CN-121978052-A - Microwave heating-based in-situ attenuated total reflection Fourier transform infrared spectrum detection method

CN121978052ACN 121978052 ACN121978052 ACN 121978052ACN-121978052-A

Abstract

The application discloses an in-situ attenuated total reflection Fourier transform infrared spectrum detection method based on microwave heating, and belongs to the technical field of spectrum detection and analysis. The method adopts a design strategy of microwave heating and infrared spectrum system division, and uses a high-refractive-index infrared reflection crystal as a unique coupling detection area to realize real-time infrared spectrum monitoring of a reaction system. The detection method disclosed by the application is particularly suitable for in-situ monitoring of hydrogenation, cracking and conversion reactions of oxygen-containing or unsaturated substituent compounds on furan rings or benzene rings, is compatible with microwave and catalytic reaction mechanism research, material interface reaction analysis and spectroscopy characterization of biomass derivative conversion processes, has the advantages of accurate temperature control, high response speed, high signal stability and good data repeatability, can dynamically track a spectrum of a complex reaction system, is compatible with a traditional external heating detection mode, and remarkably improves the space matching degree and time resolution of in-situ characterization of a microwave field.

Inventors

WANG KUI
JIANG JIANCHUN
JIANG XIAO

Assignees

中国林业科学研究院林产化学工业研究所

Dates

Publication Date: 20260505
Application Date: 20251212

Claims (10)

1. A microwave heating-based in-situ attenuated total reflection Fourier transform infrared spectrum detection method is characterized by comprising the steps of preparing a catalyst film or a catalyst-substrate composite film on the surface of a high refractive index infrared reflection crystal by adopting a spin coating method to form a stable and uniform solid active layer, loading a liquid substrate or a substrate solution on the surface of the catalyst film in a liquid film form or introducing reaction gas and trace solvent into a gas current carrying system to construct a solid-liquid-gas three-phase reaction interface, realizing rapid and uniform heating of the reaction system by a microwave heating and thermal compensation system, synchronously acquiring infrared spectrum signals in the whole reaction process, and monitoring the evolution of the intensity and displacement of a functional group absorption peak in real time so as to obtain reaction kinetics and species information; The special device comprises an in-situ flow cell, a microwave irradiation system, an infrared optical system and a temperature control module, wherein the in-situ flow cell is used for accommodating a sample and forming a closed reaction space, the microwave irradiation system is used for inputting microwave energy into the in-situ flow cell area, the infrared optical system is used for collecting real-time infrared spectrum signals, and the temperature control module is used for realizing real-time detection and adjustment of temperature in the microwave heating process, so that the temperature stability of the sample area is ensured.
2. The in-situ attenuation total reflection Fourier transform infrared spectrum detection method based on microwave heating according to claim 1 is characterized in that the in-situ flow cell comprises a flow cell main body (1), a quartz sealing cover (2), a high-refractive-index infrared reflection crystal (3), an air inlet/liquid pipeline (4) and an air outlet/liquid pipeline (5), a thermal compensation medium pipeline (6), a sample cell (7), a thermal compensation medium cell (8) and a sealing ring (9), wherein the high-refractive-index infrared reflection crystal (3) is arranged at the bottom of the flow cell main body (1), the quartz sealing cover (2) is buckled at the upper end of the flow cell main body and is provided with a through hole for inserting a temperature measuring optical fiber (23), the components are in airtight connection through the sealing ring (9), a threaded hole is arranged at the outer side of the flow cell main body (1) and is fixed on a microwave resonant cavity bottom plate through a screw, the temperature measuring optical fiber (23) is led out through a resonant cavity side wall opening and an interface, an impedance tube is arranged at the opening, the quartz sealing cover (2) and the thermal compensation medium cell (8) jointly forms a sealed thermal compensation medium cavity, the thermal compensation medium cell is communicated with an external circulation heat exchange device and is used for maintaining the reaction and the temperature compensation medium pipeline (4) and a back pressure of a reaction system to be connected with an air inlet/liquid pump (5) or a pressure regulating system.
3. The method for detecting the infrared spectrum of the in-situ attenuated total reflection fourier transform based on microwave heating according to claim 1, wherein the infrared optical system comprises an infrared light source (16), a spectrum detector (17) and an optical path unit consisting of an off-axis parabolic mirror and a reflecting mirror (22), infrared light enters a high refractive index infrared reflecting crystal (3) through an optical path impedance tube after being focused by the infrared light source (16) through the plane reflecting mirror (22) and the first off-axis parabolic mirror (18) and the second off-axis parabolic mirror (19), evanescent waves are formed through multiple total reflection in the crystal to interact with a sample to generate absorption signals, and the absorption signals are converged to the spectrum detector through a third off-axis parabolic mirror (20), the plane reflecting mirror (22) and a fourth off-axis parabolic mirror (21) after being output by the crystal.
4. The microwave heating-based in-situ attenuated total reflection fourier transform infrared spectroscopy detection method of claim 1, wherein the microwave irradiation system comprises a microwave source and a microwave resonant cavity (11) connected by a coaxial interface (10) for inputting microwave energy into the in-situ flow cell region.
5. The microwave heating-based in-situ attenuated total reflection Fourier transform infrared spectrum detection method according to claim 1, wherein the temperature control module comprises a temperature measuring optical fiber (23) and an infrared temperature probe (24) for realizing real-time detection and adjustment of temperature in the microwave heating process, so as to ensure the temperature stability of a sample area.
6. The microwave heating-based in-situ attenuation total reflection Fourier transform infrared spectrum detection method is characterized in that the flow cell main body (1) and the thermal compensation medium pool (8) are made of polyether-ether-ketone, the sealing ring (9) is made of polytetrafluoroethylene material, the high-refractive-index infrared reflection crystal (3) is made of zinc germanide or silicon dioxide material, the microwave resonant cavity (11) is made of stainless steel, surfaces of the off-axis parabolic mirror and the plane mirror (22) are plated with gold films to improve reflection efficiency, and the temperature measuring optical fiber (23) is hollow quartz waveguide optical fiber.
7. The method for detecting the infrared spectrum of the in-situ attenuated total reflection Fourier transform based on microwave heating according to claim 1, wherein the catalyst film is prepared by dispersing catalyst particles in a solvent containing a film forming agent, and adopting a spin coating mode on the surface of an infrared crystal, wherein the film forming agent is Nalfon or other fluorine polymer binders.
8. The microwave heating-based in-situ attenuated total reflection Fourier transform infrared spectrum detection method is characterized in that a reaction system adopts three in-situ reaction modes of liquid homogeneous phase, liquid-solid biphase or gas-liquid-solid triphase, a liquid film is formed by covering a solvent-substrate solution on the surface of a catalyst film in a solid-containing system, the liquid homogeneous system can directly form the liquid film on the surface of a crystal, and the different in-situ reaction modes can all realize continuous spectrum acquisition in a temperature range of 20-200 ℃.
9. The method for detecting the in-situ attenuated total reflection Fourier transform infrared spectrum based on microwave heating according to claim 1, wherein the law of the change of the absorption peak intensity of the marker functional group with time and temperature is analyzed by comparing a catalyst-free reference spectrum with a reaction spectrum so as to obtain a reaction kinetic parameter and a product generation sequence.
10. The method for in-situ attenuated total reflection fourier transform infrared spectroscopy detection based on microwave heating according to claim 1, wherein the spectroscopic detection comprises in-situ monitoring of hydrogenation, cleavage and conversion reactions of oxygen-containing or unsaturated substituent compounds on furan rings or benzene rings, compatible with microwave and catalytic reaction mechanism studies, material interface reaction analysis and spectroscopic characterization of biomass derivative conversion processes.

Description

Microwave heating-based in-situ attenuated total reflection Fourier transform infrared spectrum detection method Technical Field The application belongs to the technical field of spectrum analysis and catalytic reaction in-situ detection, and particularly relates to an in-situ attenuated total reflection Fourier transform infrared (ATR-FTIR) detection method suitable for a microwave field condition, which can realize real-time and quantitative monitoring and infrared spectrum analysis of catalytic and conversion reaction processes in a microwave irradiation environment. Background Attenuated total reflection Fourier transform infrared (ATR-FTIR) technology has the advantages of high sensitivity, in-situ monitoring, small disturbance to a reaction system and the like, and has been widely applied to catalytic characterization, reaction dynamics and interfacial chemistry process research. However, the conventional in-situ infrared detection device mostly adopts a conventional heating mode (such as electric heating or constant temperature liquid circulation), so that the design and detection requirements of an instrument in a microwave field are difficult to meet. Under microwave heating conditions, the electromagnetic field can be selectively coupled with polar molecules and metal surfaces, so that the reaction rate is remarkably accelerated and the reaction path is changed, and therefore, the in-situ characterization is needed to capture related dynamic processes. However, the traditional infrared detection pool is easy to cause problems of metal shielding, infrared light attenuation, temperature measurement errors and the like in a microwave field, so that effective coupling of a reaction system and spectrum detection is difficult to realize. In addition, in a solid-liquid-gas multiphase system, uneven temperature and medium distribution can seriously influence the stability and quantitative accuracy of infrared signals, and higher requirements are put on sample preparation accuracy and reasonability of detection flow. Aiming at the problems, researches are attempted to adopt means such as microwave transmission windows, external detectors or optical fiber remote acquisition, but the defects of complex structure, different reaction and detection environments and the like still exist, and high integration of microwave heating and in-situ infrared detection is difficult to realize. Therefore, an in-situ ATR-FTIR detection device and method capable of realizing rapid and uniform heating of a reaction system, real-time spectrum signal acquisition and temperature compensation regulation in a microwave field are needed, so as to be suitable for liquid homogeneous phase, liquid-solid dual-phase and gas-liquid-solid multi-phase reaction systems, realize real-time monitoring of evolution of catalytic surface species and functional groups and reaction kinetics, and provide an accurate experimental platform for research of catalytic mechanism and reaction kinetics. Disclosure of Invention Aiming at the problems of signal interference, temperature runaway, unmatched optical paths and the like existing in the prior in-situ infrared detection technology under the microwave heating condition, the application aims to provide an in-situ attenuated total reflection Fourier transform infrared spectrum detection method based on microwave heating, the microwave irradiation system and the attenuated total reflection Fourier transform infrared spectroscopy technology are highly integrated, so that rapid controllable heating of a reaction system in a microwave field and real-time acquisition of infrared signals are realized, a high-precision experimental platform is prepared, and the catalytic characterization, in-situ reaction analysis and other spectroscopy characterization and detection are performed based on the platform. In order to solve the technical problems, the application adopts the following technical scheme: A microwave heating-based in-situ attenuated total reflection Fourier transform infrared spectrum detection method is carried out in a special device and comprises the steps of preparing a catalyst film or a catalyst-substrate composite film on the surface of a high refractive index infrared reflection crystal by adopting a spin coating method to form a stable and uniform solid active layer, loading a liquid substrate or a substrate solution on the surface of the catalyst film in a liquid film form or introducing reaction gas and trace solvent into a gas carrier system to construct a solid-liquid-gas three-phase reaction interface, realizing rapid and uniform heating of the reaction system by a microwave heating and thermal compensation system, synchronously acquiring infrared spectrum signals in the whole reaction process, and monitoring the intensity and displacement of a functional group absorption peak in real time so as to obtain reaction kinetics and species evolution information; The special device comprises