

The catalytically active material is desirably supported by a ceramic coating (not shown), for example, a refractory oxide coating such as Al2O3, CeO2, Y203 and SiO2, and such ceramic coatings may be applied by methods known in the art, for example, as described in UK Patent Application No. 43435/75 (corresponding to West German Offenlegungsschrift 26 47 702).

Referring to Figures 3 to 6, an apparatus 20 is shown for forming a substrate 30 for coating to provide the catalyst body 10 of Figures 1 and 2.

The apparatus 20 comprises a mandrel 21 held at one end in a rotatable 3jaw chuck 22 and having at an end 23 thereof a diametrically extending slot 24. The mandrel is supported by an ejector 26 having a cylindrical bore 27 through which the mandrel 21 extends as a running fit and protrudes to expose the slot 24. The ejector 26 has one end supported inside a bush 28 in which the ejector 26 is a sliding fit, the bush 28 being rigidly held by a post 29 and having a longitudinally extending slot 32 at one side thereof extending for slightly less than half the width of the plain strip 11 or the corrugated strip 12.The ejector 26 is held near its other end by two diametrically disposed pegs 34 which locate in respective slots 36 (only one is shown) in a lever 38 which is pivotable about respective pegs 42 (only one is shown) protruding from a mounting 44, pivotable movement of the lever 38 causing longitudinal movement of the ejector 26 along the mandrel 21 and inside the bush 28. A guide 50 having a rectangular aperture 51 aligned with the slot 32 and through which the plain strip 11 and the corrugated strip 12 are to be fed together is supported by a post 52, and a chute 53 for collecting a formed substrate 30 is positioned below and at one end 23 of the mandrel 21.

A tubular magazine 55 extends from a feeding device 56 which comprises a housing 57 supported by an angle member 59 and having a rectangular cross-section aperture 58 therethrough. A slider assembly 62 extends through the aperture 58 being slidable therein, and comprises a frame 63 having a groove 65 for locating one of the clips 14 therein and providing a slideway for a flat push bar 64. In order to limit the relative movement between the frame 63 and the push bar 64, a lug 66 from the frame 63 extends into a groove 67 in the push bar 64. The magazine 55 holds a plurality of the clips 14 in abutting relationship, the clips 14 being biased towards the aperture 58 by a compression spring 69 retained at one end by an end cap 71.

A ram assembly 75 has a tubular member 76 that is aligned co-axially with the mandrel 21, the tubular member 76 having the same size bore as the bush 28 and a diametrically extending slot 77 at one side thereof aligned with the slot 32 in the bush 28. The tubular member 76 is slidably mounted on a rod 80 extending from a mounting 78, the rod 80 having a keyway 84 in which a key 82 from the tubular member 76 locates to prevent rotation of the tubular member 76. In order to support the free end of the mandrel 21, a diametrical flange 88 is positioned in the bore of the tubular member 76 near the slot 77 and has an aperture 89 in which the mandrel 21 is a running fit (see Figure 4). the tubular member 76 has a boss 79 from which two pegs 81 (only one is shown) extend diametrically to locate in respective slots 83 in a lever 85 which is pivotable about respective pegs 86 in a mounting 87 to move the tubular member 76 towards and away from the bush 28. A ram member 90 comprises a ram end 91 (not shown in Figure 4 for clarity) slidably mounted on the tubular member 76, and a rear support 92 slidably mounted on the mounting 78 and joined to the ram end 91 by a bar 93. A tension spring 95 extends between the ram end 91 and a lug 96 on the mounting 78 to bias the ram member 90 away from the mandrel 21.

In use of the apparatus of Figures 3 to 6, a plain strip 11 and a corrugated strip 12 are attached together as shown in Figure 7 to form a precursor in the form of a composite member 97 by a spot weld at 98 at one end of the corrugated strip 1 2 to expose a short portion 99 of the plain strip 11 approximately T inch long, the portion 99 then being softened by annealing at between 600 to 7000C so as to bend readily around the mandrel 21.

The composite member 97 is subsequently fed through the aperture 51 of the guide 50, and the portion 99 of the composite member 97 inserted in the slot 24. The push bar 64 is pulled to its full extent to load a clip 14 in the groove 65 and then pushed to its full extent to position the clip 14 coaxially with the tubular member 76. The tubular member 76 is subsequently moved towards the bush 28 by use of the lever 85 (see Figure 4), firstly to locate the clip 14 about the tubular member 76 as the tubular member 76 passes through the frame 63, the push bar 64 then being withdrawn, and finally to locate the slot 77 about the edge of the composite member 97. The chuck 22 is rotated so that the mandrel 21 winds the composite member 97 into a spirally coiled substrate 30 inside the bush 28 and that portion of the tubular member 76 about the composite member 97.The chuck 22 is stopped and the ram member 90 moved towards the bush 28 so as to push the clip 14 on the tubular member 76 onto the coiled substrate 30 (see Figure 5) which is then ejected out of the bush 28 by movement of the ejector 26 (see Figure 6) so that it falls into the chute 53.

The length of the composite member 97 and the internal diameter of the bush 28 are matched so that the composite member 97 is tightly wound inside the bush 28.

A plurality of substrates 30 formed in the apparatus 20 of Figures 3 to 6, may have catalytically active material applied to them by methods known in the art, for example by solution impregnation followed by decomposition, or by sputtering, plasma spraying, vapour deposition, or sintering. An optional ceramic coating may be applied either before or during the application of the catalytic coating, for example by contacting the substrates 30 with a dispersion in a liquid medium convertible on subsequent drying and firing into a ceramic, followed by the drying and firing thereof.

In one example of the provision of a catalytic coating about and inside a substrate 30, a plurality of substrates 30 after forming in the apparatus 20 were degreased and pre-oxidised by heating in air at 10000 C. Two hundred such substrates 30 were then placed in a tray and coated with alumina by contacting them with a wash-coat comprising an alumina sol (60 g/l of Al203) into which commercially available, non-dispersible alumina particles (200 g/l) had been stirred, followed by drying at 10000 and firing at 60000. The alumina had been prepared as described in our UK Patent Application No. 43435/75 (corresponding to West German Offenlegungsschrift No. 26 47 702), thus, alumina which had been prepared by a vapour phase condensation method, such as flame hydrolysis, was formed into the sol by admixture with water. This alumina coating process may be repeated if a thicker coating is desired, and coatings of thicknesses up to about 100 microns can be achieved.

The alumina coated substrates 30 were then provided with a NiO coating as a catalytically active material by contacting these substrates 30 with a solution of Ni(NO3)2, followed by drying and firing to convert the salt into the oxide which can be subsequently reduced to the catalytically active material Ni e.g. in situ.

An alternative way of providing the substrates 30 with catalytically active material is to coat the substrates 30 with a sol containing Ni compounds followed by drying and firing, and ultimately reduction.

The resulting catalyst bodies 10 formed from the substrate 30 may be disposed in a chamber (not shown) having an inlet and an outlet, to give a catalyst device that is highly satisfactory for steam reforming and methanation. The reactants enter the catalyst bodies 10 via the channels 19 and pass along the channels 19 where they contact the catalytically active material which catalyses the chemical reaction. The products of the chemical reaction subsequently flow out of the channels 19 and leave the chamber through the outlet.

Although the invention has been described in relation to the forming of a precursor comprising a relatively plain portion and an adjacent corrugated portion, the precursor might comprise adjacent portions each having corrugations at a slight helical angle (e.g. of about 50) to prevent nesting together of adjacent corrugations.

An alternative apparatus for forming a catalyst substrate is shown in Figure 8 to which reference is made. In Figure 8 an apparatus 110 is shown which comprises a rotatable spigot 111 projecting at one end from a rotary drive unit 112, and having at an end 11 3 a diametrically extending slot 114. An ejector 11 6 about the spigot 111 is actuated by a pneumatic cylinder 117 to move towards the end 113 through a shroud 119 about the spigot 111, a collecting chute 128 being positioned in front of the shroud 11 9. The shroud 119 defines a diametrical gap 122, and has a radially extending aperture 124 through which a welding beam (shown as a broken line) from a laser welding device 126 can be projected.

Opposing rolls 132,134 have a portion 136 of the circumferences thereof shaped to define interengaging shaped corrugating teeth 138a, 1 38b and have a plain portion 1 40a, 1 40b arranged to grip a metal strip 142 therebetween.

Opposing shears 1 44a, 1 44b are mounted in the rolls 132. 134 respectively, and the rolls 132, 134 are arranged to be driven through a gear train 146 from a rotary drive unit 148 which drives a driver gear 1 52 of the gear train 146.

In operation, the metal strip 142 in passing through the rolls 132. 134 is partially corrugated by the teeth 1388. 7 386 and eventually severed by the shears 1 44a, 1 44h to provide a precursor 1 55 which is fed through the gap 122 and the slot 114.The spigot 111 then rotates and winds the precursor 155 into a tightly wound spirally coiled body 156 inside the shroud 11 9 around which a circumferential weld 158 is made by the laser welding device 126 whilst the coiled body 156 is still rotating, the coiled body 156 then being ejected from the shroud 11 9 into the chute 128 by the ejector 11 6. As the precursor 155 is held at an intermediate position by the spigot 111, the precursor 155 is wound with the corrugated portion 154 and the unworked portion thereof adjacent and co-extending through the coiled body 156 so that a plurality of channels 160 are defined through the coiled body 1 56. It will be understood that guides (not shown) may be provided between the rolls 132, 134 and the shroud 119.

If desired the plain portions 140a,140b of the rolls 132, 134 may have fine indentations (not shown) to provide a roughened surface on the corresponding plain portions of the precursor 1 55 to act as a key for subsequent coatings. These indentations may for example be fine corrugations (e.g. about .003 inches deep), but nonetheless the plain portions 1 40a, 1 40b are relatively plain in comparison with the corrugating teeth 1 38a, 1 38t which may be shaped for example to provide corrugations of about 1.112 mm depth and might be angular, for example having an included angle of about 900. For some applications a coiled body 156 of about 17 mm diameter might be appropriate although other sizes may be selected, for example down to about 8 mm diameter. A convenient width of the strip 142 might also be 17 mm to provide a right circular coiled body 1 56. In some of the coiled bodies 156 between 400 to 4 channels 160 might be defined per sq cm of transverse crosssection of the coiled body 1 56, although from 200 to 25 channels 160 per sq cm is a preferred range.

As an alternative, the spigot 111 might be dispensed with and a metal rod (not shown), for example of the Fecralloy alloy used instead, the centre of the precursor 155 being spot welded by the laser welding device 126 to the rod. The precursor 155 is then wound into a coiled body on the rod and circumferentially welded by the laser welding device 126, any projecting ends of the rod subsequently being removed.

Claims (31)

1. A method of making a substrate for a catalyst body, the method comprising, (a) forming an elongate precursor from a strip or strips of a metal adapted to carry a coating comprising a catalytically active material, at least a portion of the precursor having corrugations extending transverse to the length of the precursor; (b) introducing the precursor into a shroud means therefor, which shroud means extends at least partially across the width of the precursor, and winding the precursor into a tightly wound spirally coiled body, whereby the corrugations define in part a plurality of transverse channels through the coiled body, and (c) securing the outer end of the precursor to the coiled body whilst the coiled body is restrained from unwinding by the shroud means.

2. A method as claimed in Claim 1, wherein the precursor is formed such as to provide a relatively plain portion thereof, and the precursor is wound so that the relatively plain portion and the corrugated portion are adjacent and substantially co-extensive in the coiled body so as to define the channels therebetween.

3. A method as claimed in Claim 1 or Claim 2, wherein the outer end is secured by placing a resilient clip or split ring about the body.

4. A method as claimed in Claim 2, wherein the outer end is secured by welding a substantially circumferential weld around the body whilst the body is rotated inside the shroud means.

5. A method as claimed in Claim 2 or Claim 4.

wherein the precursor is formed by feeding a continuous plain strip of the metal through revolving opposing rolls, the rolls having interengaging circumferential corrugating portions thereof and relatively plain circumferential portions thereof, and having circumferentially disposed shearing means for severing a said precursor so formed from the strip.

6. A method as claimed in Claim 5, including introducing the precursor diametrically across the shroud means and then winding the precursor at an intermediate position thereof.

7. A method as claimed in Claim 6, including welding the precursor at said intermediate position to a metal rod, and rotating the rod to wind the precursor into said coiled body about the rod.

8. A method as claimed in Claim 2, wherein the precursor is formed by welding together near one end thereof a relatively plain strip of the metal and an adjacent substantially co-extensive corrugated strip of the metal, the one end of the relatively plain strip extending beyond that of the corrugated strip, and the precursor being wound so that said one end constitutes the inner end of the precursor in the coiled body.

9. A method as claimed in Claim 8, including introducing the one end of the plain strip partially into the shroud means and then winding the precursor at or near said one end.

10. A method as claimed in any one of the preceding Claims, wherein the corrugations are about 1.125 mm deep.

11. A method as claimed in any one of the preceding Claims, wherein the corrugations are substantially of angular form.

12. A method as claimed in any one of the preceding Claims wherein the corrugations at least in part are part-circular in form.

13. A method as claimed in any one of Claims 2, or 4 to 9, wherein the relatively plain portion comprises a surface roughened to provide a key for the coating.

14. A method as claimed in any one of the preceding Claims, wherein the precursor is formed to provide a coiled body of between 8 to 17 mm diameter.

1 5. A method as claimed in any one of the preceding Claims, wherein the precursor is formed to provide about 400 to 4 channels per sq cm of transverse cross-section of the coiled body.

16. A method as claimed in Claim 15, wherein the precursor is formed to provide about 200 to 25 channels per sq cm of transverse cross-section of the coiled body.

1 7. A method as claimed in any one of the preceding Claims, wherein the precursor comprises a metal strip or strips comprising an aluminium bearing iron base alloy.

18. Apparatus for making a substrate for a catalyst body, and comprising, (a) a rotatable member having a longitudinally extending slot at one end thereof for locating therein a metallic elongate precursor for the substrate; (b) shroud means about said one end of the rotatable member and having at least one longitudinally extending slot for the passage therethrough of the precursor; (c) means for rotating the rotatable member so as to wind the precursor into a coiled body at least partially inside the shroud means; and (d) means for applying a securing means about the coiled body whilst the coiled body is restrained from unwinding by the shroud means.

19. Apparatus as claimed in Claim 18, wherein the means for applying the securing means comprises ram means for pushing a securing means in the form of a resilient clip or split ring about the coiled body.

20. Apparatus as claimed in Claim 19, wherein the ram means includes a tubular mounting member co-axial with the shroud means onto which mounting member the clip or split ring can be disposed, the mounting member being movable towards the shroud means and adapted to shroud a portion of the coiled body, and means for pushing the clip or split ring off the mounting member and on to the coiled body.

21. Apparatus as claimed in Claim 20, including feeding means for presenting a succession of the clips or split rings to the mounting member so that a said clip or split ring can be mounted on the mounting member by movement of the mounting member through the presented clip or split ring.

22. Apparatus as claimed in Claim 18, wherein the means for applying the securing means comprises means for applying a substantially circumferential weld about the coiled body whilst the coiled body is being rotated by the rotatable member, the weld comprising the securing means.

23. Apparatus as claimed in Claim 22, further comprising two opposing rolls for forming the precursor from a continuous strip of the metal, each roll having a portion of the periphery thereof provided with corrugating teeth to engage corresponding teeth in the other roll and having a relieved portion for defining a space between the other roll whereby alternate relatively plain portions and corrugated portions of the strip are provided on the strip being passed between the rolls.

24. Apparatus as claimed in Claim 23, wherein a means for shearing the strip is provided at the peripheries of the rolls, the diameters of the rolls being selected in relation to the shearing means so that a required length of the precursor is cut from the strip passing between the rolls.

25. Apparatus as claimed in Claim 23 or Claim 24, wherein the relieved portions of the peripheries of the rolls have a roughened surface to produce a correspondingly roughened surface on the relatively plain portions of the precursor.

26. A method of making a substrate for a catalyst body substantially as hereinbefore described with reference to Figures 1 to 7, or to Figure 8 of the accompanying drawings.

27. Apparatus for making a substrate for a catalyst body substantially as hereinbefore described with reference to Figures 1 to 7, or to Figure 8 of the accompanying drawings.

28. A substrate for a catalyst body made by the method as claimed in any one of Claims 1 to 17 or Claim 26.

29. A catalyst body comprising a substrate therefor as claimed in Claim 28 to which a coating comprising a catalytically active material has been applied.

30. A catalyst body as claimed in Claim 29, wherein the coating includes a support comprising a ceramic coating for the catalytically active material.

31. An application of the catalyst body of Claim 29 or Claim 30 in the catalysis of a chemical reaction, the application comprising disposing a multiplicity of the catalyst bodies as claimed in Claim 29 or Claim 30 in a chamber, and passing a fluid comprising a reactant or reactants for the chemical reaction through the chamber for the catalytically active material of the catalyst bodies to effect catalysis of the reaction.