Method and apparatus for fuel production by multistep thermochemical cycle of cobalt oxides and carbonates

Abstract

The embodiment of the present application provides a kind of cobalt oxide and carbonate multi-step method thermochemical cycle fuel production method and device, wherein the method comprises: heating cobalt trioxide to first temperature pyrolysis, generate cobalt monoxide and oxygen;The generated cobalt monoxide is mixed with carbonate, under second temperature condition, reaction occurs, generates cobaltate and carbon monoxide;Carbon dioxide is introduced into the reaction system of cobaltate and carbon monoxide, under third temperature condition, carbon monoxide and carbon dioxide in the reaction system and cobaltate react, produce cobalt trioxide and carbonate;The generated cobalt trioxide and carbonate are used to repeat the above steps, and a cycle reaction is formed.The method effectively solves the problem of high temperature in traditional thermochemical decomposition CO2, the process is simple, without the transfer of reactants, simplifies the operation, the reaction system does not contain corrosive substances and phase change process, the requirement of system equipment is low, stability is good, and the effect of CO fuel production is stable.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon dioxide resource utilization and fuel preparation, in particular to a method and device for preparing fuel by a multi-step thermal chemical cycle of cobalt oxide and carbonate. BACKGROUND

[0002] With the economic development and social progress, the consumption of fossil energy is increasing, and in the face of the double carbon target, the environmental pollution problem caused by the application of fossil energy is gradually valued, and the development of clean energy has never been paid so much attention. At the same time, in the face of huge energy saving and emission reduction pressure, how to realize the coordination between the preparation of new energy and chemical products and the control of greenhouse gases is particularly important. Through effective technical means, the resource utilization of carbon dioxide is realized, and the greenhouse gas is converted into usable fuel or high value-added chemical products, which is an effective way to solve the problem.

[0003] The preparation of carbon monoxide fuel gas by pyrolysis of carbon dioxide is an important part of carbon dioxide resource utilization. However, there are many problems in the direct pyrolysis of carbon dioxide by conventional method, such as ultra-high reaction temperature (> 3000℃), mixed carbon monoxide product and oxygen product which are not easy to separate, high risk coefficient, poor safety performance, poor system stability and high overall energy consumption. Therefore, by introducing a circulating oxygen carrier as a medium, the conventional single-step pyrolysis reaction is divided into two or even more steps, and the reaction temperature is reduced through the oxidation and reduction reaction of the oxygen carrier, thereby solving the many problems existing in the conventional direct pyrolysis.

[0004] However, the highest reaction temperature of the current common two-step high-temperature pyrolysis of carbon dioxide is close to 1500℃, and the service life and running stability of the reactor and the circulating oxygen carrier are greatly tested in the circulation process. At the same time, in order to maintain the reaction at the set temperature and promote the conversion of the reaction, the conventional two-step method needs to provide a low oxygen partial pressure environment for the reaction, which needs to cooperate with the vacuum pump and inert gas purging, further increasing the power consumption of the system. Therefore, a multi-step method for decomposing carbon dioxide to produce carbon monoxide with lower energy consumption, better technical and economic performance and better cycle performance is urgently needed. SUMMARY

[0005] In view of the above problems, the present application provides a method and device for preparing fuel by a multi-step thermal chemical cycle of cobalt oxide and carbonate, to solve the problems of high reaction temperature, poor cycle performance of oxygen carrier, high overall energy consumption of system and poor safety.

[0006] One aspect of the present application provides a method for producing fuel by a multi-step thermal chemical cycle of cobalt oxide and carbonate, comprising: heating cobalt trioxide to a first temperature to cause pyrolysis, generating cobalt monoxide and oxygen; mixing the generated cobalt monoxide with carbonate, and causing reaction at a second temperature to generate cobaltate and carbon monoxide; introducing carbon dioxide into the reaction system of the cobaltate and the carbon monoxide, and causing reaction of the carbon monoxide and the carbon dioxide with the cobaltate at a third temperature to generate the cobalt trioxide and the carbonate; and repeating the above steps using the generated cobalt trioxide and the carbonate to form a cycle reaction.

[0007] According to an embodiment of the present application, the first temperature is 850-950℃, the second temperature is 750-850℃, and the third temperature is 500-700℃.

[0008] According to an embodiment of the present application, after generating the cobalt trioxide and the carbonate, the method comprises: cooling the generated cobalt trioxide and the carbonate at the third temperature; and separating the cobalt trioxide and the carbonate to realize cycle regeneration of reaction raw materials.

[0009] According to an embodiment of the present application, the method further comprises: cooling and collecting the remaining part of the carbon monoxide.

[0010] According to an embodiment of the present application, the method further comprises: cooling and collecting the oxygen.

[0011] According to an embodiment of the present application, the total reaction equation of the method is CO2→CO+0.5O2.

[0012] Another aspect of the present application provides a device for producing fuel by a multi-step thermal chemical cycle of cobalt oxide and carbonate, comprising: a pyrolysis reaction reactor for heating cobalt trioxide to a first temperature to cause pyrolysis, generating cobalt monoxide and oxygen; a carbon monoxide production reactor for mixing the generated cobalt monoxide with carbonate, and causing reaction at a second temperature to generate cobaltate and carbon monoxide; a cycle regeneration reactor for introducing carbon dioxide into the reaction system of the cobaltate and the carbon monoxide, and causing reaction of the carbon monoxide and the carbon dioxide with the cobaltate at a third temperature to generate the cobalt trioxide and the carbonate; and a cycle reaction module for repeating the above steps using the generated cobalt trioxide and the carbonate to form a cycle reaction.

[0013] According to an embodiment of the present application, the device further comprises a first cooler for cooling the oxygen.

[0014] According to the embodiment of the present disclosure, the second cooler is further configured to cool the carbon monoxide, and a part of the carbon monoxide is input into the cyclic regeneration reactor, and the remaining part of the carbon monoxide is output to be collected.

[0015] According to the embodiment of the present disclosure, the third cooler is further configured to cool the cobaltosic oxide and the carbonate generated at the third temperature, and the solid phase separator is further configured to separate the cobaltosic oxide and the carbonate to realize cyclic regeneration of the reaction raw material.

[0016] The above-mentioned at least one technical solution adopted in the embodiment of the present application can achieve the following beneficial effects:

[0017] The present application provides a kind of cobalt oxide and carbonate multi-step method thermochemical cycle fuel production method and device, compared with traditional single kind circulation system, innovatively proposed by cobalt oxide and carbonate coupling new type circulation system, the reaction involved in cyclic reaction reactant property is stable;

[0018] The method and device can realize the step-by-step generation of high-purity oxygen and fuel gas, saving the energy consumption required for gas separation and purification in the overall process;

[0019] The overall reaction temperature of the method and device is relatively low, which effectively alleviates and avoids the problems of short service life and poor stability of the reactor and the circulating carrier caused by high reaction temperature in traditional thermochemical cycles, and large energy loss;

[0020] The carbon monoxide (CO) consumed in the third step of the method can come from the carbon monoxide product that did not timely separate from the system in the second step, in principle, the method can realize carbon dioxide as the only material input of the circulation system, greatly improving the atomic utilization rate;

[0021] The total reaction of the method is carbon dioxide decomposition to produce fuel gas, which realizes the resource utilization of carbon dioxide and zero-emission fuel preparation, is conducive to energy saving and emission reduction; by coupling other renewable energy as system energy input, the overall energy saving of the system can be further improved. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more completely understand the present application and its advantages, reference will now be made to the following description taken together with the accompanying drawings, in which:

[0023] Figure 1 The process flow chart of the cobalt oxide and sodium carbonate thermochemical three-step method for decomposing CO2 to produce CO of the present application embodiment one.

[0024] Figure 2 The process flow chart of the cobalt oxide and potassium carbonate thermochemical three-step method for decomposing CO2 to produce CO of the present application embodiment two.

[0025] Figure 3 This is a process flow diagram of the three-step cyclic decomposition method for producing CO2 from cobalt oxide and sodium carbonate using concentrated solar thermochemical methods according to Embodiment 3 of the present invention. Detailed Implementation

[0026] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the invention. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the invention for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0027] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0028] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0029] This invention discloses a multi-step thermochemical cycle method for producing fuel from cobalt oxide and carbonate. By cyclically regenerating cobalt oxide and carbonate between three steps, carbon dioxide decomposition at atmospheric pressure and below 1000°C is achieved through the cyclic reaction, including S1 to S3.

[0030] S1, Cobalt tetroxide (Co3O4) is heated to a first temperature of 850-950℃ to undergo pyrolysis, producing cobalt oxide (CoO) and oxygen (O2). The reaction equations involved in this step are as follows:

[0031] 2Co3O4→6CoO+O2

[0032] In this step, the heat source required for the reaction at 850-950℃ is widely available. It can be provided by the combustion of fossil fuels (natural gas, coal, oil, etc.) or by renewable energy sources (geothermal energy, biomass combustion, concentrated solar power, etc.) to drive the reaction. The O2 generated in the reaction automatically detaches from the system, achieving gas-solid separation, thus enabling the preparation of high-purity O2.

[0033] In step S2, the generated cobalt oxide (CoO) is mixed with carbonate (X₂CO₃) and reacted at a second temperature of 750-850℃ to produce cobaltate (XCoO₂, where X is the alkali metal element contained in the carbonate) and carbon monoxide (CO). The reaction equations involved in this step are as follows:

[0034] 2CoO + X2CO3 → 2XCoO2 + CO

[0035] As described in step (1), the heat source required for this reaction at 750-850℃ is widely available. It can be provided by the combustion of fossil fuels (natural gas, coal, oil, etc.) or by renewable energy sources (geothermal energy, biomass combustion, concentrated solar power, etc.) to drive the reaction. This reaction is a gas-solid reaction, and the generated CO can automatically leave the system. The remaining carbon monoxide is cooled and collected, achieving the preparation of high-purity CO.

[0036] S3, carbon dioxide (CO2) is introduced into the reaction system of cobaltate (XCOO2) and carbon monoxide (CO). Under a third temperature of 500-700℃, carbon monoxide (CO) and carbon dioxide (CO2) react with cobaltate (X2CO3) to produce cobalt tetroxide (CO3O4) and carbonate (X2CO3). The reaction equations involved in this step are as follows:

[0037] CO+2CO2+6XCoO2→2Co3O4+3X2CO3

[0038] The cobalt tetroxide and carbonate produced at the third temperature are cooled; the cobalt tetroxide and carbonate are separated to achieve the recycling and regeneration of the reaction raw materials.

[0039] The cobalt tetroxide (Co3O4) generated in this step will serve as a reactant to achieve the reaction in step S1 of the next cycle; the carbonate (X2CO3) will serve as a reactant to participate in the reaction in S2 of the next cycle. Thus, the above three steps achieve the recycling and regeneration of the reactants.

[0040] The carbon monoxide (CO) involved in the reaction in S3 can come from the residue in the system in the second step, or from the carbon monoxide that was not separated from the system in time in the second step. The reaction process does not require the introduction of additional gas into the system.

[0041] In this embodiment, the above steps are repeated using the generated cobalt tetroxide and carbonate to form a cyclic reaction.

[0042] In the three-step reaction involved in the above method, the reactants achieve cyclic regeneration through reaction coupling. The overall reaction of the three-step method is the decomposition reaction of carbon dioxide, i.e., CO2→CO+0.5O2.

[0043] The reactants involved in this cyclic reaction are stable, enabling the stepwise production of high-purity oxygen and fuel gas, thus saving energy consumption required for gas separation and purification in the overall process. The overall reaction temperature is relatively low, effectively alleviating and avoiding the problems of shortened reactor and circulation carrier lifespan, poor stability, and high energy loss caused by excessively high reaction temperatures in traditional thermochemical cycles. In principle, this method can make carbon dioxide the sole input to the cyclic system, greatly improving atom utilization. This method realizes the resource utilization of carbon dioxide and zero-emission fuel production, which is beneficial for energy conservation and emission reduction.

[0044] Another aspect of the present invention provides a fuel production apparatus using a multi-step thermochemical cycle of cobalt oxides and carbonates, comprising the following components.

[0045] The pyrolysis oxygen reactor 01 is used to heat cobalt tetroxide to a first temperature to cause pyrolysis, generating cobalt oxide and oxygen.

[0046] The first cooler 02 is used to cool oxygen.

[0047] The carbon monoxide production reactor 03 is used to mix the generated cobalt oxide with carbonate and react them under a second temperature condition to produce cobaltate and carbon monoxide.

[0048] The second cooler 04 is used to cool carbon monoxide, feeds a portion of the carbon monoxide into the circulating regeneration reactor 05, and outputs the remaining portion of the carbon monoxide for collection.

[0049] The circulating regeneration reactor 05 is used to introduce carbon dioxide into the reaction system of cobaltate and carbon monoxide. Under the third temperature condition, carbon monoxide and carbon dioxide react with cobaltate in the reaction system to produce cobalt tetroxide and carbonate.

[0050] The recycling reaction module is used to repeat the above steps using the generated cobalt tetroxide and carbonate to form a recycling reaction. The recycling reaction module includes: a third cooler 06, used to cool the cobalt tetroxide and carbonate generated at a third temperature; and a solid phase separator 07, used to separate the cobalt tetroxide and carbonate to achieve the recycling and regeneration of the reaction raw materials.

[0051] The following detailed description of the cobalt oxide and carbonate multi-step thermochemical cycle fuel production device is provided through specific embodiments.

[0052] Example 1

[0053] This embodiment uses sodium carbonate (Na2CO3) and cobalt oxide as the circulating working fluid to achieve a three-step decomposition of carbon dioxide (CO2) to carbon monoxide (CO). The reaction equations are as follows:

[0054] Thermal explanation of oxygen: 2Co3O4 → 6CoO + O2

[0055] Preparation of CO: 2CoO + Na₂CO₃ → 2NaCoO₂ + CO

[0056] Regeneration cycle: CO + 2CO₂ + 6NaCoO₂ → 3Na₂CO₃ + 2Co₃O₄

[0057] Figure 1 The diagram shown is a detailed flowchart of this embodiment.

[0058] (1) Cobalt oxide (Co3O4) is filled into the thermal oxygen decomposition reactor 01, and the reaction temperature is set to 850-950℃ under normal pressure to generate oxygen (O2) and cobalt oxide (CoO).

[0059] (2) The O2 generated in step (1) leaves the system, is processed by the first cooler O2, and is then collected.

[0060] (3) The CoO generated in step (1) and the sodium carbonate (Na2CO3) separated in the solid phase separator 07 are fed into the carbon monoxide production reactor 03. The reaction temperature is set to 750-850℃, and the reaction produces sodium cobaltate (NaCoO2) and carbon monoxide (CO).

[0061] (4) The CO obtained in step (3) is processed by the second cooler 04 and collected; some of the CO enters the recycling reactor 05 after cooling.

[0062] (5) The NaCoO2 obtained in step (3) and part of the CO refluxed in the second cooler 04 enter the recycling reactor 05 and react with carbon dioxide (CO2) introduced from the outside. The reaction temperature is set at 500-700℃, and the reaction produces Na2CO3 and Co3O4, thus realizing the recycling of the reaction raw materials.

[0063] (6) The Na2CO3 and Co3O4 generated in the circulating regeneration reactor 05 in step (5) are processed by the third cooler 06 and the solid phase separator 07 to achieve the separation of the two substances. The separated Na2CO3 is recycled back to the carbon monoxide production reactor 03; the separated Co3O4 is recycled back to the thermal deoxygenation reactor 01 to participate in the reactions of the next cycle.

[0064] Example 2:

[0065] This embodiment uses potassium carbonate (K2CO3) and cobalt oxide as circulating working fluids to achieve a three-step decomposition of carbon dioxide (CO2) to carbon monoxide (CO). The reaction equations are as follows:

[0066] Thermal explanation of oxygen: 2Co3O4 → 6CoO + O2

[0067] Preparation of CO: 2CoO + K2CO3 → 2KCoO2 + CO

[0068] Regeneration cycle: CO + 2CO2 + 6KCoO2 → 3K2CO3 + 2Co3O4

[0069] Figure 2 The diagram shown is a detailed flowchart of this embodiment.

[0070] (1) Cobalt oxide (Co3O4) is filled into the thermal oxygen decomposition reactor 01, and the reaction temperature is set to 850-950℃ under normal pressure to generate oxygen (O2) and cobalt oxide (CoO).

[0071] (2) The O2 generated in step (1) leaves the system, is processed by the first cooler O2, and is then collected.

[0072] (3) The CoO generated in step (1) and the potassium carbonate (K2CO3) separated in the solid phase separator 07 are fed into the carbon monoxide production reactor 03. The reaction temperature is set to 750-850℃, and the reaction produces potassium cobaltate (KCoO2) and carbon monoxide (CO).

[0073] (4) The CO obtained in step (3) is processed by the second cooler 04 and collected; some of the CO enters the recycling reactor 05 after cooling.

[0074] (5) The KCoO2 obtained in step (3) and part of the CO refluxed in the second cooler 04 enter the recycling reactor 05 and react with carbon dioxide (CO2) introduced from the outside. The reaction temperature is set at 500-700℃, and K2CO3 and Co3O4 are generated, realizing the recycling of the reaction raw materials.

[0075] (6) The K2CO3 and CO3O4 generated in the circulating regeneration reactor 05 in step (5) are processed by the third cooler 06 and the solid phase separator 07 to achieve the separation of the two substances. The separated K2CO3 is recycled back to the carbon monoxide production reactor 03; the separated Co3O4 is recycled back to the thermal deoxygenation reactor 01 to participate in the reactions of the next cycle.

[0076] Example 3:

[0077] The cobalt oxide and carbonate multi-step thermochemical cycle fuel production method involved in this invention consists of two endothermic reactions and one exothermic reaction. The thermal decomposition of oxygen and the CO production reaction are endothermic reactions, while the recycling reaction is exothermic. The endothermic reactions require an external heat source, which can come from conventional fuel combustion (coal combustion, natural gas combustion, biomass combustion, etc.), electric heating, or renewable energy heating (solar energy, geothermal energy, etc.). This embodiment, based on the cobalt oxide and carbonate multi-step thermochemical cycle fuel production method, combines concentrated solar power to provide heat for the cycle reaction, and provides an implementation scheme for concentrated solar power-driven cobalt oxide and carbonate multi-step thermochemical cycle fuel production.

[0078] In this embodiment, sunlight is concentrated using tower-type or dish-type concentrating solar power devices to utilize thermal energy and drive the endothermic reaction in the fuel recycling process. The specific process is as follows: Figure 3 As shown.

[0079] (1) A concentrated solar energy device is used to concentrate thermal energy and drive the thermal decomposition oxygen reactor 01. The cobalt oxide (Co3O4) filled in the reactor 01 reacts at 850-950℃ to generate oxygen (O2) and cobalt oxide (CoO).

[0080] (2) The O2 generated in step (1) leaves the system, is processed by the first cooler O2, and is then collected.

[0081] (3) Use a concentrated solar energy device to achieve thermal energy accumulation and drive the carbon monoxide production reactor 03. The CoO generated in step (1) and the sodium carbonate (Na2CO3) separated in the solid phase separator 07 enter the carbon monoxide production reactor 03 together. The reaction temperature is set to 750-850℃, and the reaction produces sodium cobaltate (NaCoO2) and carbon monoxide (CO).

[0082] (4) The CO obtained in step (3) is processed by the second cooler 04 and collected; some of the CO enters the recycling reactor 05 after cooling.

[0083] (5) The NaCoO2 obtained in step (3) and part of the CO refluxed in the second cooler 04 enter the recycling reactor 05 and react with carbon dioxide (CO2) introduced from the outside. The reaction temperature is set at 500-700℃, and the reaction produces Na2CO3 and Co3O4, thus realizing the recycling of the reaction raw materials.

[0084] In step (5), the Na2CO3 and Co3O4 generated in the regeneration reactor 05 are processed by the third cooler 06 and the solid phase separator 07 to separate the two substances. The separated Na2CO3 is recycled back to the carbon monoxide production reactor 03; the separated Co3O4 is recycled back to the thermal deoxygenation reactor 01 to participate in the reactions of the next cycle.

[0085] Those skilled in the art will understand that the features described in the various embodiments and / or claims of the present invention can be combined or combined in various ways, even if such combinations or combinations are not explicitly described in the present invention. In particular, the features described in the various embodiments and / or claims of the present invention can be combined or combined in various ways without departing from the spirit and teachings of the present invention. All such combinations and / or combinations fall within the scope of the present invention.

[0086] Although the invention has been shown and described with reference to specific exemplary embodiments thereof, those skilled in the art will understand that various changes in form and detail may be made to the invention without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents. Therefore, the scope of the invention should not be limited to the above embodiments, but should be determined not only by the appended claims but also by their equivalents.

Claims

1. A multi-step thermochemical cycle method for producing fuel from cobalt oxide and carbonate, characterized in that, include: When cobalt tetroxide is heated to a first temperature, it undergoes pyrolysis to produce cobalt oxide and oxygen. The generated cobalt oxide is mixed with carbonate and reacted under a second temperature condition to produce cobaltate and carbon monoxide. Carbon dioxide is introduced into the reaction system of the cobaltate and the carbon monoxide. Under a third temperature condition, the carbon monoxide in the reaction system neutralizes the carbon dioxide and reacts with the cobaltate to produce cobalt tetroxide and the carbonate. The cobalt tetroxide and the carbonate produced at the third temperature are cooled; The cobalt tetroxide and the carbonate are separated, and the above steps are repeated using the generated cobalt tetroxide and the carbonate to form a cyclic reaction.

2. The method according to claim 1, characterized in that, The first temperature is 850-950℃, the second temperature is 750-850℃, and the third temperature is 500-700℃.

3. The method according to claim 1, characterized in that, Also includes: Cool and collect the remaining portion of the carbon monoxide.

4. The method according to claim 1, characterized in that, Also includes: The oxygen is then cooled and collected.

5. The method according to claim 1, characterized in that, The overall reaction equation for this method is CO2→CO+0.5O2.

6. A multi-step thermochemical cycle fuel production apparatus using cobalt oxide and carbonate, characterized in that, include: The thermal decomposition oxygen reactor (01) is used to heat cobalt tetroxide to a first temperature to cause pyrolysis, generating cobalt oxide and oxygen. The carbon monoxide production reactor (03) is used to mix the generated cobalt oxide with carbonate and react under a second temperature condition to generate cobaltate and carbon monoxide. A circulating regeneration reactor (05) is used to introduce carbon dioxide into the reaction system of the cobaltate and the carbon monoxide. Under a third temperature condition, the carbon monoxide and the carbon dioxide in the reaction system react with the cobaltate to produce cobalt tetroxide and the carbonate. The circulating reaction module includes a third cooler (06) and a solid phase separator (07). The third cooler (06) is used to cool the cobalt tetroxide and the carbonate generated at the third temperature. The solid phase separator (07) is used to separate the cobalt tetroxide and the carbonate to realize the recycling of the reaction raw materials. The circulating reaction module is used to repeat the above steps using the generated cobalt tetroxide and the carbonate to form a circulating reaction.

7. The apparatus according to claim 6, characterized in that, Also includes: The first cooler (02) is used to cool the oxygen.

8. The apparatus according to claim 6, characterized in that, Also includes: A second cooler (04) is used to cool the carbon monoxide, input a portion of the carbon monoxide into the circulating regeneration reactor (05), and output the remaining portion of the carbon monoxide for collection.

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