Methane esterification agent for preventing gas outburst and preparation method and application method thereof

Abstract

The present application relates to the technical field of gas outburst chemical agent, in particular to a kind of methane esterification agent for preventing gas outburst and its preparation method and application method, and the methane esterification agent includes acid, I2, manganese-containing oxidizing agent and iron catalyst, relative to acid, the amount of I2 is 0.035-0.040 mol / L, the amount of manganese-containing oxidizing agent is 0.15-0.2 mol / L, and the amount of iron catalyst is 0.1-0.2 g / 100 mL;The iron catalyst is Fe-loaded MWCNTs, and the iron loading in the iron catalyst is 36-53% of the amount of MWCNTs in terms of mass content.The methane esterification agent of the present application can effectively esterify methane, and the formula and preparation method are simple and easy to operate, and the methane esterification agent has small corrosion hazard effect.

Description

Technical Field

[0001] This invention relates to the field of gas outburst prevention chemical agents, and in particular to a methane esterification agent for preventing gas outbursts, its preparation method, and its application method. Background Technology

[0002] Gas accidents pose a significant threat to the lives of miners. Research on coal seam outburst mitigation technology has become an urgent priority for ensuring safe coal mine production in my country.

[0003] Currently, the methods for gas outburst mitigation in coal mines, both domestically and internationally, are relatively limited. They primarily rely on physical methods such as drilling holes in the coal seam, creating fractures, and mining the release layer to achieve gas extraction. These methods are costly, generate significant dust, and fail to truly achieve the goals of low-energy, high-efficiency, safe, and environmentally friendly operations. Furthermore, the complex underground working environment, affected by disturbances from various operations on site pressure and other environmental factors, means that existing outburst mitigation technologies may not be able to meet the requirements of rapid mining operations.

[0004] This invention aims to study chemical methane suppression technology and develop a highly efficient, reliable, and economical methane esterifying agent to provide a new approach for underground gas control in coal mines. Summary of the Invention

[0005] The technical problem this invention aims to solve is to provide a methane esterifying agent for preventing gas outbursts, along with its preparation and application methods, thus offering a novel approach to preventing coal mine gas outbursts. This methane esterifying agent effectively esterifies methane, and its formulation and preparation method are simple and easy to operate. It also exhibits minimal corrosive effects, making it an economical and reliable new chemical anti-gas agent that can effectively prevent mine gas outbursts and ensure safe coal mine production.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] In a first aspect, the present invention provides a methane esterification agent for preventing gas outbursts, comprising an acid, I2, a manganese-containing oxidant, and an iron catalyst. The amount of I2 relative to the acid is 0.035-0.040 mol / L, the amount of the manganese-containing oxidant is 0.15-0.2 mol / L, and the amount of the iron catalyst is 0.1-0.2 mol / L. The iron catalyst is Fe-loaded MWCNTs, and the iron loading in the iron catalyst is 36-53% of the MWCNTs by mass.

[0008] In this invention, I2 has a good catalytic effect on methane and selectivity for the target product. At the same time, when combined with MWCNTs (multi-walled carbon nanotubes) loaded with an appropriate amount of Fe, it has a good catalytic effect on the low-temperature partial oxidation reaction of methane. This mixed system can effectively esterify methane.

[0009] Preferably, the Fe loading (theoretical loading) in the iron catalyst is 40-50% of the MWCNTs by mass content. Under this preferred embodiment, the loaded Fe provides suitable metal active centers while avoiding the decrease in catalyst specific surface area caused by blockage of catalyst surface channels and pores, which is more conducive to the contact reaction between active centers and methane.

[0010] Preferably, in the iron catalyst, Fe is uniformly supported on MWCNTs in the form of Fe2O3 particles with a particle size of 10-20 nm. In this preferred embodiment, the Fe2O3 in the iron catalyst (Fe / MWCNTs) is in the form of fine particles uniformly supported on multi-walled carbon nanotubes. The Fe2O3 particles are spherical with a concentrated particle size distribution, and the particle size of the Fe2O3 particles is 10-20 nm, which is beneficial for methane esterification.

[0011] Preferably, the acid is glacial acetic acid or oxalic acid. More preferably, the acid is glacial acetic acid; under this preferred embodiment, it is less corrosive to the equipment and has higher safety.

[0012] Preferably, the manganese-containing oxidant is KMnO4. In this preferred embodiment, the strong oxidizing property of KMnO4 is beneficial to the oxidation reaction of methane molecules.

[0013] Preferably, the Fe-loaded MWCNTs are prepared by impregnation.

[0014] More preferably, the impregnation process includes: mixing iron hydrate with anhydrous ethanol, while simultaneously adding MWCNTs and stirring; after the anhydrous ethanol has evaporated naturally, drying is performed, followed by grinding to obtain a black composite; finally, the composite is calcined. This preferred embodiment allows for more uniform loading of Fe onto the MWCNTs, which is more conducive to the oxidation reaction of methane molecules.

[0015] Preferably, the amount of anhydrous ethanol used is 4-6 times the mass of the iron salt hydrate.

[0016] More preferably, the iron salt hydrate is Fe(NO3)·9H2O.

[0017] More preferably, the drying temperature is 100-120°C.

[0018] More preferably, the calcination conditions include: a temperature of 300-400℃ and a time of 1-3 hours.

[0019] In the methane esterification agent of the present invention, each component can be stored separately or configured as a reagent for storage.

[0020] In a second aspect, the present invention also provides a method for preparing the methane esterifying agent described in the first aspect, comprising: adding I2, a manganese-containing oxidant and an iron catalyst to an acid.

[0021] Thirdly, the present invention also provides a method for applying the methane esterifying agent described in the first aspect, comprising: injecting the methane esterifying agent into a pre-drilled hole in the coal seam, so that it fully contacts the coal body and dissolves and esterifies the methane.

[0022] Preferably, the injection conditions for the methane esterifying agent include: temperature 150-200℃, pressure 4-5MPa, and time 3-5h.

[0023] The beneficial effects of the above-described technical solution of the present invention are as follows:

[0024] In the above scheme, the methane esterification agent has a good catalytic esterification effect on methane, which can effectively reduce the gas content in the coal seam, prevent gas outbursts, reduce the amount of gas emitted during mining, and ensure safe production underground.

[0025] The methane esterifying agent of this invention differs significantly from traditional coal seam gas outburst prevention measures in its approach to preventing gas outbursts, providing a new approach to coal mine gas control. On one hand, it transforms the approach of gas drainage into gas esterification, thereby reducing coal seam gas content, decreasing gas emission from mining faces, and preventing gas concentrations from exceeding limits. On the other hand, it transforms the original method of gas drainage and pressure relief for outburst prevention into dissolving and esterifying gas to eliminate the driving force behind gas outbursts, thus achieving the goal of preventing gas outbursts.

[0026] The application method of the methane esterifying agent of this invention is simple to operate and highly practical. Conventional methods involve injecting water into the coal seam to wet the coal body, reduce coal dust generation during mining, and improve the working environment. However, the application method of this invention, by directly injecting the methane esterifying agent, not only wets the coal body and reduces coal dust generation during mining, thus mitigating its hazards, but more importantly, during the injection process, the methane gas in the pores is dissolved and esterified by the methane esterifying agent. This leads to a decrease in pressure, reduced injection resistance, and an increased injection wetting radius. Furthermore, it forms a protective ring around the mining face, preventing methane gas from the coal body outside the injected liquid from entering the working face, thus protecting it. Attached Figure Description

[0027] Figure 1 The graph shows the catalytic effect of different concentrations of iodine solutions on methane in Example 1.

[0028] Figure 2 The graph shows the catalytic effect of different amounts of KMnO4 on methane in Example 2.

[0029] Figure 3This is a graph showing the effect of different theoretical iron loadings on the methane conversion reaction in Example 3;

[0030] Figure 4 The graph shows the effect of Fe / MWCNTs dosage on the methane conversion reaction in Example 4.

[0031] Figure 5 A graph showing the observation data curves at the water injection observation point in the application example;

[0032] Figure 6 The graph shows the observation data curves at the observation points for the application example of the esterifying agent. Detailed Implementation

[0033] To make the technical problems, solutions, and advantages of this invention clearer, a detailed description will be provided below with reference to the accompanying drawings and specific embodiments. The Fe-loaded MWCNTs are prepared by an impregnation method: First, a measured amount of Fe(NO3)·9H2O is weighed and mixed with anhydrous ethanol (the mass of ethanol is 5 times the mass of Fe(NO3)·9H2O), and MWCNTs are added simultaneously and stirred until homogeneous. After natural evaporation, the mixture is thoroughly dried in an oven at 105°C and ground to obtain a black composite. Finally, the composite is placed in a muffle furnace and calcined at 350°C for 2 hours to obtain Fe / MWCNTs.

[0034] Example 1

[0035] The I2 content in the methane esterifying agent has a significant impact on the esterification effect of methane; adding an appropriate amount of I2 will be beneficial to the esterification of coalbed methane. The components were mixed, and four different I2 concentrations were selected for experiments, with the I2 concentration as the variable, as shown in Table 1. The test results are as follows: Figure 1 As shown.

[0036] Table 1 Relationship between iodine concentration and methane catalytic reaction

[0037]

[0038] Depend on Figure 1 It is known that in the acidic solution system composed of I2 and CH3COOH, during the catalytic reaction of CH4 to produce CH3OOCH3 and CO2, the conversion rate of CH4 initially increases and then tends to stabilize with the increase of the I2 catalyst concentration. Furthermore, the I2 concentration within the range of 0.035-0.040 mol / L in this invention can balance a high conversion rate of CH4 participating in the catalytic reaction with a high production of methyl acetate. The optimal I2 catalyst concentration is 0.035 mol / L, at which point the methane conversion rate is 5.83% and the CH3OOCH3 production is 89.03 ppm.

[0039] Example 2

[0040] KMnO4 can convert Cl - I - SO3 2- Fe 2+ Sn 2+ Plasma oxidation can also oxidize many organic compounds, making it a very strong oxidant. At the same time, KMnO4 is inexpensive and has low toxicity, and potassium permanganate is very suitable for use as an oxidant under acidic media conditions.

[0041] For the catalytic oxidation of methane in acidic solutions, the yield of the target product is closely related to process conditions such as the amount of oxidant, the amount of catalyst, and the water content in the solvent. This invention optimizes the process conditions for KMnO4, an inorganic oxidant with the best oxidation performance and promising industrial application potential, and explores the optimal range of process conditions for the catalytic oxidation of methane in glacial acetic acid solvent. The results of the test method in Example 1 are as follows... Figure 2 As shown.

[0042] Table 2. Relationship between KMnO4 addition amount and methane catalytic oxidation efficiency

[0043]

[0044] from Figure 2 As can be seen, the methane conversion rate consistently increases with increasing oxidant concentration, while the methyl acetate conversion rate initially increases and then decreases with increasing KMnO4 concentration. This may be because excessive KMnO4 leads to direct oxidization of methane to CO2 during the reaction system's circulation process, without producing methyl acetate, or methyl acetate is deeply oxidized. However, the specific range of 0.15-0.2 mol / L KMnO4 concentration used in this invention achieves a balance between high methane conversion and high liquid-phase product formation. Furthermore, at a KMnO4 concentration of 0.2 mol / L, the methane conversion rate is 6.28%, and the methyl acetate concentration is 99.45 ppm.

[0045] Example 3

[0046] In this embodiment, Fe / MWCNTs catalysts with different Fe loadings were prepared during the experiment. Using 1g of MWCNTs as the support, the iron ion concentrations were 0.005mol / g, 0.010mol / g, 0.015mol / g and 0.020mol / g, respectively, and the theoretical Fe loadings XFe were 22%, 36%, 46% and 53%, respectively.

[0047] The catalytic effect of its iodine catalytic system was studied. Specific experimental conditions were: catalyst dosage 0.1 g, reaction temperature 160℃, reaction pressure 4.0 MPa, 100 mL glacial acetic acid solution, iodine concentration 0.035 mol / L, and KMnO4 concentration 0.2 mol / L. The reaction time was 3 h. The effect of the test method according to Example 1 was as follows... Figure 3 As shown.

[0048] from Figure 3 It can be seen that both methane conversion and methyl acetate yield increase with increasing theoretical Fe loading. Under 22% Fe / MWCNT catalysis, the methyl acetate production is only 225.11 ppm. When the theoretical Fe loading is within the range of 36-53%, preferably 40-50%, it can simultaneously improve both methyl acetate yield and methane conversion. Furthermore, at 46%, the methyl acetate yield reaches 341.04 ppm. This is likely because as the Fe loading increases, more metal active centers are provided, promoting the methane conversion reaction and thus improving catalyst activity. When the theoretical Fe loading increases from 46% to 53%, the methane conversion begins to decrease, and the methyl acetate production begins to decrease. This indicates that after the Fe loading reaches a certain level, further increasing the Fe loading has little effect on improving catalytic activity. This may be because excessive loading can cause blockage of catalyst surface channels and pores, reducing the specific surface area and hindering the contact reaction between active centers and methane.

[0049] Example 4

[0050] In a reaction medium of 100 mL glacial acetic acid, the dosage of Fe / MWCNTs (XFe = 46%) catalyst was varied (0.05 g, 0.10 g, 0.15 g, and 0.20 g) to investigate the effect of different catalyst dosages on the reaction. The results are as follows: Figure 4 As shown.

[0051] Specific experimental conditions: reaction temperature 160℃, reaction pressure 3MPa, 100mL glacial acetic acid solution, iodine concentration 0.035mol / L, KMnO4 concentration 0.2mol / L. Reaction time 3h, stirring speed 500rpm.

[0052] This example Figure 4It can be seen that the methane conversion rate and the target product methanol increase with the increase of Fe / MWCNTs dosage, showing a positive correlation. This may be because the increase of catalyst dosage increases the number of metal active centers, allowing methane molecules to contact more active centers and react, which is beneficial to the conversion of methane. However, the increase of catalyst dosage above 0.15 g / 100 mL shows a stable trend. When the Fe / MWCNTs dosage in 100 mL of iodine catalytic reaction medium is 0.15 g / 100 mL, the maximum methanol production in the reaction system is 363.55 ppm, while the methane conversion rate increases to 7.41%. Therefore, good overall results can only be obtained within the catalyst dosage range of 0.1-0.2 g / 100 mL of the present invention.

[0053] Compared to the simple reaction system of iodine + glacial acetic acid, the addition of Fe / MWCNTs can effectively improve the conversion of methane: the conversion rate increases from 6.28% to 7.41%, and the yield of methyl acetate increases from 99.45 ppm to 363.55 ppm.

[0054] Application examples

[0055] To verify the esterification effect of the methane esterifying agent of this invention, a field test was conducted at a coal mine working face. Two observation points were set up in the test: a water injection observation point and an esterifying agent observation point, with 10 boreholes at each observation point. The specific test plan is as follows:

[0056] (1) Drill holes are set at the observation point 1.5m above the ground, with a hole spacing of 10m, a hole diameter of 50mm, and a hole depth of 10m. Ten holes are set at each observation point in sequence.

[0057] (2) Use a sealing tool with an outer diameter of 38mm to seal the drill hole.

[0058] (3) Use a pressure pump to inject water and esterifying agent into the water injection hole and the esterifying agent hole respectively. When liquid seeps out from the coal wall near the hole, the injection can be stopped and left to stand for 24 hours.

[0059] (4) Seal off 9 boreholes at the two observation points respectively, leaving one hole for gas sampling;

[0060] (5) The total gas outflow and the methane content in the outflow gas were measured every 30 minutes for 12 hours, and a total of 25 sets of data were collected. Then, measurements were taken every 6 hours for 5 days, and a total of 20 sets of data were collected.

[0061] The borehole measurement results at the water injection observation points are shown in Table 3 below. Figure 5 As shown in Table 4, the borehole measurement results at the esterification agent observation point are as follows.

[0062] Table 3. Observation data of water injection observation points (gas volume unit: m³) 3 / min)

[0063] Number of measurements Total outflow methane content Number of measurements Total outflow methane content Number of measurements Total outflow methane content 1 0.399 0.229 16 0.534 0.397 31 0.527 0.382 2 0.413 0.249 17 0.533 0.413 32 0.499 0.36 3 0.413 0.266 18 0.526 0.411 33 0.497 0.351 4 0.449 0.282 19 0.531 0.404 34 0.546 0.383 5 0.448 0.297 20 0.519 0.389 35 0.531 0.379 6 0.467 0.308 21 0.506 0.379 36 0.506 0.362 7 0.481 0.320 22 0.506 0.369 37 0.485 0.343 8 0.494 0.340 23 0.514 0.374 38 0.509 0.332 9 0.518 0.370 24 0.488 0.364 39 0.506 0.328 10 0.530 0.393 25 0.498 0.376 40 0.48 0.332 11 0.532 0.415 26 0.513 0.389 41 0.484 0.331 12 0.544 0.434 27 0.538 0.399 45 0.468 0.315 13 0.550 0.431 28 0.513 0.387 43 0.447 0.301 14 0.534 0.412 29 0.510 0.396 44 0.432 0.299 15 0.531 0.393 30 0.528 0.389 45 0.415 0.289

[0064] Table 4. Observation data of water injection observation points (gas volume unit: m³) 3 / min)

[0065]

[0066]

[0067] From Table 3 and Figure 5 It can be seen that the total gas outflow and the methane content in the outflowing gas at the water injection observation point showed a trend of first increasing and then decreasing. After 45 measurements, the average total gas outflow was 0.498 m³. 3 / min, with an average methane content of 0.357m 3 / min, accounting for 71.7% of the total gas outflow.

[0068] From Table 4 and Figure 6 It can be seen that the total gas emission and the methane content in the emitted gas at the esterification agent observation point are relatively stable and show a decreasing trend. After 45 measurements, the average total gas emission was 0.336 m³. 3 / min, with an average methane content of 0.225m 3 / min, accounting for 67.0% of the total gas outflow.

[0069] A comparison of the water injection observation point and the esterification agent observation point shows that the esterification agent can effectively esterify methane on site, reduce the gas content of the injected coal seam, and reduce the amount of gas emission.

[0070] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A methane esterifying agent for preventing gas outbursts, characterized in that, The mixture comprises an acid, I2, a manganese-containing oxidant, and an iron catalyst. The acid is glacial acetic acid or oxalic acid, and the manganese-containing oxidant is KMnO4. Relative to the acid, the amount of I2 is 0.035-0.040 mol / L, the amount of the manganese-containing oxidant is 0.15-0.2 mol / L, and the amount of the iron catalyst is 0.1-0.2 g / 100 mL. The iron catalyst is Fe-supported MWCNTs, in which Fe is uniformly supported in the MWCNTs in the form of Fe2O3 particles. By mass content, the iron loading in the iron catalyst is 36-53% of the amount of MWCNTs. The particle size of the Fe2O3 particles is 10-20 nm.

2. The methane esterification agent according to claim 1, characterized by, The iron loading in the iron catalyst is 40-50% of the MWCNTs by mass content.

3. The methane esterifying agent according to claim 1, characterized in that, The Fe-loaded MWCNTs were prepared by impregnation.

4. The methane esterifying agent according to claim 3, characterized in that, The impregnation process includes: mixing iron salt hydrate with anhydrous ethanol, while adding MWCNTs and stirring; drying after the anhydrous ethanol evaporates naturally, followed by grinding to obtain a black composite; and finally calcining the composite.

5. The methane esterifying agent according to claim 4, characterized in that, The iron salt hydrate is Fe(NO3)·9H2O.

6. The methane esterifying agent according to claim 4, characterized in that, The drying temperature is 100-120℃.

7. The methane esterifying agent according to claim 4, characterized in that, The calcination conditions include: a temperature of 300-400℃ and a time of 1-3 hours.

8. The method for preparing the methane esterifying agent according to any one of claims 1-7, characterized in that, include: I2, a manganese-containing oxidant, and an iron catalyst are added to the acid.

9. The method of applying the methane esterifying agent according to any one of claims 1-7, characterized in that, include: The methane esterifying agent is injected into a pre-drilled hole in the coal seam to ensure full contact with the coal and dissolve the esterified methane. The injection conditions for the methane esterifying agent include: temperature 150-200℃, pressure 4-5MPa, and time 3-5h.

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