Production of a synthesis gas comprising carbon monoxide and hydrogen

Abstract

A method for producing a synthesis gas including carbon monoxide and hydrogen comprises a number of steps. In particular, the method comprises: a) providing a feedstock gas comprising methane and carbon dioxide, b) converting the feedstock gas into an intermediate product gas comprising carbon dioxide and water vapor and c) converting the intermediate product gas obtained in step b) into the synthesis gas comprising carbon monoxide and hydrogen by means of electrolysis.

The synthesis gas including carbon monoxide and hydrogen can be obtained from biogas with particularly high efficiency by means of the described method and an appropriate apparatus. To this end, the conversion of the biogas in a fuel cell is coupled with co-electrolysis in an electrolysis cell.

Claims

1. A method for production of a synthesis gas comprising carbon monoxide and hydrogen, comprising: a) providing a feedstock gas comprising methane and carbon dioxide, b) converting the feedstock gas into an intermediate product gas comprising carbon dioxide and water vapor and c) converting the intermediate product gas obtained in step b) into the synthesis gas comprising carbon monoxide and hydrogen by means of electrolysis.

2. The method according to claim 1, wherein the feedstock gas is a biogas.

3. The method according to claim 1, wherein the proportion of methane in the feedstock gas is within the range from 50 to 65% and/or the proportion of carbon dioxide in the feedstock gas is within the range from 30 to 45%.

4. The method according to claim 1, wherein the feedstock gas also comprises water vapor having a proportion within the range from 2 to 10%.

5. The method according to claim 1, wherein step b) is carried out in a solid oxide fuel cell (SOFC).

6. The method according to claim 1, wherein electrical energy generated in step b) is used for the electrolysis in step c).

7. An apparatus for production of a synthesis gas comprising carbon monoxide and hydrogen, the apparatus comprising: a fuel cell having an anode and a cathode, which are separated from one another at least by an electrolyte, and an anode space adjoining the anode and an electrolysis cell having an anode and a cathode, which are separated from one another at least by an electrolyte, and a cathode space adjoining the cathode, wherein the anode space of the fuel cell is connected to the cathode space of the electrolysis cell.

8. The apparatus according to claim 7, wherein the fuel cell and the electrolysis cell are connected to one another in such a way that electrical energy generated by the fuel cell can be used for electrolysis in the electrolysis cell.

9. The apparatus according to claim 7, wherein the anode and the cathode of the fuel cell are connected to a store for electrical energy on the input side and/or the anode and the cathode of the electrolysis cell are connected to the store for electrical energy on the output side.

10. The apparatus according claim 7, wherein the fuel cell and the electrolysis cell are arranged together in a housing.

11. The method according to claim 2, wherein the proportion of methane in the feedstock gas is within the range from 50 to 65% and/or the proportion of carbon dioxide in the feedstock gas is within the range from 30 to 45%.

12. The method according to claim 11, wherein the feedstock gas also comprises water vapor having a proportion within the range from 2 to 10%.

13. The method according to claim 12, wherein step b) is carried out in a solid oxide fuel cell (SOFC).

14. The method according to claim 13, wherein electrical energy generated in step b) is used for the electrolysis in step c).

15. The apparatus 8, wherein the fuel cell and the electrolysis cell are arranged together in a housing.

Description

[0073] In the following, the invention and the technical environment will be explained in more detail with reference to the figures. It should be noted that the invention is not supposed to be limited by the depicted embodiments. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects from the facts described in the figures and to combine them with other components and insights from the present description and/or the figures. In particular, it must be noted that the figures and in particular the depicted size ratios are only schematic. Identical reference signs denote identical objects, so that explanations from other figures can be used in a supplementary manner, if necessary. In the drawings:

[0074] FIG. 1: is a flowchart of a method according to the invention for production of a synthesis gas comprising carbon monoxide and hydrogen, and

[0075] FIG. 2: shows an apparatus according to the invention for production of a synthesis gas comprising carbon monoxide and hydrogen.

[0076] FIG. 1 shows a flowchart of a method for production of a synthesis gas comprising carbon monoxide and hydrogen. The method comprises: [0077] a) providing a feedstock gas comprising methane and carbon dioxide, [0078] b) converting the feedstock gas into an intermediate product gas comprising carbon dioxide and water vapor and [0079] c) converting the intermediate product gas obtained in step b) into the synthesis gas comprising carbon monoxide and hydrogen by means of electrolysis.

[0080] The feedstock gas is preferably biogas having a methane content within the range from 50 to 65%, a carbon dioxide content within the range from 30 to 45% and a water vapor content within the range from 2 to 10%.

[0081] FIG. 2 shows an apparatus 1 for production of a synthesis gas comprising carbon monoxide and hydrogen. The apparatus 1 comprises a fuel cell 2 designed as an SOFC cell having an anode 3 and a cathode 5, which are separated from one another at least by an electrolyte 7, and an anode space 4 adjoining the anode 3 and a cathode space 6 adjoining the cathode 5. Step b) of the method from FIG. 1 can be carried out with the fuel cell 2. Furthermore, the apparatus 1 comprises an electrolysis cell 8 having an anode 9 and a cathode 11, which are separated from one another at least by an electrolyte 13, as well as a cathode space 12 adjoining the cathode 11 and an anode space 10 adjoining the anode 9. Step c) of the method from FIG. 1 can be carried out with the electrolysis cell 8.

[0082] The two cathode spaces 6 and 12 and the two anode spaces 4 and 10 each have an inlet 16 and an outlet 17. The anode space 4 of the fuel cell 8 is connected to the cathode space 12 of the electrolytic cell 8 in that the outlet 17 of the anode space 4 of the fuel cell 8 is connected to the inlet 16 of the cathode space 12 of the electrolysis cell 8. The feedstock gas can be introduced into the anode space 4 of the fuel cell 2 via the inlet 16 of the anode space 4 of the fuel cell 2 and can in this respect be provided according to step a) of the method from FIG. 1.

[0083] Oxygen can be introduced into the inlet 16 of the cathode space 6 of the fuel cell 2. In the embodiment shown, the oxygen is introduced together with nitrogen, which is not required. Alternatively, air can also be introduced into the inlet 16 of the cathode space 6 of the fuel cell 2. The nitrogen (or the used air) can be let out of the cathode space 6 of the fuel cell 2 at the outlet 17 of the cathode space 6 of the fuel cell 2. Unconverted oxygen can also escape from the outlet 17 of the cathode space 6 of the fuel cell 2.

[0084] A flushing gas can be introduced into the inlet 16 of the anode space 10 of the electrolysis cell 8 and can be discharged from the outlet 17 of the anode space 10 together with the oxygen formed in the anode space 10. In the embodiment shown, the flushing gas is nitrogen. Alternatively, however, oxygen in particular can also be used as the flushing gas.

[0085] The fuel cell 2 and the electrolysis cell 8 are connected to one another in such a way that electrical energy produced by the fuel cell 2 can be used for electrolysis in the electrolysis cell 8. For this purpose, the anode 3 and the cathode 5 of the fuel cell 2 are connected to a store 14 for electrical energy on the input side and the anode 9 and the cathode 11 of the electrolysis cell 8 are connected to the store 14 for electrical energy on the output side.

[0086] The fuel cell 2 and the electrolysis cell 8 are arranged together in a housing 15.

[0087] A synthesis gas comprising carbon dioxide and hydrogen can be obtained from biogas with particularly high efficiency by means of the described method and the described apparatus 1. To this end, the conversion of the biogas in a fuel cell 2 is coupled with co-electrolysis in an electrolysis cell 8.

LIST OF REFERENCE SIGNS

[0088] 1 apparatus [0089] 2 fuel cell [0090] 3 anode of the fuel cell [0091] 4 anode space of the fuel cell [0092] 5 cathode of the fuel cell [0093] 6 cathode space of the fuel cell [0094] 7 electrolyte of the fuel cell [0095] 8 electrolysis cell [0096] 9 anode of the electrolysis cell [0097] 10 anode space of the electrolysis cell [0098] 11 cathode of the electrolysis cell [0099] 12 cathode space of the electrolysis cell [0100] 13 electrolyte of the electrolysis cell [0101] 14 store for electrical energy [0102] 15 housing [0103] 16 inlet [0104] 17 outlet