CN116242956A - A high temperature and high pressure transmission infrared reaction cell with low response delay - Google Patents

Abstract

The invention relates to a low-response-delay high-temperature and high-pressure transmission infrared reaction cell, which comprises a furnace body, a heating rod, and a cell body, wherein a reserved cavity is arranged in the furnace body; the heating rod is arranged in the reserved cavity; the cell The body is located in the middle of the furnace body, and the pool body is provided with a slot for fixing the sample sheet and cylindrical cavities on both sides of the slot, and optical elements and auxiliary parts are arranged in the cylindrical cavity. The cell body is provided with a through optical path, the axis of the optical path is parallel or collinear with the axis of the cylindrical cavity, and the cell body is also provided with a medium inlet and a medium outlet for the reaction medium to enter and exit. Compared with the prior art, the present invention fully considers the differences in the reaction conditions between laboratory basic research and industrial production in surface catalysis research, and is resistant to high temperature and high pressure, while having small dead volume and fast response, which is beneficial to the use of mass spectrometry to capture correlation Information on the evolution of intermediate and catalyst structures.

Description

A high temperature and high pressure transmission infrared reaction cell with low response delay

technical field

The invention relates to the technical field of in-situ characterization of solid catalysts, in particular to a high-temperature and high-pressure transmission infrared reaction cell with low response delay.

Background technique

Studying the evolution behavior of species and the catalyst itself in the catalytic process under the actual industrial application conditions is of great significance for in-depth understanding of the activation mechanism of molecules on the surface of solid catalysts and guiding the creation of efficient and specific catalysts. Infrared spectroscopy is an important means to study the adsorption of species on the surface of solid catalysts based on the change of dipole moment of molecules due to polarization, and can obtain the vibration information of species-related chemical bonds. X-ray absorption spectrum (XAS) is divided into near-edge absorption spectrum (XANES) and extended edge absorption spectrum (EXAFS). The bonding information of elements and other elements and the coordination number of each shell play an important role in understanding the structural evolution of the active center and the related local charge distribution.

With the development of surface science, researchers no longer simply care about the corresponding relationship between the structure of the catalyst before and after the reaction and the catalytic performance. Real-time and accurate capture of the changes of related species and structures during the catalytic process can provide basis and guidance for understanding the activation mechanism of molecules and designing highly selective catalysts.

However, at this stage, many experimental characterizations cannot meet the reaction conditions for actual industrial applications, so many related scientific research results cannot be directly applied to actual production; in addition, some reaction intermediates have relatively short lifetimes, how to extract their evolution However, there are still some difficulties in the current research. It can be seen that there is an urgent need to construct a reaction cell that can meet the reaction conditions of practical industrial applications, and is resistant to high temperature and high pressure, and has a small dead volume and fast response, which is conducive to capturing the evolution information of related intermediates and catalyst structures by coupled mass spectrometry. .

Contents of the invention

The purpose of the present invention is to provide a low-response delay high-temperature and high-pressure transmission infrared reaction cell in order to overcome the defects in the above-mentioned prior art, fully considering the difference in reaction conditions between laboratory basic research and industrial production in surface catalysis research , high temperature and high pressure resistance, small dead volume and fast response, which is conducive to capturing the evolution information of related intermediates and catalyst structures by mass spectrometry.

The purpose of the present invention can be achieved through the following technical solutions:

The invention provides a high temperature and high pressure transmission infrared reaction cell with low response delay, including a furnace body, a heating rod, and a cell body, wherein specifically:

There is a reserved cavity in the furnace body;

The heating rod is arranged in the reserved cavity;

The cell body is arranged in the middle of the furnace body, and the cell body is provided with a slot for fixing the sample sheet and cylindrical cavities on both sides of the slot, and optical elements and auxiliary parts are arranged in the cylindrical cavity. The cell body is provided with a through optical path, the axis of the optical path is parallel or collinear with the axis of the cylindrical cavity, and the cell body is also provided with a medium inlet and a medium outlet for the reaction medium to enter and exit.

Further, a medium pipeline is provided inside the cavity, communicating with the inlet and outlet of the medium, for providing the medium environment required by the reaction system. The inside of the medium inlet and outlet opening is provided with a built-in thread for installing pipeline interface parts.

Further, the cylindrical cavities on both sides of the slot are coaxial and have unequal diameters.

Further, an optical path pad is also provided in the card slot, and the sample piece is arranged in the middle of the optical path pad.

Further, the optical element includes two windows with unequal diameters respectively matched with two cylindrical cavities, and one side of the two windows is in contact with the sample sheet and the optical path pad.

Further, the auxiliary part includes a sealing gasket, a pressure ring and a compression screw arranged on the side of the window near the light path.

Further, the pressure ring is fastened to the cell body by a compression screw, so as to realize the compression of the sealing gasket. When in use, place an optical path pad, a small window, a sealing gasket, and a compression ring in sequence on the side of the cylindrical cavity with a larger diameter in the cell body, and then use a hexagonal wrench of the corresponding specification to slightly tighten the compression screw on this side; then place it on the other side. Put the sample piece to be tested in the smaller cylindrical cavity on one side, then put in the optical path pad, large window, sealing gasket and pressure ring in sequence, then install the compression screw on this side, and then install the larger other side the compression screw.

Further, the cell body is provided with a galvanic couple hole, and a thermocouple is inserted in the galvanic couple hole.

Further, the pool body is a cuboid structure with chamfers on the lower surface, and the reserved cavity matches the shape of the pool body.

Further, the high-temperature and high-pressure transmission infrared reaction cell with low response delay further includes a water-cooled jacket, and the furnace body is arranged in the water-cooled jacket. The assembled reaction cell body is placed in the cavity reserved by the heating jacket, a thermocouple is inserted into the thermocouple hole reserved on the upper part of the reaction cell body, and the medium pipeline is connected through the relevant medium inlet and outlet, and then the water cooling jacket is connected to the preset The cooling water pipeline can be used to complete the construction of the test in-situ reaction pool.

Further, a cooling liquid chamber is provided in the water-cooling jacket, and water inlets and outlets communicating with the cooling liquid chamber are provided on both sides of the water-cooling jacket for injection and discharge of cooling water;

The bottom plate of the water-cooling jacket is fixed on the optical bench of the test optical path by fasteners.

Compared with the prior art, the present invention has the following technical advantages:

In this scheme, the transmission infrared reaction cell can provide a reaction temperature below 600°C and withstand a reaction pressure of 3MPa, and the reaction cell involved can accept the time-space velocity test below GHSV=300,000mL g _cat ^-1 h ^-1 ; the dead volume is small , the response delay is low, and the connected mass spectrometer can quickly (seconds to hundreds of milliseconds) obtain the species response signal during the reaction.

Description of drawings

Fig. 1 and 2 are the schematic diagrams of the front view and side view of the reaction cell body of the present invention;

3 and 4 are schematic diagrams of the front and top views of the heating jacket of the present invention;

Fig. 5 and 6 are the front view and side view structural schematic diagrams of the water-cooled jacket of the present invention;

Fig. 7 is the physical figure of reaction cell body and heating mantle of the present invention;

Among them: 1. Sample sheet; 2. Galvanic couple hole; 3. Cell body; 4. Compression screw 1; 5. Pressure ring 1; 6. Small window; 7. Sealing gasket 1; 8. Optical path pad; 9 , gasket 2; 10, compression screw 2; 11, pressure ring 2; 12, large window; 13, medium inlet; 14, medium outlet; 15, light path; 16, heating rod; 17, furnace body fixing hole; 18. Furnace body; 19. Water inlet hole; 20. Water outlet hole; 21. Bottom plate fixing hole; 22. Bottom plate; 23. Water cooling jacket-bottom plate fixing hole.

Fig. 8 is the CO adsorption infrared spectrogram of the MnO _x catalyst obtained in the test of the embodiment of the present invention;

Fig. 9 is a mass spectrometry signal response curve obtained in the test of the embodiment of the present invention.

Fig. 10 is the XANES spectrogram during the reduction process of the MnO _x catalyst obtained in the test of the embodiment of the present invention.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The features such as component models, material names, connection structures, control methods, algorithms, etc. that are not clearly stated in this technical solution are regarded as common technical features disclosed in the prior art.

One of the objectives of the present invention is to provide a high-temperature and high-pressure transmission infrared reaction cell with low response delay, which can be used for in-situ transmission infrared characterization in heterogeneous catalytic reactions, and to obtain high-temperature and high-pressure transmission of related species on the surface of solid catalysts during high-temperature and high-pressure catalysis. Mass infrared spectroscopy and low-latency mass spectrometry response signals provide experimental data for further understanding of surface catalytic processes under actual industrial production conditions.

In order to achieve the above object of the present invention and make its features and advantages more comprehensible, further description will be made below in conjunction with the accompanying drawings and specific implementations.

Example 1

The high-temperature and high-pressure transmission infrared reaction cell with low response delay includes a furnace body 18, a heating rod 16, and a cell body 3, wherein a reserved cavity is arranged in the furnace body 18; the heating rod 16 is arranged in the reserved cavity; the cell body 3 is located in the middle of the furnace body 18, and the pool body 3 is provided with a slot for fixing the sample piece 1 and cylindrical cavities arranged on both sides of the slot, and the cylindrical cavity is provided with optical elements and auxiliary A through optical path 15 is provided on the pool body 3, and the axial direction of the optical path 15 is parallel or collinear with the axial direction of the cylindrical cavity. Media inlet 13 and media outlet 14. The cavity volume of the card slot is only 0.05cm ³ , the residence time of gas at a flow rate of 10mL/min at normal pressure is 20s, and the gas residence time of seconds to hundreds of milliseconds can be realized by adjusting the gas speed

The cylindrical cavities on both sides of the slot are coaxial and have unequal diameters. An optical path pad 8 is also arranged in the card slot, and the sample piece 1 is arranged in the middle of the optical path pad 8 . The optical element includes two windows with unequal diameters respectively matched with two cylindrical cavities, and one side of the two windows is in contact with the sample sheet 1 and the optical path pad 8 .

During specific implementation, the loaded sample sheet can be spread on the bottom of the cylindrical cavity on the side with a larger diameter by virtue of its own mechanical support strength. The cylindrical cavities can be used to place windows, seals, mounts and related optical components. The above-mentioned relevant components can be disassembled, and the top of the cylindrical cavity is provided with internal threads for installing compression screws. The top of the reaction pool is provided with round holes for fixing thermocouples, and the inlets and outlets for medium exchange are located on both sides of the thermocouple holes.

The auxiliary parts include a gasket, a pressure ring and a pressure screw arranged on the side of the window close to the optical path 15 . The compression ring is fastened on the pool body 3 by compression screws, so as to realize the compression of the sealing gasket. The cell body 3 is provided with a galvanic couple hole 2, and a thermocouple is inserted in the galvanic couple hole 2. The pool body 3 is a cuboid structure with chamfered corners on the lower surface. The pool body as a whole is a flat cuboid with two corners truncated at the lower end. The reserved cavity matches the shape of the pool body 3 . The medium inlet and outlet for the introduction and export of the medium are located on both sides of the galvanic couple hole 2 .

The low-response delay high-temperature and high-pressure transmission infrared reaction cell also includes a water-cooled jacket, and the furnace body 18 is arranged in the water-cooled jacket. A cooling liquid chamber is provided in the water-cooling jacket, and water inlets 19 and water outlets 20 communicated with the cooling liquid chamber are provided on both sides of the water-cooling jacket for injection and discharge of cooling water; the bottom plate 22 of the water-cooling jacket is passed through fasteners Fixed on the optical table of the test light path.

In this embodiment, firstly, the components of the heating mantle and the water-cooling jacket shown in FIGS. 3-6 are assembled, and fixed on the relevant experimental table through the openings reserved on the bottom plate of the water-cooling jacket. As for the reaction pool, first install the relevant accessories on the side of the cylindrical cavity with a larger diameter, and place the optical path pad 8, large window 12, sealing pad 2#9 and pressure ring 2#11 in sequence from the inside to the outside. , and then slightly tighten the compression screw 2#10 with a hex wrench of appropriate specification. Next, turn the reaction cell over to the uninstalled side, put in the pressed manganese oxide sample, place the optical path pad 8, small window 6, sealing pad 1#7 and pressure ring 1#5 in sequence, and use a hexagonal wrench to install Tighten the compression screw 1#4, and then further tighten the compression screw 2#10 on the side of the large window. After the installation is completed, the gas path is connected through the medium inlet 13 and the medium outlet 14 to ensure that the reaction tank is well airtight before subsequent experiments can be carried out.

Compression screw 4,10 adopts external thread, inner hexagonal design, and hexagonal hole is the light path, also is the working hole of tightening tool. In this reaction cell, the cell body formed by the packaging of the relevant sealing parts and fixing parts can withstand the reaction atmosphere below 3MPa.

Place the reaction cell with the sample in the heating jacket and connect it to the optical path, and use an infrared spectrometer to check the connectivity of the optical path and whether the thickness of the sample is appropriate. After correcting, insert the thermocouple into the couple hole and start the related experiment.

Use the dry pump of the vacuum device connected to the gas circuit to pump the air pressure of the reaction cell to 10 ^-3 mbar, and then slowly inject 20% H ₂ /N ₂ mixed gas to return to normal pressure, set the gas flow rate to 10mL/min, and set the gas flow rate to 5 The heating rate of ℃/min was increased to 400 ℃, and the reduction treatment was carried out for 2-4 hours until the collected spectrum was stable, and then the atmosphere of 20% H ₂ /N ₂ mixed gas was lowered to room temperature. Subsequently, 10 mL/min of Ar gas was used to purge for 1 h until the collected spectra were stable. Then close the access of Ar gas, and use the pump of the connected vacuum device to pump the reaction cell to 10 ⁻⁷ mbar. After the system is stable, use the leak valve to leak into the CO atmosphere of the required pressure. Figure 8 shows the transmission infrared spectra of CO adsorbed on the surface of manganese oxide samples at different pressures.

In this embodiment, the temperature rise rate is optimized to be 5-10°C/min, the windows used are ZnSe windows, the thermocouples are K-type thermocouples, the upper limit of the pressure that the reaction cell can withstand is 3MPa, and the upper limit of the temperature is 600°C. ℃.

Example 2

In this embodiment, first install the relevant accessories on the side of the cylindrical cavity with a larger diameter, and place the optical path pad 8, the large window 12, the sealing pad 2#9, and the pressure ring 2#11 in sequence from the inside to the outside. , and then slightly tighten the compression screw 2#10 with a hex wrench of appropriate specification. Next, turn the reaction cell over to the non-installed side, place the optical path pad 8, the small window 6, the gasket 1#7 and the pressure ring 1#5 in sequence, use a hexagonal wrench to install the compression screw 1#4, and then Further tighten the compression screw 2#10 on the side of the large window. After the installation is completed, the gas path is connected through the medium inlet 13 and the medium outlet 14 to ensure that the reaction tank is well airtight before subsequent experiments can be carried out. The gas path connected to the medium outlet 14 is connected to the mass spectrometry inlet. Prepare two gas paths, _H2 gas and Ar gas in this embodiment, which are connected to a six-way valve, and then the six-way valve is connected to the gas path connected to the medium inlet 13.

Use the dry pump of the connected vacuum device to evacuate the air pressure of the reaction cell to 10 ^-3 mbar to check the airtightness of the cell body. After correcting, slowly inject Ar gas, return the system pressure to normal pressure, set its flow rate to 15mL/min, and set the _H2 gas flow rate to 15mL/min. Use mass spectrometry to collect the corresponding signals of _H2 and Ar, that is, the signals corresponding to the mass-to-charge ratio m/z of 2 and 40. After the collected mass spectrum signal is stable, the six-way valve is used to connect H ₂ , and the signal response curve of the mass spectrometry-related species is recorded. The test results are shown in Figure 9 .

Example 3

In this embodiment, firstly, the heating jacket and the components of the water-cooling jacket shown in Fig. 2 and Fig. 3 are assembled, and fixed on the relevant experimental table through the openings reserved in the bottom plate of the water-cooling jacket. As for the reaction pool, first install the relevant accessories on the side of the cylindrical cavity with a larger diameter, and place the optical path pad 8, beryllium window 12, sealing gasket 2#9 and pressure ring 2#11 in sequence from the inside to the outside. , and then slightly tighten the compression screw 2#10 with a hex wrench of appropriate specification. Next, turn the reaction cell over to the non-installed side, put in the pressed manganese oxide sample, place the optical path pad 8, beryllium window 6, sealing pad 1#7 and pressure ring 1#5 in sequence, and use a hexagonal wrench to install Tighten the compression screw 1#4, and then further tighten the compression screw 2#10 on the side of the large window. After the installation is completed, the gas path is connected through the medium inlet 13 and the medium outlet 14 to ensure that the reaction tank is well airtight before subsequent experiments can be carried out.

Place the reaction cell with the sample in the heating mantle and connect it to the optical path, adjust the energy of the beamline of the relevant line station of the synchrotron radiation source to the K-edge absorption value of manganese, turn on the light to check the connectivity of the optical path, the transmission signal of the sample and Whether the sample thickness is appropriate. After correcting, insert the thermocouple into the couple hole and start the related experiment.

Use 10mL/min normal pressure _N2 gas purging, increase the temperature to 400°C at a rate of 5°C/min, start the follow-up experiment until the collected XAS spectrum is stable, and then switch to 10mL/min 20% _H2 /N ₂ mixed gas at atmospheric pressure reduction, and XAS spectra were collected at the same time. Fig. 10 is based on the reaction cell disclosed in the present invention, XANES spectrogram data during the reduction process of the manganese oxide catalyst.

The above descriptions of the embodiments are for those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described here to other embodiments without creative effort. Therefore, the present invention is not limited to the above-mentioned embodiments. Improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims (10)

1. A low-response-delay high-temperature high-pressure transmission infrared reaction tank is characterized by comprising

The furnace comprises a furnace body (18), wherein a reserved cavity is arranged in the furnace body (18);

a heating rod (16) arranged in the reserved cavity;

the tank body (3) is arranged in the middle of the furnace body (18), a clamping groove for fixing the sample sheet (1) and a cylindrical cavity arranged on two sides of the clamping groove are arranged in the tank body (3), an optical element and an auxiliary piece are arranged in the cylindrical cavity, a through optical path (15) is arranged on the tank body (3), the axial direction of the optical path (15) is parallel or collinear with the axial direction of the cylindrical cavity, and a medium inlet (13) and a medium outlet (14) for reaction medium to enter and exit are also arranged on the tank body (3).

2. The low-response-delay high-temperature high-pressure transmission infrared reaction tank as claimed in claim 1, wherein the cylindrical cavities at two sides of the clamping groove are coaxial and have different diameters.

3. The low-response-delay high-temperature high-pressure transmission infrared reaction cell according to claim 1, wherein an optical path pad (8) is further arranged in the clamping groove, and the sample piece (1) can be arranged in the middle of the optical path pad (8).

4. A low response delay high temperature high pressure transmissive infrared reaction cell according to claim 3 wherein the optical element comprises 2 different diameter louvers matching 2 cylindrical cavities respectively, one side of each louver being in abutment with the sample tab (1) and the optical path pad (8).

5. The low-response-delay high-temperature high-pressure transmission infrared reaction tank according to claim 4, wherein the auxiliary parts comprise a sealing gasket, a compression ring and a compression screw which are arranged on the side of the window sheet close to the optical path (15).

6. The low-response-delay high-temperature high-pressure transmission infrared reaction tank according to claim 5, wherein the compression ring is fastened on the tank body (3) through compression screws, so that the sealing gasket is compressed.

7. The low-response-delay high-temperature high-pressure transmission infrared reaction tank according to claim 1, wherein a thermocouple hole (2) is formed in the tank body (3), and a thermocouple is inserted into the thermocouple hole (2).

8. The low-response-delay high-temperature high-pressure transmission infrared reaction tank according to claim 1, wherein the tank body (3) is of a cuboid structure with a chamfer on the lower surface, and the reserved cavity is matched with the tank body (3) in shape.

9. The low-response-delay high-temperature high-pressure transmission infrared reaction tank according to claim 1, wherein the low-response-delay high-temperature high-pressure transmission infrared reaction tank further comprises a water-cooling jacket, and the furnace body (18) is arranged in the water-cooling jacket.

10. The low-response-delay high-temperature high-pressure transmission infrared reaction tank according to claim 9, wherein a cooling liquid cavity is arranged in the water-cooling jacket, and a water inlet (19) and a water outlet (20) which are communicated with the cooling liquid cavity are arranged at two sides of the water-cooling jacket and are used for injecting and discharging cooling water;

the bottom plate (22) of the water-cooling jacket is fixed on the optical table of the test light path through a fastener.

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