DE102006023148A1 - Device for the treatment of exhaust gas of an internal combustion engine - Google Patents

Abstract

The device (1) according to the invention for the treatment of exhaust gas (2) of an internal combustion engine, comprising at least one metering line (4) for adding an aqueous solution, a hydrolysis catalyst (5) connected to the metering line (4) and an SCR catalyst (7), wherein the SCR catalyst (7) of exhaust gas (2) can be flowed through, characterized in that at least one rod-shaped heating element (9) is formed, by means of which at least one of the following components is heated: a) at least parts of the feed line (4 ) and b) the hydrolysis catalyst (5). The apparatus (1) according to the invention permits the formation of a feed line (4) which can be heated by a rod-shaped element (9) and a corresponding hydrolysis catalyst (5), with which an aqueous solution comprising urea can be vaporized and subsequently to a gas stream containing ammonia ( 22) is hydrolyzable in a compact design. This gas stream (22) serves as a reducing agent in the SCR process. The compact arrangement allows installation even in very limited space. By not flowed through by exhaust hydrolysis catalyst (5), the volume of the hydrolysis catalyst (5) can be significantly reduced because significantly smaller mass flows of gas must be hydrolyzed here.

Description

object The present invention is an apparatus for processing exhaust gas of an internal combustion engine, wherein in particular the Reduction of the nitrogen oxide content of the exhaust gas by means of a selective catalytic reduction (Selective Catalytic Reduction, SCR) in Foreground is. In particular, the present is concerned Invention with the provision of reducing agents which are selective act on nitrogen oxides such as ammonia in particular.

The exhaust of internal combustion engines has substances whose emission into the environment is undesirable. For example, in many countries nitrogen oxides (NO _x ) may only be contained in the exhaust gas of internal combustion engines up to a certain limit value. In addition to internal engine measures, which can be reduced by selecting a suitable operating point of the internal combustion engine, the emission of nitrogen oxides, aftertreatment methods have been established with which a further reduction of nitrogen oxide emissions is possible.

One way to further reduce nitrogen oxide emissions is the so-called selective catalytic reduction. Here, a selective reduction of nitrogen oxides to molecular nitrogen (N ₂ ) using a reducing agent. One possible reducing agent is ammonia (NH ₃ ). Ammonia is often not stored in the form of ammonia, but rather an ammonia precursor is stored, which is converted into ammonia if necessary. Possible ammonia precursors are, for example, urea ((NH ₂ ) ₂ CO), ammonium carbamate, isocyanic acid (HCNO), cyanuric acid and the like. In particular, urea has proven to be easy to store. Preferably, the urea is stored in the form of a urea-water solution. Urea and especially urea water solution is harmless to health, easy to distribute and store. Such a urea hydrogen solution is marketed under the name "Ad Blue".

From the DE 199 13 462 A1 a method is known in which a urea-water solution upstream of a hydrolysis catalyst is metered into a partial flow of an exhaust gas of an internal combustion engine. Upon impact with the hydrolysis catalyst, hydro- and thermolysis of the urea into ammonia takes place during operation, which is used as a reducing agent in a downstream SCR catalyst. The process described here has the disadvantage that the hydrolysis catalyst is cooled by the evaporation of the urea-water solution. In particular, when large amounts of ammonia are needed, it can come at least in areas of the hydrolysis to such a strong cooling that here the hydrolysis reaction no longer or no longer completely runs. In addition, exhaust gas flows through this state of the art of the hydrolysis catalyst. As a result, there are relatively large mass flows, by means of which the hydrolysis catalyst is to be dimensioned correspondingly large. This causes costs and space required, which is often not so available especially in modern automobiles.

Of these, The present invention is based on the object, to propose a device with those of the prior art known disadvantages can be alleviated at least.

These Task is solved by a device having the features of the independent claim. Advantageous developments are the subject of the respective dependent claims.

• a) zumindest Teile der Zugabeleitung und
• b) der Hydrolysekatalysator.

The device according to the invention for the treatment of exhaust gas of an internal combustion engine comprises at least one metering line for adding an aqueous solution, a hydrolysis catalyst connected to the metering line and an SCR catalyst, the exhaust gas flowing through the SCR catalytic converter. According to the invention, at least one rod-shaped heating element is formed, by means of which at least one of the following components can be heated:

• a) at least parts of the feed line and
• b) the hydrolysis catalyst.

Under a rod-shaped Heating element is understood in particular to be an electrically heatable element, in which a heating element embedded in a corresponding medium is. In particular, this may be a jacket tube, which is heated from the inside by the corresponding heating element. In this jacket tube may preferably a heating cartridge such as a ceramic heating cartridge may be formed, which is a ceramic element comprising a heating conductor embedded therein.

A hydrolysis catalyst is understood to mean a flow-through component which catalyzes a hydrolysis of a reducing agent precursor to form a reducing agent. In particular, a hydrolysis catalyst is understood to mean a component which comprises a catalytic coating by means of which the hydrolysis of urea to ammonia can be catalyzed. In particular, the aqueous solution comprises at least one reducing agent precursor of a reducing agent for use in the SCR process. A reducing agent precursor is understood in particular to mean a substance which can split off the reducing agent or into this can be converted. Preferably, the aqueous solution comprises at least urea. Other ingredients in the aqueous solution are possible and according to the invention, in particular substances by means of which the freezing point of the aqueous solution can be reduced. In particular, these are formic acid and / or ammonium formate. The connection between the feed line and the hydrolysis catalyst is designed so that during operation completely evaporated solution enters the hydrolysis catalyst.

The inventive device In particular, it includes an SCR catalyst in the exhaust pipe is formed and can be flowed through by exhaust gas while metering line and hydrolysis outside the exhaust pipe are formed and are not flowed through by exhaust gas. This makes it possible Hydrolysis catalysts whose volume compared to conventional, permeable by exhaust gas Hydrolysis catalysts can be significantly reduced. So have conventional hydrolysis catalysts a volume of at least 500 ml and more, while according to the present Invention of the hydrolysis catalyst have less than 100 ml volume can.

Especially becomes the device according to the invention operated so that the metering line is heated so that in her an evaporation of the aqueous solution he follows. Preferred here is an embodiment in which a full Evaporation, d. H. an evaporation of at least 90% by weight, preferably at least 95% by weight of the aqueous solution, more preferably at least 98% by weight of the aqueous solution he follows. The heating takes place essentially via the rod-shaped Heating element. The device according to the invention can advantageously for the treatment of the exhaust gases of stationary and / or mobile Internal combustion engines are used, in particular for processing the exhaust gases of motor vehicles, in particular automobiles, passenger cars, Lorries, motorized two-wheelers and / or so-called All terrain vehicles, watercraft and / or aircraft.

• a) zumindest Teile der Zugabeleitung und
• b) der Hydrolysekatalysator.

According to an advantageous embodiment of the device according to the invention, at least one of the present components is formed around the rod-shaped heating element:

• a) at least parts of the feed line and
• b) the hydrolysis catalyst.

in this connection In particular, the metering line may be about the rod-shaped heating element be formed winding around. Preferred here is an embodiment, in which the feed line is essentially spiral-shaped is, wherein the axis of symmetry of the spiral coaxial with the longitudinal axis of the rod-shaped Heating element is formed. The hydrolysis catalyst can be used in Formed a honeycomb body which is around the rod-shaped Heating element is formed around, preferably limited in the form of an annular honeycomb body through an inner and an outer jacket tube, but also canals include, directly in the heating element and / or in a heating element surrounding jacket tube are introduced.

These Embodiment of the device according to the invention allows a very compact construction of the device according to the invention, so that even in situations with only a small installation space such as especially in motor vehicles, an effective evaporation of the aqueous Solution at at the same time very compact construction of the device according to the invention can be achieved.

According to one further advantageous embodiment of the device according to the invention the metering line comprises at least one channel, at least partially formed by a jacket tube of the heating element.

Under a jacket tube is understood here in particular a shell that outside forms the or of the electric heat conductor of the rod-shaped heating element is. The jacket tube can be made of metallic, ceramic, glass or a similar one Material having temperatures of preferably 400 ° C and more, more preferably 600 ° C and more can withstand being manufactured.

According to one further advantageous embodiment of the device according to the invention the at least one channel is formed in the jacket tube.

This means in particular that introduced into the jacket tube channels be, for example, by abrasive manufacturing processes and / or directly in the production of the corresponding jacket tube, for example by appropriate extrusion.

According to one further advantageous embodiment of the device according to the invention is the at least one channel on the inside of the casing tube of Heating element and outside from a sleeve, which is coaxial with the heating element, limited.

In particular, this is one or more channels which are formed substantially helically around the rod-shaped heating element and / or which have an annular gap-shaped cross-section which is bounded on the inside by the jacket tube and on the outside by the sleeve. Also preferred is an embodiment in which the cross section of the metering line, in particular of the one or more channels changes. Thus, for example, an annular gap-shaped channel may be formed whose diameter increases monotonously or strictly monotonously along the rod-shaped heating element.

• a) zumindest Teilen der Zugabeleitung und
• b) dem Hydrolysekatalysator.

According to a further advantageous embodiment of the device according to the invention, a sleeve is formed outside the heating element, which is at least partially in thermal contact with at least one of the following components:

• a) at least parts of the metering line and
• b) the hydrolysis catalyst.

So allows the sleeve, the radially outside of the Heating element and preferably also radially outside at least of parts the metering line and / or the hydrolysis catalyst, the metering line formed of the hydrolysis catalyst and / or the at least one channel is, the introduction of heat from the outside. In particular, the sleeve comprises another heating conductor and is particularly as a or comprising a ring-shaped Heating element formed. So can a very even distribution the heat around the rod-shaped Heating conductor around guaranteed which leads to very uniform evaporation and / or hydrolysis results.

According to one further advantageous embodiment of the device according to the invention is the sleeve heated.

For this has the sleeve in particular, as well as the rod-shaped heating element electrical connections on, by means of which the sleeve and / or the rod-shaped Heating element can be supplied with electricity. This allows heating the corresponding channels both inside and outside.

According to one further advantageous embodiment of the device according to the invention For example, the hydrolysis catalyst comprises an annular honeycomb body which for a Fluid can flow through channels between an inner jacket tube and an outer jacket tube.

in this connection includes the honeycomb body preferably at least one at least partially structured, in particular corrugated, metallic layer through which formed the hydrolysis channels become. The channels point a hydrolysis of a reducing agent precursor to a reducing agent catalyzing coating on. An embodiment is preferred the at least the inner jacket tube of the hydrolysis in thermal contact with the rod-shaped heating element, preferably similar to this is connected and / or formed on this fitting. Prefers If a further heating element is formed radially outside the hydrolysis catalytic converter, by means of which by the outer jacket tube Heat in the hydrolysis catalyst can be registered.

According to one further advantageous embodiment of the device according to the invention the hydrolysis catalyst is at least partially of at least a hydrolysis channel formed, at least partially by a Jacket tube of the heating element is formed.

in this connection For example, the at least one hydrolysis channel may be similar to that described above a channel as a realization of the metering line in the jacket tube of the heating element be formed or, for example, inside of the jacket tube of the heating element to be limited. Preferred here is an embodiment, in particular can in this case the channels or the feed line and / or the hydrolysis channels merge into each other, in particular the same channel, which possibly a change the permeable Cross section learns and which in at least a portion of a hydrolysis coating having.

Prefers is an embodiment in which the hydrolysis channel in the jacket tube is trained.

Especially is here in the surrounding the heating element of the rod-shaped heating element structure, which is referred to here as a jacket tube, for example by abrasive Techniques a channel introduced.

According to one further advantageous embodiment of the device according to the invention the hydrolysis channel is on the inside of the jacket tube of the heating element and outside from a sleeve, which is coaxial with the heating element, limited.

Especially is the outside lying sleeve also heatable, allowing a heat input takes place both inside and outside in the hydrolysis channel, so that if possible uniform temperature control one possible full Hydrolysis of the reducing agent precursor to reducing agent can. Preferred is an embodiment in which the sleeve in thermal Contact to the hydrolysis channel is.

in the Below, the invention will be explained in more detail with reference to the attached figures, without them on the embodiments and details shown there limited would. It show schematically:

1 an embodiment of the device according to the invention;

2 a detail of a first embodiment of a device according to the invention in longitudinal section;

3 a detail of a first embodiment in a partially exploded sectional view;

4 a detail of a second embodiment in a partially exploded view;

5 a detail of the second embodiment in a longitudinal section and

6 An embodiment of a hydrolysis of a device according to the invention.

1 schematically shows a device 1 for the treatment of an exhaust gas 2 a not shown internal combustion engine. The device 1 includes at least one in 2 as an annular gap-shaped channel 3 addition line 4 , In 1 is the feed line 4 for the sake of clarity not shown. The metering line 4 is with a hydrolysis catalyst 5 and serves to add an aqueous solution to the hydrolysis catalyst 5 , The aqueous solution is placed in a reservoir 6 stored. The aqueous solution comprises at least one reducing agent precursor, in particular urea. A reducing agent precursor is understood as meaning a substance from which a reducing agent can be split off or to which it can react. The reducing agent is suitable for use in the selective catalytic reduction of nitrogen oxides (Selective Catalytic Reduction, SCR).

Furthermore, the device according to the invention comprises 1 an SCR catalyst 7 , which of the exhaust 2 can be flowed through. This is the SCR catalyst 7 in the exhaust pipe 8th formed during the hydrolysis catalyst 5 and the metering line 4 outside the exhaust pipe 8th are formed. Furthermore, the device according to the invention comprises 1 at least one rod-shaped heating element 9 , by means of which at least parts of the feed line 4 and / or the hydrolysis catalyst 5 are heated.

addition line 4 and reservoir 6 are through a promotion line 10 connected with each other. In addition, not shown conveying means may be formed, for example pumps, in particular metering pumps, with which the aqueous solution of at least one reducing agent precursor from the reservoir 6 in the metering line 4 is eligible.

In operation arises in the device according to the invention 1 by evaporation of the aqueous solution in the addition line 4 by means of the rod-shaped heating element 9 and subsequent hydrolysis in the hydrolysis catalyst 5 a gaseous substance mixture which comprises at least one reducing agent for the selective catalytic reduction of nitrogen oxides. This is preferably ammonia. This gaseous mixture, which in particular due to the complete evaporation of the aqueous solution in the metering line 4 and subsequent hydrolysis in the hydrolysis catalyst 5 is produced, is in a mouth area 11 in the exhaust pipe 8th fed. Here are funds 12 for generating a negative pressure in the exhaust pipe 8th in the mouth area 11 provided that prevent exhaust during normal operation 2 from the exhaust pipe 8th in the hydrolysis catalyst 5 and / or the metering line 4 reach. The means 12 create a calming or dead zone in the flow, which is the corresponding negative pressure in the mouth area 11 cause.

2 shows schematically in longitudinal step a first embodiment of a detail of the device according to the invention. This is on the rod-shaped heating element 9 which faces outward through a lateral surface 13 having casing pipe 14 is limited, an annular gap-shaped channel 3 as a feed line 4 educated. The jacket tube 14 can in this case cohesively with the rod-shaped heating element 9 be connected or part of the same. The circular channel 3 So is inside through the lateral surface 13 limited. Outside the stabför shaped heating element 9 is a sleeve 15 educated. The sleeve 15 thus limits the annular gap-shaped channel 3 outward. The sleeve 15 can be heated to ensure the most even temperature distribution around the channel 3 to be able to produce. According to an advantageous embodiment, the radius of the annular gap changes over the length of the sleeve 15 or the rod-shaped heating element 9 , In this case, the smallest diameter becomes the aqueous solution 16 introduced into the annular gap, in the different areas of the annular gap-shaped channel 3 warmed up, evaporated and overheated and leaves the annular gap-shaped channel 3 as gaseous substance mixture 19 , Subsequently, the gaseous substance mixture 19 the hydrolysis catalyst 5 fed, where a hydrolysis of the reducing agent precursor contained in the gaseous mixture to reducing agent takes place. The rod-shaped heating element 9 and the sleeve 15 have in the present embodiment electrical connections 17 on, by means of which the sleeve or the rod-shaped heating element 9 can be connected to an appropriate power supply. Here, the heating conductor 18 which in the rod-shaped heating element and / or in the sleeve 15 is designed to be regulated with power.

3 shows this first embodiment in a partially exploded perspective view. Here are the heating conductors 18 in the sleeve 15 to recognize.

4 schematically shows a further embodiment in detail. The rod-shaped heating element 9 is from a jacket pipe 14 surrounded, which may also be integrally formed with the rod-shaped heating element or cohesively connected thereto. In the jacket tube 14 is a channel 3 let in, which in the first area 20 as a feed line 4 for the aqueous solution 16 serves. By the rod-shaped heating element 9 will be in the first area 20 the aqueous solution evaporates, leaving the second area 21 of the canal 3 is traversed by a gaseous mixture of substances. The second area 21 of the canal 3 is provided with a hydrolysis in particular from urea to ammonia-promoting coating and thus serves as a hydrolysis channel 36 or as a hydrolysis catalyst 5 ,

After the hydrolysis leaves a vapor stream 22 the channel 3 , which comprises reducing agent, in particular ammonia. Over the jacket pipe 14 can a sleeve 15 be pushed, as by the arrow 23 indicated. This sleeve 15 can, for example, itself via appropriate heating conductors 18 so that the sleeve too 15 is heated, leaving the channel 3 is heated both from the outside and from the inside. Alternatively or cumulatively, the sleeve is 15 after bringing into contact with the jacket tube 14 , which preferably takes place cohesively, in particular by soldering, welding, pressing or the like in thermal contact with the jacket tube 14 , This can be done, for example, by the web areas 24 between the individual turns of the canal 3 be achieved. As a result, with sufficiently high thermal conductivity through the land areas 24 a heating also through the sleeve 15 take place without active heating means are formed here. The sleeve 15 has a constriction 25 on, which helps to reduce heat conduction in the sleeve 15 between the first area 20 and the second area 21 serves. This can be achieved that the sleeve 15 in the fields of 20 . 21 each part of a separate control loop, so that therefore the hydrolysis catalyst 5 and the metering line 3 can be heated separately from each other. Regardless of this, it is advantageously possible that the rod-shaped heating element 9 and / or the sleeve 15 have different heating zones, so that the heating power can be made variable. This means in particular that preferably in the longitudinal direction of the rod-shaped heating element 9 and / or the sleeve 15 Areas may be formed, which can be acted upon with different heating power. Thus, in particular the different processes, especially in the complete evaporation of the aqueous solution 16 Be taken into account. Here, first, a warm up of the aqueous solution 16 , Then an evaporation and then preferably overheating of the resulting vapor instead, each with different heat inputs are needed. This can be achieved by different heating zones of the rod-shaped heating element 9 and / or the sleeve 15 Be taken into account. In particular, here is such a design of the rod-shaped heating element 9 and / or the sleeve 15 possible and advantageous, during operation as a function of the operating parameters, in particular depending on the amount of aqueous solution to be evaporated 16 a change in length of the different heating zones can be achieved.

5 shows a further embodiment in longitudinal section. Here, for the sake of clarity, only cutouts are shown schematically. To a rod-shaped substantially around the longitudinal axis 26 rotary heating element 9 with electrical connections 17 Different elements are formed. Immediately following the rod-shaped heating element 9 is a jacket pipe 14 educated. In the jacket tube 14 is a channel 3 introduced, for example, eroded, milled or the like. Between the individual turns of the canal 3 which is substantially helical about the longitudinal axis 26 is formed are land areas 24 intended. The jacket tube 14 is with the rod-shaped heating element 9 connected, in particular materially connected, is in thermal contact with these and / or is in the rod-shaped heating element 9 integrated. Outside the jacket pipe 14 is a sleeve 15 educated. This sleeve 15 is also with electrical connections 17 provided and can be used to heat the channel 3 serve from the outside. Outside the sleeve 15 is a first thermal insulator 27 designed as a thick-walled thermal insulation, for example, in the form of a block of material. This is intended to prevent the heat radiation to the outside. Furthermore, a second thermal insulator 28 designed, with which in particular a delivery line 10 about which the channel 3 with a reser voir 6 connectable is thermally insulated. First thermal insulator 27 and second thermal insulator 28 can be formed in one piece. Radially outside the second thermal insulator 28 is a Peltier element 29 educated. A Peltier element is understood to mean, in particular, an electrical component which, when current flows through, generates a temperature difference which is based on the so-called Peltier effect. Preferably, a Peltier element comprises 29 one or more elements of p- and n-doped semiconductor material, which are alternately interconnected via electrically conductive material. The sign of the temperature difference is dependent on the direction of the current flow, so that both a cooling and a heating with a Peltier element 29 is feasible.

In the present embodiment, the Peltier element is used 29 in particular for cooling the delivery line 10 and is therefore about the elektri connections 17 switched accordingly. Second thermal insulator 28 and Peltier element 29 are preferably exclusively in the area of the delivery line 10 and their entry or their connection area with the channel 3 educated. The channel 3 flows preferentially into a hydrolysis channel 36 , Here, the flow-through cross section of the channel 3 that of the hydrolysis channel 36 correspond. Furthermore, the cross section of the hydrolysis channel 36 be larger than the channel 3 , Also preferred is the at least one hydrolysis channel 36 similar to the channel 3 in the jacket tube 14 the rod-shaped heating element 9 educated.

6 schematically shows an embodiment of a hydrolysis catalyst 5 , This comprises an annular honeycomb body 30 , The annular honeycomb body 30 is made of at least one at least partially structured sheet metal layer 31 constructed, which are drawn for clarity only in a partial area. In the present example, in addition substantially smooth sheet metal layers 32 educated. At least partially structured sheet metal layers 31 and essentially smooth sheet metal layers 32 together form permeable cavities 33 , which are traversed by a fluid. The sheet metal layers 31 . 32 are at their outer periphery by an outer jacket tube 34 and at its inner periphery by an inner jacket tube 35 limited. Inside the inner jacket tube 35 is preferably a rod-shaped heating element 9 educated. Here, the inner jacket tube 35 the jacket pipe 14 the rod-shaped heating element 9 correspond or the sheet metal layers 30 . 31 can directly on the rod-shaped heating element 9 and / or the jacket tube 14 be attached. The outer jacket tube is preferred 34 with a corresponding sleeve 15 connected, via the continued heat in the annular honeycomb body 30 can be introduced.

The device according to the invention 1 allows the formation of a through a rod-shaped element 9 heated feed line 4 and a corresponding hydrolysis catalyst 5 with which an aqueous solution comprising urea is vaporisable and then to a gas stream containing ammonia 22 can be hydrolyzed in a compact design. This gas stream 22 serves as a reducing agent in the SCR process. The compact arrangement allows installation even in very limited space. By the not flowed through by exhaust hydrolysis 5 may be the volume of the hydrolysis catalyst 5 be significantly reduced, since here much smaller mass flows of gas must be hydrolyzed.

1

contraption for the treatment of exhaust gas of an internal combustion engine

2

exhaust

3

channel

4

addition line

5

hydrolysis catalyst

6

reservoir

7

SCR catalyst

8th

exhaust pipe

9

Rod-shaped heating element

10

delivery line

11

mouth area

12

medium for generating a negative pressure

13

lateral surface

14

casing pipe

15

shell

16

Aqueous solution

17

electrical connection

18

heating

19

Gaseous substance mixture

20

first Area

21

second Area

22

steam power

23

arrow

24

web region

25

constriction

26

longitudinal axis

27

first thermal insulator

28

second thermal insulator

29

Peltier element

30

Ring-shaped honeycomb body

31

At least partially structured metallic layer

32

in the Substantially smooth metallic layer

33

Flow-through cavity

34

Outer casing pipe

35

Interior Matelrohr

36

Hydrolysekanal

Claims (13)

Contraption ( 1 ) for the treatment of exhaust gas ( 2 ) of an internal combustion engine, comprising at least one metering line ( 4 ) for adding an aqueous solution, one with the addition line ( 4 ) connected hydrolysis catalyst ( 5 ) and an SCR catalyst ( 7 ), the SCR catalyst ( 7 ) of exhaust gas ( 2 ) is flowed through, characterized in that at least one rod-shaped heating element ( 9 ) is formed, by means of which at least one of the following components is heated: a) at least parts of the feed line ( 4 ) and b) the hydrolysis catalyst ( 5 ). Device according to Claim 1, in which at least one of the following components surround the rod-shaped heating element ( 9 ) is formed around: a) at least parts of the feed line ( 4 ) and b) the hydrolysis catalyst ( 5 ). Device according to one of the preceding claims, in which the metering line ( 4 ) at least one channel ( 3 ), which at least partially by a jacket tube ( 14 ) of the heating element ( 9 ) is formed. Apparatus according to claim 4, wherein the at least one channel ( 3 ) in the jacket tube ( 14 ) is trained. Apparatus according to claim 3 or 4, wherein the at least one channel ( 3 ) inside of the jacket tube ( 14 ) of the heating element ( 9 ) and on the outside of a sleeve ( 15 ) coaxial with the heating element ( 9 ) is limited. Device according to one of the preceding claims, in which outside the heating element ( 9 ) a sleeve ( 15 ), which is at least partially in thermal contact with at least one of the following components: a) at least parts of the feed line ( 4 ) and b) the hydrolysis catalyst ( 5 ). Device according to Claim 6, in which the sleeve ( 15 ) is formed radially outside at least one of the following components: a) at least parts of the feed line ( 4 ) and b) of the hydrolysis catalyst ( 5 ). Apparatus according to claim 6 or 7, wherein the sleeve ( 15 ) is heated. Device according to one of the preceding claims, in which the hydrolysis catalyst ( 5 ) an annular honeycomb body ( 30 ), which is permeable to a fluid cavities ( 33 ) between an inner jacket tube ( 35 ) and an outer jacket tube ( 34 ) having. Device according to Claim 9, in which the annular honeycomb body ( 30 ) with its inner jacket tube ( 35 ) at least partially with the rod-shaped heating element ( 9 ) is in thermal contact. Device according to one of the preceding claims, in which the hydrolysis catalyst ( 5 ) at least partially of at least one hydrolysis channel ( 36 ) is formed, at least partially by a jacket tube ( 14 ) of the heating element ( 9 ) is formed. Apparatus according to claim 11, wherein the at least one hydrolysis channel ( 36 ) in the jacket tube ( 14 ) is trained. Apparatus according to claim 10 or 11, wherein the hydrolysis channel ( 36 ) inside of the jacket tube ( 14 ) of the heating element ( 9 ) and on the outside of a sleeve ( 15 ) coaxial with the heating element ( 9 ) is limited.