Process and Device for Producing Hydrogen, Carbon Monoxide and a Carbon-Containing Product

Abstract

The invention relates to a process for producing hydrogen, carbon monoxide and a carbon-containing product in at least one reaction apparatus, wherein the at least one reaction apparatus comprises a bed of carbon-containing material and is characterized in that the bed of carbon-containing material in the at least one reaction apparatus is alternately heated to a temperature of >800° C. and, no later than upon reaching a temperature of 1800° C., cooled to a maximum of 800° C., wherein hydrogen and carbon monoxide are produced during the heating phase and carbon and hydrogen are produced during the cooling phase.

Claims

1. A process for producing molecular hydrogen (H.sub.2), carbon monoxide and a carbon-containing product, the process comprising the following steps: (a) providing molecular hydrogen (H.sub.2) and molecular oxygen (O.sub.2), (b) heating a bed of carbon-containing material to a temperature of >800° C. by reacting the molecular hydrogen (H.sub.2) with the molecular oxygen (O.sub.2), wherein steps (a) and (b) proceed in the same reaction apparatus (R0), (c) drawing off the synthesis gas formed, containing molecular hydrogen (H.sub.2) and carbon monoxide, (d) ending the provision of molecular hydrogen (H.sub.2) and molecular oxygen (O.sub.2) no later than upon reaching a temperature of the bed of carbon-containing material of 1800° C., (e) providing a gaseous hydrocarbon stream and decomposing the hydrocarbons in the presence of the bed of carbon-containing material to give carbon and molecular hydrogen (H.sub.2), the temperature of the bed of carbon-containing material decreasing in the process, (f) drawing off the molecular hydrogen (H.sub.2), (g) ending the provision of a gaseous hydrocarbon stream no later than upon reaching a temperature of the bed of carbon-containing material of ≤900° C., and (h) withdrawing at least a portion of the carbon-containing material of the bed, wherein the carbon-containing material includes a deposit comprising the carbon-containing product.

2. The process as claimed in claim 1, wherein the reaction apparatus (R0) is connected to a further reaction apparatus, which likewise contains a bed of carbon-containing material, and while steps (e) to (h) are conducted in the reaction apparatus (R0), steps (a) to (d) are conducted in the further reaction apparatus, and the molecular hydrogen (H.sub.2) formed in the reaction apparatus (R0) is fed at least in part to the further reaction apparatus and is reacted with molecular oxygen (O.sub.2), and on reaching the respective temperatures, the process regime is inverted, and while steps (a) to (d) are conducted in the reaction apparatus (R0), steps (e) to (h) are conducted in the further reaction apparatus.

3. The process as claimed in claim 1, wherein molecular hydrogen (H.sub.2) and molecular oxygen (O.sub.2) are introduced into the reaction apparatus (R0) and/or the further reaction apparatus and combusted, preferably at the respective end of the reaction apparatus (R0) and/or further reaction apparatus at which they are introduced.

4. The process as claimed in claim 1, wherein the respective bed of carbon-containing material in the reaction apparatus (R0) and/or the further reaction apparatus is alternately heated to a temperature of >900° C. and, no later than upon reaching a temperature of 1800° C., cooled to ≤900° C.

5. The process as claimed in claim 1, wherein the respective bed of carbon-containing material in the reaction apparatus (R0) and/or the further reaction apparatus is heated to a temperature in the range from 1400° C. to 1800° C.

6. The process as claimed in claim 1, wherein the respective bed of carbon-containing material in the reaction apparatus (R0) and/or the further reaction apparatus is cooled to a temperature of ≤900° C.

7. The process as claimed in claim 1, wherein the gaseous hydrocarbon stream is natural gas or methane.

8. The process as claimed in claim 1, wherein the respective bed of carbon-containing material in the reaction apparatus (R0) and/or the further reaction apparatus is a fixed bed.

9. The process as claimed in claim 1, wherein the provision of molecular hydrogen (H.sub.2) and molecular oxygen (O.sub.2) and of the gaseous hydrocarbon stream are operated in flow reversal.

10. The process as claimed in claim 1, wherein steps (a) to (h) as an overall process are repeated cyclically and continuously.

11. The process as claimed in claim 1, wherein in a further step (d1), between steps (d) and (e), a gaseous stream is led through the reaction apparatus (R0) and/or the further reaction apparatus as an agent for purging, preferably composed of molecular hydrogen (H.sub.2).

12. The process as claimed in claim 1, wherein in a further step (g1), between steps (g) and (h), a gaseous stream is led through the reaction apparatus (R0) and/or the further reaction apparatus as a purging agent, preferably composed of molecular hydrogen (H.sub.2) or methane.

13. The process as claimed in claim 1, wherein, when heating the bed of carbon-containing material to a temperature of 1600° C., an H.sub.2/CO ratio of approximately 4 and a carbon yield of approximately 50% are achieved.

14. A process of producing an electrode, comprising utilizing the carbon-containing product of claim 1 as an electrode material.

15. An apparatus for performing the process as claimed in claim 1, wherein the apparatus for producing molecular hydrogen (H.sub.2), carbon monoxide and a carbon-containing product comprises the following components which are operatively connected to one another at least at times: (A) two or three reaction apparatuses (R0, R1; R0, R2; R1, R2; R0, R1, R2) each comprising a bed of carbon-containing material, (B) a first means for introducing and/or discharging fluids at one respective end of the reaction apparatuses (R0, R1; R0, R2; R1, R2; R0, R1, R2), and (C) a second means for introducing and/or discharging fluids at the respective other end of the reaction apparatuses (R0, R1; R0, R2; R1, R2; R0, R1, R2).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0144] In the drawings:

[0145] FIG. 1 shows the principle of the process steps for performing the process according to the invention

[0146] FIG. 2 shows the principle for performing the process according to the invention when at least two reaction apparatuses are coupled together.

DETAILED DESCRIPTION OF THE INVENTION

[0147] FIG. 1 schematically shows stages 1 to 5 for performing the process according to the invention in a reaction apparatus (R0), equipped with a carbon-containing bed (1), a means (2) at the top of the reaction apparatus (R0) and a second means (3) at the bottom of the reaction apparatus (R0), which are used for introducing and discharging the gases and material streams employed in the process.

[0148] In stage 1, oxygen and hydrogen are introduced at the top of the reaction apparatus (R0) via means (2) into the interior of the reaction apparatus (R0) and combusted. The oxygen reacts with the hydrogen to give water, with the release of heat. At the same time, the carbon-containing bed (1) heats up as a result of the thermal energy formed during the exothermic reaction, to a temperature of between 1400° C. and 1800° C. The resulting water reacts with the carbon in the carbon-containing bed (1) to form synthesis gas, consisting of carbon monoxide and hydrogen. The synthesis gas as product is drawn off at the bottom of the reaction apparatus (R0) via means (3). The dashed temperature front line (9) shown in the reaction apparatus (R0) schematically indicates the cool state of the carbon-containing bed (1), where the temperature front (9) at the start of the reaction is situated in the upper region of the reaction apparatus (R0), since the bed has not yet heated up. In the heating phase of the carbon-containing bed, the temperature front shifts into the lower region of the reaction apparatus (R0), which is schematically illustrated with the solid temperature front line (10) in the heated state.

[0149] In stage 2, the feed of oxygen and hydrogen into the reaction apparatus (R0) is stopped upon reaching the maximum plateau temperature, which is in the range from 1400 to 1800° C. in the carbon-containing bed (1). In the event that the reaction apparatus (R0) still has water residues, hydrogen for purging the reaction apparatus (R0) is introduced at the top of the reaction apparatus (R0) via means (2) and discharged at the bottom of the reaction apparatus (R0) via means (3). This allows the water residues to be removed from the reaction system. The solid temperature front line (10) shows that the carbon-containing bed remains heated.

[0150] Subsequently, in stage 3 hydrocarbon is introduced at the bottom of the reaction apparatus (R0) via means (3). By means of the thermal energy stored in the carbon-containing bed (1), the hydrocarbon is pyrolyzed to hydrogen and carbon, the carbon-containing bed (1) cooling to not more than 900° C. in the process. The newly formed hydrogen is drawn off as product via means (2), while the carbon formed is deposited on the carbon-containing bed (1) as carbon-containing product. The amount of carbon-containing product per cycle is set here via the mass of carbon and the amount of energy stored. As a result of the cooling of the carbon-containing bed (1), the solid temperature front line (10) shifts into the upper region of the reaction apparatus (R0). The dashed temperature front line (9) indicates the cooled temperature front.

[0151] In stage 4, with a continuous removal of the carbon-containing bed (1), the temperature front is kept in a defined region of the reaction apparatus (R0). This can be illustrated with the temperature profile line, the temperature front here being shown by way of example up to the middle of the reaction apparatus (R0). To further lower the temperature, the reaction apparatus (R0) is purged with a hydrocarbon or hydrogen, by introducing the corresponding gas at the bottom of the reaction apparatus (R0) via means (3) and discharging it at the top of the reaction apparatus (R0) via means (2).

[0152] In stage 5, a portion of the carbon-containing bed (1) is withdrawn from the reaction apparatus (R0) and new carbon-containing material is introduced. The reaction apparatus (R0) is then back in the starting state and the process can start from the beginning. The process can therefore be performed cyclically and continuously.

[0153] FIG. 2 shows an embodiment for performing the process according to the invention using two reaction apparatuses (R1) and (R2) which are connected to one another via connection (8) and which each include a carbon-containing bed—(1a) and (1b). In phase 1, hydrocarbon is introduced at the bottom of the reaction apparatus (R1) via means (5) and pyrolytically decomposed at a temperature of ≥900° C., typically from 1400° C. to 1800° C., forming carbon and hydrogen. The carbon is deposited on the carbon-containing bed (1a), while a portion of the hydrogen is discharged at the top of the reaction apparatus (R1) via means (4) and another portion is led into the second reaction apparatus (R2) via the connection (8). This hydrogen is fed to the oxygen and hydrogen introduced at the top of the reaction apparatus (R2) via means (6). The hydrogen fed from the reaction apparatus (R1) is combusted superstoichiometrically with the oxygen and the other hydrogen at the top of the reaction apparatus (R2), the carbon-containing bed (1b) heating up to a temperature of 1400° C. to 1800° C. in the process. This results in the formation of water, this water reacting further with the carbon in the carbon-containing bed (1b) to give synthesis gas. The synthesis gas is then drawn off at the bottom of the reaction apparatus (R2) via means (7). At the same time, the carbon-containing bed (1a) of the reaction apparatus (R1) cools down during the pyrolysis.

[0154] When the maximum plateau temperature of 1400 to 1800° C. is reached in the reaction apparatus (R2), the introduction of the reactant gases is stopped and the overall process is inverted.

[0155] In phase 2, hydrocarbon is introduced at the bottom of the reaction apparatus (R2) via means (7) and is then pyrolytically decomposed into hydrogen and carbon by means of the thermal energy in the carbon-containing bed (1b). The pyrolysis carbon is deposited on the carbon-containing bed (1b), while a portion of the hydrogen is discharged at the top of the reaction apparatus (R2) via means (6). The other portion of the hydrogen is led into the reaction apparatus (R1) via connection (8), with oxygen and hydrogen simultaneously being introduced at the top of the reaction apparatus (R1) via means (4) and these gases being combusted together to form water. This combustion reaction in turn heats the carbon bed (1a) in the reaction apparatus (R1). The water reacts with the carbon in the carbon-containing bed (1a) to give synthesis gas, which is drawn off at the bottom of the reaction apparatus (R1) via means (5). At the same time, the carbon-containing bed (1b) of the reaction apparatus (R2) cools down during the pyrolysis.

[0156] Partial removal of the carbon-containing product from the carbon-containing bed can be effected both cyclically and continuously. The passage of hydrogen or hydrocarbons for purging or cooling the reaction apparatus and/or the carbon-containing bed is preferably conducted between the individual steps.

[0157] Phase 1 then starts again and the process is continued in alternating fashion or cyclically. It is thus possible to continuously simultaneously produce hydrogen, carbon monoxide and a carbon-containing product and to discharge them from the system.

LIST OF REFERENCE SIGNS

[0158] R0 reaction apparatus [0159] R1 reaction apparatus [0160] R2 reaction apparatus [0161] 1 carbon-containing bed [0162] 1a carbon-containing bed [0163] 1b carbon-containing bed [0164] 2 means for introducing and/or discharging [0165] 3 means for introducing and/or discharging [0166] 4 means for introducing and/or discharging [0167] 5 means for introducing and/or discharging [0168] 6 means for introducing and/or discharging [0169] 7 means for introducing and/or discharging [0170] 8 connection [0171] 9 dashed temperature front line [0172] 10 solid temperature front line