Method for co-production of carbon dioxide sequestration and syngas by coupling saline aquifer activation and coalbed oxidation gasification

Abstract

The application discloses a kind of carbon dioxide sequestration and synthesis gas cogeneration method coupling saline aquifer activation and coal seam oxidative gasification, comprising the following steps: (1) saline aquifer activation and basalt mineralization;(2) coal seam oxidative gasification;(3) reduction reaction and gas generation;(4) high-temperature membrane separation purification.The application initiates "saline activation-oxidative gasification-in situ separation" three-stage reaction system, CO2 conversion rate breaks through 85%;Utilize the catalytic effect of Cl- in saline to accelerate basalt dissolution (reaction rate is increased by 2-3 times);Through air injection, coal oxidation self-heating is initiated, temperature self-balancing system is established, and external energy consumption is reduced by more than 90%;Develop high-temperature membrane separation technology, realize underground in-situ gas purification, and separation energy consumption is reduced to 0.8kW·h / m 3 .

Description

Technical Field

[0001] This invention relates to a method for carbon dioxide sequestration and syngas co-production that couples saline aquifer activation with coal seam oxidation and gasification, belonging to the field of clean energy technology. Background Technology

[0002] In traditional saline aquifer sequestration technology, the dissolution rate of CO2 in saline water is low (usually <1 mol / kg·h), resulting in a mineralization efficiency of less than 30%, making it difficult to achieve efficient CO2 sequestration. Coal seam gas injection technology has significant drawbacks; gas channeling easily occurs when injecting CO2 or air alone, resulting in syngas production of less than 400 m³. 3 / ton CO2; In terms of gas separation technology, conventional cryogenic separation methods not only have high energy consumption (>2.5kW·h / m³), but also... 3 Syngas is not suitable for complex underground environments with high temperatures, which limits its application scope. Summary of the Invention

[0003] To address the problems existing in the prior art, the present invention provides a method for carbon dioxide sequestration and syngas co-production that couples saline aquifer activation with coal seam oxidation and gasification.

[0004] To achieve the above objectives, the present invention employs a method for carbon dioxide sequestration and syngas co-production that couples saline aquifer activation with coal seam oxidation and gasification, comprising the following steps:

[0005] (1) Activation of saline aquifers and mineralization of basalt

[0006] CO2 is pressurized to a supercritical state and mixed with brine from the saline layer to form an acidic solution. This acidic solution is then injected into the basalt layer for mineralization.

[0007] Real-time monitoring of the conductivity and pH of the solution injected into the basalt layer determines whether mineralization is complete;

[0008] (2) Coal seam oxidation gasification

[0009] After mineralization is completed, the mineralization solution is injected into the mixed coal seam of coking coal and gas coal, and air is injected at the same time. The permeability of the mixed coal seam is ≥20mD; otherwise, hydraulic fracturing pretreatment is carried out to make the fracture length ≥50m and the conductivity ≥30D·cm.

[0010] The initial temperature of the mixed coal seam is raised to 500℃ by electric heating to trigger the exothermic reaction of coal oxidation. The external heat source is then turned off, and the temperature is maintained at 650-850℃ by adjusting the air injection rate.

[0011] (3) Reduction reaction and gas generation

[0012] A high-temperature reaction zone with a radius of 5-10m is formed in the coal seam, centered on the injection well, where CO2 dissolved in the mineralization solution undergoes a reduction reaction with the oxidized semi-coke;

[0013] Collect the mixed gas and use a gravity separator to initially separate the gas and liquid phases;

[0014] (4) High-temperature membrane separation and purification

[0015] The mixed gas was introduced into a zirconia-based porous ceramic membrane module and separated under conditions of 800-900℃ and 0.3-0.8MPa, with a permeability selectivity coefficient of CO and H2 ≥50.

[0016] The gas flow rate is controlled by a circulation loop to ensure that the purity of the synthesis gas is ≥95%, the CO content in the synthesis gas is 50-60 vol%, the H2 content is 35-45 vol%, and the residual gas is returned to the reaction zone for secondary use.

[0017] As an improvement, the supercritical state in step (1) is a pressure of 8-15 MPa and a temperature of 35-50℃; CO2 pressurized to the supercritical state is mixed with saline water with a mineralization of ≥50 g / L at a volume ratio of 1:2-1:4 to form an acidic solution with a pH of 3.5-4.0.

[0018] As an improvement, the Cl of the brine in the saline layer - Concentration ≥ 50 g / L, and Fe 3+ Content ≤0.1g / L.

[0019] As an improvement, in step (1), the acidic solution is at a concentration of 10-20 mg / L. 3 Injecting basalt into the formation at a rate of 1.2-1.8 times the formation pressure, which ranges from 5 to 12 MPa; the basalt layer has a porosity ≥8%, a permeability ≥10 mD, and a CaO+MgO content ≥12 wt%.

[0020] As an improvement, in step (1), mineralization is considered complete when the conductivity is ≥15 mS / cm and the pH is stable at 4.0-4.5 for 24 hours.

[0021] As an improvement, in step (2), the mass ratio of coking coal to gas coal in the mixed coal seam is 1:3; the mineralization solution is applied at a concentration of 0.5-1.2 m... 3 Injected into the mixed coal seam at a rate of / h, while simultaneously injecting at a rate of 0.2-0.6m. 3 Air is injected at a rate of / min, with an injection volume of 1.2-1.8 m³ / min based on the oxygen requirement per ton of coal. 3 calculate.

[0022] As an improvement, the hydraulic fracturing pretreatment in step (2) involves injecting a 5-10% HCl solution in conjunction with a proppant, resulting in a fracture conductivity ≥50 D·cm. The proppant is 20 / 40 mesh ceramsite.

[0023] As an improvement, in step (2), when the temperature exceeds 850°C, water is injected for cooling, and the amount of water injected is ≤ 10% of the total flow rate of the solution.

[0024] As an improvement, in step (3), gaseous CO2 is added to maintain the molar ratio of CO2 to semi-coke at 1:1.5-1:2.0. The amount of CO2 added is dynamically controlled by an online mass spectrometer to maintain the partial pressure of CO2 in the reaction zone ≥1.5MPa.

[0025] As an improvement, in step (4), the mixed gas is... 3 / (h·m 2 The flow rate is fed into a zirconia-based porous ceramic membrane module, and the surface of the ceramic membrane is coated with a nano CeO2 layer with a thickness of 50-200nm.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] (1) It pioneered a three-stage reaction system of “salt water activation-oxidation gasification-in-situ separation”, achieving a CO2 conversion rate of over 85%.

[0028] This three-stage reaction system achieves highly efficient CO2 conversion and cascade utilization through multi-stage synergistic coupling, representing a qualitative leap compared to traditional single-stage treatment technologies. The first stage utilizes the chemical reaction between saline water and supercritical CO2 to complete the initial dissolution of CO2 and the fixation of basalt mineralization. The second stage utilizes coal seam oxidation and gasification to further convert CO2 in the mineralized solution into core components of syngas. The third stage achieves the recycling of unreacted CO2 through in-situ separation, forming a closed-loop system of "fixation-conversion-recycling." The deep synergy of the three stages enables a comprehensive CO2 conversion rate exceeding 85%, significantly improving the utilization efficiency of carbon resources.

[0029] (2) Utilizing Cl in saline water - The catalytic effect accelerates the dissolution of basalt, increasing the reaction rate by 2-3 times.

[0030] Utilizing the high concentration of Cl in the saline aquifer - The dual catalytic mechanism (≥50 g / L) significantly enhances the dissolution efficiency of basalt. On the one hand, Cl... - Ca produced by the dissolution of basalt 2+ Mg 2+ It forms stable, soluble complexes, disrupting the mineral dissolution-precipitation equilibrium and promoting the continuous dissolution of minerals such as anorthite; on the other hand, Cl... -Reducing the surface tension of the solution enhances its permeability within the pores of basalt, thereby expanding the reaction contact area. Under the same injection conditions, high Cl content... - The dissolution rate of basalt in saline water systems is much higher than that in Cl-free systems. - This system effectively shortens the mineralization reaction cycle, laying the foundation for efficient operation of subsequent processes.

[0031] (3) By injecting air to induce coal oxidation and self-heating, a temperature self-balancing system is established, reducing external energy consumption by more than 90%.

[0032] This invention utilizes air-injected coal oxidation self-heating and dynamic temperature balance technology to achieve low-energy operation of the reaction process. In the initial stage, an electric heater raises the coal bed temperature to 500°C to trigger the oxidation reaction. The large amount of heat released from the oxidation of coal and air (≥250 MJ of heat per ton of coal) maintains the high temperature required for the reaction, eliminating the need for continuous external heating. Simultaneously, by precisely adjusting the air injection rate and considering the endothermic characteristics of the reduction reaction, stable control of the reaction temperature between 650-850°C is achieved. During stable operation, the system can completely shut off external heat sources, reducing external energy consumption by more than 90% compared to traditional processes that rely entirely on electric or fuel heating, significantly improving the process's economic efficiency.

[0033] (4) Develop high-temperature resistant membrane separation technology to achieve in-situ underground gas purification, reducing separation energy consumption to 0.8 kW·h / m 3 .

[0034] Breaking through the high energy consumption bottleneck of traditional surface gas separation, an innovative underground in-situ high-temperature membrane separation technology has been developed. Utilizing a zirconia-silicon carbide composite ceramic membrane (coated with a nano-CeO2 layer), it possesses excellent high-temperature resistance (800-900℃), high-pressure resistance (0.3-0.8MPa), and high selectivity (CO and H2 permeability selectivity coefficient ≥50), allowing for in-situ separation directly near the coal seam reaction zone. The mixed gas can be directly introduced into the membrane module without surface cooling, achieving efficient separation by utilizing differences in gas molecule size. The permeate gas directly yields syngas with a purity ≥95%. This technology eliminates the gas cooling-heating stage in traditional processes, and combined with optimized membrane module driving pressure, reduces separation energy consumption to 0.8 kW·h / m³. 3 Compared with traditional low-temperature distillation separation technology (energy consumption 2.5-3.0 kW·h / m³), 3 This reduces costs by more than 60%, significantly improving the economic efficiency of the syngas purification process. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this application are described in detail below. It should be understood that the embodiments of this application and the specific features in the embodiments are detailed descriptions of the technical solutions of this application, rather than limitations thereof. In the absence of conflict, the embodiments of this application and the technical features in the embodiments can be combined with each other.

[0036] A method for carbon dioxide sequestration and syngas co-production coupled with saline aquifer activation and coal seam oxidation gasification includes the following steps:

[0037] (1) Activation of saline aquifers and mineralization of basalt:

[0038] ① CO2 captured from a coal-fired power plant is pressurized to a supercritical state (pressure 8-15 MPa, temperature 35-50℃), and mixed with saline water with a mineralization ≥50 g / L at a volume ratio of 1:2-1:4 to form an acidic solution with a pH of 3.5-4.0; the Cl- content of the saline water layer... - Concentration ≥ 50 g / L, and Fe 3+ The content should be ≤0.1g / L to prevent mineral precipitation from clogging the pores;

[0039] ② Add acidic solution at 10-20m 3 Injecting the basalt layer at a rate of / day, with an injection pressure of 1.2-1.8 times the formation pressure (formation pressure range 5-12 MPa), the basalt layer must meet the following requirements: porosity ≥8%, permeability ≥10 mD, and CaO+MgO content ≥12 wt%. When the acidic solution is injected into the fracture network of the basalt layer, it triggers a rapid mineralization reaction.

[0040] CaAl2Si2O8 (calcium feldspar) + 8H + →Ca 2+ +2Al3++2H4SiO4;

[0041] Ca 2+ +CO32-→CaCO3↓(calcite);

[0042] ③ Monitor the conductivity and pH of the solution in real time. When the conductivity is ≥15mS / cm and the pH is stable at 4.0-4.5 for 24 hours, it is determined that the mineralization is complete (mineral dissolution saturation). The mineralization solution is then directly introduced into the coal seam through the connecting pipe.

[0043] (2) Coal seam oxidation gasification:

[0044] ①Containing Cl - Mineralization solutions with a concentration ≥35 g / L were prepared at a concentration of 0.5-1.2 m. 3 Injected at a rate of / h into a mixed coal seam with a coking coal to gas coal mass ratio of 1:3, while simultaneously injecting at a rate of 0.2-0.6m... 3Air is injected at a rate of / min, with the air injection volume based on the oxygen requirement of 1.2-1.8 m³ / min per ton of coal (dry, ash-free). 3 Calculations are performed; the mixed coal seam must meet the requirement of permeability ≥ 20mD, otherwise hydraulic fracturing pretreatment is required (fracture length ≥ 50m, conductivity ≥ 30D·cm); the hydraulic fracturing pretreatment is performed by co-injection of 5-10% HCl solution and proppant, the fracture conductivity is ≥ 50D·cm, and the proppant is 20 / 40 mesh ceramsite;

[0045] ② The initial temperature of the coal seam is raised to 500℃ by an electric heater to trigger the exothermic reaction of coal oxidation (heat generation ≥250MJ / ton of coal). Then the external heat source is turned off and the temperature is maintained at 650-850℃ by adjusting the air injection rate.

[0046] The specific related reactions are as follows:

[0047] C (coal) + O2 → CO2 (exothermic, ΔH = -393 kJ / mol);

[0048] CO2 + C → 2CO (endothermic, ΔH = +172 kJ / mol);

[0049] C + H₂O → CO + H₂ (water-gas reaction);

[0050] ③ When the temperature exceeds 850℃, emergency water injection cooling should be carried out (the amount of water injected should be ≤ 10% of the total flow rate of the solution);

[0051] (3) Reduction reaction and gas generation:

[0052] ① A high-temperature reaction zone with a radius of 5-10m is formed in the coal seam, centered on the injection well. The CO2 dissolved in the mineralization solution (concentration ≥0.8mol / L) undergoes a reduction reaction with the oxidized semi-coke.

[0053] CO2 + C (half char) → 2CO (ΔH = +172 kJ / mol)

[0054] C (semi-coke) + H₂O (solution) → CO + H₂ (ΔH = +131 kJ / mol)

[0055] ② Supplement gaseous CO2 to maintain a CO2 to semi-coke molar ratio of 1:1.5-1:2.0. The amount of CO2 supplemented is dynamically controlled by an online mass spectrometer to maintain a CO2 partial pressure ≥1.5MPa in the reaction zone.

[0056] ③ Collect mixed gas through independent gas extraction wells and use a gravity separator to initially separate the gas and liquid phases;

[0057] (4) High-temperature membrane separation and purification:

[0058] The mixed gas was at a speed of 0.5-1.2 m 3 / (h·m 2 The flow rate is fed into a zirconia-based porous ceramic membrane module (pore size 0.5-2nm), and the surface of the ceramic membrane is coated with a nano CeO2 layer (thickness 50-200nm) to adsorb residual H2S (concentration ≤200ppm); separation is carried out under the conditions of 800-900℃ and 0.3-0.8MPa, and the permeability selectivity coefficient of CO and H2 is ≥50.

[0059] The gas flow rate is controlled by a circulation loop to ensure that the purity of the synthesis gas is ≥95% (CO 50-60 vol%, H2 35-45 vol%), and the residual gas is returned to the reaction zone for secondary use.

[0060] In some embodiments, a transition buffer system may be provided between step (1) and step (2) of the present invention, the structure of which includes:

[0061] Underground storage tanks: 50-100m³ 3 It is made of acid-resistant material (such as Hastelloy C276) and has a built-in multi-stage filtration device (pore size decreases step by step: 10μm→1μm→0.1μm) to prevent clogging. The suspended solids content in the filtered solution is ≤50mg / L, ensuring that the coal seam fracture permeability loss is <5%.

[0062] pH adjustment unit: Equipped with an automatic dosing system, injecting NaOH or Ca(OH)2 solution to adjust the pH of the mineralization solution from 4.0-4.5 to 5.5-6.0. This is used to regulate the reactivity, and pH adjustment can inhibit Fe in subsequent coal seams. 3+ Oxidation side reaction (Fe) 3+ +H₂O→Fe(OH)₃↓+3H + );

[0063] Sediment separator: Removes unreacted mineral particles (particle size > 0.5 mm) by centrifugal force (2000-3000 rpm).

[0064] The transition buffer system of a certain project has a volume of 80m³. 3 Filtration accuracy 0.1μm;

[0065] Suspended solids removal rate: 98.7% (from 520 mg / L to 6.5 mg / L); Coal seam permeability retention rate: 97.3% (35 mD → 34.1 mD after fracturing).

[0066] In some embodiments, the following anti-channeling technologies can be used to prevent gas channeling:

[0067] Wellbore sealing: The injection well adopts a combination structure of high-temperature cement and expansion packer (temperature resistance 900℃, pressure resistance 25MPa);

[0068] Packer spacing ≤ 50m, and after expansion, the fit with the well wall ≥ 95%.

[0069] In some embodiments, dynamic pressure control is implemented: formation pressure is monitored in real time (accuracy ±0.1MPa), and the gas injection rate is controlled by a PID algorithm to ensure that the coal seam pressure is ≤80% of the fracture opening pressure;

[0070] Set a pressure safety threshold: when the pressure fluctuation exceeds ±10%, trigger the emergency shutdown procedure.

[0071] In some embodiments, to accurately control the migration and diffusion patterns of gas within geological bodies, tracer monitoring is performed: a krypton-85 tracer (concentration 1-5 ppm) is injected, and the gas is detected using a surface detector (sensitivity 0.01 Bq / m²). 3 Real-time monitoring of gas migration paths.

[0072] The environmental impact assessment of the method of this invention is as follows:

[0073] (1)Cl - Recycling and wastewater treatment

[0074] ①Cl - Material balance

[0075] Input: saline layer Cl - Total amount = mineralization × water injection volume (e.g., 72g / L × 100m³) 3 =7200kg);

[0076] Output: Synthesis gas carrying Cl - (in HCl form): ≤1% (approximately 72 kg);

[0077] Waste liquid Cl - Concentration: Concentrated to 200 g / L using an evaporation crystallization device, recovering NaCl (purity ≥ 99%), with a remaining waste liquid volume of < 5 m³. 3 / 10,000 tons of CO2.

[0078] ② Processing flow

[0079] Waste liquid → Multi-effect evaporator (energy consumption 35kW·h / m³) 3 → Crystallized salt (industrial grade) + condensate (reuse).

[0080] (2) Heavy metal migration control

[0081] ① Monitoring and processing

[0082] Online heavy metal detector (ICP-MS): Real-time monitoring of Ni, Cr, and As concentrations (thresholds: Ni ≤ 0.1 mg / L, Cr ≤ 0.05 mg / L);

[0083] Emergency response: When heavy metals exceed the standard, chelating resin (such as EDTA derivative) is injected to adsorb pollutants, and the waste liquid is discharged after being separated by a special membrane (molecular weight cutoff of 500 Da) to meet the standards.

[0084] (3) Environmental compliance

[0085] The quality of the produced water meets the Class III water requirements of the "Groundwater Quality Standard" (GB / T 14848-2017).

[0086] Syngas impurities: H2S≤10ppm, which are catalytically oxidized to SO42- by CeO2 coating and then solidified.

[0087] The method of this invention is compared with traditional CCUS (carbon capture, utilization, and storage) as follows:

[0088] (1) Membrane module lifespan and replacement cost: The zirconia-based porous ceramic membrane used in this invention has a lifespan of 5-8 years and a replacement cost of US$120 / m². 2 The annual maintenance cost per unit area, after amortization, is only $15-24 / m². 2 The annual maintenance cost of a traditional CCUS cryogenic separation tower is $80 / m³. 3 Furthermore, the equipment lifespan is relatively short (typically 3-5 years). Therefore, the membrane module lifespan of the present invention is extended by 40%-67%, and the annual maintenance cost is reduced by 70%-81%, significantly reducing long-term equipment investment.

[0089] (2) Basalt Pretreatment Costs: This invention addresses pretreatment processes such as fracturing in basalt formations, achieving a unit CO2 treatment cost of $15-20 / ton CO2, thanks to efficient fracturing technology and resource recycling design. In contrast, traditional CCUS brine storage requires complex formation modification and sealing treatments, costing as much as $30-40 / ton CO2. Therefore, this invention reduces pretreatment costs by 50%, significantly compressing early-stage engineering investment while ensuring geological stability.

[0090] (3) Energy consumption cost: This invention achieves a net energy efficiency of +18% (self-heating mode) by relying on a coal seam oxidation self-heating system, without the need for a large amount of additional energy to maintain the reaction. Instead, it achieves positive energy efficiency gains through energy recovery. Traditional CCUS requires continuous consumption of external energy (such as electricity and fuel), with an energy cost of US$50-60 per ton of CO2 processed. This invention completely reverses the high energy consumption situation of traditional processes, turning energy consumption into energy efficiency gains.

[0091] (4) Syngas revenue: The high-purity syngas (purity ≥ 95%) co-produced by this invention can generate $0.12-0.15 / m³. 3The direct economic benefits, calculated based on the total process cost, can cover 70% of the total operating costs. Traditional CCUS only achieves CO2 sequestration, without any product revenue, and is purely a cost expenditure. Therefore, this invention transforms a pure cost input into a cost-benefit balance model, significantly improving the commercial feasibility of the process through product value-added.

[0092] (5) Commercialization

[0093] ① Investment recovery period

[0094] In a large-scale application scenario with an annual CO2 processing capacity of 100,000 tons, this invention, calculated at an electricity price of $0.08 / kWh, leverages the continuous revenue from syngas co-production (covering 70% of total operating costs), allowing for a payback period of 6-8 years. This period is significantly shorter than traditional carbon treatment technologies, enabling rapid capital recovery and profit conversion.

[0095] Traditional ECBM+CCS technology only has the single function of CO2 storage and lacks the revenue support from syngas and other products. It relies entirely on pure cost input, resulting in an investment payback period of more than 15 years and a commercial capital turnover efficiency far lower than that of this invention.

[0096] ② Cost advantage

[0097] The net cost of processing each ton of CO2 using this invention is only US$35, a 70.8% reduction compared to US$120 for traditional CCUS technology. This cost reduction primarily stems from reduced energy expenditures due to the self-heating system, reduced equipment replacement costs due to the longer lifespan of the membrane modules, and operational costs offset by syngas revenue. Furthermore, the membrane separation energy consumption of this invention is as low as 0.7 kW·h / m³. 3 Compared to the traditional technology's 2.8 kWh / m 3 The decrease reached 75%. An annual CO2 processing capacity of 100,000 tons corresponds to a syngas production of 6-7 million m³. 3 Calculations show that this could save over $1.5 million in electricity costs annually, further enhancing cost competitiveness.

[0098] The heavy metal control effect of the method of the present invention is shown in Table 1 below.

[0099] Table 1. Effects of Heavy Metal Control

[0100] heavy metal Input concentration (mg / L) Output concentration (mg / L) Ni 0.25 0.08 Cr 0.12 0.03 As 0.05 0.01

[0101] Based on monitoring data, this invention has a significant removal effect on heavy metals (Ni, Cr, As) that may be released during the dissolution of basalt:

[0102] Nickel (Ni): The input concentration was 0.25 mg / L, and the output concentration was reduced to 0.08 mg / L after treatment, achieving a removal rate of 68%. This treatment effect resulted in a nickel concentration far below the limit of 0.1 mg / L for Class III water in the "Groundwater Quality Standard" (GB / T 14848-2017), meeting environmental discharge requirements.

[0103] Chromium (Cr): The initial input concentration was 0.12 mg / L, and the output concentration after treatment was only 0.03 mg / L, with a removal rate as high as 75%. This concentration is lower than the limit for chromium in Class III water (0.05 mg / L), effectively controlling the risk of chromium migration and diffusion.

[0104] Arsenic (As): The input concentration was 0.05 mg / L, and after treatment it was reduced to 0.01 mg / L, with a removal rate of 80%. The arsenic concentration after treatment was far below the Class III water limit (0.05 mg / L), further verifying the effectiveness of the heavy metal control measures in this invention.

[0105] Furthermore, those skilled in the art will understand that although some embodiments described herein include certain features found in other embodiments but not others, combinations of features from different embodiments are also within the scope of protection of this invention and form different embodiments. For example, in the embodiments described above, those skilled in the art can use them in combination based on known technical solutions and the technical problems to be solved by this application.

Claims

1. A method for carbon dioxide sequestration and syngas co-production coupled with saline aquifer activation and coal seam oxidation gasification, characterized in that, Includes the following steps: (1) Activation of saline aquifers and mineralization of basalt CO2 is pressurized to a supercritical state and mixed with brine from the saline layer to form an acidic solution. This acidic solution is then injected into the basalt layer for mineralization. Real-time monitoring of the conductivity and pH of the solution injected into the basalt layer determines whether mineralization is complete; (2) Coal seam oxidation gasification After mineralization is completed, the mineralization solution is injected into the mixed coal seam of coking coal and gas coal, and air is injected at the same time. The permeability of the mixed coal seam is ≥20mD; otherwise, hydraulic fracturing pretreatment is carried out to make the fracture length ≥50m and the conductivity ≥30D·cm. The initial temperature of the mixed coal seam is raised to 500℃ by electric heating to trigger the exothermic reaction of coal oxidation. The external heat source is then turned off, and the temperature is maintained at 650-850℃ by adjusting the air injection rate. (3) Reduction reaction and gas generation A high-temperature reaction zone with a radius of 5-10m is formed in the coal seam, centered on the injection well, where CO2 dissolved in the mineralization solution undergoes a reduction reaction with the oxidized semi-coke; Collect the mixed gas and use a gravity separator to initially separate the gas and liquid phases; (4) High-temperature membrane separation and purification The mixed gas was introduced into a zirconia-based porous ceramic membrane module and separated under conditions of 800-900℃ and 0.3-0.8MPa, with a permeability selectivity coefficient of CO and H2 ≥50. The gas flow rate is controlled by a circulation loop to ensure that the purity of the synthesis gas is ≥95%, the CO content in the synthesis gas is 50-60 vol%, the H2 content is 35-45 vol%, and the residual gas is returned to the reaction zone for secondary use.

2. The method for carbon dioxide sequestration and syngas co-production coupled with saline aquifer activation and coal seam oxidation gasification according to claim 1, characterized in that, In step (1), the supercritical state is a pressure of 8-15 MPa and a temperature of 35-50℃. CO2 pressurized to the supercritical state is mixed with saline water with a mineralization of ≥50 g / L at a volume ratio of 1:2-1:4 to form an acidic solution with a pH of 3.5-4.

0.

3. The method for carbon dioxide sequestration and syngas co-production coupled with saline aquifer activation and coal seam oxidation gasification according to claim 2, characterized in that, The Cl - concentration is > 50 g / L and the Fe 3+ content is < 0.1 g / L.

4. The method for carbon dioxide sequestration and syngas co-production coupled with saline aquifer activation and coal seam oxidation gasification according to claim 1, characterized in that, The acid solution in step (1) is injected into the basalt layer at a rate of 10-20 m 3 / day, the injection pressure is 1.2-1.8 times the formation pressure, the formation pressure ranges from 5-12 MPa; the porosity of the basalt layer is ≥8%, the permeability is ≥10 mD, and the CaO+MgO content is ≥12 wt%.

5. The method for carbon dioxide sequestration and syngas co-production coupled with saline aquifer activation and coal seam oxidation gasification according to claim 1, characterized in that, In step (1), when the conductivity is ≥15mS / cm and the pH is stable at 4.0-4.5 for 24 hours, mineralization is considered complete.

6. The method for carbon dioxide sequestration and syngas co-production coupled with saline aquifer activation and coal seam oxidation gasification according to claim 1, characterized in that, In step (2), the mass ratio of coking coal to gas coal in the mixed coal seam is 1:3; the mineralization solution is applied at a concentration of 0.5-1.2 m... 3 Injected into the mixed coal seam at a rate of / h, while simultaneously injecting at a rate of 0.2-0.6m. 3 Air is injected at a rate of / min, with an injection volume of 1.2-1.8 m³ / min based on the oxygen requirement per ton of coal. 3 calculate.

7. The method for carbon dioxide sequestration and syngas co-production coupled with saline aquifer activation and coal seam oxidation gasification according to claim 1, characterized in that, The hydraulic fracturing pretreatment in step (2) involves injecting a 5-10% HCl solution in conjunction with a proppant, resulting in a fracture conductivity ≥50 D·cm. The proppant is 20 / 40 mesh ceramsite.

8. The method for carbon dioxide sequestration and syngas co-production coupled with saline aquifer activation and coal seam oxidation gasification according to claim 1, characterized in that, In step (2), when the temperature exceeds 850°C, water is injected for cooling, and the amount of water injected is ≤ 10% of the total flow rate of the solution.

9. The method for carbon dioxide sequestration and syngas co-production coupled with saline aquifer activation and coal seam oxidation gasification according to claim 1, characterized in that, In step (3), gaseous CO2 is added to maintain the molar ratio of CO2 to semi-coke at 1:1.5-1:2.

0. The amount of CO2 added is dynamically controlled by an online mass spectrometer to maintain the partial pressure of CO2 in the reaction zone ≥1.5MPa.

10. The method for carbon dioxide sequestration and syngas co-production coupled with saline aquifer activation and coal seam oxidation gasification according to claim 1, characterized in that, In step (4), the mixed gas is at a flow rate of 0.5-1.2m 3 / (h·m 2 The flow rate is fed into a zirconia-based porous ceramic membrane module, and the surface of the ceramic membrane is coated with a nano CeO2 layer with a thickness of 50-200nm.