In-situ scattering reflection Fourier transform infrared spectrum detection device

Abstract

The invention discloses an in-situ scattering reflection Fourier transform infrared spectrum detection device, and belongs to the field of infrared spectrum analysis and testing. Comprising a temperature and pressure control pool, a temperature control system and a signal acquisition system. A window is arranged on the surface of a sealing cover of the temperature control and pressure control pool and is used for light incidence and signal acquisition; a cylinder is arranged in the detection device main body, the heating temperature control pipe is embedded into the top end of the cylinder, and the sample pool is embedded into the heating temperature control pipe and is tightly attached to the inner wall of the heating temperature control pipe; the temperature control system comprises a heating temperature control pipe, a temperature thermocouple, a power supply and a temperature controller. In the signal acquisition system, incident light is focused and coupled by a convex lens A and enters an optical fiber, the optical fiber is conducted and irradiates a sample, generated diffuse reflection signal light is collected by an off-axis parabolic mirror A and an off-axis parabolic mirror B and then is converged by an off-axis parabolic mirror C, the direction is adjusted by a plane mirror, and the divergence angle is adjusted by a convex lens B and then enters a detector. The device has the advantages of simple structure, easiness in processing, operation and maintenance, low sample consumption, easiness in sample recovery and the like.

Description

Technical Field

[0001] The invention belongs to the field of infrared spectrum analysis and testing, and is an in-situ diffuse reflection infrared detection device suitable for catalytic reactions under high temperature and high pressure conditions. Background Art

[0002] In-situ infrared is one of the common methods to study the mechanism of catalytic reactions. It can reflect the intermolecular interactions and intermediate structures through infrared characteristic peaks. Diffuse reflectance Fourier transform infrared spectroscopy (DRIFT) is often used to characterize gas-solid phase catalytic reaction processes. By detecting the changes in diffuse reflectance infrared signals on the surface of solid catalysts, the conformational changes of gas reactants and their adsorption and desorption processes with catalysts can be monitored.

[0003] The sample pool of existing detection devices usually adopts a three-window structure, which is used for the entry of infrared light and ultraviolet-visible light and the collection of diffuse reflected infrared signals. The light entry angle and signal collection efficiency are limited by the window position and size, so the signal detection sensitivity is low. In addition, the temperature control device usually uses a heating coil or heating rod placed at the bottom of the sample pool for overall temperature control. The distance from the sample is relatively far, and the temperature gradient generated is relatively large, which makes it impossible to accurately control and monitor the sample temperature. Summary of the invention

[0004] The purpose of the present invention is to solve the above-mentioned technical shortcomings and provide an in-situ scattered reflection Fourier transform infrared detection device, which can realize in-situ diffuse reflection infrared spectroscopy detection of chemical reactions of solid catalysts under constant temperature and pressure conditions. The device has the characteristics of simple operation, precise temperature control and high signal detection efficiency.

[0005] An in-situ scattering reflection Fourier transform infrared spectrum detection device comprises a temperature and pressure control cell, a temperature control system and a signal acquisition system.

[0006] The temperature and pressure control cell comprises a detection device body 1, a sealing cover 2, an air inlet pipe 6, an air outlet pipe 8, a water cooling channel 11, and a sample cell 13; the surface of the sealing cover 2 is provided with three windows for light incidence and signal collection; the sealing cover 2 is buckled on the detection device body 1, and forms a closed cavity with the detection device body 1; a cylindrical tube is provided in the detection device body 1, a heating temperature control tube 17 is embedded in the top of the cylindrical tube, and the sample cell 13 is embedded in the heating temperature control tube 17, and is tightly fitted with the inner wall of the heating temperature control tube 17;

[0007] The temperature control system includes a heating temperature control tube 17, a temperature measuring thermocouple 18, a power supply 19 and a temperature controller 20. The temperature measuring thermocouple 18 is fixed to the bottom of the sample pool 13. The heating temperature control tube 17 is connected to the power supply 19. The temperature measuring thermocouple 18 is connected to the temperature controller 20 for real-time monitoring and control of the sample temperature.

[0008] The signal acquisition system includes convex lens A21, optical fiber 22, off-axis parabolic mirror A23, off-axis parabolic mirror B24, off-axis parabolic mirror C25, plane reflector 26, and convex lens B27. The incident light is focused and coupled by convex lens A21 into optical fiber 22, and optical fiber 22 conducts and irradiates the sample. The generated diffusely reflected signal light is collected by off-axis parabolic mirror A23 and off-axis parabolic mirror B24, converged by off-axis parabolic mirror C25, adjusted in direction by plane reflector 25, and enters the detector after adjusting the divergence angle by convex lens B27.

[0009] Furthermore, the power line at the bottom of the heating temperature control tube 17 is led out from the bottom of the cylindrical tube, and a sealing ring is sleeved on the led-out power line;

[0010] Furthermore, threaded sealing holes are symmetrically arranged on the lower surface of the detection device body 1, and corresponding through holes are arranged on the bottom plate 4, and the bottom plate 4 is fixed to the bottom of the detection device body 1 by screws.

[0011] Furthermore, the sample pool 13 is a crucible made of aluminum nitride;

[0012] Furthermore, the bottom of the sample pool 13 is a metal mesh structure for gas to pass through and fully react with the fixed sample.

[0013] Furthermore, a heat insulating pad 12 is arranged at the bottom of the heating temperature control tube 17, and the heat insulating pad 12 is made of high-silica cloth.

[0014] Furthermore, the water cooling channel 11 is evenly distributed in the detection device body 1, and the water inlet 9 and the water outlet 10 of the water cooling channel 11 are both connected to the cooling water circulation machine.

[0015] Furthermore, one end of the air inlet pipe 6 is connected to the air inlet connector 5, and the other end is used to input the reaction gas into the enclosed space; one end of the air outlet pipe 8 is connected to the air outlet connector 7, and the other end is used to output the reaction gas.

[0016] Furthermore, the material of the heating temperature control tube 17 is alumina ceramic.

[0017] Furthermore, the materials of the convex lens A21 and the convex lens B27 are both calcium fluoride, the surfaces of the off-axis parabolic mirror A23, the off-axis parabolic mirror C25, the off-axis parabolic mirror B24 and the plane reflector 26 are gold films, and the optical fiber 22 is a hollow-core quartz waveguide optical fiber.

[0018] Furthermore, the periphery of the sealing cover 2 is fixed to the upper surface of the detection device body 1 by two fastening plates 3 .

[0019] Furthermore, the three windows on the sealing cover 2 are respectively an excitation light incident window 14 and two signal light collection windows 15 , and a window sealing ring 16 is arranged between the sealing cover 2 and the windows.

[0020] Furthermore, a groove is provided at the bottom of the sealing cover 2 for filling a sealing rubber ring.

[0021] The present invention has the following beneficial effects:

[0022] 1. The temperature and pressure control cell of the present invention is easy to disassemble and replace solid samples.

[0023] 2. The sample crucible of the present invention fits tightly with the inner wall of the heating tube, so that the sample is heated stably and evenly. The temperature measuring thermocouple is fixed at the bottom of the crucible, which can realize accurate temperature control of the sample.

[0024] 3. The signal acquisition system of the present invention uses optical fiber to transmit incident light, which makes it easier to adjust the angle of the incident light and reduces the energy loss of the light beam. The signal light is transmitted through two windows and collected by a parabolic mirror, which improves the efficiency of signal collection and detection.

[0025] 4. The device of the present invention has the advantages of simple structure, easy processing, easy operation and maintenance, small sample consumption, and easy sample recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a three-dimensional structural view of the present invention.

[0027] Figure 2 It is a front cross-sectional view of the present invention.

[0028] Figure 3 It is a top view of the present invention.

[0029] Figure 4 It is a cross-sectional view of the air intake passage of the present invention.

[0030] Figure 5 It is a cross-sectional view of the water cooling channel of the present invention.

[0031] Figure 6 It is a schematic diagram of the optical system of the present invention.

[0032] Figure 7 It is a top view of the optical system of the present invention.

[0033] In the figure: 1 detection device body, 2 sealing cover, 3 fastening sheet, 4 bottom plate, 5 air inlet connector, 6 air inlet pipe, 7 air outlet connector, 8 air outlet pipe, 9 water inlet, 10 water outlet, 11 water cooling channel, 12 thermal insulation pad, 13 sample pool, 14 excitation light incident window, 15 signal light collection window, 16 window sealing ring, 17 heating temperature control tube, 18 temperature measuring thermocouple, 19 power supply, 20 temperature controller, 21 convex lens A, 22 optical fiber, 23 off-axis parabolic mirror A, 24 off-axis parabolic mirror B, 25 off-axis parabolic mirror C, 26 plane reflector, 27 convex lens B. DETAILED DESCRIPTION

[0034] The present invention is further described in detail below with reference to the accompanying drawings:

[0035] See also Figure 1 , Figure 2 , Figure 3 and Figure 6 The present invention is an in-situ scattered reflection Fourier transform infrared spectrum detection device, comprising a temperature and pressure control cell, a temperature control system and a signal acquisition system.

[0036] The temperature and pressure control cell comprises a detection device body 1, a sealing cover 2, a fastening sheet 3, a bottom plate 4, an air inlet connector, an air inlet pipe 6, an air outlet connector 7, an air outlet pipe 8, a water inlet 9, a water outlet 10, a water cooling channel 11, an insulation pad 12, and a sample pool 13; the detection device body is in the shape of a rectangular parallelepiped, with a cylindrical groove in the center; the sealing cover 2 is hemispherical and connected with a lower edge, and three symmetrically distributed windows are arranged on the hemispherical surface, namely an excitation light incident window 14 and two signal light collection windows 15, which are respectively used for infrared light to be incident on the sample surface and output infrared light for subsequent collection, a window sealing ring 16 is arranged between the sealing cover 2 and the window, and a thread is arranged on the inner wall of the window for inserting a threaded retaining ring to seal the window; the window The mouth is made of calcium fluoride and has a diameter of 15 mm; the lower surface of the sealing cover 2 is provided with a groove for filling the sealing ring; the sealing cover 2 is buckled on the detection device body 1, and the lower edge of the sealing cover 2 is embedded in the sinking groove on the upper surface of the detection device body 1 to make the surface flush and form a closed cavity with the detection device body 1; the periphery of the sealing cover 2 and the upper surface of the detection device body 1 are sealed with screws through two fastening plates 3; the two fastening plates 3 are symmetrically placed on both sides of the upper end cover, and their arc-shaped notches are embedded with the outer surface of the upper end cover hemisphere; the upper surface of the detection device body 1 is provided with four threaded sealing holes, and the two fastening plates 3 are provided with screw holes, and the fastening plates 3 are fixed to the upper end of the detection device body 1 by screws, thereby ensuring the sealing of the closed cavity. The bottom plate 4 is fastened to the bottom of the detection device body 1 by screws.

[0037] The temperature control system consists of a heating temperature control tube 17, a temperature measuring thermocouple 18, a power supply 19 and a temperature controller 20. The heating temperature control tube 17 is made of alumina ceramic and is connected to the power supply 19 through a wire. The temperature measuring thermocouple 18 is fixed to the bottom of the sample pool 13. The temperature measuring thermocouple 18 is connected to the PID temperature controller 20 through a wire for real-time monitoring and regulation of the sample temperature.

[0038] The optical system includes a convex lens A21, an optical fiber 22, an off-axis parabolic mirror A23, an off-axis parabolic mirror B24, an off-axis parabolic mirror C25, a plane reflector 26, and a convex lens B27, wherein the incident light is coupled into the optical fiber 22 by the convex lens A21, the optical fiber 22 transmits the incident light and the incident angle can be adjusted by the displacement stage so that the light beam irradiates the center of the sample pool 13; the diffusely reflected light is collected by the off-axis parabolic mirror A23 and the off-axis parabolic mirror B (24) and then converged again by the off-axis parabolic mirror C25, the propagation direction of the light is changed by the plane reflector 26, and the light is emitted after being converged by the convex lens B27.

[0039] A cylindrical tube is provided in the center of the closed cavity of the detection device body 1, which is connected to the bottom of the detection device body 1 and is provided with four through holes. A layer of high-silicon oxide cloth heat insulation pad 12 with a thickness of 1 mm is laid on the bottom of the cylindrical tube. The heating temperature control tube 17 is embedded in the cylindrical tube and placed on the heat insulation pad 12. Two wires connected to the bottom of the heating temperature control tube 17 are led out from the through holes to the power supply 19. The other two through holes are used to output the reaction gas and lead out the temperature measuring thermocouple 18 wires, and the lead-out wires are covered with sealing rings; the sample pool 13 is made of aluminum nitride ceramics with a through hole. The sample pool 13 has a hole for convenient loading or removing of the sample pool 13, and a fine stainless steel mesh is placed at the bottom so that the sample can be filled therein. The sample pool 13 is embedded in the heating temperature control tube 17 and supported by the wall of the heating temperature control tube 17. The outer wall of the sample pool 13 is in close contact with the inner wall of the heating temperature control tube 17; the temperature measuring contact of the temperature measuring thermocouple 18 is close to the bottom of the sample, and the external wire is connected to the PID temperature controller 20 to feed back the temperature of the sample in real time so as to control the reaction temperature at about the target temperature; the hollow part of the cylindrical tube structure is filled with an insulating heat insulation pad 12.

[0040] Six threaded sealing holes are symmetrically arranged on the lower surface of the detection device body, and six corresponding symmetrical through holes and four central through holes are arranged on the bottom plate 4. The wires and the air outlets pass through the central through holes respectively. At the same time, screws are passed through the symmetrical through holes to fix the bottom plate 4 to the bottom of the detection device body 1, compressing the sealing ring on the wire to ensure the airtightness of the closed cavity.

[0041] See also Figure 1 and Figure 4 The diameter of the air inlet pipe 6 is 1.8 mm, one end of which is connected to the air inlet connector 5 and the other end is connected to the closed cavity, which is used to input the reaction gas into the closed space; the diameter of the air outlet pipe 8 is 0.9 mm, one end of which passes through the insulation pad 12 and is connected to the bottom through hole of the sample pool 13, and the other end is connected to the air outlet connector 7 for outputting the reaction gas; the air inlet connector 5 is installed on the right outer wall of the detection device body 1, and the air outlet connector 7 is installed on the lower surface of the detection device body 1.

[0042] See also Figure 2 and Figure 5A door-shaped water-cooling channel 11 is provided inside the side wall of the detection device body. The water-cooling channel 11 surrounds the closed cavity and has a diameter of 4 mm. The longitudinal channel is 38 mm long, and the two transverse channels are 54 mm long. The center of the longitudinal channel is 3 mm higher than the center of the transverse channel. The cooling water inlet and outlet are installed on the right outer wall of the detection device body 1; it is used to cool the temperature of the closed cavity and the detection device body 1.

[0043] See also Figure 6 , the arrow in the figure indicates the direction of light propagation. In the optical system, the incident light is converged and coupled into the optical fiber for transmission through the calcium fluoride convex lens A21. The diameter of the convex lens A21 is 12.7 mm and the focal length is 15 mm. The optical fiber 22 is a hollow-core infrared optical fiber with a length of 50 cm. The angle of the incident light can be controlled by adjusting the optical fiber so that the light is perpendicular to the infrared incident window of the upper end cover and irradiates the center of the sample pool 13; after the sample surface diffusely reflects the light, it is emitted from the two infrared exit windows, and the light is collected and converged by the off-axis parabolic mirror A23 and the off-axis parabolic mirror B24, and then converged to the plane reflector by the off-axis parabolic mirror C25. The plane reflector is used to change the direction of light propagation. The light is converged by the calcium fluoride convex lens B27 and then emitted. The diameter of the convex lens B is 25.4 mm and the focal length is 25 mm. The diameter of the silver-plated plane reflector 26 is 25 mm, the diameter of the gold-plated off-axis parabolic mirror A23 and the gold-plated off-axis parabolic mirror B24 are 50.8 mm, and the effective focal length is 50.8 mm; the diameter of the gold-plated off-axis parabolic mirror C is 25.4 mm, and the effective focal length is 101.6 mm.

[0044] The working method of the present invention is as follows: the sample is loaded into the sample pool 13, and the sample pool 13 is placed into the heating tube using tweezers, the sealing cover 2 on the upper end of the detection device body 1 is buckled, and the four screws of the through hole of the fastening plate 3 are tightened to ensure that the closed cavity is completely sealed. The reaction gas is input into the closed cavity from the air inlet connector 5 through the air inlet pipe 6, and the mixed gas is then output through the air outlet connector 7 through the air outlet pipe 8 to maintain the high pressure environment of the closed cavity; after the gas fills the cavity, the cooling water circulation machine is turned on, and the cooling water is input into the water cooling channel 11 through the water inlet 9, and then flows out through the water outlet 10; the PID temperature controller 20 is turned on, and the power supply 19 of the heating temperature control tube 17 is connected after setting the target reaction temperature. The temperature measuring thermocouple 18 can measure the real-time temperature of the sample, and the feedback adjustment is made by the PID temperature controller 20, so that the sample temperature finally reaches and is maintained at the target reaction temperature; the circulation of cooling water is maintained during the reaction heating process, which can take away the excessive heat of the cavity and protect the circuit.

Claims

1. An in-situ scattered reflection Fourier transform infrared spectroscopy detection device, characterized in that: Including temperature and pressure control cell, temperature control system and signal acquisition system; The temperature and pressure control cell comprises a detection device body (1), a sealing cover (2), an air inlet pipe (6), an air outlet pipe (8), a water cooling channel (11), and a sample cell (13); the surface of the sealing cover (2) is provided with three windows for light incidence and signal collection; the sealing cover (2) is buckled on the detection device body (1) to form a closed cavity with the detection device body (1); a cylindrical tube is provided in the detection device body (1), a heating temperature control tube (17) is embedded in the top of the cylindrical tube, and the sample cell (13) is embedded in the heating temperature control tube (17) and is tightly fitted with the inner wall of the heating temperature control tube (17); The temperature control system comprises a heating temperature control tube (17), a temperature measuring thermocouple (18), a power supply (19) and a temperature controller (20), wherein the temperature measuring thermocouple (18) is fixed to the bottom of the sample pool (13); the heating temperature control tube (17) is connected to the power supply (19); the temperature measuring thermocouple (18) is connected to the temperature controller (20) for real-time monitoring and control of the sample temperature; The signal acquisition system comprises a convex lens A (21), an optical fiber (22), an off-axis parabolic mirror A (23), an off-axis parabolic mirror B (24), an off-axis parabolic mirror C (25), a plane reflector (26), and a convex lens B (27); wherein the incident light is focused and coupled by the convex lens A (21) into the optical fiber (22), the optical fiber (22) conducts and irradiates the sample, the generated diffuse reflection signal light is collected by the off-axis parabolic mirror A (23) and the off-axis parabolic mirror B (24), and then converged by the off-axis parabolic mirror C (25), the direction of which is adjusted by the plane reflector 25, and the divergence angle is adjusted by the convex lens B (27) before entering the detector.

2. The in-situ scattered reflection Fourier transform infrared spectroscopy detection device according to claim 1, characterized in that: The power line at the bottom of the heating temperature control tube (17) is led out from the bottom of the cylindrical tube, and a sealing ring is sleeved on the led-out power line.

3. The in-situ scattered reflection Fourier transform infrared spectroscopy detection device according to claim 1, characterized in that: The lower surface of the detection device body (1) is symmetrically provided with threaded sealing holes, and the bottom plate (4) is provided with corresponding through holes, and the bottom plate (4) is fixed to the bottom of the detection device body (1) by screws.

4. The in-situ scattered reflection Fourier transform infrared spectroscopy detection device according to claim 1, characterized in that: The sample pool (13) is a crucible made of aluminum nitride; the bottom of the sample pool (13) is a metal mesh structure for gas to pass through and fully react with the fixed sample.

5. The in-situ scattered reflection Fourier transform infrared spectroscopy detection device according to claim 1, characterized in that: A heat insulation pad (12) is arranged at the bottom of the heating temperature control tube (17), and the heat insulation pad (12) is made of high-silicon cloth.

6. The in-situ scattered reflection Fourier transform infrared spectroscopy detection device according to claim 1, characterized in that: The water cooling channel (11) is evenly arranged in the detection device body (1); the water inlet (9) and the water outlet (10) of the water cooling channel (11) are both connected to a cooling water circulation machine; one end of the air inlet pipe (6) is connected to the air inlet connector (5), and the other end is used to input the reaction gas into the enclosed space; one end of the air outlet pipe (8) is connected to the air outlet connector (7), and the other end is used to output the reaction gas.

7. The in-situ scattered reflection Fourier transform infrared spectroscopy detection device according to claim 1, characterized in that: The material of the heating temperature control tube (17) is alumina ceramics; the materials of the convex lens A (21) and the convex lens B (27) are both calcium fluoride; the surfaces of the off-axis parabolic mirror A (23), the off-axis parabolic mirror C (25), the off-axis parabolic mirror B (24) and the plane reflector (26) are gold films; and the optical fiber (22) is a hollow-core quartz waveguide optical fiber.

8. The in-situ scattered reflection Fourier transform infrared spectroscopy detection device according to claim 1, characterized in that: The periphery of the sealing cover (2) and the upper surface of the detection device body (1) are fixed via two fastening plates (3).

9. The in-situ scattered reflection Fourier transform infrared spectroscopy detection device according to claim 1, characterized in that: The three windows on the sealing cover (2) are respectively an excitation light incident window (14) and two signal light collection windows (15), and a window sealing ring (16) is arranged between the sealing cover (2) and the windows.

10. The in-situ scattered reflection Fourier transform infrared spectroscopy detection device according to claim 1, characterized in that: The bottom of the sealing cover (2) is provided with a groove for filling the sealing rubber ring.

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