Application of a palladium-based catalyst in catalytic oxidation of coal-bed gas to produce methanol and method for producing methanol

Abstract

The application discloses application of a palladium-based catalyst in a catalytic oxidation coal bed gas methanol preparation reaction and a methanol preparation method, the catalyst is a palladium doped rod-like rutile, a doped phase of the catalyst is palladium, and a doped main body of the catalyst is rod-like rutile. The application can convert low-concentration methane in coal bed gas into methanol, has higher methanol yield and selectivity compared with prior art, can realize effective utilization of clean energy, and has a good application prospect.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to the application of a palladium-based catalyst in the catalytic oxidation of coalbed methane to produce methanol and a method for producing methanol. Background Technology

[0002] Coalbed methane, a by-product of coal mining, is a clean energy source, primarily composed of methane. Higher concentrations of coalbed methane are used in gas supply, chemical production, and thermal power generation. However, low-concentration and ultra-low-concentration coalbed methane are often directly released into the atmosphere due to their limited utilization, which is not only a waste of resources but also a contributing factor to the greenhouse effect.

[0003] Methanol is an extremely important organic chemical raw material, and its production from natural gas is the most efficient from an atom economy perspective. Currently, the traditional method for producing methanol from methane is the coal gasification-Fischer-Tropsch synthesis process, which converts coalbed methane into syngas, followed by catalytic conversion to methanol. However, methane steam reforming is a typical energy-intensive process, requiring high temperature and high pressure. If the direct catalytic oxidation of coalbed methane to methanol could be achieved, it would significantly reduce energy consumption and improve economic efficiency, which is of great significance. Methane is a tetrahedral compound composed of four identical carbon-hydrogen bonds, and its chemical properties are quite stable. The energy required to break the first carbon-hydrogen bond is higher than that required to break subsequent carbon-hydrogen bonds; therefore, the key technical challenge lies in the selectivity of the catalytic oxidation of methane to methanol.

[0004] Chinese patent application CN116196939A discloses a composite metal oxide catalyst, its preparation method, and its application in the catalytic production of methanol from low-concentration coalbed methane. The composite metal oxide catalyst comprises a support, which is cerium oxide, and an active component, which is a composite metal oxide of copper oxide and iridium oxide. The catalyst is simple to prepare and exhibits certain reactivity and cycle stability in the oxidation of low-concentration coalbed methane to methanol. However, the methanol yield of this system is low, limiting its potential for industrial application. Furthermore, the catalyst material employs a bimetallic active component, and its catalytic mechanism remains unclear. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide an application of a palladium-based catalyst in the catalytic oxidation of coalbed methane to produce methanol and a method for producing methanol, wherein the method can produce methanol under mild conditions and the methanol yield is high.

[0006] The present invention solves the above-mentioned technical problems through the following technical means:

[0007] The application of a palladium-based catalyst in the catalytic oxidation of coalbed methane to produce methanol, wherein the palladium-based catalyst is palladium-doped rod-shaped rutile.

[0008] Preferably, the palladium-based catalyst contains 0.1-5.0 wt% palladium.

[0009] Preferably, the palladium-based catalyst contains 0.25-2.0 wt% palladium.

[0010] Preferably, the palladium-based catalyst contains 0.5 wt% palladium.

[0011] Preferably, the palladium source in the palladium-based catalyst is introduced by doping. The specific preparation method includes the following steps: dissolving isopropanol and titanium isopropoxide in glycolic acid solution, adding palladium nitrate, stirring, and continuing to stir until the solution is transparent after heating; the resulting solution is placed in a hydrothermal reactor for hydrothermal reaction; after the reaction is completed, the solid and liquid are separated, washed, dried, ground, and calcined to obtain the palladium-based catalyst.

[0012] Preferably, the palladium source in the palladium-based catalyst is introduced by impregnation. The specific preparation method includes the following steps: isopropanol and titanium isopropoxide are dissolved in glycolic acid solution, stirred, and the solution is heated and stirred until transparent; the resulting solution is placed in a hydrothermal reactor for hydrothermal reaction, and after the reaction is completed, the solid and liquid are separated, washed, dried, ground, calcined, and then added to an aqueous palladium nitrate solution for heating and aging. The resulting solid is ground and calcined to obtain the palladium-based catalyst.

[0013] Preferably, it also includes the addition of copper ions in combination with a palladium-based catalyst.

[0014] The present invention also proposes a method for producing methanol from coalbed methane by catalytic oxidation of the palladium-based catalyst, comprising the following steps: introducing coalbed methane into a reaction vessel containing a copper ion solution and a palladium-based catalyst, and introducing carbon monoxide as an auxiliary gas; raising the temperature and stirring the mixture to carry out the reaction, and collecting the produced methanol from the liquid phase after the reaction is completed.

[0015] Preferably, the pressure of the coalbed methane is 1-3.0 MPa; the pressure of the carbon monoxide is 0.2-1.0 MPa; and the concentration of copper ions in the copper ion solution is 1-100 mmol / L.

[0016] Preferably, the stirring rate is 600-1000 rpm; the reaction temperature is 100-200℃; and the reaction time is 0.5-4 h.

[0017] Preferably, during the preparation of the palladium-based catalyst, the calcination temperature is 400-700℃, more preferably 600℃ or 500℃.

[0018] The advantages of this invention are:

[0019] This invention provides a reaction system for the catalytic oxidation of coalbed methane to methanol using a palladium-based catalyst. The catalyst employs palladium-doped rod-shaped rutile, with palladium as the dopant phase and rod-shaped rutile as the main dopant. The highly dispersed palladium sites serve as catalytic active centers, capable of converting low-concentration methane in coalbed methane into methanol. This reaction system can produce methanol under relatively mild conditions, with high methanol yield and high selectivity for methanol from methane. The selectivity for methanol in liquid oxygen-containing products is 100%. CO promotes the activation of O2 molecules, enhancing the catalyst's activation ability for methane molecules, while Cu... 2+ As a free radical scavenger, it effectively avoids excessive oxidation of products such as methanol and effectively improves the selectivity of methanol in the products. Attached Figure Description

[0020] Figure 1 This is a scanning electron microscope image of the palladium-doped rod-shaped rutile obtained in Example 1 of the present invention;

[0021] Figure 2 The yield diagrams for methanol production from coalbed methane catalyzed by the catalysts prepared in Examples 1-8 of this invention are shown.

[0022] Figure 3 This is a yield diagram of methanol production from coalbed methane catalyzed by the catalysts in Examples 1, 9, and 10 of this invention;

[0023] Figure 4 This is a yield diagram of methanol production from coalbed methane catalyzed by the catalyst in Examples 1, 11, and 12 of this invention;

[0024] Figure 5 This is a yield diagram of methanol production from coalbed methane catalyzed by the catalyst in Examples 1 and 13-16 of this invention;

[0025] Figure 6 This is a yield diagram of methanol production from coalbed methane catalyzed by the catalyst in Examples 1 and 17-22 of this invention;

[0026] Figure 7 The yield diagram shows the methanol production from coalbed methane catalyzed by the catalysts prepared in Example 1 and Comparative Examples 1-6 of this invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Unless otherwise specified, all test materials and reagents used in the following examples are commercially available.

[0029] Unless otherwise specified in the embodiments, the techniques or conditions described in the literature in this field or in accordance with the product manual may be followed.

[0030] Example 1

[0031] In this embodiment, a doped 0.5wt% Pd-rR catalyst was prepared as follows: 10.0 mL of isopropanol and 10.0 mL of titanium isopropoxide were dissolved in 100 mL of 1.6 M glycolic acid solution, and 33.4 mg of Pd(NO3)2·2H2O was added. The mixture was stirred for 10 min, and the solution was heated to 90 °C and stirred for 3 h until transparent. The resulting solution was placed in a hydrothermal reactor and hydrothermally heated at 200 °C for 24 h. The solid was separated by centrifugation, washed three times with deionized water and three times with anhydrous ethanol, and dried at room temperature for 12 h. The solid was collected and ground, and calcined in a muffle furnace at 600 °C for 4 h. The product obtained was a palladium-based catalyst, denoted as 0.5wt% Pd-rR. The scanning electron microscope image is shown below. Figure 1 As shown, it is palladium-doped rod-shaped rutile. The catalytic performance of the 0.5 wt% Pd-rR catalyst prepared in this embodiment was tested in a closed reactor. The test conditions were as follows: 2.0 MPa coalbed methane was introduced into a reactor containing 20 mL of deionized water, 40 mg CuCl2·2H2O (corresponding to a copper ion concentration of 11.73 mmol / L), and 20 mg of the above catalyst. Then, 0.5 MPa carbon monoxide was introduced as an auxiliary gas. The temperature was raised to 150 °C and the reaction was stirred at 800 rpm for 1 h. The methanol produced was then collected by distillation from the liquid phase in the reactor.

[0032] In this embodiment, a palladium-based catalyst, labeled Pd-rR, was prepared via a doping method, with a methanol yield of 1972.73 μmol·gcat. -1 ·h -1 .

[0033] Example 2

[0034] In this embodiment, a supported 0.5wt% Pd / rR catalyst was prepared as follows: 10.0 mL of isopropanol and 10.0 mL of titanium isopropoxide were dissolved in 100 mL of 1.6 M glycolic acid solution and stirred for 10 min. The solution was then heated to 90 °C and stirred for 3 h until transparent. The resulting solution was placed in a hydrothermal reactor and hydrothermally heated at 200 °C for 24 h. The solid was separated by centrifugation, washed three times with deionized water and three times with anhydrous ethanol, and dried at room temperature for 12 h. The solid was collected and ground, and calcined in a muffle furnace at 600 °C for 4 h. The resulting product was denoted as rR. 12.6 mg of Pd(NO3)2·2H2O was added to 25 mL of water and stirred for 2 h until dissolved. Then, 1 g of rR support was added, and the mixture was heated to 60 °C and aged for 12 h. The solid was collected and ground, and calcined in a muffle furnace at 500 °C for 4 h. The resulting product was denoted as Pd / rR. The catalytic performance of the 0.5 wt% Pd / rR catalyst prepared in this embodiment was tested in a closed reactor. The test conditions were as follows: 2.0 MPa coalbed methane was introduced into the reactor containing 20 mL of deionized water, 40 mg CuCl2·2H2O and 20 mg of the above catalyst, followed by the introduction of 0.5 MPa carbon monoxide as an auxiliary gas; the temperature was raised to 150 °C and the reaction was stirred at 800 rpm for 1 h. The methanol produced was then collected by distillation from the liquid phase in the reactor.

[0035] In this embodiment, a palladium-based catalyst, labeled Pd / rR, was prepared by impregnation, with a methanol yield of 1780.95 μmol·gcat. -1 ·h -1 .

[0036] Example 3

[0037] The difference between this embodiment and Example 1 is that the mass fraction of Pd doping is 0.25 wt%, and the mass of Pd(NO3)2·2H2O is 16.7 mg. Everything else is the same as in Example 1. The methanol yield calculation results are as follows: Figure 2 As shown.

[0038] Example 4

[0039] The difference between this embodiment and Example 1 is that the mass fraction of Pd doping is 1.0 wt%, and the mass of Pd(NO3)2·2H2O is 66.8 mg. Everything else is the same as in Example 1. The methanol yield calculation results are as follows: Figure 2 As shown.

[0040] Example 5

[0041] The difference between this embodiment and Example 1 is that the mass fraction of Pd doping is 2.0 wt%, and the mass of Pd(NO3)2·2H2O is 133.6 mg; otherwise, they are the same as in Example 1. The calculated methanol yield is as follows: Figure 2 As shown.

[0042] Example 6

[0043] The difference between this embodiment and Example 2 is that the mass fraction of Pd loading is 0.25 wt%, and the mass of Pd(NO3)2·2H2O is 6.3 mg; otherwise, they are the same as in Example 2. The calculated methanol yield is as follows: Figure 2 As shown.

[0044] Example 7

[0045] The difference between this embodiment and Example 2 is that the mass fraction of Pd loading is 1.0 wt%, and the mass of Pd(NO3)2·2H2O is 25.1 mg; otherwise, they are the same as in Example 2. The calculated methanol yield is as follows: Figure 2 As shown.

[0046] Example 8

[0047] The difference between this embodiment and Example 2 is that the mass fraction of Pd loading is 2.0 wt%, and the mass of Pd(NO3)2·2H2O is 50.2 mg; otherwise, they are the same as in Example 2. The calculated methanol yield is as follows: Figure 2 As shown.

[0048] Figure 2 The horizontal axis represents the mass fraction of Pd doping in the catalyst, such as... Figure 2 As shown, the methanol products obtained by the doped Pd-rR catalysts in Examples 1-4 for methane oxidation were all higher than those obtained by the supported Pd / rR catalysts in Examples 5-8, and the optimal palladium content in the doped Pd-rR catalysts was 0.5 wt%.

[0049] Example 9

[0050] The difference between this embodiment and Example 1 is that the coalbed methane pressure in the reaction system is 1.0 MPa; otherwise, they are the same as in Example 1. The calculated methanol yield is as follows: Figure 3 As shown.

[0051] Example 10

[0052] The difference between this embodiment and Example 1 is that the coalbed methane pressure in the reaction system is 3.0 MPa; otherwise, they are the same as in Example 1. The calculated methanol yield is as follows: Figure 3 As shown.

[0053] like Figure 3 As shown, when the pressure of coalbed methane in the reaction system increases from 1 MPa to 3 MPa, the yield of methanol obtained by catalytic oxidation of methane by the doped Pd-rR catalyst gradually increases.

[0054] Example 11

[0055] The difference between this embodiment and Example 1 is that the CO pressure in the reaction system is 0.2 MPa; otherwise, they are the same as in Example 1. The calculated methanol yield is as follows: Figure 4 As shown.

[0056] Example 12

[0057] The difference between this embodiment and Example 1 is that the CO pressure in the reaction system is 1.0 MPa; otherwise, they are the same as in Example 1. The calculated methanol yield is as follows: Figure 4 As shown.

[0058] like Figure 4 As shown, when the CO pressure in the reaction system increases from 0.2 MPa to 1.0 MPa, the methanol yield obtained by the catalytic oxidation of methane by the doped Pd-rR catalyst gradually increases.

[0059] Example 13

[0060] The difference between this embodiment and Example 1 is that the reaction temperature during the catalytic performance test was 100°C; otherwise, it was the same as Example 1. The calculated methanol yield is as follows: Figure 5 As shown.

[0061] Example 14

[0062] The difference between this embodiment and Example 1 is that the reaction temperature during the catalytic performance test was 120°C; otherwise, it was the same as Example 1. The calculated methanol yield is as follows: Figure 5 As shown.

[0063] Example 15

[0064] The difference between this embodiment and Example 1 is that the reaction temperature during the catalytic performance test was 170°C; otherwise, it was the same as Example 1. The calculated methanol yield is as follows: Figure 5 As shown.

[0065] Example 16

[0066] The difference between this embodiment and Example 1 is that the reaction temperature during the catalytic performance test was 200℃, while all other aspects were the same as in Example 1. The calculated methanol yield is as follows: Figure 5 As shown.

[0067] like Figure 5 As shown, when the temperature of the reaction system increases from 100℃ to 200℃, the methanol yield obtained by the oxidation of methane by the doped Pd-rR catalyst first increases and then decreases, with the optimal reaction temperature being 170℃.

[0068] Example 17

[0069] The difference between this example and Example 1 is that the concentration of copper ions added to the reaction system is 1 mmol / L; otherwise, they are the same as in Example 1. The calculated methanol yield is as follows: Figure 6 As shown.

[0070] Example 18

[0071] The difference between this example and Example 1 is that the concentration of copper ions added to the reaction system is 2.93 mmol / L; otherwise, they are the same as in Example 1. The calculated methanol yield is as follows: Figure 6 As shown.

[0072] Example 19

[0073] The difference between this example and Example 1 is that the concentration of copper ions added to the reaction system is 5.87 mmol / L; otherwise, they are the same as in Example 1. The calculated methanol yield is as follows: Figure 6 As shown.

[0074] Example 20

[0075] The difference between this example and Example 1 is that the concentration of copper ions added to the reaction system is 8.80 mmol / L; otherwise, they are the same as in Example 1. The calculated methanol yield is as follows: Figure 6 As shown.

[0076] Example 21

[0077] The difference between this example and Example 1 is that the concentration of copper ions added to the reaction system is 23.46 mmol / L; otherwise, they are the same as in Example 1. The calculated methanol yield is as follows: Figure 6 As shown.

[0078] Example 22

[0079] The difference between this embodiment and Example 1 is that the concentration of copper ions added to the reaction system is 100 mmol / L; otherwise, they are the same as in Example 1. The calculated methanol yield is as follows: Figure 6 As shown.

[0080] like Figure 6 As shown, when the concentration of copper ions in the reaction system increases from 1 mmol / L to 100 mmol / L, the methanol yield obtained by the oxidation of methane by the doped Pd-rR catalyst first increases and then tends to stabilize, with the optimal copper ion concentration being 11.73 mmol / L.

[0081] Comparative Example 1

[0082] In this comparative example, a 0.5 wt% Ni-rR catalyst was prepared as follows: 10.0 mL of isopropanol and 10.0 mL of titanium isopropoxide were dissolved in 100 mL of 1.6 M glycolic acid solution, and 54.22 mg of NiCl2·6H2O was added. The mixture was stirred for 10 min, and the solution was heated to 90 °C and stirred for another 3 h until transparent. The resulting solution was placed in a hydrothermal reactor and hydrothermally heated at 200 °C for 24 h. The solid was separated by centrifugation, washed three times with deionized water and three times with anhydrous ethanol, and dried at room temperature for 12 h. The solid was collected, ground, and calcined in a muffle furnace at 600 °C for 4 h. The resulting product was denoted as Ni-rR. The catalytic performance of the catalyst was tested using the same method as in Example 1, and the calculated methanol yield is shown below. Figure 7 As shown.

[0083] Comparative Example 2

[0084] In this comparative example, a 0.5 wt% Au-rR catalyst was prepared as follows: 10.0 mL of isopropanol and 10.0 mL of titanium isopropoxide were dissolved in 100 mL of 1.6 M glycolic acid solution, and 26.77 mg of HAuCl4·3H2O was added. The mixture was stirred for 10 min, and the solution was heated to 90 °C and stirred for 3 h until transparent. The resulting solution was placed in a hydrothermal reactor and hydrothermally heated at 200 °C for 24 h. The solid was separated by centrifugation, washed three times with deionized water and three times with anhydrous ethanol, and dried at room temperature for 12 h. The solid was collected, ground, and calcined in a muffle furnace at 600 °C for 4 h. The resulting product was denoted as Au-rR. The catalytic performance of the catalyst was tested using the same method as in Example 1, and the calculated methanol yield is shown below. Figure 7 As shown.

[0085] Comparative Example 3

[0086] In this comparative example, a 0.5 wt% Cu-rR catalyst was prepared as follows: 10.0 mL of isopropanol and 10.0 mL of titanium isopropoxide were dissolved in 100 mL of 1.6 M glycolic acid solution, and 36.24 mg of CuCl2·2H2O was added. The mixture was stirred for 10 min, and the solution was heated to 90 °C and stirred for another 3 h until transparent. The resulting solution was placed in a hydrothermal reactor and hydrothermally heated at 200 °C for 24 h. The solid was separated by centrifugation, washed three times with deionized water and three times with anhydrous ethanol, and dried at room temperature for 12 h. The solid was collected, ground, and calcined in a muffle furnace at 600 °C for 4 h. The resulting product was denoted as Cu-rR. The catalytic performance of the catalyst was tested using the same method as in Example 1, and the calculated methanol yield is shown below. Figure 7 As shown.

[0087] Comparative Example 4

[0088] In this comparative example, a 0.5 wt% Mo-rR catalyst was prepared as follows: 10.0 mL of isopropanol and 10.0 mL of titanium isopropoxide were dissolved in 100 mL of 1.6 M glycolic acid solution, and 38.63 mg of MoCl5 was added. The mixture was stirred for 10 min, and the solution was heated to 90 °C and stirred for 3 h until transparent. The resulting solution was placed in a hydrothermal reactor and hydrothermally heated at 200 °C for 24 h. The solid was separated by centrifugation, washed three times with deionized water and three times with anhydrous ethanol, and dried at room temperature for 12 h. The solid was collected, ground, and calcined in a muffle furnace at 600 °C for 4 h. The resulting product was denoted as Mo-rR. The catalytic performance of the catalyst was tested using the same method as in Example 1, and the calculated methanol yield is shown below. Figure 7 As shown.

[0089] Comparative Example 5

[0090] In this comparative example, a 0.5 wt% Ir-rR catalyst was prepared as follows: 10.0 mL of isopropanol and 10.0 mL of titanium isopropoxide were dissolved in 100 mL of 1.6 M glycolic acid solution, and 20.97 mg of IrCl3·6H2O was added. The mixture was stirred for 10 min, and the solution was heated to 90 °C and stirred for 3 h until transparent. The resulting solution was placed in a hydrothermal reactor and hydrothermally heated at 200 °C for 24 h. The solid was separated by centrifugation, washed three times with deionized water and three times with anhydrous ethanol, and dried at room temperature for 12 h. The solid was collected, ground, and calcined in a muffle furnace at 600 °C for 4 h. The resulting product was denoted as Ir-rR. The catalytic performance of the catalyst was tested using the same method as in Example 1, and the methanol yield was calculated as follows: Figure 7 As shown.

[0091] Comparative Example 6

[0092] In this comparative example, a 0.5 wt% Rh-rR catalyst was prepared as follows: 10.0 mL of isopropanol and 10.0 mL of titanium isopropoxide were dissolved in 100 mL of 1.6 M glycolic acid solution, and 27.43 mg of RhCl3 was added. The mixture was stirred for 10 min, and the solution was heated to 90 °C and stirred for another 3 h until transparent. The resulting solution was placed in a hydrothermal reactor and hydrothermally heated at 200 °C for 24 h. The solid was separated by centrifugation, washed three times with deionized water and three times with anhydrous ethanol, and dried at room temperature for 12 h. The solid was collected, ground, and calcined in a muffle furnace at 600 °C for 4 h. The resulting product was denoted as Rh-rR. The catalytic performance of the catalyst was tested using the same method as in Example 1, and the calculated methanol yield is shown below. Figure 7 As shown.

[0093] Figure 7 The yield variation of rod-shaped rutile catalysts doped with different active components in the selective oxidation of methane was investigated. The results show that the Pd-rR catalyst yielded the highest methanol.

[0094] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for producing methanol from coalbed methane using a palladium-based catalyst, characterized in that: Includes the following steps: Coalbed methane is introduced into a reactor containing a copper ion solution and a palladium-based catalyst, with carbon monoxide introduced as an auxiliary gas; the temperature is increased and the mixture is stirred to carry out the reaction; after the reaction is completed, the methanol produced is collected from the liquid phase; the palladium-based catalyst is palladium-doped rod-shaped rutile.

2. The method for producing methanol from coalbed methane using a palladium-based catalyst according to claim 1, characterized in that: In the palladium-based catalyst, the mass fraction of palladium is 0.1-5.0 wt%.

3. The method for producing methanol from coalbed methane using a palladium-based catalyst according to claim 1, characterized in that: In the palladium-based catalyst, the mass fraction of palladium is 0.25-2.0 wt%.

4. The method for producing methanol from coalbed methane using a palladium-based catalyst according to claim 1, characterized in that: In the palladium-based catalyst, the mass fraction of palladium is 0.5 wt%.

5. The method for producing methanol from coalbed methane using a palladium-based catalyst according to claim 1, characterized in that: The palladium source in the palladium-based catalyst is introduced by doping. The specific preparation method includes the following steps: isopropanol and titanium isopropoxide are dissolved in glycolic acid solution, palladium nitrate is added, and the mixture is stirred. After the solution is heated, stirring is continued until it becomes transparent. The resulting solution is placed in a hydrothermal reactor for hydrothermal reaction. After the reaction is completed, the solid and liquid are separated, washed, dried, ground, and calcined to obtain the palladium-based catalyst.

6. The method for producing methanol from coalbed methane using a palladium-based catalyst according to claim 1, characterized in that: The palladium source in the palladium-based catalyst is introduced by impregnation. The specific preparation method includes the following steps: isopropanol and titanium isopropoxide are dissolved in glycolic acid solution and stirred. After the solution is heated, stirring is continued until it becomes transparent. The resulting solution is placed in a hydrothermal reactor for hydrothermal reaction. After the reaction is completed, the solid and liquid are separated, washed, dried, ground, calcined, and then added to an aqueous palladium nitrate solution for heating and aging. The resulting solid is ground and calcined to obtain the palladium-based catalyst.

7. The method for producing methanol from coalbed methane using a palladium-based catalyst according to claim 1, characterized in that: The pressure of the coalbed methane is 1-3.0 MPa; the pressure of the carbon monoxide is 0.2-1.0 MPa; and the concentration of copper ions in the copper ion solution is 1-100 mmol / L.

8. The method for producing methanol from coalbed methane using a palladium-based catalyst according to claim 1, characterized in that: The stirring rate is 600-1000 rpm; the reaction temperature is 100-200℃, and the reaction time is 0.5-4 h.

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