A method and operating system for hydrogen-carbon co-conversion and carbon sequestration in a geological body

Abstract

The embodiment of the present application provides a method for hydrogen-carbon co-conversion and carbon sequestration in a geological body and an operation system thereof. The method comprises the following steps: injecting water, carbon dioxide and a catalyst into the geological body, carrying out hydrogen production, carbon dioxide mineralization and in-situ methanation, and obtaining methane. The catalyst comprises at least one of nickel, iron, cobalt and molybdenum or an oxide thereof; and the geological body comprises silicate minerals. The method is used to realize the integrated operation of long-term stable sequestration of carbon dioxide and energy conversion process, so as to improve the comprehensive energy utilization efficiency of the geological sequestration system.

Description

Technical Field

[0001] This application relates to the field of mass energy engineering, and in particular to a method and operating system for hydrogen-carbon co-conversion and carbon sequestration in geological bodies. Background Technology

[0002] Geological carbon dioxide sequestration is considered an important technological pathway to achieve large-scale greenhouse gas emission reduction and carbon neutrality goals. By injecting carbon dioxide into underground geological bodies and utilizing the reaction between the carbon dioxide and mineral components within these bodies, long-term stable fixation of carbon dioxide can be achieved, thereby reducing the risk of its emission into the atmosphere. In particular, geological bodies rich in reactive elements such as calcium, magnesium, and iron can undergo mineralization reactions with carbon dioxide under geological conditions to form stable carbonate minerals, which are considered to have high sequestration safety and stability.

[0003] Existing technologies primarily focus on the mineralization and sequestration of carbon dioxide within the aforementioned geological bodies, emphasizing the safety of carbon dioxide injection, mineralization efficiency, and long-term sequestration stability. However, within these geological bodies, some reactive minerals undergo redox reactions in the presence of water, releasing energy in the process. For example, iron-bearing minerals undergo valence state transformation and generate hydrogen during water-rock reactions (serpentinization). Such hydrogen production processes are typically considered independent geological or geochemical phenomena and have not yet been integrated with carbon dioxide geological sequestration processes to establish a systematic synergistic utilization mechanism, thus hindering the further resource recovery of hydrocarbons.

[0004] Therefore, how to synergistically achieve carbon dioxide sequestration, in-situ hydrogen generation, and further conversion and utilization of carbon-hydrogen energy within the same geological body, and construct a geological synergistic reaction system that takes into account both carbon emission reduction and energy recovery, is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] This application provides a method and operating system for hydrogen-carbon co-conversion and carbon sequestration in geological bodies, so as to achieve the effect of long-term stable carbon dioxide sequestration and integrated operation of energy conversion process.

[0006] In a first aspect, embodiments of this application provide a method for hydrogen-carbon co-conversion and carbon sequestration in a geological body, comprising: introducing water, carbon dioxide and a catalyst into the geological body to carry out a reaction to obtain methane;

[0007] The catalyst includes at least one of nickel, iron, cobalt, molybdenum or its oxides;

[0008] The geological body includes silicate minerals.

[0009] In one possible implementation, the porosity of the geological body is 5% to 25%.

[0010] And / or, the temperature of the geological body is 50℃~250℃;

[0011] And / or, the pressure of the geological body is 5 MPa to 30 MPa;

[0012] And / or, the geological body is buried at a depth of 800m to 3500m;

[0013] And / or, the permeability of the geological body is 10. -15 m 2 ~10 -13 m 2 .

[0014] In one possible implementation, the geological body includes at least one of the active components of ferrous ions, magnesium ions, and calcium ions.

[0015] In one possible implementation, the ferrous ions in the geological body have a mass fraction of 4% to 12%.

[0016] And / or, the magnesium ions in the geological body have a mass fraction of 1% to 30%;

[0017] And / or, the mass fraction of the calcium ions in the geological body is 0.1% to 15%.

[0018] In one possible implementation, the carbon dioxide includes at least one of supercritical carbon dioxide and gaseous carbon dioxide.

[0019] In one possible implementation, the method includes:

[0020] The water is injected into the geological body to carry out a hydrogen production reaction, then the carbon dioxide is injected to carry out a carbon mineralization reaction, and finally the catalyst is injected to carry out an in-situ methanation reaction to obtain the methane;

[0021] Alternatively, the carbon dioxide is injected into the geological body to carry out a carbon mineralization reaction, followed by the injection of water to carry out a hydrogen production reaction, and finally the catalyst is injected to carry out an in-situ methanation reaction to obtain the methane;

[0022] Alternatively, the water and carbon dioxide are simultaneously injected into the geological body to carry out hydrogen production and carbon mineralization reactions, followed by the injection of the catalyst to carry out in-situ methanation to obtain the methane;

[0023] Alternatively, the catalyst can be injected into the geological body, followed by the injection of water to carry out a hydrogen production reaction, and finally the carbon dioxide can be injected to carry out a carbon mineralization reaction and an in-situ methanation reaction to obtain the methane;

[0024] Alternatively, the catalyst may be injected into the geological body, followed by the injection of carbon dioxide to carry out a carbon mineralization reaction, and finally the water may be injected to carry out a hydrogen production reaction and an in-situ methanation reaction to obtain the methane;

[0025] Alternatively, the catalyst can be injected into the geological body, followed by the injection of water and carbon dioxide to carry out hydrogen production, carbon mineralization, and in-situ methanation reactions to obtain methane.

[0026] In one possible implementation, the molar ratio of water to carbon dioxide is (1~15):1;

[0027] And / or, the mass ratio of the catalyst, the water and the carbon dioxide is (0.01~1):(5~80):(10~150).

[0028] In one possible implementation, the water injection temperature is 20℃~120℃, the water injection pressure is 5MPa~35MPa, and the water injection flow rate is 0.05mL / min~10mL / min.

[0029] And / or, the carbon dioxide injection temperature is 20℃~120℃, the carbon dioxide injection pressure is 5MPa~35MPa, and the carbon dioxide injection flow rate is 0.05mL / min~10mL / min;

[0030] And / or, the catalyst injection temperature is 20℃~120℃, the catalyst injection pressure is 5MPa~35MPa, and the catalyst injection flow rate is 0.01mL / min~5mL / min.

[0031] In one possible implementation, the reaction includes a hydrogen production reaction, a carbon mineralization reaction, and a methanation reaction.

[0032] Secondly, embodiments of this application provide an operating system for implementing the above-described method, comprising:

[0033] An injection unit for injecting the water, the carbon dioxide, and the catalyst into the geological body;

[0034] The reaction control unit is used to control the injection pressure, injection temperature, injection flow rate, or injection sequence of the water, the carbon dioxide, and the catalyst.

[0035] A response monitoring unit is used to acquire product information of the reaction;

[0036] The extraction unit is used to extract the methane to the ground or a designated gathering and transportation system.

[0037] This application provides a method and operating system for hydrogen-carbon co-conversion and carbon sequestration in a geological body. It utilizes water-rock reaction to produce hydrogen in situ, and simultaneously utilizes carbon dioxide mineralization reaction to achieve carbon sequestration. Furthermore, it uses a metal-containing catalyst to drive a methanation reaction to convert carbon dioxide into methane, thereby integrating the carbon sequestration and energy conversion processes into the same geological body. Attached Figure Description

[0038] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0039] Figure 1 A flowchart for hydrogen-carbon co-conversion and carbon sequestration in geological bodies provided in this application;

[0040] Figure 2 This is a schematic diagram illustrating the operation of hydrogen-carbon co-conversion and carbon sequestration using basaltic geological formations within an operating system.

[0041] Figure 3 This is a schematic diagram illustrating the operation of hydrogen-carbon co-conversion and carbon sequestration using peridotite geological formations within an operating system.

[0042] Figure 4 The efficiency curve of the mineralization reaction in Example 1;

[0043] Figure 5 The hydrogen production curve is shown in Example 1;

[0044] Figure 6 The methane production curve in Example 1;

[0045] Figure 7 The curves showing the changes in carbon dioxide conversion rate and methane selectivity for Examples 12-18 are shown.

[0046] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0047] Exemplary embodiments will now be described in detail. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0048] First, let me explain the terms used in this application:

[0049] Water-rock reaction: refers to the series of physical and chemical interactions that occur between rocks in the Earth's crust and water bodies (mainly groundwater, seawater, hydrothermal magma, etc.).

[0050] Hydrogen production reaction: refers to a specific type of chemical reaction in which hydrogen gas (H2) is generated during the interaction between water and rocks. The core mechanism is serpentinization. When iron-magnesium-rich ultramafic rocks (such as peridotite, commonly found on the ocean floor and in ophiolite belts) encounter water, a chemical reaction occurs, and minerals in the original rock (such as olivine) are altered to form a new green mineral—serpentine. In this process, ferrous iron (Fe(II)) in the rock is oxidized to ferric iron (Fe(III)) (for example, forming magnetite), while hydrogen ions in the water are reduced, thus producing hydrogen gas.

[0051] Carbon mineralization reaction: refers to the process by which rocks interact with carbon dioxide (CO2), ultimately transforming the gaseous CO2 into hard rocks (carbonate minerals): CO2 gas dissolves in water to form weakly acidic "carbonated water". This weakly acidic water reacts with minerals in rocks or solid waste, releasing calcium, magnesium and other ions into the water. The released calcium and magnesium ions combine with carbonate ions dissolved in the water, eventually precipitating out to form extremely stable, solid carbonate minerals such as calcite (calcium carbonate) or magnesite (magnesium carbonate).

[0052] Methanation reaction: refers to the process in which carbon monoxide (CO) and carbon dioxide (CO2) react with hydrogen (H2) under the action of a catalyst to ultimately produce methane (CH4) and water (H2O).

[0053] In existing technical solutions, there is a lack of systematic coupling design between carbon dioxide sequestration, hydrogen production reaction and methanation reaction, which leads to the need for additional hydrogen supply in the energy conversion process, low carbon resource utilization efficiency and high engineering implementation cost.

[0054] The method for hydrogen-carbon co-conversion and carbon sequestration in geological bodies provided in this application achieves long-term stable carbon dioxide sequestration and in-situ conversion of carbon-hydrogen energy by synergistically regulating multiple geochemical reaction pathways (including hydrogen production reaction, carbon dioxide mineralization reaction and methanation reaction) in the same geological body.

[0055] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0056] This application provides a method for hydrogen-carbon co-conversion and carbon sequestration in a geological body. The method includes: introducing water, carbon dioxide and a catalyst into the geological body to react and obtain methane; the catalyst includes at least one of elemental nickel, iron, cobalt, molybdenum or their oxides; the geological body includes silicate minerals.

[0057] In the method provided in this embodiment, the injected water serves as both the starting point and the medium for the reaction. For example... Figure 1 As shown, it undergoes hydration with minerals in the rock (especially olivine), a process known as serpentinization. When rich in Fe... 2+ When minerals (such as the fir olivine end-member in olivine) react with water, Fe 2+ It is oxidized to ferric iron (Fe3+) 3+ ), and at the same time, protons (H) in the water + The gas is reduced to produce hydrogen (H2). This process can be represented by equation I:

[0058] (Fe,Mg)₂SiO₄ (olivine) + H₂O → serpentine + Fe₃O₄ (magnetite) + H₂ (hydrogen) + Mg 2+ (Entering the solution) Formula I

[0059] like Figure 1 As shown, the injected CO2 dissolves in water to form carbonic acid, making the water weakly acidic. This acidic water accelerates the dissolution of rock minerals, releasing Mg. 2+ and Ca 2+ Plasma. These ions then react with carbonate ions (CO3) in the water. 2- ) or bicarbonate (HCO3) - The CO2 combines with and precipitates to form extremely stable carbonate minerals (such as magnesite MgCO3 and calcite CaCO3), thereby permanently sealing in CO2.

[0060] Therefore, by injecting CO2, not only is carbon sequestration directly achieved, but the resulting acidic environment may also promote mineral dissolution, thereby releasing more Fe for hydrogen production. 2+ This led to the synergistic conversion of hydrogen and carbon, as well as carbon sequestration.

[0061] More importantly, the surfaces of the added catalysts, such as nickel (Ni) and cobalt (Co), can easily break down hydrogen molecules (H2) into two highly reactive hydrogen atoms, providing ample raw materials for subsequent reactions. For example... Figure 1 As shown, oxygen vacancies generated on the surfaces of nickel, iron, cobalt, molybdenum, or their oxides are active sites for capturing and activating CO2. They can adsorb CO2 molecules and loosen their chemical bonds, making them easier to convert. Therefore, the surface of the catalyst provides a reaction platform for activated hydrogen atoms and carbon-containing intermediates, guiding them to efficiently generate methane while suppressing side reactions (such as the production of carbon monoxide).

[0062] In this application, the addition of a catalyst converts underground-generated hydrogen and carbon dioxide into methane, essentially producing a "ready-to-use" fuel that can be seamlessly integrated into existing energy networks, significantly reducing the cost and technological barriers to energy storage and transportation. Moreover, compared to mineralization and storage of carbonate minerals (such as magnesite), methane production represents a hybrid "carbon utilization + storage" model. A portion of the carbon is extracted and utilized as a high-value energy product, while the remaining CO2 can also be mineralized, achieving permanent and secure geological storage.

[0063] More importantly, the CO2 methanation reaction is a strongly exothermic process (releasing 165 kJ of heat for every 1 mol of methane produced). Conducted in situ underground, this heat can be fed back to the reaction system, helping to maintain the required temperature and creating a self-sustaining, virtuous cycle that reduces the need for external energy.

[0064] In some embodiments, the geological body comprising silicate ore may be at least one of basalt and peridotite.

[0065] When the geological body is basalt, the hydrogen-carbon co-conversion and carbon sequestration processes within it are as follows: Figure 2 As shown, when the geological body is peridotite, the hydrogen-carbon co-conversion and carbon sequestration processes within the geological body are as follows: Figure 3 As shown.

[0066] In some specific implementations, the porosity of the geological body is 5% to 25%.

[0067] In geological formations, when rich in minerals (such as Ca produced by reactions) 2+ Mg 2+ When a fluid flows through pores of varying sizes, it is more likely to reach supersaturation in larger pores, where crystals also grow more readily. In smaller pores, strong interfacial tension and mineral crystal curvature increase the effective solubility of the minerals, allowing the fluid to remain stable and prevent precipitation even in a supersaturated state. Therefore, in this embodiment, by controlling the porosity of the geological body to 5%–25%, a sufficient number of tiny pores are provided to offer a large specific surface area and strong capillary forces, allowing the reaction to proceed fully and retain the products; simultaneously, a finite but stable network of fractures or channels ensures the continuous injection and circulation of fluids such as water and carbon dioxide.

[0068] For example, the porosity of a geological body can be a range of 5%, 10%, 15%, 20%, 25%, or any combination thereof.

[0069] In some specific implementations, the temperature of the geological body is 50℃~250℃.

[0070] In this embodiment, by controlling the temperature of the geological body to be between 50°C and 250°C, the dissolution rate of minerals (such as olivine and pyroxene) in the rock can be significantly accelerated, allowing them to release calcium and magnesium ions for CO2 sequestration more quickly. At the same time, the high temperature also accelerates the precipitation process of carbonate minerals.

[0071] For example, the temperature of the geological body can be a range of 50°C, 100°C, 150°C, 200°C, 250°C, or any combination thereof.

[0072] In some specific implementations, the pressure of the geological body is 5MPa to 30MPa.

[0073] It's understandable that pressure acts as a "dissolution booster" for CO2. In deeper formations, higher pressure allows CO2 to dissolve more fully in formation water, forming carbonic acid. This not only increases the reactivity of CO2 but also enhances its ability to "erode" rocks, thereby accelerating the entire carbon sequestration process.

[0074] For example, the pressure of the geological body can be a range of 5 MPa, 10 MPa, 15 MPa, 20 MPa, 25 MPa, 30 MPa, or any combination thereof.

[0075] In some embodiments, the location and rate of precipitation can be managed to some extent by precisely controlling the temperature and pressure of the geological body. This allows mineral precipitation to occur in a broad rock matrix far from the injection well, achieving permanent preservation.

[0076] In some specific implementations, the burial depth of the geological body is 800m to 3500m.

[0077] Sufficient burial depth provides the necessary temperature and pressure, which not only kinetically accelerates reactions such as mineral dissolution and carbon mineralization, but also converts CO2 into a supercritical state. Supercritical CO2 combines the low viscosity of a gas with the high density of a liquid, making it an ideal form for underground storage and reaction participation, greatly improving space utilization efficiency. Moreover, the geological body at this depth makes the overlying mudstone, shale, and other caprocks more plastic and dense, effectively sealing off high-pressure fluids below.

[0078] For example, the burial depth of the geological body can be a range of 800m, 1000m, 1500m, 2000m, 2500m, 3000m, 3500m or any combination thereof.

[0079] In some specific implementations, the permeability of the geological body is 10. -15 m 2 ~10 -13 m 2 .

[0080] Permeability is a measure of a rock's ability to allow fluids to pass through it. By controlling the permeability of a geological body to be 10... -15 m 2 ~10 -13 m 2 This ensures that a reasonable injection pressure is maintained, preventing "injection failure" or overloading of surface equipment due to poor permeability. Simultaneously, it allows the fluid to widely contact reactive minerals in the reservoir (such as iron-magnesium-rich olivine and serpentine), thereby improving the overall reservoir utilization. Furthermore, suitable permeability allows for a continuous supply of fresh acidic water (rich in CO2) to react with the rock, dissolving Mg. 2+ Fe 2+ Simultaneously, it can promptly remove reaction products (such as H2) and supersaturated ore-forming materials (used to form carbonates), preventing local blockage and allowing the reaction to continue. For the highly exothermic methanation reaction, permeability affects the convective dissipation of heat. Appropriate permeability can retain some of the heat of reaction, forming thermal feedback and maintaining the reaction temperature.

[0081] For example, the permeability of the geological body can be 1.0 × 10⁻⁶. -15 m 2 5.0×10 -15 m 2 1.0×10 -14 m 2 5.0×10 -14 m 2 1.0×10 -13 m 2 A range consisting of , or any two of them.

[0082] In some specific implementations, the geological body includes at least one of ferrous ions, magnesium ions, and calcium ions.

[0083] In some specific implementations, the mass fraction of ferrous ions in the geological body is 4% to 12%.

[0084] For example, the mass fraction of ferrous ions in the geological body can be 4%, 6%, 8%, 10%, 12%, or any combination thereof.

[0085] In some specific implementations, the mass fraction of magnesium ions in the geological body is 1% to 30%.

[0086] For example, the mass fraction of magnesium ions in the geological body can be a range of 1%, 5%, 10%, 15%, 20%, 25%, 30%, or any two of these.

[0087] In some specific implementations, the mass fraction of calcium ions in the geological body is 0.1% to 15%.

[0088] For example, the mass fraction of calcium ions in a geological body can be a range of 0.1%, 1%, 5%, 10%, 15%, or any combination thereof.

[0089] In some specific implementations, the reactions include hydrogen production, carbon mineralization, and methanation.

[0090] In some specific embodiments, the method for hydrogen-carbon co-conversion and carbon sequestration in geological bodies provided in this application may include the following:

[0091] Water is injected into the geological body to produce hydrogen, followed by the injection of carbon dioxide to produce carbon mineralization, and then a catalyst is injected to produce in-situ methanation to obtain methane.

[0092] At this point, injecting water into the geological body serves two purposes. First, it raises the reservoir pressure, providing a pressure buffer for the subsequent injection of lower-density CO2 and gaseous products (H2, CH4), reducing the risk of gas fingering and leakage. Second, the contact between water and iron-magnesium-rich rocks (such as peridotite and basalt) initiates serpentinization. Although this step is slow, it allows for the early release of some Fe. 2+ Furthermore, water can dissolve the soluble salts already present in the rock, clearing the tiny pores and opening up pathways for subsequent fluids.

[0093] After the reservoir is fully wetted by water, the CO2 injected into the geological body dissolves in the pre-existing formation water to form carbonic acid. This weakly acidic fluid actively dissolves rock minerals (especially silicate minerals), not only expanding pores and fractures and increasing local permeability, thus clearing obstacles for the subsequent transport of catalyst particles, but also dissolving and releasing large amounts of Ca for carbon sequestration. 2+ Mg 2+ And Fe, a key raw material for hydrogen production 2+ In addition, CO2 molecules are highly polar and will preferentially adsorb onto the active sites on the surface of rock minerals. This prevents the subsequently injected catalyst from being over-adsorbed and wasted on the rock surface, ensuring that the catalyst reaches the fluid-rock interface where it is more needed.

[0094] After flushing with water and carbon dioxide, harmful impurities (such as H2S and organic sulfur) that might be present in the formation water are displaced or reacted away. Injecting a catalyst at this point significantly extends its lifespan. Furthermore, from a thermodynamic perspective, the mineralization reaction between CO2 and rock is a spontaneous but slow process, while the methanation reaction involving a catalyst is rapid and strongly exothermic. By first adjusting the reservoir to a suitable temperature and pressure state through the CO2-water-rock reaction, and then finally injecting the catalyst, the heat of reaction can be effectively utilized, avoiding the disorderly release of heat that could damage the reservoir.

[0095] In some embodiments, water and carbon dioxide are simultaneously injected into the geological body to carry out hydrogen production and carbon mineralization reactions, followed by the injection of a catalyst to carry out in-situ methanation to obtain methane.

[0096] At this moment, the injected CO2 reacts immediately with water to form carbonic acid (H2CO3). From the instant of injection, this "acidic water" begins a strong chemical "attack" on the rocks and minerals along its path (such as iron- and magnesium-rich silicates). This immediate acid etching effect can dissolve soluble minerals in the rocks (such as calcite and some feldspar), rapidly expand pores and throats, and actively increase the permeability of the reservoir. It also rapidly and in large quantities releases key ions for subsequent reactions, such as Ca2+ used for carbon sequestration. 2+ Mg 2+ And Fe for hydrogen production or catalytic reactions 2+ It is suitable for geological bodies with strong heterogeneity that require rapid establishment of connectivity.

[0097] In some embodiments, a catalyst is injected into the geological body, followed by the injection of water to carry out a hydrogen production reaction, and finally carbon dioxide is injected to carry out a carbon mineralization reaction and an in-situ methanation reaction to obtain methane.

[0098] In this anhydrous state, nano- or micro-sized catalyst particles (such as oxides of Ni, Fe, and Co) are more easily injected as aerosols or dry powders with a carrier gas (such as N2), achieving maximum spreading and adsorption on the dry rock pore surface. Without water interference, the catalyst can adhere more firmly to the mineral surface, forming a high density of active sites.

[0099] When water is subsequently injected, it reacts with the pre-spread metal or metal oxide catalyst, activating the catalyst in situ. Simultaneously, the water begins to react with the rock minerals, releasing Fe... 2+ This process generates some initial H2. Since the catalyst is already in place, this in-situ generated H2 can be immediately captured by the catalyst and used for subsequent reactions.

[0100] When CO2 is finally injected, it faces a pre-heated system: the rock is producing H2, and the catalyst is activated and waiting. The injection of CO2 will immediately trigger a highly efficient methanation reaction (CO2 + H2 → CH4 + 2H2O), achieving a synergistic conversion of hydrogen and carbon.

[0101] In some embodiments, a catalyst is injected into the geological body, followed by the injection of carbon dioxide to carry out a carbon mineralization reaction, and finally water is injected to carry out a hydrogen production reaction and an in-situ methanation reaction to obtain methane.

[0102] When the catalyst is firmly adsorbed on the mineral surface and there is no water film blocking it, the carbon dioxide injected before the water can carry the unfixed catalyst particles into even smaller pores, while dissolving or extracting the small amount of bound water or organic matter originally in the rock pores, thus clearing a "clean surface" for subsequent reactions.

[0103] Although CO2 does not form carbonic acid in the absence of water, as a weak Lewis acid, it can still adsorb and interact with alkaline sites on the surface of rocks and minerals, slightly activating the mineral lattice and preparing for subsequent dissolution. CO2 is injected first to fill the pores, establishing a high-pressure CO2 environment. When water is injected last, it propels along the channels opened by the CO2, forming a complex miscible or immiscible displacement, avoiding the waterlock effect that might occur with water injection alone.

[0104] Some catalysts (such as zero-valent iron and nickel) may be over-oxidized or passivated when exposed to water. Initial contact with CO2 may form a thin protective layer of carbonate or carbide on the catalyst surface, modulating its subsequent reactivity with water. Moreover, in this sequence, all reactants arrive simultaneously, and the reaction occurs concurrently throughout the reservoir, creating a "fully mixed" reaction field that facilitates the rapid establishment of thermodynamic equilibrium.

[0105] In some embodiments, a catalyst is injected into the geological body, followed by the simultaneous injection of water and carbon dioxide to carry out hydrogen production, carbon mineralization, and in-situ methanation reactions to obtain methane.

[0106] First, a catalyst is injected, followed by water and carbon dioxide. The resulting carbonic acid violently dissolves the rock, rapidly releasing large amounts of Mg. 2+ Ca 2+ (For carbon sequestration) and Fe 2+ (For hydrogen production); simultaneously, it flushes the catalyst, removing any trace oxide film that may exist on the catalyst surface, bringing it into a highly active state and thus expanding the reaction interface. The key to this addition sequence is that the hydrogen production reaction (from the rock) and the hydrogen consumption reaction (methanation) occur almost simultaneously. The catalyst is located on the rock surface, meaning that once H2 is generated, it is captured by the nearby catalyst and reacts with CO2 to produce CH4 before it has a chance to diffuse or escape. This "in-situ utilization" greatly improves the hydrogen conversion efficiency and reduces the loss of intermediate products.

[0107] In some specific implementations, the molar ratio of water to carbon dioxide is (1~15):1.

[0108] For commonly used catalysts such as nickel-based catalysts, the redox properties of the reaction atmosphere directly affect their stability. In some embodiments of this application, an excessively high water-to-carbon ratio injected into the geological body may cause oxidation of the catalyst's active components, while an excessively low ratio may lead to carbon deposition; both can result in catalyst deactivation. Therefore, controlling the molar ratio of water to carbon dioxide to (1~15):1 is beneficial for maintaining stable catalyst operation. Simultaneously, it allows carbon dioxide to completely dissolve in water, thereby significantly reducing the upward buoyancy caused by its density difference, eliminating the main driving force for leakage through caprock fissures or faults, and significantly improving the long-term safety of the sealed-in storage.

[0109] For example, the molar ratio of water to carbon dioxide can be 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1 or any combination thereof.

[0110] In some specific implementations, the mass ratio of catalyst, water and carbon dioxide is (0.01~1):(5~80):(10~150).

[0111] By adjusting the ratio of the three components, it is possible to pursue high reactant conversion rates while also ensuring high selectivity of the target product, thus guaranteeing the economic efficiency and sustainability of the process.

[0112] For example, the mass ratio of catalyst, water and carbon dioxide can be 0.01:5:10, 0.05:10:50, 0.1:20:70, 0.5:40:100, 1:60:120, 1:80:150 or any combination thereof.

[0113] In some specific implementations, the water injection temperature is 20℃~120℃, the water injection pressure is 5MPa~35MPa, and the water injection flow rate is 0.05mL / min~10mL / min.

[0114] In some specific implementations, the carbon dioxide injection temperature is 20℃~120℃, the carbon dioxide injection pressure is 5MPa~35MPa, and the carbon dioxide injection flow rate is 0.05mL / min~10mL / min.

[0115] In some specific embodiments, the catalyst injection temperature is 20℃~120℃, the catalyst injection pressure is 5MPa~35MPa, and the catalyst injection flow rate is 0.01mL / min~5mL / min.

[0116] The method for hydrogen-carbon co-conversion and carbon sequestration in geological bodies provided in this application utilizes the in-situ reaction of active minerals with water within the geological body to generate hydrogen, eliminating the need for external hydrogen supply and reducing system energy consumption and engineering complexity. It employs a mobile, in-situ depositable catalyst to form methanation active sites under formation conditions, achieving deep coupling between the catalytic system and the geological body. This method overcomes the technical limitation of the separation between carbon sequestration and energy conversion processes. Through the coordinated control of reaction sequence, injection conditions, and extraction methods, it achieves long-term stable carbon dioxide sequestration and energy utilization in parallel, improving the overall energy utilization efficiency of the geological sequestration system.

[0117] This application also provides an operating system for implementing the above method, comprising:

[0118] The injection unit is used to inject water, carbon dioxide, and catalysts into the geological body;

[0119] The reaction control unit is used to control the injection pressure, injection temperature, injection flow rate, or injection sequence of water, carbon dioxide, and catalyst.

[0120] The response monitoring unit is used to acquire product information of the reaction;

[0121] The extraction unit is used to extract methane to the ground or a designated gathering and transportation system.

[0122] The technical solution of this application will be further described below with specific embodiments.

[0123] Example 1

[0124] A method for hydrogen-carbon co-conversion and carbon sequestration in a geological body consisting of basalt at a depth of 1000m–3000m, with a porosity of 15.58%, a temperature of 100℃, a pressure of 15MPa, and a permeability of 5.34×10⁻⁶. -14 m 2 The geological body contains 6.23% ferrous ions, 4.22% magnesium ions, and 7.87% calcium ions by mass.

[0125] Under laboratory conditions, a high-temperature, high-pressure reaction device was constructed to simulate the underground geological environment. The device simulated the temperature, pressure, and fluid environment of the underground reservoir and served to hold basalt samples and reaction fluids. The overall reaction process is as follows: Figure 1 As shown, the operating system utilizes basalt geological formations for hydrogen-carbon co-conversion and carbon sequestration. Figure 2 As shown, the specific steps include the following:

[0126] S1, supercritical carbon dioxide is injected into the basalt reservoir through a reaction device at a flow rate of 0.25 mL / min, an injection temperature of 100℃, and an injection pressure of 17 MPa. The carbon dioxide dissolves under formation conditions and reacts with metal ions dissolved during the water-rock reaction to form carbonate minerals, thus achieving carbon dioxide mineralization and sequestration. The corresponding mineralization reaction efficiency curve is shown below. Figure 4 As shown, this is used to characterize the mineralization process in a simulated environment;

[0127] S2, water is injected into the basalt reservoir through a reaction device at a flow rate of 0.50 mL / min, an injection temperature of 100℃, and an injection pressure of 17 MPa. Iron- and magnesium-containing active minerals in the basalt reservoir undergo redox reactions with the water, generating hydrogen in situ under formation conditions. The corresponding hydrogen production curve is shown below. Figure 5 As shown, this is used to characterize the occurrence of the hydrogen production process under simulated conditions;

[0128] S3. In the above process, nickel oxide (NiO), a catalyst with migratory and in-situ deposition characteristics, is injected into the basalt reservoir through an injection well. The injection flow rate is 0.10 mL / min, the injection temperature is 100℃, and the injection pressure is 17 MPa. NiO migrates into the reservoir pores or fractures with carbon dioxide and / or water fluids, and is deposited or transformed under the influence of formation temperature, pressure, and geochemical environment, forming methanation active sites in situ.

[0129] S4, the hydrogen generated in the aforementioned hydrogen production process, under the influence of the methanation active sites formed by nickel oxide, drives the dissolution or adsorption of carbon dioxide in the basalt reservoir, thereby undergoing a methanation reaction to generate methane in situ; the corresponding methane generation curve is shown below. Figure 6 As shown, this is used to characterize the in-situ methanation reaction process in a simulated environment;

[0130] S5 involves collecting or extracting methane generated in situ from basalt reservoirs after methane formation, thereby realizing the energy utilization of methane.

[0131] Example 2

[0132] A method for hydrogen-carbon co-conversion and carbon sequestration in a geological body is disclosed. The process is the same as in Example 1, except that the geological body used is peridotite, buried at a depth of 800m~2500m, with a porosity of 10.23%, a temperature of 100℃, a pressure of 15MPa, and a permeability of 2.87×10⁻⁶. -14 m 2The geological body contains 6.83% ferrous ions, 24.11% magnesium ions, and 1.07% calcium ions by mass. A schematic diagram of the operating system using the peridotite geological body for hydrogen-carbon co-conversion and carbon sequestration is shown below. Figure 3 As shown.

[0133] Example 3

[0134] A method for hydrogen-carbon co-conversion and carbon sequestration in a geological body, using the same geological body as in Example 1, and the process is basically the same as in Example 1, except that water is injected first, followed by supercritical carbon dioxide.

[0135] Example 4

[0136] A method for hydrogen-carbon co-conversion and carbon sequestration in a geological body, using the same geological body as in Example 1, and the process is basically the same as in Example 1, except that water and supercritical carbon dioxide are injected simultaneously first, and then a catalyst nickel oxide is injected.

[0137] Example 5

[0138] A method for hydrogen-carbon co-conversion and carbon sequestration in a geological body, using the same geological body as in Example 1, and the process is basically the same as in Example 1, except that a catalyst for nickel oxide is injected first, followed by water, and finally supercritical carbon dioxide is injected.

[0139] Example 6

[0140] A method for hydrogen-carbon co-conversion and carbon sequestration in a geological body, using the same geological body as in Example 1, and the process is basically the same as in Example 1, except that a catalyst for nickel oxide is injected first, followed by supercritical carbon dioxide, and finally water is injected.

[0141] Example 7

[0142] A method for hydrogen-carbon co-conversion and carbon sequestration in a geological body, using the same geological body as in Example 1, and the process is basically the same as in Example 1, except that a catalyst for nickel oxide is injected first, followed by the simultaneous injection of water and supercritical carbon dioxide.

[0143] Example 8

[0144] A method for hydrogen-carbon co-conversion and carbon sequestration in a geological body, using the same geological body as in Example 1, and the process is basically the same as in Example 1, except that the catalyst used is nano-α-Fe2O3.

[0145] Example 9

[0146] A method for hydrogen-carbon co-conversion and carbon sequestration in a geological body, using the same geological body as in Example 1, and the process is basically the same as in Example 1, except that the catalyst used is Co3O4.

[0147] Example 10

[0148] A method for hydrogen-carbon co-conversion and carbon sequestration in a geological body, using the same geological body as in Example 1, and the process is basically the same as in Example 1, except that the catalyst used is nano-MoO3.

[0149] Example 11

[0150] A method for hydrogen-carbon co-conversion and carbon sequestration in a geological body, using the same geological body as in Example 1, and the process is basically the same as in Example 1, except that the reaction device is sealed and purged under an inert atmosphere to eliminate the influence of residual air in the system; then supercritical carbon dioxide and hydrogen are injected simultaneously, and the molar ratio of added hydrogen to supercritical carbon dioxide is controlled to be 4:1 (close to the theoretical stoichiometric ratio of methanation reaction), and water is not injected.

[0151] Example 12

[0152] A method for hydrogen-carbon co-conversion and carbon sequestration in a geological body, using the same geological body as in Example 1, and the process is basically the same as in Example 11, except that the temperature of the geological body is 60°C.

[0153] Example 13

[0154] A method for hydrogen-carbon co-conversion and carbon sequestration in a geological body, using the same geological body as in Example 1, and the process is basically the same as in Example 11, except that the temperature of the geological body is 80°C.

[0155] Example 14

[0156] A method for hydrogen-carbon co-conversion and carbon sequestration in a geological body, using the same geological body as in Example 1, and the process is basically the same as in Example 11, except that the temperature of the geological body is 120°C.

[0157] Example 15

[0158] A method for hydrogen-carbon co-conversion and carbon sequestration in a geological body, using the same geological body as in Example 1, and the process is basically the same as in Example 11, except that the temperature of the geological body is 140°C.

[0159] Example 16

[0160] A method for hydrogen-carbon co-conversion and carbon sequestration in a geological body, using the same geological body as in Example 1, and the process is basically the same as in Example 11, except that the temperature of the geological body is 160°C.

[0161] Example 17

[0162] A method for hydrogen-carbon co-conversion and carbon sequestration in a geological body, using the same geological body as in Example 1, and the process is basically the same as in Example 11, except that the temperature of the geological body is 180°C.

[0163] Example 18

[0164] A method for hydrogen-carbon co-conversion and carbon sequestration in a geological body, using the same geological body as in Example 1, and the process is basically the same as in Example 11, except that the temperature of the geological body is 200°C.

[0165] Comparative Example 1

[0166] A method for hydrogen-carbon co-conversion and carbon sequestration in a geological body, using the same geological body as in Example 1, and the process is basically the same as in Example 1, except that a catalyst for nickel oxide oxidation (NiO) is not used.

[0167] Comparative Example 2

[0168] A method for hydrogen-carbon co-conversion and carbon sequestration in a geological body, using the same geological body as in Example 1, and the process is basically the same as in Example 1, except that water is not injected.

[0169] The following tests were performed on the processes of Examples 1-11 and Comparative Examples 1-2 described above:

[0170] Mineralization efficiency: Before the reaction begins, the initial mass of the dried basalt or peridotite sample is recorded, and the content of mineralizable ions such as Ca and Mg in the initial fluid is determined. After the reaction time is reached, a liquid sample from the reaction apparatus is collected, and the changes in Ca and Mg ion concentrations in the liquid phase are measured using inductively coupled plasma optical emission spectrometry (ICP-OES). Simultaneously, after the reaction is completed, the solid sample is removed, dried, and its mass is recorded. Mineralization efficiency is expressed as the mass of CO2 fixed per unit volume of geological body, with units of kgCO2 / m³. 3 The calculation formula is:

[0171]

[0172] Where ƞ represents the mineralization efficiency per unit geological body, m0 is the initial mass before the reaction, m1 is the mass of the solid sample after the reaction, c0 is the initial concentration of mineralizable ions such as Ca and Mg in the liquid, c1 is the concentration of mineralizable ions after the reaction, and V sV is the volume of the geological sample in the reaction apparatus. l0 V is the initial volume of the fluid. l1 M represents the volume of the fluid after the reaction (water may be injected during the reaction). i This represents the relative mass fraction of mineralizable ions such as Ca and Mg.

[0173] Hydrogen production: During the reaction, gas samples from the outlet of the reaction unit are collected at preset time points, detected by gas chromatography (GC), and the H2 concentration is quantitatively analyzed by external standard method, with the unit being ppm.

[0174] Methane production: During the reaction, gas samples were collected from the outlet of the reaction apparatus at preset time points, and detected by gas chromatography (GC). The concentration of CH4 was quantitatively analyzed by external standard method, with the unit being ppm.

[0175] The test results are detailed in Table 1.

[0176] Table 1

[0177]

[0178] As shown in Table 1, the method provided in this application achieves hydrogen-carbon co-conversion and carbon sequestration in geological bodies, and can obtain a yield of greater than or equal to 5.42 kg CO2 / m³. 3 The mineralization efficiency, hydrogen production greater than 310 ppm, and methane production greater than 61 ppm.

[0179] To verify the promoting effect of the catalyst provided by this invention on the methanation reaction under simulated formation conditions in the laboratory, this application used hydrogen as an external hydrogen source to react with carbon dioxide in Examples 11-18 to carry out the methanation reaction, and controlled the molar ratio of hydrogen to carbon dioxide to be close to the theoretical stoichiometric ratio of the methanation reaction. The test results of Example 11 show that, without the addition of water, Example 11 still achieved efficient conversion of carbon dioxide to methane, and compared with Example 1, the amount of methane produced in Example 11 increased significantly. Therefore, the catalyst provided by this application can catalyze the reaction of hydrogen and carbon dioxide to produce methane.

[0180] The following performance tests were performed on Examples 12-18:

[0181] CO2 conversion rate: Gas samples were collected before and after the reaction, and the change in CO2 concentration was measured using a gas chromatograph (GC). The CO2 conversion rate was calculated by combining the total amount of CO2 entering the system with the amount of CO2 remaining after the reaction. The calculation formula is as follows:

[0182]

[0183] Among them, XCO2 n represents the CO2 conversion rate. CO2, in n represents the CO2 concentration in the gas sample before the reaction. CO2, out This represents the CO2 concentration in the gas sample after the reaction.

[0184] Methane selectivity: After the reaction, gas samples were collected, and the concentration changes of carbon-containing gases such as CH4 and CO were measured using gas chromatography (GC). The methane selectivity was characterized by the proportion of CH4 in all carbon-containing gaseous products. The calculation formula is as follows:

[0185]

[0186] Among them, S CH4 For CH4 selectivity, n CH4 n represents the CH4 concentration in the gas sample after the reaction. CO n represents the CO concentration in the gas sample after the reaction. r This represents the concentration of other carbon-containing gases in the gas sample after the reaction.

[0187] For detailed test results, please see Figure 7 :Depend on Figure 7 It is known that when the temperature of the geological body is less than or equal to 140℃, the methane conversion rate (i.e., methane selectivity) remains essentially unchanged as the temperature of the geological body increases. However, when the temperature of the geological body exceeds 140℃, the methane selectivity decreases slightly with increasing temperature. Simultaneously, the carbon dioxide conversion initially increases rapidly, and then its rate of increase tends to stabilize. This indicates that when the temperature of the geological body is between 60℃ and 140℃, using the catalyst provided in this application to promote the in-situ methanation reaction can achieve a methane selectivity greater than 99%.

[0188] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A method for hydrogen-carbon co-conversion and carbon sequestration in a geological body, characterized in that, include: Water, carbon dioxide, and a catalyst are introduced into a geological body, and hydrogen production, carbon mineralization, and methanation reactions are carried out in situ within the geological body to produce methane. The hydrogen production reaction generates hydrogen gas in situ by reacting water with active minerals in the geological body. The methanation reaction uses the in-situ generated hydrogen gas and the carbon dioxide as reactants to generate methane under the action of the catalyst. The catalyst includes at least one of nickel, iron, cobalt, molybdenum or their oxides; the molar ratio of water to carbon dioxide is (1~15):1; the mass ratio of the catalyst, water and carbon dioxide is (0.01~1):(5~80):(10~150). The geological body comprises silicate minerals; the temperature of the geological body is 50℃~250℃, the burial depth of the geological body is 800m~3500m, the porosity of the geological body is 5%~25%, and the geological body includes active components of ferrous ions, magnesium ions, and calcium ions, wherein the mass fraction of ferrous ions in the geological body is 4%~12%, the mass fraction of magnesium ions in the geological body is 1%~30%, and the mass fraction of calcium ions in the geological body is 0.1%~15%. The water injection temperature is 20℃~120℃, the water injection pressure is 5MPa~35MPa, and the water injection flow rate is 0.05mL / min~10mL / min. The carbon dioxide injection temperature is 20℃~120℃, the carbon dioxide injection pressure is 5MPa~35MPa, and the carbon dioxide injection flow rate is 0.05mL / min~10mL / min. The catalyst is injected at a temperature of 20°C to 120°C, at a pressure of 5 MPa to 35 MPa, and at a flow rate of 0.01 mL / min to 5 mL / min.

2. The method according to claim 1, characterized in that, The pressure of the geological body is 5MPa~30MPa; And / or, the permeability of the geological body is 10. -15 m 2 ~10 -13 m 2 .

3. The method according to claim 1, characterized in that, The carbon dioxide includes at least one of supercritical carbon dioxide and gaseous carbon dioxide.

4. The method according to claim 1, characterized in that, The method includes: The water is injected into the geological body to carry out a hydrogen production reaction, then the carbon dioxide is injected to carry out a carbon mineralization reaction, and finally the catalyst is injected to carry out an in-situ methanation reaction to obtain the methane; Alternatively, the carbon dioxide is injected into the geological body to carry out a carbon mineralization reaction, followed by the injection of water to carry out a hydrogen production reaction, and finally the catalyst is injected to carry out an in-situ methanation reaction to obtain the methane; Alternatively, the water and carbon dioxide are simultaneously injected into the geological body to carry out hydrogen production and carbon mineralization reactions, followed by the injection of the catalyst to carry out in-situ methanation to obtain the methane; Alternatively, the catalyst can be injected into the geological body, followed by the injection of water to carry out a hydrogen production reaction, and finally the carbon dioxide can be injected to carry out a carbon mineralization reaction and an in-situ methanation reaction to obtain the methane; Alternatively, the catalyst may be injected into the geological body, followed by the injection of carbon dioxide to carry out a carbon mineralization reaction, and finally the water may be injected to carry out a hydrogen production reaction and an in-situ methanation reaction to obtain the methane; Alternatively, the catalyst can be injected into the geological body, followed by the simultaneous injection of water and carbon dioxide to carry out hydrogen production, carbon mineralization, and in-situ methanation reactions to obtain methane.

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