Fuel cell system and fuel cell system control method

Abstract

The invention relates to a fuel cell system control method. A fuel cell system (100) is used in the fuel cell system control method. This fuel cell system is provided with: a raw material supply mechanism (1) for supplying a raw material; a water vapor supply mechanism (2) for supplying water vapor to the raw material supply mechanism (1); a fuel cell (3) for generating electric energy from an oxidizing agent and hydrogen generated from the raw material; and a reuse gas, which is at least part of an anode exhaust gas discharged from an anode (3A) of the fuel cell (3), to the raw material supply mechanism (1). And a circulating gas recycling mechanism (4). The flow rate of water vapor flowing through the water vapor supply mechanism (2) is controlled according to the flow rate of carbon dioxide contained in the reuse gas flowing through the reuse gas mechanism (4).

Description

Technical Field

[0001] The present disclosure relates to a fuel cell system and a fuel cell system control method. Background Art

[0002] The exhaust gas discharged from the fuel cell contains carbon dioxide. Patent Document 1 discloses a technique in which a raw gas is reformed using carbon dioxide contained in the exhaust gas (anode off-gas) to generate a synthesis gas, and the synthesis gas is supplied to the fuel cell.

[0003] Prior Art Literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2010-15860 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In the above-mentioned technologies, improvements are sought in the energy efficiency of fuel cell systems.

[0008] In view of the above situation, the present disclosure aims to provide a fuel cell system and a fuel cell system control method that can improve energy efficiency.

[0009] Solutions to Solve Problems

[0010] As a style of the fuel cell system control method involved in the present disclosure, the above-mentioned fuel cell system control method uses a fuel cell system, and the above-mentioned fuel cell system comprises: a raw material supply mechanism, which supplies raw materials; a water vapor supply mechanism, which supplies water vapor to the above-mentioned raw material supply mechanism; a fuel cell, which generates electrical energy from an oxidant and hydrogen generated from the above-mentioned raw materials; and a recycling gas mechanism, which circulates at least a part of the anode exhaust gas discharged from the anode of the above-mentioned fuel cell, namely, the recycled gas, to the above-mentioned raw material supply mechanism, and controls the water vapor flow rate flowing in the above-mentioned water vapor supply mechanism according to the flow rate of carbon dioxide contained in the above-mentioned recycled gas flowing in the above-mentioned recycling gas mechanism.

[0011] As a style of the fuel cell system involved in the present disclosure, the above-mentioned fuel cell system comprises: a raw material supply mechanism, which supplies raw materials; a water vapor supply mechanism, which supplies water vapor to the above-mentioned raw material supply mechanism; a fuel cell, which generates electrical energy from an oxidant and hydrogen generated from the above-mentioned raw materials; a recycling gas mechanism, which circulates at least a part of the anode exhaust gas discharged from the anode of the above-mentioned fuel cell, namely, the recycled gas, to the above-mentioned raw material supply mechanism; and a control unit, which controls the flow rate of water vapor flowing in the above-mentioned water vapor supply mechanism according to the flow rate of carbon dioxide contained in the above-mentioned recycled gas flowing in the above-mentioned recycled gas mechanism.

[0012] Effects of the Invention

[0013] According to the present disclosure, a fuel cell system and a fuel cell system control method capable of improving energy efficiency can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the fuel cell system involved in Embodiment 1.

[0015] Figure 2 This is a flowchart of the fuel cell system control method involved in the second embodiment.

[0016] Figure 3 This is a flowchart of a fuel cell system control method according to the third embodiment.

[0017] Figure 4 This is a schematic diagram of a fuel cell system according to a fourth embodiment.

[0018] Figure 5 This is a schematic diagram of a fuel cell system according to Embodiment 5. DETAILED DESCRIPTION

[0019] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In addition, the scope of the present disclosure is not limited to the following embodiments, and any changes can be made within the scope of the technical concept of the present disclosure.

[0020] Implementation method 1.

[0021] Figure 1 Schematic diagram of the fuel cell system 100 according to Embodiment 1. Figure 1 As shown, the fuel cell system 100 includes a raw material supply mechanism 1, a water vapor supply mechanism 2, a fuel cell 3, a recycled gas mechanism 4, a control unit 5, a reformer 6, an air supply mechanism 7, a mixer 8, a water vapor generator 9, an anode exhaust gas mechanism 10, a supply path 11 and a separation unit 12.

[0022] The raw material supply mechanism 1 supplies raw materials. The raw materials include methane (CH 4 ) and other carbon-containing compounds (for example, hydrocarbons). The raw material is introduced into the raw material supply mechanism 1 from the supply path 31 through the mixer 8. Hereinafter, methane is exemplified as the carbon-containing compound.

[0023] The water vapor supply mechanism 2 supplies water vapor (H 2 O). The water vapor supply mechanism 2 guides the water vapor obtained from the water vapor generator 9 to the mixer 8.

[0024] A steam reforming reaction is carried out by the raw material and the steam in the reformer 6. The steam reforming reaction is, for example, in accordance with the following formula (I) and formula (II).

[0025] CH 4 +H 2 O→CO+3H 2 …(I)

[0026] CO+H 2 O→CO 2 +H 2 …(II)

[0027] A carbon dioxide reforming reaction using carbon dioxide contained in the raw material and the recycled gas is performed in the reformer 6. The carbon dioxide reforming reaction is, for example, in accordance with the following formula (III) and formula (IV).

[0028] CH 4 +CO 2 →2CO+2H 2 …(III)

[0029] 2CO+2H 2 O→2CO 2 +2H 2 …(IV)

[0030] In the reformer 6, a reformed gas is obtained by a water vapor reforming reaction and a carbon dioxide reforming reaction. The reformed gas includes hydrogen (H 2 ).

[0031] The reformer 6 preferably has a steam reforming catalyst and a carbon dioxide reforming catalyst. As the steam reforming catalyst, Ni-loaded alumina, Ru-loaded alumina, etc. can be cited. The steam reforming catalyst promotes the steam reforming reaction. As the carbon dioxide reforming catalyst, Ni-loaded yttrium oxide, Pt-loaded yttrium oxide, etc. can be cited. The carbon dioxide reforming catalyst promotes the carbon dioxide reforming reaction. The steam reforming catalyst and the carbon dioxide reforming catalyst can be mixed together and filled into the reformer 6. The steam reforming catalyst and the carbon dioxide reforming catalyst can also be formed into layers different from each other and filled into the reformer 6. For example, it can be considered to fill each catalyst into the reformer 6 according to the temperature zone suitable for the steam reforming catalyst and the carbon dioxide reforming catalyst to function.

[0032] The air supply mechanism 7 supplies air (oxidant) to the fuel cell 3. The air supplied from the air supply mechanism 7 is an oxygen-containing gas. The oxygen-containing gas contains oxygen (O 2 ) as an oxidant.

[0033] The reformed gas obtained by the reformer 6 is supplied to the anode 3A of the fuel cell 3. The air supplied from the air supply mechanism 7 is supplied to the cathode 3B of the fuel cell 3. The fuel cell 3 is supplied with hydrogen (H 2 )'s modified gas reacts with air (oxidant) to generate electricity.

[0034] For example, in the case of a solid oxide fuel cell, the reaction at the anode 3A is in accordance with the following formula (V). The reaction at the cathode 3B is in accordance with the following formula (VI), for example.

[0035] H 2 +O 2－ →H 2 O+2e － …(V)

[0036] 1 / 2O 2 +2e － →O 2－ …(VI)

[0037] The anode 3A of the fuel cell 3 discharges an anode exhaust gas. The anode exhaust gas includes, for example, carbon dioxide (CO 2 ), water vapor (H 2 O), carbon monoxide (CO), and methane (CH 4 ).

[0038] The anode exhaust gas mechanism 10 takes in the anode exhaust gas from the fuel cell 3 (anode 3A) and guides the anode exhaust gas to the separation unit 12 via the steam generator 9 .

[0039] The separator 12 can condense a part of the anode off-gas supplied from the anode off-gas mechanism 10 .

[0040] The recycled gas mechanism 4 supplies at least a portion of the anode exhaust gas as recycled gas. Specifically, the recycled gas mechanism 4 guides at least a portion of the anode exhaust gas as recycled gas from the separator 12 to the mixer 8. Thus, the recycled gas mechanism 4 circulates the recycled gas to the raw material supply mechanism 1.

[0041] The supply path 11 branches off from the recycled gas mechanism 4. The supply path 11 guides a part of the recycled gas to a burner (not shown) thermally connected to the reformer 6.

[0042] The steam generator 9 heats the water supplied from the separation unit 12 by heat exchange with the anode exhaust gas, thereby obtaining steam.

[0043] The fuel cell system control method according to the first embodiment will be described.

[0044] The control unit 5 obtains the flow rates of the gas components of the recycled gas flowing through the recycled gas mechanism 4, and controls the flow rate of the water vapor flowing through the water vapor supply mechanism 2 according to the flow rates. The flow rate of the recycled gas flowing through the recycled gas mechanism 4 is detected by a flow meter 22 provided in the recycled gas mechanism 4. For the control of the flow rate of the water vapor flowing through the water vapor supply mechanism 2, a mass flow controller 23 provided in the water vapor supply mechanism 2 is used.

[0045] In the present embodiment, hydrogen is generated by both water vapor modification and carbon dioxide modification. Here, thermal energy is required to generate water vapor in the water vapor generator 9. Therefore, in a situation where hydrogen can be sufficiently generated by carbon dioxide modification, the overall energy efficiency of the system can be improved by reducing the dependence on water vapor modification. In contrast, in a situation where carbon dioxide for carbon dioxide modification is insufficient, the operation of the system can be stabilized by effectively utilizing water vapor modification. In view of the above, for example, when the flow rate of carbon dioxide contained in the recycled gas increases and exceeds the first set value, the control unit 5 reduces the flow rate of water vapor. In a situation where the flow rate of carbon dioxide contained in the recycled gas decreases and is lower than the second set value, the control unit 5 increases the flow rate of water vapor.

[0046] In the fuel cell system control method, the flow rate of water vapor flowing in the water vapor supply mechanism 2 is controlled according to the flow rate of carbon dioxide contained in the recycled gas. Therefore, an appropriate reforming reaction can be performed in the reformer 6 by water vapor reforming and carbon dioxide reforming. In the fuel cell system control method, since water vapor reforming and carbon dioxide reforming are used together, the supply amount of water vapor can be suppressed. Therefore, the energy consumption for generating water vapor in the water vapor generator 9 can be reduced. Therefore, the energy efficiency of the fuel cell system 100 can be improved.

[0047] In this fuel cell system control method, a part of the anode exhaust gas is returned to the upstream side of the fuel cell 3 as the recycled gas, so that the raw material can be effectively utilized and the energy efficiency of the fuel cell system 100 can be improved.

[0048] In this fuel cell system control method, since the flow rate of water vapor is controlled according to the flow rate of carbon dioxide contained in the recycled gas, even when the amount of anode exhaust gas, that is, the flow rate of carbon dioxide in the anode exhaust gas is small, such as at startup, the efficiency of the reforming reaction can be suppressed from decreasing.

[0049] Implementation method 2.

[0050] Figure 2 This is a flowchart of a fuel cell system control method according to Embodiment 2. Note that the same reference numerals are used for the components common to those in Embodiment 1, and description thereof will be omitted.

[0051] like Figure 2 As shown, the fuel cell system control method executes a raw material flow rate detection step S1, a carbon dioxide flow rate calculation step S2, a water vapor flow rate calculation step S3, and a water vapor flow rate determination step S4.

[0052] In the raw material flow rate detection step S1, the flow rate of the raw material in the raw material supply mechanism 1 is detected. The flow rate of the raw material can be detected by a flow meter 24 provided in the supply path 31 (see Figure 1 ).

[0053] In the carbon dioxide flow rate calculation step S2, the carbon dioxide (CO 2 ) flow rate. For example, the flow rate of carbon dioxide can be calculated based on information on the operating conditions of the reformer 6 and the fuel cell 3 (gas consumption, gas generation, reaction gas utilization rate, reaction temperature, etc.), flow rate information of the raw material, the flow rate of water vapor flowing in the water vapor supply mechanism 2, the flow rate ratio of the recycled gas to the anode exhaust gas, etc. (refer to Figure 1 ).

[0054] The flow rate of the recycled gas can be detected by a flow meter 22 provided in the recycled gas mechanism 4 (see Figure 1 ). In addition, the flow rate of the anode exhaust gas mechanism 10 can be calculated according to various operating conditions of the fuel cell 3. Therefore, the flow rate ratio of the recycled gas to the anode exhaust gas can be calculated based on the flow rate obtained by removing the condensation amount calculated based on the condensation temperature of the separation unit 12 from the flow rate of the anode exhaust gas mechanism 10 and the detection value of the flow meter provided in the recycled gas mechanism 4.

[0055] In the water vapor flow rate calculation step S3, the water vapor (H 2For example, the flow rate of water vapor in the recycled gas can be calculated based on the flow rate of the raw material, the consumption of water vapor in the reformer 6, the amount of water vapor generated at the fuel cell, the amount of condensation at the separator 12, and the flow rate of the recycled gas.

[0056] In the water vapor flow rate determination step S4 , the control unit 5 controls the flow rate of water vapor flowing through the water vapor supply mechanism 2 using the mass flow controller 23 based on, for example, the flow rate of carbon dioxide in the reused gas and the flow rate of water vapor in the reused gas.

[0057] The flow rate of carbon dioxide in the recycled gas calculated in the carbon dioxide flow rate calculation step S2 can also be calculated based on information on the operating conditions of the reformer 6 and the fuel cell 3 (gas consumption, gas generation, reaction gas utilization rate, reaction temperature, etc.), flow rate information of the raw material, the flow rate of water vapor flowing in the water vapor supply mechanism 2, and the flow rate ratio of the recycled gas to the anode exhaust gas. According to this calculation method, the system configuration becomes simpler than when a dedicated sensor for detecting the carbon dioxide flow rate is used, so that low cost can be achieved.

[0058] In this fuel cell system control method, the flow rate of water vapor flowing in the water vapor supply mechanism 2 is controlled according to the flow rates of carbon dioxide and water vapor in the recycled gas. Therefore, the water vapor reforming reaction and the carbon dioxide reforming reaction can be stably performed in the reformer 6 at appropriate water vapor flow rates and carbon dioxide flow rates.

[0059] Implementation method 3.

[0060] Figure 3 This is a flowchart of a fuel cell system control method according to Embodiment 3. Note that the same reference numerals are used for the components common to other embodiments, and description thereof will be omitted.

[0061] like Figure 3 As shown, the fuel cell system control method includes a raw material flow rate detection step S1, a carbon dioxide flow rate calculation step S2, a water vapor flow rate calculation step S3, a carbon monoxide flow rate calculation step S5, a methane flow rate calculation step S6 and a water vapor flow rate determination step S4.

[0062] In the carbon monoxide flow rate calculation step S5, the flow rate of carbon monoxide (CO) of the recycled gas of the recycled gas mechanism 4 is calculated. For example, the flow rate of carbon monoxide can be calculated based on the flow rate of the raw material, the flow rate of the water vapor flowing in the water vapor supply mechanism 2, the amount of carbon monoxide generated and consumed in the reformer 6 and the fuel cell 3, and the flow rate of the recycled gas.

[0063] In the methane flow rate calculation step S6, the methane (CH 4For example, the flow rate of methane can be calculated based on the flow rate of the raw material, the flow rate of the water vapor flowing in the water vapor supply mechanism 2, the consumption and reaction amount of methane in the reformer 6 and the fuel cell 3, and the flow rate of the recycled gas.

[0064] In the water vapor flow determination step S4, the control unit 5 controls the flow rate of water vapor flowing in the water vapor supply mechanism 2 by the mass flow controller 23, for example based on the flow rate of carbon dioxide in the recycled gas, the flow rate of water vapor in the recycled gas, the flow rate of carbon monoxide in the recycled gas, and the flow rate of methane in the recycled gas.

[0065] The sum of the flow rate (number of moles per unit time) of the water vapor from the water vapor supply mechanism 2 and the flow rate (number of moles per unit time) of the water vapor of the recycled gas is set to S1. The sum of the carbon contained in the raw material (number of moles per unit time), the flow rate (number of moles per unit time) of the carbon monoxide of the recycled gas, and the flow rate (number of moles per unit time) of the methane of the recycled gas is set to C1. The ratio of S1 to C1 (S1 / C1) is preferably less than 2.5. If S1 / C1 is less than 2.5, the amount of water vapor used for water vapor reforming can be reduced. Therefore, the energy used to generate water vapor in the water vapor generator 9 can be reduced.

[0066] The sum of the flow rate (number of moles per unit time) of water vapor from the water vapor supply mechanism 2, the flow rate (number of moles per unit time) of water vapor of the recycled gas, and the flow rate (number of moles per unit time) of carbon dioxide of the recycled gas is set to S2. The ratio (S2 / C1) of S2 to C1 is preferably 2 or more. If S2 / C1 is 2 or more, the ratio of water vapor modification in the modification reaction is improved, thereby achieving a stable modification reaction with less carbon deposition. Thus, it is possible to achieve an improvement in system efficiency.

[0067] In this fuel cell system control method, the flow rate of water vapor flowing in the water vapor supply mechanism 2 is controlled according to the flow rates of carbon dioxide, water vapor, carbon monoxide, and methane in the recycled gas. Therefore, stable water vapor reforming and carbon dioxide reforming can be achieved in the reformer 6.

[0068] The fuel cell system control method when the load of the fuel cell 3 changes is described. When the load of the fuel cell 3 changes, it is preferred that the water vapor flow rate determination step is performed based on at least load information obtained from the operating conditions of the fuel cell 3 and flow rate information of carbon dioxide of the recycled gas.

[0069] According to this fuel cell system control method, when the load increases, it is possible to suppress a decrease in the reaction efficiency of water vapor reforming and carbon dioxide reforming in the reformer 6 .

[0070] Implementation method 4.

[0071] Figure 4 Schematic diagram of a fuel cell system 200 according to Embodiment 4. Note that the same reference numerals are used for the components common to other embodiments, and description thereof will be omitted.

[0072] like Figure 4 As shown, the fuel cell system 200 includes a thermometer 25 for detecting the temperature of water vapor in the separation unit 12. The detection value of the thermometer 25 indicates the condensation temperature of the anode off-gas in the separation unit 12.

[0073] In this fuel cell system control method, since the detection value of the thermometer 25 indicates the condensation temperature of the anode off-gas, the control unit 5 can determine the flow rate of water vapor in the reused gas based on the detection value of the thermometer 25 .

[0074] Implementation method 5.

[0075] Figure 5 It is a schematic diagram of a fuel cell system 300 according to Embodiment 5. Note that the same reference numerals are given to the same components as those in other embodiments, and description thereof will be omitted.

[0076] like Figure 5 As shown, the fuel cell system 300 includes an ejector 308 instead of the mixer 8 (see Figure 1 ). The ejector 308 is provided in the raw material supply mechanism 1. The water vapor supply mechanism 2, the supply path 31 and the recycled gas mechanism 4 are connected to the ejector 308. The ejector 308 uses the water vapor from the water vapor supply mechanism 2 as a driving fluid to attract the recycled gas from the recycled gas mechanism 4. The ejector 308 can also use the water vapor from the water vapor supply mechanism 2 as a driving fluid to attract the raw material from the supply path 31.

[0077] A flow meter 26 for detecting the flow rate of the recycled gas is provided in the supply path 11. If the flow meters 22 and 26 have the same specifications, the flow rate ratio of the recycled gas to the anode exhaust gas can be calculated based on the detection value of the flow meter 22 and the detection value of the flow meter 26, regardless of the composition of the mixed gas flowing in the supply path 11 and the recycled gas mechanism 4. The control unit 5 can control the flow rate of the water vapor flowing in the water vapor supply mechanism 2 in consideration of the flow rate ratio.

[0078] In this fuel cell system control method, since the ejector 308 can be used to suck the recycled gas and the raw material, energy saving can be achieved compared to the case where the recycled gas and the raw material are supplied using a blower or the like.

[0079] In addition, the technical scope of the present disclosure is not limited to the above-mentioned embodiments, and various modifications can be added without departing from the scope of the concept of the present disclosure.

[0080] For example, in Figure 1 In the fuel cell system 100 shown, the reformer 6 is provided separately from the fuel cell 3, but the reforming reaction can also be performed inside the fuel cell. Therefore, the fuel cell system may also be configured without the reformer.

[0081] exist Figure 1 In the fuel cell system 100 shown, the steam generator 9 generates steam by heat exchange with the anode exhaust gas, but the configuration of the steam generator is not particularly limited. The steam generator may generate steam by, for example, utilizing the exhaust heat of the fuel cell. The steam generator may generate steam by, for example, utilizing the heat inside the reformer.

[0082] Description of Reference Numerals

[0083] 1 ... raw material supply mechanism, 2 ... water vapor supply mechanism, 3 ... fuel cell, 4 ... recycling gas mechanism, 5 ... control unit, 6 ... reformer, 100, 200, 300 ... fuel cell system.

Claims

1. A fuel cell system control method, wherein, the above fuel cell system control method uses a fuel cell system, the above fuel cell system includes: a raw material supply mechanism that supplies raw materials; a water vapor supply mechanism that supplies water vapor to the above raw material supply mechanism; a fuel cell that generates electric power from an oxidant and hydrogen generated from the above raw materials; and a recycled gas mechanism that circulates at least a part of the anode exhaust gas discharged from the anode of the above fuel cell, i.e., the recycled gas, to the above raw material supply mechanism, and controls the water vapor flow rate flowing in the above water vapor supply mechanism according to the flow rate of carbon dioxide contained in the above recycled gas flowing in the above recycled gas mechanism.

2. The fuel cell system control method according to claim 1, wherein, the following steps are performed: a raw material flow rate detection step of detecting the flow rate of the above raw materials in the above raw material supply mechanism; a carbon dioxide flow rate calculation step of calculating the flow rate of carbon dioxide of the above recycled gas in the above recycled gas mechanism; a water vapor flow rate calculation step of calculating the flow rate of water vapor of the above recycled gas in the above recycled gas mechanism; and a water vapor flow rate determination step of determining the flow rate of the above water vapor.

3. The fuel cell system control method according to claim 2, wherein, the following steps are performed: a carbon monoxide flow rate calculation step of calculating the flow rate of carbon monoxide of the above recycled gas in the above recycled gas mechanism; and a methane flow rate calculation step of calculating the flow rate of methane of the above recycled gas in the above recycled gas mechanism.

4. The fuel cell system control method according to claim 2 or 3, wherein, the above water vapor flow rate determination step is performed at least based on the flow rate of the above carbon dioxide of the above recycled gas, the flow rate of the above water vapor of the above recycled gas, and the flow rate of the above raw materials.

5. The fuel cell system control method according to any one of claims 2 to 4, wherein, when the load of the above fuel cell changes, the above water vapor flow rate determination step is performed at least based on the load information obtained from the operating conditions of the above fuel cell and the flow rate information of the above carbon dioxide of the above recycled gas.

6. The fuel cell system control method according to any one of claims 2 to 5, wherein, the flow rate of the above carbon dioxide of the above recycled gas is calculated based on the information of the operating conditions of the above fuel cell, the flow rate information of the above raw materials, the flow rate of the above water vapor flowing in the above water vapor supply mechanism, and the flow rate ratio of the above recycled gas to the above anode exhaust gas.

7. The fuel cell system control method according to any one of claims 2 to 6, wherein, the flow rate of the above water vapor of the above recycled gas is determined according to the condensation temperature of the above anode exhaust gas.

8. The fuel cell system control method according to any one of claims 2 to 7, wherein, an ejector that attracts the above recycled gas with the above water vapor from the above water vapor supply mechanism is used.

9. A fuel cell system, wherein, the above fuel cell system includes: a raw material supply mechanism that supplies raw materials; A water vapor supply mechanism that supplies water vapor to the raw material supply mechanism; A fuel cell that generates electric power from an oxidizer and hydrogen generated from the raw material; A recycled gas mechanism that circulates at least a part of the anode exhaust gas discharged from the anode of the fuel cell, i.e., the recycled gas, to the raw material supply mechanism; and A control unit that controls the water vapor flow rate flowing through the water vapor supply mechanism based on the flow rate of carbon dioxide contained in the recycled gas flowing through the recycled gas mechanism.

10. The fuel cell system according to claim 9, wherein, the fuel cell system further includes a reformer that reforms the raw material, the reformer includes a water vapor reforming catalyst that promotes a water vapor reforming reaction and a carbon dioxide reforming catalyst that promotes a carbon dioxide reforming reaction.

Images