Experimental method and device for in-situ diffuse reflection Fourier transform infrared spectrum

Abstract

The invention discloses an experimental method and device for in-situ diffuse reflection Fourier transform infrared spectroscopy, and belongs to the field of mechanism exploration of low-temperature adsorption and desorption of adsorbents. According to the method, a pretreatment gas circuit and a reaction gas circuit are built, inert gas in the pretreatment gas circuit pretreats a sample, adsorption and desorption treatment is carried out in an in-situ reaction tank, and the in-situ reaction tank is provided with a double-circulation cooling system and a temperature control device, so that the reaction temperature is stable, and the reaction time is shortened; the problem that condensed water vapor of an in-situ infrared spectrum interferes with an infrared spectrum signal under the condition that the temperature is lower than the room temperature is solved, and adsorption and desorption can be carried out under the low-temperature condition of-10-25 DEG C. The experimental method disclosed by the invention is simple and easy to implement, expands the in-situ diffuse reflection Fourier transform infrared spectroscopy to the field of adsorbents, can capture intermediate products generated in low-temperature adsorption and desorption processes of the adsorbent in real time, and explores adsorption and desorption mechanisms.

Description

Technical Field

[0001] This invention relates to the field of investigating the mechanism of low-temperature adsorption and desorption of adsorbents, and in particular to an experimental method and apparatus for in-situ diffuse reflectance Fourier transform infrared spectroscopy. Background Technology

[0002] In the field of environmental pollution control, adsorbents play a crucial role in the adsorption and filtration of polluting gases. Studies have found that the adsorption capacity of most adsorbents decreases with increasing temperature; therefore, developing highly efficient adsorbents for low-temperature conditions has become an important direction for improving adsorption efficiency. However, current research on the adsorption and desorption mechanisms of adsorbents at low temperatures is still relatively scarce, and there is a lack of effective real-time monitoring methods to capture intermediate products during the reaction process, resulting in insufficient understanding of the low-temperature adsorption mechanism.

[0003] In-situ diffuse reflectance Fourier transform infrared spectroscopy has been applied to the study of reaction mechanisms under high temperature and high pressure conditions for catalysts, but its application in the field of adsorbents is extremely limited. This is mainly due to two technical challenges: First, under low temperature conditions, condensation easily occurs in the in-situ reaction tank, and the strong infrared absorption peak of water vapor will seriously interfere with the infrared spectral signal, leading to data distortion; second, there is a temperature conduction difference between traditional refrigeration equipment and the in-situ reaction tank, resulting in a large deviation between the actual temperature and the set temperature, making precise temperature control impossible, and thus affecting the accuracy and repeatability of experimental results. Therefore, there is an urgent need to develop an in-situ infrared spectroscopy method suitable for the study of adsorbent adsorption-desorption mechanisms at low temperatures to solve the above technical problems. Summary of the Invention

[0004] To address the problem of inaccurate temperature control and strong infrared absorption peaks of condensed water vapor interfering with spectral signals and causing data distortion in experiments studying the adsorption-desorption mechanism of adsorbents under low-temperature conditions, this invention provides an in-situ diffuse reflectance Fourier transform infrared spectroscopy experimental method and apparatus to aid in the investigation of the adsorption-desorption mechanism of adsorbents under low-temperature conditions. This method can capture intermediate products generated by adsorbents during low-temperature adsorption and desorption in real time, thereby enabling in-depth investigation of the adsorption and desorption mechanisms.

[0005] This invention provides an experimental apparatus for in-situ diffuse reflectance Fourier transform infrared spectroscopy, comprising a pretreatment gas path and a reaction gas path, which are respectively connected to an in-situ reaction cell. The in-situ reaction cell is equipped with a dual-circulation cooling system, which includes an inner circulation cooling system and an outer circulation cooling system. The inner circulation cooling system is used to cool the sample cup of the in-situ reaction cell, and the outer circulation cooling system is used to cool the outer shell of the in-situ reaction cell. The in-situ reaction cell is equipped with a temperature control device and is also connected to a Fourier transform infrared spectrometer.

[0006] The in-situ reaction tank is connected to the exhaust gas collection device.

[0007] Both the pretreatment gas path and the reaction gas path are equipped with pressure reducing valves and mass flow meters.

[0008] This invention also provides an experimental method for in-situ diffuse reflectance Fourier transform infrared spectroscopy, including: The sample was placed in an in-situ reaction cell, an inert gas was introduced, and the sample was heated. The dual-circulation cooling system is activated, with the internal circulation cooling system controlling the temperature inside the in-situ reaction tank and the external circulation cooling system controlling the temperature outside the in-situ reaction tank, forming a temperature gradient isolation layer. Set the adsorption infrared spectrum acquisition parameters. When the sample reaches the reaction temperature, the Fourier transform infrared spectrometer acquires the background spectrum, and the reaction gas is introduced to acquire the infrared spectrum of the adsorption process in real time. After the sample has completed adsorption, the flow of reaction gas is stopped, the desorption infrared spectrum acquisition parameters are set, the sample is heated, and the infrared spectrum of the desorption process is acquired in real time.

[0009] The reactant gas can be a single reactant gas or a mixture of reactant gases.

[0010] The flow rates of the inert gas and the reactant gas are 0.1 mL / min to 200 mL / min.

[0011] The adsorption infrared spectral acquisition parameters and desorption infrared spectral acquisition parameters are both set to: spectral resolution of 2 cm⁻¹. -1 ~10cm -1 The number of scans is 2 to 50, and the acquisition mode is absorption spectroscopy or transmission spectroscopy.

[0012] The reaction temperature of the sample is -10~25℃.

[0013] The heating process specifically involves heating the sample to 100℃~1000℃ using an inert gas at a heating rate of 2℃ / min~15℃ / min, and holding the temperature for 0.5h~10h.

[0014] The internal circulation cooling system is controlled at a temperature of -60℃ to 20℃, while the external circulation cooling system is controlled at room temperature.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention has the following significant beneficial effects: The device provided by the present invention is equipped with a dual - cycle cooling system. The inner - cycle cooling system is used to cool the sample cup in the in - situ reaction cell, and the outer - cycle cooling system maintains the temperature of the outer shell at room temperature. The temperature - gradient isolation layer formed by the cooperation of the two fundamentally solves the problem of condensate generation in the in - situ reaction cell under low - temperature conditions, avoids the interference of condensate on the infrared spectral signal, and ensures the accuracy and reliability of spectral data. The temperature - control device配套 with the dual - cycle cooling system realizes the real - time monitoring and precise regulation of the core temperature of the in - situ reaction cell. By adjusting the refrigeration parameters of the outer - cycle cooling system, the core reaction temperature can be stably controlled within the range of - 10~25°C, and the temperature fluctuation is extremely small, greatly ensuring the stability and repeatability of experimental conditions, and laying a solid foundation for the comparative analysis and mechanism exploration of experimental results.

[0016] The successful expansion of the in - situ diffuse reflectance Fourier transform infrared spectroscopy provided by the present invention in the field of adsorbents realizes the real - time monitoring of the adsorption and desorption processes of adsorbents under low - temperature conditions of - 10~25°C, and can capture the intermediate products generated during the process; it provides accurate experimental evidence for exploring the adsorption and desorption mechanisms, helps researchers understand the action mechanism of adsorbents at the molecular level, and provides theoretical guidance for the development of new and efficient adsorbents. The entire experimental method is reasonably designed, the operation steps are clear, without complex equipment and processes, and has the characteristics of low - cost and high - precision temperature control, which is convenient for popularization and application in scientific research and production. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, so they should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative work, other related drawings can also be obtained based on these drawings.

[0018] Figure 1 It is a schematic structural diagram of the experimental device of the in - situ diffuse reflectance Fourier transform infrared spectroscopy of the present invention; Figure 2 It is an in - situ adsorption infrared spectrogram collected in Example 1; Figure 3 It is an in - situ adsorption infrared spectrogram collected in Example 2; Figure 4 It is an in - situ desorption infrared spectrogram collected in Example 3; Among them, 1. Pretreatment gas path; 2. Reaction gas path; 3. In - situ reaction cell; 4. Pressure reducing valve; 5. Mass flowmeter; 6. Dual - cycle cooling system; 7. Temperature - control device; 8. Fourier transform infrared spectrometer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0020] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0021] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0022] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0023] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0024] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass described in the embodiments of this application can be a mass unit known in the chemical industry, such as μg, mg, g, or kg.

[0025] like Figure 1As shown, an experimental apparatus for in-situ diffuse reflectance Fourier transform infrared spectroscopy includes two gas path systems: a pretreatment gas path 1 and a reaction gas path 2. The pretreatment gas path 1 and the reaction gas path 2 are connected to the in-situ reaction cell 3 via three-way valves. Both the pretreatment gas path 1 and the reaction gas path 2 are equipped with pressure reducing valves 4 and mass flow meters 5. The gases used in the pretreatment gas path 1 and the reaction gas path 2, after exiting the gas source, are first depressurized by the pressure reducing valves 4, and then their flow rates are controlled by the mass flow meters 5. The in-situ reaction cell 3 is equipped with a dual-circulation cooling system 6, which includes an internal circulation cooling system and an external circulation cooling system. The internal circulation cooling system is used to cool the sample cup of the in-situ reaction cell, and the external circulation cooling system is used to cool the outer shell of the in-situ reaction cell 3. The in-situ reaction cell 3 is connected to a temperature control device 7, which can display the core temperature of the in-situ reaction cell in real time. The temperature of the reaction core is controlled by adjusting the cooling parameters of the internal circulation cooling system. The in-situ reaction cell 3 is also connected to the Fourier transform infrared spectrometer 8, which is used to collect the infrared spectra of adsorption or desorption; the in-situ reaction cell 3 is also connected to the exhaust gas collection device.

[0026] In some embodiments, the pretreatment gas path 1 is an inert gas, and the reaction gas path 2 is a single reaction gas or a reaction gas that has been mixed by itself.

[0027] In some embodiments, the temperature control device 7 is a thermocouple temperature control device.

[0028] The dual-circulation cooling system 8 is equipped with a refrigerator for both the internal and external circulation cooling systems. The inner wall of the in-situ reaction tank 3 and the outer wall of the sample cup form a circulating coolant channel, which is connected to the refrigerator to form the internal circulation cooling system. The inner side wall of the outer shell of the in-situ reaction tank 3 is equipped with a circulating coolant channel, which is connected to the refrigerator to form the external circulation cooling system. Temperature control is achieved by using liquid cooling.

[0029] An in-situ diffuse reflectance Fourier transform infrared spectroscopy method for low-temperature adsorption and desorption of adsorbents specifically includes the following steps: The sample is placed in the in-situ reaction chamber 3, and inert gas is introduced into the in-situ reaction chamber 3 by opening the pretreatment gas path 1. The mass flow meter 5 of the pretreatment gas path 1 controls the flow rate of the inert gas to be 0.1 mL / min to 200 mL / min. The sample is heated to 100℃ to 1000℃ at a heating rate of 2℃ / min to 15℃ / min and held for 0.5h to 10h to remove impurities and moisture from the sample surface.

[0030] Before sample processing is completed, a dual-circulation cooling system is activated. The inner circulation cooling system directly cools the sample cup in the in-situ reaction cell, while the outer circulation cooling system maintains the outer shell temperature close to room temperature, forming a temperature gradient isolation layer. The temperature control device 7 monitors the temperature of the in-situ reaction cell in real time and regulates the temperature of the reaction core by adjusting the cooling parameters of the inner circulation cooling system (range -60℃ to 20℃). The outer circulation cooling system is used to control the temperature of the outer shell of the in-situ reaction cell 3 to room temperature.

[0031] It should be noted that a temperature gradient isolation layer refers to a structure that creates a temperature gradient when there is a temperature difference between the internal and external environments. This prevents the internal circulation system from directly approaching room temperature and avoids overheating due to heat dissipation, thus making the internal circulation temperature more stable. For example, if the room temperature is 30 degrees Celsius, the external circulation temperature is 20 degrees Celsius, and the internal circulation temperature is -10 degrees Celsius, the internal circulation temperature will not be directly 30 degrees Celsius due to the presence of the external circulation, creating a temperature gradient. The internal circulation system will not overheat due to heat dissipation, resulting in greater stability.

[0032] Set the adsorption infrared spectral acquisition parameters to a spectral resolution of 2 cm⁻¹. -1 ~10cm -1 The number of scans is 2 to 50, and the acquisition mode is absorption spectroscopy or transmission spectroscopy, with a preferred spectral resolution of 4 cm⁻¹. -1 Or 8cm -1 The instrument performed 32 scans in absorption spectroscopy mode. Once the sample reached the reaction temperature and stabilized at the target temperature, the Fourier transform infrared spectrometer 8 first acquired the background spectrum, then opened the reaction gas path 2 to introduce the reaction gas, controlling the flow rate of the reaction gas to be 0.1 mL / min to 200 mL / min, and acquired the infrared spectrum of the adsorption process in real time.

[0033] After the adsorbent has completed adsorption, turn off reaction gas path 2, stop the flow of reaction gas, and set the desorption infrared spectroscopy acquisition parameters to a spectral resolution of 2 cm⁻¹. -1 ~10cm -1 The number of scans is 2 to 50, and the acquisition mode is absorption spectroscopy or transmission spectroscopy, with a preferred spectral resolution of 4 cm⁻¹. -1 Or 8cm -1 The sample was scanned 32 times in absorption spectroscopy mode. Then, inert gas was introduced into the pretreatment gas path 1, and the flow rate of the reaction gas was controlled at 0.1 mL / min to 200 mL / min. Alternatively, the sample was heated for desorption at a rate of 2℃ to 15℃ / min. The infrared spectrum of the desorption process was collected in real time during the heating process.

[0034] During the experiment, different absorbents were selected for tail gas treatment based on the properties of the reacting gases. The absorbents could be different alkaline solutions (such as NaOH solution, ammonia water, calcium hydroxide solution, etc.) or solid adsorbents (such as zeolite molecular sieves, etc.). After being absorbed and treated by the absorbents, the tail gas was introduced outdoors.

[0035] This invention provides an in-situ diffuse reflectance Fourier transform infrared spectroscopy method for the low-temperature adsorption and desorption of adsorbents, aiding in the investigation of the adsorption and desorption mechanisms of adsorbents under low-temperature conditions. This method can capture intermediate products generated during the low-temperature adsorption and desorption process in real time, thus providing strong support for in-depth research into the adsorption and desorption mechanisms. This invention employs a dual-cycle cooling system combined with a temperature control device to achieve precise control of low-temperature conditions. Specifically, the dual-cycle cooling system uses an internal circulation cooling system to cool the sample cup of the in-situ reaction cell, while an external circulation cooling system maintains the outer shell temperature, forming a temperature gradient isolation layer. This effectively prevents condensation in the in-situ reaction cell at low temperatures, solving the problem of interference with infrared spectral signals due to condensation vapor at temperatures below room temperature. Simultaneously, the connected temperature control device can display the core temperature of the in-situ reaction cell in real time. By adjusting the cooling parameters of the internal circulation cooling system, precise control of the core reaction temperature can be achieved, ensuring the stability and repeatability of experimental conditions.

[0036] Example 1: Mechanism study of N2O adsorption by activated carbon at low temperature (10℃) Reaction gas path setup Two gas paths were constructed: pretreatment gas path 1, consisting of N2, used for sample purging, and reaction gas path 2, consisting of N2O. Both N2 and N2O were drawn from the gas source, passed through pressure reducing valve 4, and then controlled at a flow rate of 50 mL / min by mass flow meter 5. The pretreatment and reaction gas paths were connected via a three-way valve before entering the in-situ reaction chamber.

[0037] Sample pretreatment Take 10 mg of activated carbon sample and place it in an in-situ reaction tank. Introduce N2 and heat the sample to 200 °C at a heating rate of 10 °C / min. Maintain the temperature for 2 hours to remove impurities and moisture from the sample surface.

[0038] Low temperature control The dual-circulation cooling system is activated. The inner circulation cooling system is set to 10℃ to directly cool the sample cups in the in-situ reaction cell; the outer circulation cooling system is set to 22℃ to maintain the outer shell temperature of the in-situ reaction cell. The core temperature of the in-situ reaction cell is monitored in real time using a thermocouple temperature control device to ensure it remains stable at 10℃±0.2℃.

[0039] In-situ adsorption infrared spectroscopy acquisition After the temperature stabilizes, set the spectral acquisition parameters: spectral resolution of 4 cm⁻¹. -1The scan was performed 32 times, and the acquisition mode was absorption spectroscopy. First, the background spectrum was acquired, then N2O gas was introduced, and the infrared spectrum of the adsorption process was acquired in real time, with spectral data recorded every 2 minutes.

[0040] Exhaust gas treatment Since N2O is an acidic gas, NaOH solution is selected as the absorbent. The exhaust gas is passed into the NaOH solution for absorption and treatment before being discharged outdoors.

[0041] like Figure 2 As shown, in the initial few minutes, N2O molecules are primarily physically adsorbed by activated carbon through van der Waals forces. As time progresses, functional groups (such as hydroxyl or carboxyl groups) on the activated carbon surface undergo chemisorption with N2O molecules, forming chemical bonds. This chemisorption process makes the N2O molecules more firmly adsorbed onto the activated carbon surface, thus prolonging the adsorption time. Eventually, the adsorption process reaches equilibrium, and the amount of N2O molecules adsorbed on the activated carbon surface no longer changes with time. At this point, the interaction between the functional groups on the activated carbon surface and the N2O molecules also tends to stabilize.

[0042] Example 2: Mechanism study of N2O adsorption by activated carbon at low temperature (-7℃) Reaction gas path setup Two gas paths were constructed: pretreatment gas path 1, consisting of N2, was used for sample purging, and reaction gas path 2, consisting of N2O. Both N2 and N2O were drawn from the gas source, passed through pressure reducing valve 4, and then controlled at a flow rate of 90 mL / min by mass flow meter 5. The pretreatment and reaction gas paths were connected via a three-way valve before entering the in-situ reaction chamber.

[0043] Sample pretreatment Take 10 mg of activated carbon sample and place it in an in-situ reaction tank. Introduce N2 and heat the sample to 200 °C at a heating rate of 10 °C / min. Maintain the temperature for 2 hours to remove impurities and moisture from the sample surface.

[0044] Low temperature control The dual-circulation water system is activated. The internal circulation cooling system is set to -30℃ to directly cool the core of the in-situ reaction tank; the external circulation cooling system is set to 20℃ to maintain the temperature of the outer shell of the in-situ reaction tank. The temperature of the core of the in-situ reaction tank is monitored in real time by a thermocouple temperature control device to ensure that it is stable at -7℃±0.2℃.

[0045] In-situ adsorption infrared spectroscopy acquisition After the temperature stabilizes, set the spectral acquisition parameters: spectral resolution of 8 cm⁻¹. -1 The scan was performed 32 times, and the acquisition mode was absorption spectroscopy. First, the background spectrum was acquired, then N2O gas was introduced, and the infrared spectrum of the adsorption process was acquired in real time, with spectral data recorded every 2 minutes.

[0046] Exhaust gas treatment Since N2O is an acidic gas, NaOH solution is selected as the absorbent. The exhaust gas is passed into the NaOH solution for absorption and treatment before being discharged outdoors.

[0047] like Figure 3 As shown, in the initial stage of adsorption, N2O is mainly adsorbed onto the activated carbon surface through physical forces. With increasing adsorption time, N2O reacts chemically with the functional groups on the activated carbon surface, forming new chemical bonds, thus achieving chemical adsorption. In the initial stage of adsorption, water may compete with N2O for adsorption sites on the activated carbon surface, but in the later stage, water may form hydrogen bonds with N2O, promoting N2O adsorption.

[0048] Example 3: Mechanism study of N2O desorption by activated carbon at low temperature Reaction gas path setup Two gas paths were constructed: pretreatment gas path 1, containing N2, was used for sample purging; reaction gas path 2, containing N2O, was used. Both N2 and N2O were supplied from the gas source via pressure reducing valve 4. The flow rate of pretreatment gas path 1 was controlled at 90 mL / min by mass flow meter 5, and the flow rate of reaction gas path 2 was controlled at 100 mL / min by mass flow meter 5. The pretreatment and reaction gas paths were connected via a three-way valve and then entered the in-situ reaction cell.

[0049] Sample pretreatment Take 10 mg of activated carbon sample and place it in an in-situ reaction tank. Introduce N2 and heat the sample to 200 °C at a heating rate of 10 °C / min. Maintain the temperature for 2 hours to remove impurities and moisture from the sample surface.

[0050] Low temperature control The internal circulation cooling system temperature is set at -30℃, and the external circulation cooling system temperature is set at 20℃. The core temperature of the in-situ reaction tank is stabilized at -7℃±0.2℃ by a thermocouple temperature control device.

[0051] In-situ desorption infrared spectroscopy acquisition First, an in-situ adsorption experiment was conducted according to Example 2 to obtain an adsorption-saturated activated carbon sample. Then, the reaction gas was turned off. The spectral resolution was set to 2 cm⁻¹. -1 The scan was performed 50 times, and the acquisition mode was absorption spectroscopy. The internal circulation cooling system was turned off, and the temperature was increased to 200℃ at a rate of 5℃ / min using a thermocouple temperature control device. The spectrum was recorded every 2 minutes.

[0052] Exhaust gas treatment Since N2O is an acidic gas, NaOH solution is selected as the absorbent. The exhaust gas is passed into the NaOH solution for absorption and treatment before being discharged outdoors.

[0053] like Figure 4As shown, the desorption process is not only a simple physical desorption, but also involves a surface catalytic decomposition reaction. The functional groups on the surface of activated carbon act as reactants, providing active sites for the decomposition of N2O, converting it into nitrogen gas (N2) and consuming it. The generation and desorption of gaseous N2 are the reasons for the eventual "desorption" of N2O.

[0054] Example 4: Mechanism study of N2O adsorption by activated carbon at low temperature (-10℃) Reaction gas path setup Two gas paths were constructed: pretreatment gas path 1, consisting of N2, was used for sample purging, and reaction gas path 2, consisting of N2O. Both N2 and N2O were drawn from the gas source, passed through pressure reducing valve 4, and then controlled at a flow rate of 90 mL / min by mass flow meter 5. The pretreatment and reaction gas paths were connected via a three-way valve before entering the in-situ reaction chamber.

[0055] Sample pretreatment Take 10 mg of activated carbon sample and place it in an in-situ reaction tank. Introduce N2 and heat the sample to 1000 °C at a heating rate of 15 °C / min. Hold the temperature for 0.5 h to remove impurities and moisture from the sample surface.

[0056] Low temperature control The dual-circulation water system is activated. The internal circulation cooling system is set to -60℃ to directly cool the core of the in-situ reaction tank; the external circulation cooling system is set to 20℃ to maintain the temperature of the outer shell of the in-situ reaction tank. The temperature of the core of the in-situ reaction tank is monitored in real time by a thermocouple temperature control device to ensure that it is stable at -10℃±0.2℃.

[0057] In-situ adsorption infrared spectroscopy acquisition After the temperature stabilizes, set the spectral acquisition parameters: spectral resolution of 10 cm⁻¹. -1 The scan was performed twice, and the acquisition mode was absorption spectroscopy. First, the background spectrum was acquired, then N2O gas was introduced, and the infrared spectrum of the adsorption process was acquired in real time, with spectral data recorded every 2 minutes.

[0058] Exhaust gas treatment Since N2O is an acidic gas, NaOH solution is selected as the absorbent. The exhaust gas is passed into the NaOH solution for absorption and treatment before being discharged outdoors.

[0059] Example 5: Mechanism study of N2O adsorption by activated carbon at low temperature (25℃) Reaction gas path setup Two gas paths were constructed: pretreatment gas path 1, consisting of N2, used for sample purging, and reaction gas path 2, consisting of N2O. Both N2 and N2O were drawn from the gas source, passed through pressure reducing valve 4, and then controlled at a flow rate of 0.1 mL / min by mass flow meter 5. The pretreatment and reaction gas paths were connected via a three-way valve before entering the in-situ reaction chamber.

[0060] Sample pretreatment Take 10 mg of activated carbon sample and place it in an in-situ reaction tank. Introduce N2 and heat the sample to 100 °C at a heating rate of 2 °C / min. Maintain the temperature for 10 h to remove impurities and moisture from the sample surface.

[0061] Low temperature control The dual-circulation water system is activated. The internal circulation cooling system is set to 25℃ to directly cool the core of the in-situ reaction tank; the external circulation cooling system is set to 25℃ to maintain the temperature of the outer shell of the in-situ reaction tank. The temperature of the core of the in-situ reaction tank is monitored in real time by a thermocouple temperature control device to ensure that it is stable at 25℃±0.2℃.

[0062] In-situ adsorption infrared spectroscopy acquisition After the temperature stabilizes, set the spectral acquisition parameters: spectral resolution of 10 cm⁻¹. -1 The scan was performed 50 times, and the acquisition mode was absorption spectroscopy. First, the background spectrum was acquired, then N2O gas was introduced, and the infrared spectrum of the adsorption process was acquired in real time, with spectral data recorded every 2 minutes.

[0063] Exhaust gas treatment Since N2O is an acidic gas, NaOH solution is selected as the absorbent. The exhaust gas is passed into the NaOH solution for absorption and treatment before being discharged outdoors.

[0064] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values; these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. In the following, various technical solutions can, in principle, be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0065] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still make modifications or equivalent substitutions to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the protection scope of the claims of the present invention pending approval.

Claims

1. An experimental apparatus for in-situ diffuse reflectance Fourier transform infrared spectroscopy, characterized in that, It includes a pretreatment gas path (1) and a reaction gas path (2), which are connected to the in-situ reaction cell (3) respectively. The in-situ reaction cell (3) is equipped with a dual-circulation cooling system (6), which includes an inner circulation cooling system and an outer circulation cooling system. The inner circulation cooling system is used to cool the sample cup of the in-situ reaction cell, and the outer circulation cooling system is used to cool the outer shell of the in-situ reaction cell. The in-situ reaction cell (3) is equipped with a temperature control device (7), and the in-situ reaction cell (3) is also connected to a Fourier transform infrared spectrometer (8).

2. The experimental apparatus for in-situ diffuse reflectance Fourier transform infrared spectroscopy according to claim 1, characterized in that, The in-situ reaction tank (3) is connected to the exhaust gas collection device.

3. The experimental apparatus for in-situ diffuse reflectance Fourier transform infrared spectroscopy according to claim 1, characterized in that, Both the pretreatment gas path (1) and the reaction gas path (2) are equipped with pressure reducing valves (4) and mass flow meters (5).

4. An experimental method for an in-situ diffuse reflectance Fourier transform infrared spectroscopy experimental apparatus as described in any one of claims 1-3, characterized in that, include: The sample was placed in the in-situ reaction cell (3), an inert gas was introduced, and the sample was heated. The dual-circulation cooling system (6) is turned on. The internal circulation cooling system controls the temperature inside the in-situ reaction tank, and the external circulation cooling system controls the external temperature of the in-situ reaction tank, forming a temperature gradient isolation layer. Set the adsorption infrared spectrum acquisition parameters. When the sample reaches the reaction temperature, the Fourier transform infrared spectrometer (8) acquires the background spectrum, introduces the reaction gas, and acquires the infrared spectrum of the adsorption in real time. After the sample has completed adsorption, the flow of reaction gas is stopped, the desorption infrared spectrum acquisition parameters are set, the sample is heated, and the infrared spectrum of the desorption process is acquired in real time.

5. The experimental method of the experimental apparatus for in-situ diffuse reflectance Fourier transform infrared spectroscopy according to claim 4, characterized in that, The reactant gas can be a single reactant gas or a mixture of reactant gases.

6. The experimental method of the experimental apparatus for in-situ diffuse reflectance Fourier transform infrared spectroscopy according to claim 4, characterized in that, The flow rates of the inert gas and the reactant gas are 0.1 mL / min to 200 mL / min.

7. The experimental method of the experimental apparatus for in-situ diffuse reflectance Fourier transform infrared spectroscopy according to claim 4, characterized in that, The adsorption infrared spectral acquisition parameters and desorption infrared spectral acquisition parameters are both set to: spectral resolution of 2 cm⁻¹. -1 ~10cm -1 The number of scans is 2 to 50, and the acquisition mode is absorption spectroscopy or transmission spectroscopy.

8. The experimental method of the experimental apparatus for in-situ diffuse reflectance Fourier transform infrared spectroscopy according to claim 4, characterized in that, The reaction temperature of the sample is -10~25℃.

9. The experimental method of the experimental apparatus for in-situ diffuse reflectance Fourier transform infrared spectroscopy according to claim 4, characterized in that, The heating process specifically includes: The sample is heated to 100℃~1000℃ using an inert gas at a heating rate of 2℃ / min~15℃ / min and held for 0.5h~10h.

10. The experimental method of the experimental apparatus for in-situ diffuse reflectance Fourier transform infrared spectroscopy according to claim 4, characterized in that, The internal circulation cooling system has a controlled temperature of -60℃ to 20℃, while the external circulation cooling system has a controlled temperature of room temperature.

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