A method for in-situ Raman measurement of carbon deposition on a catalyst for oxidizing methane-containing gas to methanol

Abstract

A method for in-situ Raman measurement of carbon deposition on catalysts for the oxidation of methane-containing gas to methanol mainly uses an in-situ Raman system centered around a high-temperature and high-pressure microscopic Raman in-situ reaction cell, and a supporting gas system, a programmable temperature control system, a data acquisition system, and a water cooling system. Under gas-phase conditions, through different atmospheres, different temperatures, and different reaction times, the carbon deposition of non-carbon catalysts in the process of oxidizing coalbed methane (methane) to methanol is quantitatively measured. In the present invention, carbon deposition-related data is obtained by integrating the peak areas of the D band and G band of carbon in the in-situ Raman spectrum signal. Changing the atmosphere, temperature, and reaction time will cause changes in the D band and G band data, and the effects of the atmosphere, temperature, and reaction time on carbon deposition of non-carbon catalysts in the oxidation of coalbed methane (methane) to methanol are studied through the changes in the data. By reducing the carbon deposition deactivation of the catalyst, the service life of non-carbon catalysts in the oxidation of coalbed methane (methane) to methanol is extended.

Description

Technical Field

[0001] The present invention relates to the technical field of oxidizing methane-containing gas to methanol, and particularly to a method for in-situ Raman measurement of carbon deposition on a catalyst for oxidizing methane-containing gas to methanol. Background Art

[0002] Coalbed methane is mainly rich in CH4 and is the most abundant and cheapest natural gas resource with great utilization potential. However, the current utilization rate of coalbed methane is not high, and there is a problem of direct venting. This has caused a large amount of resource waste, aggravated the greenhouse effect and environmental hazards. Methane has a much shorter lifespan in the atmosphere than carbon dioxide, yet the harmfulness of methane is about 28 - 36 times that of carbon dioxide [M.Ravi, M.Ranocchiari, J.A. van Bokhoven, The Direct Catalytic Oxidation of Methane to Methanol - A Critical Assessment, Angewandte Chemie, 56(2017)16464 - 16483]. Therefore, it is necessary to convert methane. Currently, however, the methane in coalbed methane is mainly converted into methanol, a chemical raw material that is easy to transport and has many uses, through an energy - intensive industrial two - step process. This industrial production not only has a high processing cost but also produces some greenhouse gas. Therefore, the direct one - step conversion of methane in coalbed methane to methanol by catalytic technology is a more worthy - of - attention technology, which can not only improve the economic benefits of coalbed methane but also reduce greenhouse gas emissions [S.Cao, K.Zhang, B.Hanna, E.Al - Sayed, Methane oxidation by green oxidant to methanol over zeolite - based catalysts, Chinese Chemical Letters, 33(2022) 1757 - 1762; S.A.M.Ahmed, N.Jidnyasa, R.J.Krupadam, G.Hippargi, Y.Taraka Prabhu, U.Pal, S.S.Rayalu, P.Nagababu, Improved heterogeneous catalytic conversion of methane to methanol at ambient conditions, Journal of Environmental Chemical Engineering, 8(2020)104103]. However, in the process of directly converting methane to methanol, methanol is prone to over - oxidation to form carbon dioxide and lead to the formation of carbon deposition, which deactivates the catalyst. Therefore, studying the generation of carbon deposition during the reaction process is conducive to further exploring the mechanism of methane - to - methanol conversion and designing more efficient and economically viable catalysts and reaction conditions.

[0003] Raman spectroscopy is usually used to detect the carbon signal of the catalyst after the reaction. By analyzing the D band (about 1335 cm-1 ) and G belt (approximately 1580cm -1 ) to qualitatively measure the carbon deposition behavior in the catalyst. However, this measurement can usually only be used for catalysts after the reaction, and is not effective for the carbon deposition signal of the catalyst during the reaction and under changing reaction conditions. Therefore, by installing a high-temperature and high-pressure micro-Raman in-situ reaction cell and its supporting atmosphere control system, temperature control system, Raman data acquisition control system and safety measures and protection measures, the high-temperature and high-pressure in-situ Raman system can detect the carbon deposition change behavior of non-carbon catalysts in the process of coalbed methane (methane) oxidation to methanol under different atmospheres, different temperatures and different reaction times. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for in-situ Raman measurement of carbon deposition on catalysts for producing methanol by oxidation of methane-containing gas. The method is a new method for quantitatively measuring carbon deposition of non-carbon catalysts in the production of methanol by oxidation of coalbed methane (methane) using high temperature and high pressure in-situ Raman, and can detect the carbon deposition behavior of non-carbon catalysts in the production of methanol by oxidation of coalbed methane (methane) under different atmospheres, different temperatures and different reaction times.

[0005] The methane-containing gas is coalbed methane and / or methane.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A method for in-situ Raman measurement of carbon deposition on a catalyst for producing methanol by oxidation of methane-containing gas, using in-situ Raman spectroscopy to measure and obtain Raman spectral signals of non-carbon catalyst samples in a process of producing methanol by oxidation of methane-containing gas under different atmospheres, different reaction temperatures and different reaction times, extracting the integral areas of carbon D-band peaks and G-band peaks from the spectral signals, and comparing them with the integral areas of carbon D-band peaks and G-band peaks of a standard sample with a known carbon content, to calculate the carbon deposition amount of the non-carbon catalyst, and the calculation formula is:

[0008]

[0009] Among them, the unit of carbon deposition of non-carbon catalyst is mg / g; the unit of D band and G band peak area of ​​non-carbon catalyst is integrated area, dimensionless; the unit of k value is (mg / g) -1 .

[0010] A high-temperature and high-pressure in-situ Raman system comprises a high-temperature and high-pressure microscopic Raman in-situ reaction cell and its matching gas control system, temperature control system, Raman data acquisition control system and safety protection measures.

[0011] In the present invention, the term "high temperature" means a temperature not higher than 1000°C.

[0012] In the present invention, the term "high pressure" refers to a pressure not exceeding 3 MPa.

[0013] Furthermore, there is a ceramic crucible inside the high-temperature microscopic Raman in-situ reaction cell for placing the catalyst, and it has good sealing performance to maintain the pressure within 3 MPa. At the same time, there are gas flow channels and water-cooling channels.

[0014] Furthermore, the gas control system is composed of gas cylinders, digital flow meters, and connecting pipes, and can introduce different gases into the high-temperature and high-pressure microscopic Raman in-situ reaction cell.

[0015] Furthermore, the control range of the digital flow meter is 0 to 50 ml per minute.

[0016] Furthermore, the different gases include methane, methane-oxygen mixture, methane-steam mixture, and methane-oxygen-steam mixture.

[0017] Furthermore, the temperature control system can control the temperature of the bottom of the high-temperature microscopic Raman in-situ reaction cell and the surface of the detection mirror.

[0018] Furthermore, the temperature control range of the high-temperature microscopic Raman in-situ reaction cell is 50 - 600 °C.

[0019] Furthermore, the data acquisition system mainly obtains spectral signals by measuring the non-carbon catalyst in the ceramic crucible inside through the window of the high-temperature microscopic Raman in-situ reaction cell with Raman spectroscopy.

[0020] Furthermore, the wavelength of the incident light source of the Raman spectroscopy used is 532 nm, and the laser energy is 10% of the rated power.

[0021] Furthermore, the signals related to carbon deposition in the measured spectral signals are the D band (about 1335 cm -1 ) and the G band (about 1580 cm -1 ).

[0022] Furthermore, the safety protection measures mainly use a water cooler to connect the pipes on the surface of the high-temperature and high-pressure microscopic Raman in-situ reaction cell to reduce the temperature of the device environment, and to protect the reaction cell window and Raman spectroscopy from high-temperature damage to the instrument.

[0023] Further, by processing the Raman spectrum data of the standard sample (mordenite MOR standard containing carbon black) and obtaining the standard curve of the catalyst carbon deposition amount, the specific test steps are as follows: Prepare a carbon black mordenite (MOR) standard sample, and the mass content of carbon black is expressed as the mass of carbon black divided by the total mass of the standard, with the unit of mg / g. Measure the Raman spectrum data of multiple groups of standard samples by in-situ Raman, plot the scatter diagram of the peak area of the G band and D band - carbon deposition content, and calculate the k value of the peak area constant of the G band and D band per unit mass of the standard sample by the method of linear regression.

[0024] Further, for the measurement method, the specific measurement process is as follows: Place the non-carbon catalyst in a small ceramic crucible inside the high-temperature microscopic Raman in-situ reaction cell, then connect the pipeline between the high-temperature microscopic Raman in-situ reaction cell and the gas cylinder so that the carbon deposition behavior of the catalyst under different atmospheres can be measured. Connect a water-cooled pipeline to the upper layer of the high-temperature microscopic Raman in-situ reaction cell to keep the surface temperature of the lens low to prevent damage to the instrument. Connect a temperature control heating device so that the Raman spectrum can measure the signal of the catalyst in the high-temperature microscopic Raman in-situ reaction cell at different temperatures. Before introducing the reaction gas, first introduce nitrogen to sweep away the excess gas, then set the test temperature, introduce the reaction gas at the set temperature, measure the spectral signal under specific conditions by Raman spectroscopy, and extract the changes in the D band and G band signals to evaluate the changes in the carbon deposition behavior. The specific calculation process is as follows: Extract the integral areas of the D band peak and G band peak of carbon from the spectral signal, compare them with the integral areas of the D band peak and G band peak of carbon in the standard sample with known carbon content, and calculate the carbon deposition amount of the non-carbon catalyst. The calculation formula is:

[0025]

[0026] The unit of the carbon deposition amount of the non-carbon catalyst is mg / g, the unit of the peak area is the integral area, dimensionless, and the unit of k is (mg / g) -1 。

[0027] Therefore, the carbon deposition behavior at different temperatures in one atmosphere, the carbon deposition behavior at different atmospheres at a specific temperature, and the change behavior of carbon deposition with time at a specific temperature and specific atmosphere can be measured by the whole set of in-situ Raman devices.

[0028] Beneficial effects:

[0029] The benefits of the present invention are reflected in being able to qualitatively measure the carbon deposition of non-carbon catalysts during the reaction of coalbed methane (methane) oxidation to methanol, and studying the effects of atmosphere, temperature, and reaction time on carbon deposition of non-carbon catalysts in the oxidation of coalbed methane (methane) to methanol through the changes in data. By reducing the carbon deposition deactivation of the catalyst, the service life of non-carbon catalysts in the oxidation of coalbed methane (methane) to methanol can be extended. It is possible to more deeply reveal the carbon deposition behavior of non-carbon catalysts during the reaction of coalbed methane (methane) oxidation to methanol under different reaction atmospheres such as coalbed methane (methane), coalbed methane (methane)-oxygen mixture, and coalbed methane (methane)-oxygen-water vapor mixture, different reaction temperatures from 50 to 600 °C, and different reaction times from 1 to 6 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 : In-situ Raman system and device connection diagram.

[0031] Figure 2 : Standard curve of integrated area of G band and D band - carbon deposition amount for the standard sample of carbon black and mordenite mixture.

[0032] Figure 3 : Raman spectral signal data measured for the copper-exchanged MOR zeolite catalyst under different atmospheres of methane, methane-oxygen mixture, and methane-oxygen-water vapor mixture, at a reaction temperature of 320 °C and a reaction time of 1 h.

[0033] Figure 4 : Raman spectra measured for the copper-exchanged MOR zeolite catalyst in methane atmosphere, at different reaction temperatures, and a reaction time of 30 min.

[0034] Figure 5 : Raman spectra measured for the copper-exchanged MOR zeolite catalyst in methane atmosphere, at a reaction temperature of 320 °C, and a reaction time ranging from 10 min to 90 min. DETAILED DESCRIPTION OF THE INVENTION

[0035] The following examples are used to further illustrate the present invention in conjunction with the accompanying drawings of the specification, but the present invention is not limited thereto.

[0036] In the following examples, the non-carbon catalyst used is a self-synthesized copper-exchanged MOR zeolite catalyst. By dropping 15 ml of 0.5 mol / L copper nitrate solution into 10 g of MOR zeolite, stirring for 12 hours, drying and grinding, repeating the ion exchange process with 15 ml of 0.5 mol / L copper nitrate solution 3 times, with each exchange time being 12 h, filtering to obtain the precipitate, drying in an oven at 60 °C for 4 hours, and then calcining in a tubular furnace at 600 °C for 2 hours under a nitrogen protection atmosphere.

[0037] Calculation formulas in Examples 2 - 4: where the value of k is

[0038] such as Figure 1 As shown, the components and connection methods of the in-situ high-temperature Raman device: The core is an in-situ reaction cell for high temperature and high pressure. The catalytic reaction takes place in the reaction cell part. It has a built-in heating device as the temperature control system. The sample is located in the center of the heating furnace, and the temperature can be programmed. There are pressure and temperature sensors at the reaction cell to detect the temperature and pressure inside the reaction cell. The atmosphere system uses oxygen cylinders, methane cylinders, nitrogen cylinders, and a steam generator as gas sources, and digital flow meters are used to control the flow rates of each reaction gas. Data acquisition consists of a Raman spectrometer and a computer, and a computer program is used to control the Raman spectroscopy acquisition. The safety protection measures consist of a water cooler and water pipes to ensure that the outer shell of the in-situ reaction cell works at a safe temperature.

[0039] Example 1

[0040] By processing the Raman spectroscopy data of a standard sample (a mordenite MOR standard containing carbon black), a standard curve for the carbon deposition amount of the catalyst is obtained and plotted as Figure 2 , and the specific test steps are as follows: Prepare a carbon black mordenite standard sample by mixing a certain mass of carbon black (Cabot vulcan xc-72, Macklin) and mordenite (SAR: 25-30, ZRCATALYST CO., LTD). The mass content of carbon black (the mass of carbon black divided by the total mass of the standard) is 20 mg / g, 50 mg / g, 100 mg / g, 150 mg / g, 200 mg / g, 300 mg / g, and 500 mg / g respectively. Under a nitrogen atmosphere of 20 ml / min and at a temperature of 320 °C, multiple groups of Raman spectroscopy data of the standard samples are measured, and a peak area-content curve is plotted. The peak area constants k of the G band and D band per unit mass of the standard sample are calculated by the method of linear regression. The formula is:

[0041]

[0042] Example 2

[0043] This example mainly studies the influence of different reaction atmospheres on the carbon deposition behavior of non-carbon catalysts during the reaction of methane oxidation to methanol, mainly through a set of such as Figure 1The in-situ Raman measurement system shown in the figure is used. First, 0.1 g of copper-exchanged MOR zeolite (denoted as Cu-MOR) is loaded into the internal ceramic crucible of the high-temperature and high-pressure microscopic Raman in-situ reaction cell. After the high-temperature and high-pressure microscopic Raman in-situ reaction cell is sealed, it is connected to a digital flowmeter through a pipeline. The digital flowmeter is externally connected to a methane gas cylinder (purity 99%), an oxygen gas cylinder (21% with the rest being nitrogen), and a nitrogen gas cylinder (purity 99%). Subsequently, the steam inlet pipeline is connected through a ferrule. The pipeline is equipped with a syringe for adjusting the water intake and a heating jacket for heating water into steam. The set temperature of the heating jacket is 140 degrees Celsius. After connecting the gas control system, the water-cooling pipeline of the water chiller is connected to the upper window passage of the high-temperature microscopic Raman in-situ reaction cell to complete the safety protection measures to avoid damage to the lens and Raman spectrum caused by high temperature. Then, the temperature control device of the high-temperature and high-pressure microscopic Raman in-situ reaction cell is connected to ensure temperature control and detection of the high-temperature microscopic Raman in-situ reaction cell. After connecting the gas control system, the temperature control system, and the safety protection measures, the high-temperature and high-pressure microscopic Raman in-situ reaction cell is placed under the Raman spectroscopy lens, and the focal length is adjusted to clearly observe the catalyst through the window of the high-temperature and high-pressure microscopic Raman in-situ reaction cell. The digital flowmeter is turned on, and the nitrogen gas flow rate is set to 50 ml / min to purge the catalyst surface for 30 min to make the catalyst in an inert gas atmosphere. Subsequently, the internal temperature of the high-temperature microscopic Raman in-situ reaction cell is raised to 320 °C at a heating rate of 10 degrees Celsius per minute. Then, the nitrogen gas flow and the temperature of 320 °C are maintained for 30 min to remove the bound water in the catalyst. After drying, the pure nitrogen gas is switched to a mixture of 10 ml / min methane gas + 15 ml / min nitrogen gas. After 60 min, the catalyst is measured with a light source with a wavelength of 532 nm and an intensity of 10% to obtain the Raman spectrum data of Cu-MOR in a methane atmosphere. Subsequently, the high-temperature microscopic Raman in-situ reaction cell is cooled to room temperature, and 0.1 g of Cu-MOR catalyst is reloaded. After purging with 50 ml / min nitrogen gas for 30 min, it is heated to 320 °C and dried for 30 min. Subsequently, the gas is switched to a mixture of 10 ml / min methane gas + 5 ml / min oxygen (methane-oxygen volume ratio is 2:1) + 15 ml / min nitrogen gas. After reacting for 60 min, the catalyst is measured with a light source with a wavelength of 532 nm and an intensity of 10% to obtain the Raman spectrum data of Cu-MOR in a methane-oxygen mixture atmosphere.Subsequently, the high-temperature in-situ Raman reaction cell was cooled to room temperature, and 0.1 g of Cu-MOR catalyst was reloaded. After purging with 50 ml of nitrogen for 30 min, it was heated to 320 °C and dried for 30 min. Subsequently, the gas was switched to a mixture of 10 ml / min methane + 5 ml / min oxygen + 40 ml / min steam (obtained by injecting water at a rate of 0.016 g / min through a syringe) (methane:oxygen:steam volume ratio of 2:1:8) + 15 ml / min nitrogen. After reacting for 60 min, the catalyst was measured with a light source with a wavelength of 532 nm and an intensity of 10% to obtain the Raman spectral data of Cu-MOR in the methane-oxygen-steam mixed gas atmosphere. The obtained data was plotted. Figure 3 , and analyzed and compared to analyze the carbon deposition behavior during the reaction of methane oxidation to methanol under different atmospheres of methane, methane-oxygen mixed gas, and methane-oxygen-steam mixed gas, at a reaction temperature of 320 °C and a reaction time of 1 h. As Figure 3 shown, it can be observed that the carbon deposition of Cu-MOR is the most serious in the pure methane atmosphere, and through the calculation formula:

[0044]

[0045] it was calculated that the maximum carbon deposition amount was: 166 mg / g

[0046] Example 3

[0047] This example mainly studies the influence of different reaction temperatures on the carbon deposition behavior of non-carbon catalysts during the reaction of methane oxidation to methanol, mainly through a set of such as Figure 1The in-situ Raman measurement system shown in the figure is used. First, 0.1 g of copper-exchanged MOR zeolite (denoted as Cu-MOR) is loaded into the inner ceramic crucible of the high-temperature and high-pressure microscopic Raman in-situ reaction cell. After the high-temperature and high-pressure microscopic Raman in-situ reaction cell is sealed, it is connected to a digital flowmeter through a pipeline. The digital flowmeter is externally connected to a methane gas cylinder (purity 99%), an oxygen gas cylinder (21% with the rest being nitrogen), and a nitrogen gas cylinder (purity 99%). Subsequently, a steam inlet pipeline is connected through a ferrule. The pipeline is equipped with a syringe for adjusting the water intake and a heating jacket for heating water into steam. The set temperature of the heating jacket is 140 degrees Celsius. After connecting the gas control system, the water-cooling pipeline of the water chiller is connected to the upper window passage of the high-temperature microscopic Raman in-situ reaction cell to complete the safety protection measures to avoid damage to the lens and Raman spectrum caused by high temperature. Then, the temperature control device of the high-temperature and high-pressure microscopic Raman in-situ reaction cell is connected to ensure temperature control and detection of the high-temperature microscopic Raman in-situ reaction cell. After connecting the gas control system, the temperature control system, and the safety protection measures, the high-temperature and high-pressure microscopic Raman in-situ reaction cell is placed under the Raman spectroscopy lens, and the focal length is adjusted to clearly observe the catalyst through the window of the high-temperature and high-pressure microscopic Raman in-situ reaction cell. The digital flowmeter is turned on, and the nitrogen gas flow rate is set to 50 ml / min to purge the catalyst surface for 30 min to make the catalyst in an inert gas atmosphere. Subsequently, the internal temperature of the high-temperature microscopic Raman in-situ reaction cell is raised to 120 degrees Celsius at a heating rate of 10 degrees Celsius per minute. Then, the nitrogen gas flow and the temperature of 120 degrees Celsius are maintained for 30 min to remove the bound water in the catalyst. After drying, the pure nitrogen gas is switched to a mixture of 10 ml / min of methane gas + 15 ml / min of nitrogen gas. After 30 min, the catalyst is measured with a light source with a wavelength of 532 nm and an intensity of 10% to obtain the Raman spectrum data of Cu-MOR at 120 degrees Celsius. Subsequently, the high-temperature microscopic Raman in-situ reaction cell is cooled to room temperature, 0.1 g of Cu-MOR catalyst is reloaded, and after purging with 50 ml of nitrogen for 30 min, it is heated to 220 degrees Celsius and dried for 30 min. Then, the gas is switched to a mixture of 10 ml / min of methane gas + 15 ml / min of nitrogen gas. After reacting for 30 min, the catalyst is measured with a light source with a wavelength of 532 and an intensity of 10% to obtain the Raman spectrum data of Cu-MOR at 220 degrees Celsius. Subsequently, the high-temperature microscopic Raman in-situ reaction cell is cooled to room temperature, 0.1 g of Cu-MOR catalyst is reloaded, and after purging with 50 ml of nitrogen for 30 min, it is heated to 320 degrees Celsius and dried for 30 min. Then, the gas is switched to a mixture of 10 ml / min of methane gas + 15 ml / min of nitrogen gas. After reacting for 30 min, the catalyst is measured with a light source with a wavelength of 532 nm and an intensity of 10% to obtain the Raman spectrum data of Cu-MOR at 320 degrees Celsius.Subsequently, the high-temperature in-situ Raman reaction cell was cooled to room temperature, and 0.1 g of Cu-MOR catalyst was reloaded. After purging with 50 ml of nitrogen for 30 min, it was heated to 420 °C and dried for 30 min. Subsequently, the gas was switched to a mixture of 10 ml / min methane gas + 15 ml / min nitrogen. After reacting for 30 min, the catalyst was measured with a light source with a wavelength of 532 nm and an intensity of 10% to obtain the Raman spectral data of Cu-MOR at 420 °C. The obtained data was plotted. Figure 4 , and analyzed and compared to analyze the carbon deposition behavior during the reaction of methane to methanol over Cu-MOR under different reaction temperatures of 120 °C, 220 °C, 320 °C, and 420 °C, in a methane atmosphere, and with a reaction time of 30 min. As Figure 4 shown, it can be observed that the carbon deposition of Cu-MOR is the most serious at 420 °C, and through the calculation formula:

[0048]

[0049] the maximum carbon deposition amount was calculated to be: 200 mg / g

[0050] Example 4

[0051] This example mainly studies the effect of different reaction times on the carbon deposition behavior of non-carbon catalysts during the reaction of methane to methanol, mainly through a set of such as Figure 1The in-situ Raman measurement system shown in the figure is used. First, 0.1 g of copper-exchanged MOR zeolite (denoted as Cu-MOR) is loaded into the internal ceramic crucible of the high-temperature and high-pressure microscopic Raman in-situ reaction cell. After the high-temperature and high-pressure microscopic Raman in-situ reaction cell is sealed, it is connected to a digital flowmeter through a pipeline. The digital flowmeter is externally connected to a methane gas cylinder (purity 99%), an oxygen gas cylinder (21% with the rest being nitrogen), and a nitrogen gas cylinder (purity 99%). Subsequently, a steam inlet pipeline is connected through a ferrule. The pipeline is equipped with a syringe for adjusting the water intake and a heating jacket for heating water into steam. The set temperature of the heating jacket is 140 degrees Celsius. After connecting the gas control system, the water-cooling pipeline of the water chiller is connected to the upper window passage of the high-temperature microscopic Raman in-situ reaction cell to complete the safety protection measures to avoid damage to the lens and Raman spectrum caused by high temperature. Then, the temperature control device of the high-temperature and high-pressure microscopic Raman in-situ reaction cell is connected to ensure temperature control and detection of the high-temperature microscopic Raman in-situ reaction cell. After connecting the gas control system, the temperature control system, and the safety protection measures, the high-temperature and high-pressure microscopic Raman in-situ reaction cell is placed under the Raman spectroscopy lens, and the focus is adjusted to clearly observe the catalyst through the window of the high-temperature and high-pressure microscopic Raman in-situ reaction cell. The digital flowmeter is turned on, and the nitrogen flow rate is set to 50 ml / min to purge the catalyst surface for 30 min to make the catalyst in an inert gas atmosphere. Subsequently, the internal temperature of the high-temperature microscopic Raman in-situ reaction cell is raised to 320 °C at a heating rate of 10 degrees Celsius per minute. Then, the nitrogen gas flow and the temperature of 320 °C are maintained for 30 min to remove the bound water in the catalyst. After drying, the pure nitrogen gas is switched to a mixture of 10 ml / min of methane gas + 15 ml / min of nitrogen gas. After 10 min, the catalyst is measured with a light source with a wavelength of 532 nm and an intensity of 10% to obtain the Raman spectral data of Cu-MOR reacting for 10 min. Subsequently, the catalyst is measured with a light source with a wavelength of 532 nm and an intensity of 10% at reaction times of 30 min, 40 min, 50 min, 60 min, 80 min, and 90 min to obtain the Raman spectral data of Cu-MOR reacting for 30 min, 40 min, 50 min, 60 min, 80 min, and 90 min. The obtained data is plotted as Figure 5 , and analyzed and compared to analyze the carbon deposition behavior during the reaction process of oxidizing coalbed methane (methane) to methanol by Cu-MOR under the conditions of coalbed methane (methane) atmosphere, reaction temperature of 320 °C, and reaction times of 10 min, 30 min, 40 min, 50 min, 60 min, 80 min, and 90 min. As Figure 5 shown, it can be observed that the carbon deposition content in Cu-MOR increases with the prolongation of the reaction, and through the calculation formula:

[0052]

[0053] The calculated maximum carbon deposition amount is: 135 mg / g

[0054] The parts not elaborated in detail in the present invention belong to the well-known technologies of those skilled in the art. The above-described embodiments are only descriptions of the preferred embodiments of the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solution of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for in-situ Raman measurement of carbon deposition on the catalyst for the oxidation of coalbed methane to methanol, characterized in that: In-situ Raman spectroscopy was used to measure and obtain the Raman spectral signals of non-carbon catalyst samples under different atmospheres, different reaction temperatures, and different reaction times during the oxidation of coalbed methane to methanol. The integrated areas of the D-band peak and G-band peak of carbon were extracted from the spectral signals and compared with those of a standard sample with a known carbon content. The carbon deposition amount of the non-carbon catalyst was calculated using the following formula: ; The method specifically includes the following steps: placing a non-carbon catalyst into a ceramic crucible inside a high-temperature and high-pressure in-situ Raman reaction cell, then connecting the pipeline between the high-temperature and high-pressure in-situ Raman reaction cell and the gas cylinder so that the carbon deposition behavior of the catalyst under different atmospheres can be measured, connecting a water-cooling pipeline to the upper layer of the high-temperature and high-pressure in-situ Raman reaction cell, and connecting a temperature-controlled heating device so that the Raman spectrum can measure the signal of the catalyst in the high-temperature and high-pressure in-situ Raman reaction cell at different temperatures; before introducing the reaction gas, first introduce nitrogen to sweep away the excess gas, then set the test temperature, introduce different reaction gases at the set temperature, measure the spectral signal under predetermined conditions through Raman spectroscopy, and extract the quantitative changes in the D-band and G-band signals of carbon to evaluate the dynamic changes in the carbon deposition behavior; the method can measure the carbon deposition of the non-carbon catalyst during the reaction of oxidizing coalbed methane to methanol, and study the effects of atmosphere, temperature, and reaction time on the carbon deposition of the non-carbon catalyst in the oxidation of coalbed methane to methanol through the changes in data, so as to extend the service life of the non-carbon catalyst in the oxidation of coalbed methane to methanol by reducing the carbon deposition deactivation of the catalyst; The calculation method of the k value is as follows: Using carbon black mixed with mordenite as the standard sample, the mass content of carbon black is expressed as the mass of carbon black divided by the total mass of the standard substance, with the unit of mg / g. Raman spectral data of multiple groups of standard samples were measured by in-situ Raman, and a scatter plot of the integrated area of the G-band and D-band peaks versus the carbon deposition content was plotted. The k value of the G-band and D-band peak areas per unit mass of the standard sample was calculated using the method of linear regression. The unit of peak area is integral area, dimensionless, and the unit of k is (mg / g). -1 .

2. The method according to claim 1, characterized in that: The method uses an in-situ reaction device. Through atmosphere control, temperature control, and Raman signal data acquisition control under safety protection measures, it ensures that during the oxidation of coalbed methane to methanol by the non-carbon catalyst, the laser of the Raman spectrometer passes through the reaction cell window and obtains the Raman spectral signals of the non-carbon catalyst samples under different atmospheres, different reaction temperatures, and different reaction times.

3. The method according to claim 1, characterized in that: The method uses an in-situ reaction device. The reaction device includes a high-temperature and high-pressure microscopic Raman in-situ reaction cell. Inside the high-temperature and high-pressure microscopic Raman in-situ reaction cell, there is a ceramic crucible for placing the catalyst, and it has a sealing performance to maintain a pressure not higher than 3 MPa. At the same time, there are gas flow channels and a device environmental water cooling channel.

4. The method according to claim 2, characterized in that: The atmosphere control includes a gas control system composed of gas cylinders, digital flow meters, and connecting pipes, which can introduce different gases into the high-temperature and high-pressure microscopic Raman in-situ reaction cell. The gases include one or more of methane, methane-oxygen mixture, methane-steam mixture, and methane-oxygen-steam mixture, and their flow rates are controlled.

5. The method according to claim 2, characterized in that: The temperature control includes: A temperature control system composed of a temperature control heating and temperature control device and a high-temperature and high-pressure microscopic Raman in-situ reaction cell can control the temperature at the bottom of the high-temperature and high-pressure microscopic Raman in-situ reaction cell and the temperature of the detection reaction cell window. The bottom temperature is the reaction temperature for the oxidation of methane to methanol, and its control range is 50 - 1000 °C.

6. The method according to claim 2, characterized in that: The Raman signal data acquisition control includes obtaining the spectral signal by measuring the non-carbon catalyst in the internal ceramic crucible of the high-temperature and high-pressure microscopic Raman in-situ reaction cell through the laser of the Raman spectrum passing through the reaction cell window, and extracting the signals of the D-band peak and G-band peak of its carbon. The wavelength of the incident light source of the Raman spectrum is 532 nm, and the energy of the laser is 10% of the rated power of the laser.

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