DE2360266A1 - FULL METAL CATALYST ELEMENT - Google Patents

Description

DB.-ING. DIFL.-ING. M.SC. -1PL.-PKVS. OR. . OIPL.-PHYS.

HÖGER - LEGAL RIGHTS - GRIESSBACH - HAECKER

PATENT LAWYERS IN STUTTGART

A to 195 b

k - 163

August 28, 1973

Universal Oil Products Company

Ten UOP Plaza

Algonquin & Mt. Prospect Roads

Des Piaines, Illinois 60016

UNITED STATES.

Full metal catalyst element

The invention relates to a full metal catalytic converter element for converting combustible constituents with a gas flow a carrier made of a heat-resistant alloy and with an activated coating of at least one platinum metal.

All-metal catalysts are generally used in catalytic Combustion of harmful gases or vapors is of particular benefit, as is the case with various industrial processes occur, e.g. in ovens for drying or burning Enamel, lacquer or other materials for coating surfaces. In addition, all-metal catalysts are increasing Scope for the catalytic conversion of harmful components

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BAD ORiGiMAL

A ¹ ^ o 195 bk - 163

August 28, 19 7 3

the exhaust gases from turbines as well as diesel and gasoline engines .

In all of these applications it is important that the catalyst material has the largest possible catalytically active surface per unit volume. To achieve a possible large surface area has already been proposed as catalyst material, catalyst elements in the form of spheres or pills Or to be provided in the form of crimped strips and a large number of such catalyst elements in boxes - or frame-shaped catalyst units with permeable wall areas to be arranged on the inlet and outlet side in the gas stream to be cleaned.

Proceeding from this prior art, the present invention was based on the object of providing a new type of form To propose catalyst element with improved catalytic effect.

This object is solved by an all-metal catalyst element of the initially described type, which is characterized in that it is formed X-shaped _wenf 3 _e.

Such a full metal catalyst element can be used with particular advantage for the catalytic conversion of the harmful Components of the exhaust gases from ovens and internal combustion engines insert. In addition, catalyst elements are in accordance with of the invention particularly suitable for combining hydrogen and oxygen in exhaust gases, as for example in Nuclear power plants arise because they can be easily removed from the catalyst units and replaced.

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BATH ORIGINAL

It was found that all-metal-1 catalysts compared to certain other catalysts which have a support made of an inorganic oxide or a ceramic material,
have certain advantages, since they withstand fairly high temperatures - and at the same time can also be used where moisture can be present, since their effect is not impaired by moisture. In connection with the present invention, there are also various advantages with regard to the pourability and the exchangeability of the helical catalyst elements. Will this
for example for the catalytic treatment of exhaust gases from
Nuclear power plants are used, so it is of advantage ₅ that the
small helical catalyst elements easily into the
Catalyst units can be filled and are able to present a large catalytically active surface in the interior of relatively small housing, so that an improved catalytic effect is achieved with smaller catalyst units. In fact, the small helical catalyst elements can be filled into the containers of the catalyst units
and are poured out of these in order to replace them, as is also possible with the pill-shaped catalyst elements. On the other hand, in the case of the helical catalyst elements, there are never any problems with regard to abrasion and the
Breaking, as is the case with pill-shaped catalyst elements and the helical catalyst elements according to FIG. The present invention also prove to be more resistant to thermal shock. Some of these benefits
can also be achieved with the known mat-shaped catalyst units made from crimped strips, but on the other hand it is always necessary to replace the catalyst elements designed as crimped strips, the housing or the
Completely dismantle the support structure of the catalytic converter unit.

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It was previously suggested in U.S. Patents 2,658,742 and 2,720,494 for treating noxious gases and vapors Vollirietall-Katore lemente to use, wherein the patents mentioned also disclose processes for producing such catalyst elements. The advantage of catalytic combustion of volatile combustible components from industrial processes is of course reduced Heat demand and in the large, related, annual fuel savings that lead to higher Quickly amortize installation costs. With a purely thermal combustion of the harmful components of a Gas flow, for example, a temperature between about 59 3 ° C and about 816 ° C may be required while on the other hand catalytic combustion at an inlet temperature between about 316 ° C and about 371 ° C. The fuel savings are obvious.

In any case, it can be regarded as a significant advantage of the present invention that it provides a small, helical all-metal catalyst element for use in a Suggests bed of catalyst elements in which at one given volume, a large calatytically active surface can be achieved.

Furthermore, it is an advantage of the present invention that it proposes an all-metal catalyst element, wherein the Catalyst unit a large number of actively coated elements and each element consists of a small diameter wire wound into a helix and a short one Has length so that the plurality of elements can be treated as one mass, in the sense that the catalyst elements can be poured into and out of a container.

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The invention thus leads to a full metal catalytic converter unit for converting the combustible components of a gaseous flow, the catalytic converter unit having a large surface area per unit volume and being limited by spaced apart perforated holding devices through which the gaseous flow can be passed and between which there is a plurality of catalytically coated very small _w endeIförmigen catalyst elements is, each comprising a high temperature resistant alloy has as a carrier, so that the coil-shaped catalyst elements on the one hand have a large active surface which can be the other hand, used at high temperatures, and finally through a small opening between the mounting means or can be poured into and out of the catalyst unit.

The base materials used in the known types of Kata-. used for the precious metal coating consisted of various special alloys with a high nickel content, such as nickel-chromium and Nickel-chromium-iron alloys, such as those commercially available under the brand names "Chromel", "Nikrothal" and "jp.chrome" are. These alloys had stainless steel grades compared to the common and more widely used types of stainless steel lower nickel content the desired properties, namely a high thermal and electrical resistance. However, recent developments have now shown that with regard to For improved economy and other advantages, a nickel-free alloy can be used as the base material can, which consists essentially of iron, * chromium and aluminum and which has a high temperature resistance.

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BATHROOM ORIGINAL ¹

Such alloys are, for example, under the trademark "Kanthai" and "Alkrothai" in stores.

As with mats made from crimped strips of catalyst material, which are arranged between grids can also be used when using smaller coils or helicals Catalyst elements built from a wire of small diameter between holding grids of larger catalyst units which in the plane of the gas inlet opening has an area of several square feet. The housing for the helical Catalyst elements can in turn be arranged edge to edge in order to form a catalyst wall with which an exhaust gas flow or a certain reaction flow is brought into contact.

Although no exact scientific clarification has yet been found it appears that, despite the use of the same cleaning and separation processes, when coating or Electroplating of the small helical catalyst elements as when coating strip-shaped base material and despite " Applying the same activation process for the helical catalyst elements per unit surface area a little greater activity is achieved.

Before the precious metal coating is deposited, a torture should be carried out of the metal with a strong detergent or other suitable fat-dissolving substance. Following a Cleaning and rinsing are also preferably carried out by gently etching the metal until the surface of the base material has become dull or porous to a certain extent. The etching can take place, for example, with a hydrochloric acid solution or with a hydrochloric acid solution in the presence of chlorine iron oxide. The etching process can then be followed by a further rinse in water or a mild detergent,

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BATH ORIGINAL

in order to prepare the base material for the deposition of a metal of the platinum group. The platinum, the palladium or a mixture of metals of the platinum group can then be deposited on the base material by dip plating or by electroplating to obtain a uniform layer of the desired metal or the getfünsch + s metal of the entire surface of the base member. a peeignete Platt j ei ~ 7ösun $ r are obtained when SPFE Lsw & i se by a balzsäurelösung P] a ti nchlorid bcifj it In this The helical bases, which are located in a basket, are then immersed in the liquid solution, whereby they are connected to the negative pole (cathode) of the electroplating device. Carbon rods can be used as positive electrodes or anodes Plating process is carried out for a long enough time to achieve a coating of about 0.1 Tr ^: to maintain strength. In general, the plating time will be less than about 5 minutes. The plating process should also be carried out so as to avoid the evolution of hydrogen in the plating solution, which is normally heated to a temperature between about 71 ° C and about 82 ° C.

Following the plating of the helical base elements the same is then rinsed and dried before conditioning or activation of the precious metal surface of the ■ coated elements takes place. The conditioning or Activation can be done in a number of ways. However, the activation is preferably carried out in the same way as in the crimped ribbons for mat-shaped catalytic units, i.e. by placing the elements at a high temperature in the area between about 482 C and about 538 C in direct contact with the hot exhaust gas flow from a Burner and in the presence of naphtha or hexane vapors, which the hot exhaust gas flow between the flame of the burner

409845/1062 ORIGINAL BATHROOM

und'dem coated element are supplied. This treatment or conditioning leads to a "preactivation" of the whole batch of elements, with the correct sequence of the Pre-activation during this temperature treatment can be easily monitored by paying attention to when the Spread of a bright red glow over the entire surface and through the material of the elements. The surface of the Elements obtained in this process step is blunt and generally dark in color and possessing some porosity and considerable surface area of "active" Centers "after cooling down.

In general, the catalyst elements are subsequent to the Activated cleaning, electroplating and conditioning and can be sold or used. In certain cases, however, it is desirable to have the elements with a stronger To provide Edelmetallbeschxchtung and thus an increased service life of the same when oxidizing the combustible components to get from exhaust gases. In these cases, a new or second coating can be carried out using the application the same electrodeposition process described above, the second being Once coated elements are then also rinsed, dried and conditioned again as described above. It has also proven beneficial to circulate the plating solution through a bed of cation exchange resin leaves to remove dissolved cationic impurities originating from the base metal and thus become one better controlled plating process. Normally one would expect the plating process to be cationic. However, since no precious metals are removed from the plating solution as it passes through the bed of the cation exchange resin, it appears that the plating is done anionically. the

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2330266 Si

Solution can be used as an effluent through the cation exchange resin be directed; but it is also possible to circulate the entire solution through the cation exchange resin or let the solution circulate for a given time. The acidic cation exchange resin can be sulfonated A mixed polymer of styrene and Diviny'lbenzol or, for example, a commercially available cation exchange resin, such as it is, for example, commercially available under the brand name "Dowex 50 W", namely in pearl or spherical form.

Different types can be used for different oxidation processes used by coatings. For example, platinum or palladium alone can be used in certain combustion processes Blends may be beneficial in other cases, while blends are beneficial of platinum and palladium can be used. In general, mixtures of platinum and palladium give a better one Adhesion of the coating to the base metal and better Resistance to extremely high temperatures. In still other cases it can be platinum, palladium or a Mixture of these two metals, for example ruthenium, thor, iridium or another metal of the platinum group in small amounts Quantities are added. If an additional metal component is desired in the noble metal coating, the plating solution can be used the corresponding metal salt can be added, so that a corresponding alloying or admixture of the desired Metal component generated in the electroplating surface will. In general, the plating solution is formulated to provide a layer thickness under the appropriate working conditions of about 0.1 mm in a period of 5 minutes or less.

Further details and advantages of the invention are provided below explained in more detail with reference to a drawing and / or are the subject of the protection claims. In the drawing show:

- 10 -

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Figs. 1 and 2 enlarged representations of spiral-shaped Catalyst elements according to the invention with different dimensions j

3 shows a modified embodiment of a catalytic converter element according to the invention with rectangular Helical turns;

Fig. K. an Arrhenius diagram comparing the

Reaction rate constants for catalyst elements according to the invention and for mat-shaped catalysts made from crimped ribbons and

5 is a diagram comparing the conversion when recombining hydrogen with oxygen for helical catalyst elements according to the invention and mat-shaped catalysts curled ribbons.

From Figures 1 to 3 of the drawing, which enlarged Dar-. Positions of different execution forms of catalyst elements show according to the invention, it becomes clear in what way the small helical catalyst elements relate to their shape, diameter and length can be changed. It is known that the catalyst elements according to FIG 2 both have circular helical turns, but different dimensions, while the element according to FIG. 3 is rectangular Has helical turns. The helical catalyst elements are normally made from a wire of a suitable type Alloy made in the same way as coil springs and each have several helical or helical turns. In particular, the helix turns can be circular, oval, rectangular, etc., and it is not intended that the invention be to be limited to any particular shape of the helical turns.

- 11 -

409845/1062

There is also the possibility of using the helical catalyst elements by extruding a suitable alloy by means of a hollow helical shape rather than making them by winding a previously straight wire onto a core. So the term "helical" comes with others Words in the present application have a very general meaning to and it should encompass any small helical structure. In the same sense, the expression "screwdriver-shaped" is also used used, which is intended to capture generally helical structures, as they are by winding a wire on a oval or rectangular core can be obtained, wherein the resulting elements are not always exactly circular. It should also be pointed out that the dimensions given in the description and the drawing apply only to the exemplary embodiments and that the invention does not apply to these dimensions is limited. On the other hand, however, it has been shown in the course of tests that none of the specified dimensions Nesting of the helical catalyst elements takes place, which leads to the filling and pouring of the catalyst elements into or out of the catalytic converter unit is made more difficult or prevented. This applies to all species of housings, especially for those with grid-shaped holding devices.

At this point it should also be pointed out that depending on the desired. Method of making the small V / end-shaped catalyst elements, the helical windings formed in this way that neighboring turns touch each other. However, it is considered more favorable if the helical turns do not touch and if their distance is smaller than D (see Fig. 1 and 2), i.e. 'smaller than the strength or, the diameter of the wire used, so that prevents The strength of the wire made of a metal alloy can be that the individual coils nest inside one another

- 12 -

409845/1062

typically between US wire sizes 30 and 40, respectively. at diameters ranging from about 0.127 mm to about 0.381 mm. Ls is also desirable that the hardness of the used Wire is sufficiently large, so that a simple bending or deformation of the vendular elements is prevented which could otherwise lead to the Bend helical elements around each other, which could lead to irregularities in the packing density. As mentioned above, the wire or the alloy for the helical catalyst elements by extrusion and simultaneous Generating the helix shape so it is not intended to be typical with the term "wire" to capture prefabricated wires, which are only then converted A small core or mandrel can be wound to obtain the specific size or shape of the finished helical elements.

For a series of tests, in which a mixture of hydrogen, oxygen, steam and air was used as the simulated "pecombination" gas, small helical catalyst elements of two different sizes were made up of 6.35 cm long pieces of wire made of Chromel D, an alloy A of the following composition 'tion: 36% Ni, 18% Cr, Eest Fe, as it is, for example, commercially available under the brands, produced with a diameter of o ^ 2032 mm and the results obtained with these catalyst elements were compared with the results obtained with a commercially available one Mat were made from curled ribbons. The ribbons were also made of alloy A with a width of about 1.6 mm and a thickness of about 0.17 mm and were curled into a small plug-shaped mat that was about 4.78 cm in diameter and about 3 cm deep , 18 cm. To hold the small helical catalyst elements, small wire baskets were used, which consisted of D-wire of the alloy Λ with a mesh size of 4 (16 mesh), the diameter of the basket being about 4.78 cm and the depth about 3.18 again cm. I _n a case had the helical catalyst

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elements were about 3.81 mm in diameter and about 1.57 mm long. In another case, the helical ones possessed Catalyst elements were about 1.90 mm in diameter and about 3.81 mm long. The wire baskets took hold of the Catalyst elements with a diameter of 3.81 mm an amount of about 3 2 grams and of the catalyst elements with 1.9 mm in diameter, an amount of about 50 grams The mats and baskets were all electroplated applied coating and were activated by the same process, making them a porous spongy coating possessed of palladium and platinum.

The test reactor was about 5.08 cm in diameter and consisted of a stainless steel tube of type 316, -Mr. 10. In addition, electrical heating and insulation were provided on the outside to keep things different in the reactor Generate temperatures. Thermocouples were also connected to the reactor to "control inlet and outlet temperatures." measure up. The inside of the peactor tube was used to accommodate the Catalyst units with a diameter of about U, 78 cm, and one mat or one cup was tested in each trial.

Regarding the surface of the examined catalyst elements it should be noted that the reference unit (made of crimped

2 3 system) had a surface area of about 10.11 cm / cm, while in the case of the basket with helical catalyst elements with a diameter of about 3.81 mm the surface about

2 3
Was 16.92 cm / cm and for the basket with helical catalyst elements about 1.9 mm in diameter

2 3
24.79 cm / cm. The surface areas per unit volume therefore behaved in the case of the mat-shaped catalyst element and the larger and smaller helical catalyst elements

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something like 1: 1.67 and 1: 2.45.

Tables I ₅ II and III (see pages 17-19) show test results for various tests which were achieved with a _{flow containing H 9} and O 2, which also contained some steam and air. (Specifically, the steam accounted for about 99 mol%, the hydrogen (H) about 0.50 mol%, and the oxygen (O ₂ ) about 0.2H7%, while the air was about 0.330 Kcl%. of the entire flow.)

In order to enable a better comparison of the reading results, Fig. H of the drawing shows an Arrhenius diagram with falling lines to illustrate the calculated reaction rate constants, with the peak velocity constant above the reciprocal average

5 o -1 temperature T or above 1.25 / Τ _β χ 10 (C) is plotted., Ilan recognizes in Fig. M- that the test results were approximately the same at temperatures above about 163 ° C, although about 5G % more catalyst material was contained in the basket with the helical catalyst elements with a diameter of approximately 1.9 mm. Furthermore, when compared with the results obtained with the conventional hat made of crimped edges, it can be seen that the results with the small helical elements were about 2.5 times better. This result could be expected from a comparison of the surfaces, since the surface of the helical small diameter catalyst elements was about 2.5 times larger than the surface of the mat-shaped catalyst element. With regard to the helical catalyst element with a larger diameter, however, there is an unexpected improvement in performance, since the performance here is still 2.5 times better, while the surface area was only about 1.6 times as large in comparison with the card-shaped catalyst element.

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BAD ORiGiNAL

I _n a further series of tests was a mat-shaped catalyst unit having a diameter of about 4.7 8 cm and a height of about 3 cm from Chrome1 IS D-tape having a width of about 1.59 mm, and uses a thickness of about 0.127 mm , Which

2
had a surface area of about 5 23 cm , and this had been compared to catalyst units which contained helical catalyst elements of the type described above, ie catalyst elements with a diameter of about 0.19 mm and about 3.81 mm. In all cases such an amount of helical catalyst elements was used per catalyst unit that the same upper

2
area of 523 cm.

In all experiments, the total gas flow through the catalyst bed was in each case about 0.502 πΓ / min and the nominal The composition of the gas batch was as follows:

Steam = 98.92 1-1% ^H 2 ⁼ 0.50 Mol% ° 2 ⁼ 0.25 Col-% Air = 0.33 Iiol% total 100.00

Furthermore, each catalyst unit was at five different Checked inlet temperatures between about 149 ° C and about

3 71 C.

The test results are summarized in Table IV below and shown graphically in Figure 5 of the drawing (see page 20).

- IG -

409845/1062 ORIGINAL BATHROOM

A review of the data recorded in the tables and inspection of the graphs of this data shows that. the two catalyst units with the small ones helical catalyst elements according to the invention, a have higher catalytic activity than did the curled ribbon. It also shows that the helical Elements with a smaller diameter produce slightly better results than those with a larger diameter. At this point in time it is not entirely clear why better activity is obtained with the smaller diameter elements, especially as in both Cases the same nominal surface is present and coating and activation take place in identical process steps. In any case, it would appear that the advantages in terms of catalytic! Activity one way or the other Way from the geometric differences in the shape of the helical elements according to the invention and also from the pourability soi / ie from the possibility of to achieve a high total surface area of elements per unit volume in a given catalyst unit.

At this point it should be pointed out again that the experiments presented in connection with the above The sizes and shapes indicated are not intended to limit the present invention in any way. Rather, the invention is generally seen in the new spiral shape of the catalyst elements. In particular, it can be assumed that the Dimensions of the helical catalyst elements with respect to their diameter and length are not always below of about 0.635 mm, as larger dimensions can be advantageous to a given surface area and to obtain a predetermined pressure drop in a special catalyst unit, which has a plurality of helical Contains catalyst elements.

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BATH ORIGINAL

vt O O ro UO in 00 1-1 τ-Λ cn O r O r-- ro nt UJ O) CO cn JX vH O) •H O

nt O Lf) LO CNl CD

O LO LO Γ- ro cn

co • c- CO CT) co. σ> O OI O σι

ZT C - CO

nt

C--

Ε4 ■ · egg τΗ τ-Ι Il CO · ■ (U OO -μ
4-> (Ü rtJ
>, ϋ —J -μ tsl • rl ti to M. • rl ( ¹ y c; OJ 4-> 4-> 1-1 rH γ-Ι (U Z- " ω t- ^: X ^ Xi Q) Sh <ύ ■ Η (U H (U > Sh C. O Q) -μ , C U cn > v
rH ι—
Mh Sh ■ μ QJ

CO

T-I

Γ Currently ΟΟ C-- vH O σι r cn O CSi co Γ- OO OI rt cn cn O cn O

OO OO C-- r- Γ- rv OO Ü) TH Oil I.

to CSl OO O O CT) T-H CT) W. O CO O) OO LO OO Oil vH cn O O

r. CL) C- Γ- CO O Currently -H

LO C - CO

C-- Zt Zt

O Ou

JX

CO

C--

JX

co O

U) -μ ü - I.
cn Q) Ή O ι ί-ι C. ■ Η Q) -μ
• Η μ I. Q) ω (U CO Q) C. ω ■ μ + -> N N rti + -> approx • μ ω + -> • Η Sh Q) • Η I. • Η cn ς: Q) - ^ cn Q) cn XS Q £ t Yes C. C. O ο β X \ ΓΖ) in O • rl U) Q) U (U •H Xi + -> . > , C υ cn ^ Ü Sh Sh rö ω 3 Q) O) O) ι-5 > ho

2

Δ09845 / 1062

BATH ORIGINAL

3 q 5 76 1 0 7th 0 Q 4M 2 G 11 78 9 ^Q. , 88 0, 9, 3 3 99, 88 α.α
.jo, 77 Γ.
- 5th Oil C06C- Cl , 009909 , 015 Cl

Table II

_o Catalyst elements with approx. 1.9 nc ί

Surface ratio to mat = 1: 2.45

oo '

"^ Experiment No. 1

O cn conversion % 99.80

OI ^s «*

Dwell time 0.013 86 9

Q. (sec)

f ^ 'reaction

speed constant

, K (sec- ¹ ) 448.4 673.5 ', 437.3 685.5 329.05 420.0

Average ■ ■ U)

temperature CD

fO _r \ 1OG2.5 1472 1075. 1478 925 1025.6 ο

^{c UJ} κ?

Table III

Mat with curled ribbons

O CD CO

Inlet temp. ( ⁰ C). 111.8 conversion % .97.25

Dwell time (sec)

Reaction

speed

constant

K (see ^-1 ) 110.2

Average temperature

( ⁰ C) 899.4

188
, 27

285
, 56

296
99, 24

371 99, 72

,8th

, 2

1075.6 1290

219, 1

374 99.74

0.03757 0.02794 0.02330 '0.02227 0.02002 0.02053

293.9 291.5

1315.6 1U79.4 1487.5

CO CTJ

Table IV

Attempt no. H concentration K "concentration
at the exit implementation Average catalyst at the entrance Mole ppm in % temp. T ₀ in ° C Type O Mole ppm co co 102 JN 1 4970 62 97.95 160 cn 2 4950 49 98.75 215 * · «, 3 5020 39 99, 02 269 mat ο 4th 5000 33 99, 22 324 cn 5 4920 99, 33 3 80 ro 16.3 6th 4920 11.0
10.1
9.8 99, 67 165 7th
8th
9 4880
4950
49 70 8.2 99.77
99, 80
99, 80 220
275
332 1.9 mm 0
helical
elements 10 4970 25, 5 99, 84 387 11 4830 14.4 99, 47 163 12th 49 70 12, 5 99, 71 216 3, 81 mm 0 13th 4970 12.4 99, 75 275 turn if öfssi. 14th 4930 11, 1 99, 75 32 6 Elements <a) 15th 49 30 99, 77 384 ω

Claims (7)

Patent claims: (Ϊ) Full metal catalytic converter element 'for converting combustible Components of a gas flow with a carrier from a heat-resistant alloy and with an activated coating of at least one platinum metal, characterized in that that it is helical. 2. Catalyst element according to claim 1, characterized in that that the distance between the individual coil turns is smaller than the diameter of the material of the turns. 3. Catalyst element according to claim 1 and 2, characterized in that that its mean diameter and length is less than about 6.35 mm. 4. Catalyst element according to claim 1 to 3, characterized in that that the material forming the helix has a diameter between about 127 mm and about 0.381 mm. 5. Catalyst element according to claim 1 to 4, characterized in that that the refractory alloy for the carrier is a nickel-chromium-iron alloy. 6. catalyst element according to claim 1 to 4, characterized in that that the heat-resistant alloy for the carrier ■ is a chromium-aluminum-iron alloy. 409845/1062 to 7. Use of a catalyst element according to one or more of claims 1-6, in a catalyst unit, with a basket-like housing and at least one closable filling opening. 409845/1062 Blank page