Oven with specific catalyst, method

Abstract

An oven includes a cooking compartment for preparing food, a vapor extraction apparatus designed to extract vapors from the cooking compartment, and a catalyst fluidically coupled to the vapor extraction apparatus and designed to convert catalytically the vapors extracted in the vapor extraction apparatus. The catalyst includes a carrier and a layer of catalyst material applied on the carrier. In a normal mode of the oven for preparing food to be cooked, the catalyst has a concentration of acetic acid in the converted vapors which concentration of acetic acid amounts to less than or equal to 5 ppm. The oven is also able to operate in a pyrolysis mode which differs from the normal mode.

Claims

1. An oven, comprising: a cooking compartment for preparing food; a vapor extraction apparatus designed to extract vapors from the cooking compartment; and a catalyst fluidically coupled to the vapor extraction apparatus and embodied to convert catalytically the vapors extracted in the vapor extraction apparatus, said catalyst including a carrier and a layer of catalyst material applied on the carrier, said oven designed to operate in a normal mode in which food to be cooked is prepared and the catalyst has a concentration of acetic acid in the converted vapors amounts to less than or equal to 5 ppm, and a pyrolysis mode which differs from the normal mode.

2. The oven of claim 1, wherein the catalyst is embodied such that a concentration of acetic acid in the converted vapors in the normal mode of the oven amounts to between 1 ppm and 5 ppm.

3. The oven of claim 1, wherein the catalyst is embodied such that, in the pyrolysis mode of the oven, a concentration of acetic acid in the converted vapors is less than 100 ppb.

4. The oven of claim 1, wherein the catalyst has an activity rate for a comparison substance, which activity rate at a temperature value in the normal mode of the oven is less than or equal to 35%, in particular less than or equal to 30%, in particular less than or equal to 20%, and at a temperature value in the pyrolysis mode of the oven is greater than 70%, in particular greater than 80%, in particular greater than 90%.

5. The oven of claim 4, wherein the comparison substance is CO or C3H6.

6. The oven of claim 4, wherein the temperature value in the normal mode is less than or equal to 330° C., in particular less than or equal to 300° C.

7. The oven of claim 1, wherein the temperature value in the pyrolysis mode is greater than or equal to 400° C., in particular greater than or equal to 485° C.

8. The oven of claim 1, wherein the catalyst material is free from precious metal, in particular the catalyst material is free from platinum and palladium.

9. The oven of claim 1, wherein the catalyst material has a first metal oxide having a metal from the manganese group, a second metal oxide having a metal from the copper group, and a third metal oxide having a metal from the lanthanides.

10. The oven of claim 9, wherein a proportion of the first metal oxide relative to the total catalyst material amounts to between 1.0 and 2.0, in particular in comparison to at least one other component of the catalyst material, in particular to a second metal oxide of the catalyst material and/or to a third metal oxide of the catalyst material.

11. The oven of claim 9, wherein a proportion of the second metal oxide relative to the total catalyst material amounts to between 0.5 and 1.5, in particular in comparison to at least one other component of the catalyst material, in particular to a first metal oxide of the catalyst material and/or to a third metal oxide of the catalyst material.

12. The oven of claim 9, wherein a proportion of the third metal oxide relative to the total catalyst material amounts to between 2.0 and 4.0, in particular in comparison to at least one other component of the catalyst material, in particular to a first metal oxide of the catalyst material and/or to a second metal oxide of the catalyst material.

13. The oven of claim 1, wherein the carrier of the catalyst has a honeycomb structure and/or the carrier has a surface greater than 40,000 mm.sup.2, in particular a surface between 40,000 mm.sup.2 and 100,000 mm.sup.2.

14. The oven of claim 1, further comprising a heating element, said catalyst being arranged at a distance from the heating element.

15. The oven of claim 14, wherein the distance is between greater than or equal to 12 mm.

16. The oven of claim 14, wherein the distance is between 12 mm and 25 mm.

17. A method, comprising: operating an oven in a normal mode in which food to be cooked in a cooking compartment is prepared; extracting vapors from the cooking compartment; and converting by a catalyst the vapors in the normal mode of the oven such that a concentration of acetic acid in the converted vapors amounts to less than or equal to 5 ppm.

18. The method of claim 17, further comprising: operating the oven in a pyrolysis mode which differs from the normal mode; and designing the catalyst in the pyrolysis mode such that a concentration of acetic acid in the converted vapors is less than 100 ppb.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Exemplary embodiments of the invention will now be described in greater detail making reference to schematic drawings, in which:

[0040] FIG. 1 shows a schematic representation of an exemplary embodiment of an oven according to the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE PRESENT INVENTION

[0041] FIG. 1 shows an oven 1 in a schematic vertical sectional representation. The oven 1 has a housing 2. A muffle 3, which with its walls delimits a cooking compartment 4, is arranged in the housing 2. The oven 1 also has a door 5, which is arranged movably on the housing 2. The door 5 is provided to close a loading opening 6 of the muffle 3 on the front side. Furthermore, the oven 1 has at least one heating element 7. The heating element 7 is provided for the intended purpose in its primary function of generating heat during a preparation program of the cooking appliance 1. The heating element 7 can be for example a grill heating element or a top heating element or a bottom heating element or a ring heating element. In one exemplary embodiment, the oven 1 has a catalyst 8. The catalyst 8 is arranged at a distance from the heating element 7, wherein this distance amounts in particular to between 12 mm and 25 mm. In particular, in the present exemplary embodiment this distance is measured at the point at which the catalyst 8 is closest to the heating element 7. This distance can be measured for example in the horizontal direction.

[0042] The oven 1 also has a vapor extraction apparatus 9. Vapors arising in particular during the operation of the oven 1 in the cooking compartment 4 can be extracted by way of this vapor extraction apparatus 9 from the cooking compartment 4 and out of the oven 1 via an exhaust duct 10 of the vapor extraction apparatus 9. In particular, it is provided for example that an outlet opening 11 is formed on a front panel of the oven 1, via which these vapors, in particular the catalytically processed flows, can be expelled.

[0043] In one exemplary embodiment, the oven 1 also has a fan 12. By way of said fan, the vapors can be sucked out of the cooking compartment 4 and expelled via the exhaust duct 10. The catalyst 8 is arranged such that it is arranged in this generated vapor flow, and these vapors are thus catalytically converted by way of the catalyst 8.

[0044] In one exemplary embodiment, the catalyst 8 has at least one carrier 13. At least one coating 14 is applied on this at least one carrier 13. In one exemplary embodiment, this coating 14 has a catalyst material. The catalyst material of this coating 14 is advantageously free from precious metals. In particular, the catalyst material has a first metal oxide having a metal from the manganese group. This metal oxide is advantageously manganese oxide (MnO). A mass proportion of this first metal oxide advantageously amounts to between 1.0 and 2.0 relative to the total catalyst material. In one exemplary embodiment, the catalyst material has a second metal oxide which differs from the first metal oxide. This second metal oxide has a metal from the copper group. In particular, this second metal oxide is Cu.sub.2O. The mass proportion of the second metal oxide advantageously amounts to between 0.5 and 1.5 relative to the total catalyst material. In one exemplary embodiment, the catalyst material advantageously has a third metal oxide which differs from the first two metal oxides. The third metal oxide has a lanthanide as the metal. This lanthanide is advantageously cerium. This third metal oxide is advantageously Ce.sub.2O.sub.3. A mass proportion of the third metal oxide advantageously amounts to between 2.0 percent and 4.0 percent relative to the total catalyst material. Advantageously, the catalyst material can be made only of these three metal oxides.

[0045] In one exemplary embodiment, the carrier 13 has a honeycomb structure. In particular, its surface is greater than 40,000 mm.sup.2, in particular between 40,000 mm.sup.2 and 100,000 mm.sup.2.

[0046] The oven 1 has a normal mode. In the normal mode, in accordance with the intended purpose preparation programs for preparing food to be cooked are carried out in the receiving compartment 4. The normal mode advantageously extends over a temperature range from temperatures of less than 330° C. to this maximum value of 330° C. The oven 1 also has a pyrolysis mode which is different from a normal mode. This pyrolysis mode is not provided for preparing food to be cooked in the cooking compartment 4. In the pyrolysis mode, temperatures of greater than or equal to 485° C. are set in particular in the cooking compartment 4.

[0047] In one exemplary embodiment, the catalyst 8 has an activity rate for a substance, in particular for an oxidation of the substance, in particular ethanol, which is less than or equal to 35 percent at temperature values in the normal mode. In one exemplary embodiment, the catalyst 8 has an activity rate at temperature values in the pyrolysis mode which is greater than 70 percent, in particular with regard to the oxidation of this substance.

[0048] In one exemplary embodiment, the catalyst 8 is embodied such that, in the normal mode of the oven 1, a concentration of acetic acid in the converted vapors amounts to less than or equal to 5 ppm, in particular between 1 ppm and 5 ppm. In one exemplary embodiment, the catalyst 8 is embodied such that, in the pyrolysis mode of the oven 1, a concentration of acetic acid in the converted vapors is less than 100 ppb.