阅读说明：本技术 一种用于动态检测缺陷的原位真空反应系统 (In-situ vacuum reaction system for dynamically detecting defects ) 是由 董帆 何烨 任琴 孙艳娟 盛剑平 于 2021-08-10 设计创作，主要内容包括：本发明公开了一种用于动态检测缺陷的原位真空反应系统,包括电子顺磁共振波谱仪、原位真空反应仓、气路单元、真空单元、光照单元、温控单元、混合瓶,所述电子顺磁共振波谱仪的检测腔体内部放置原位真空反应仓,所述气路单元通过管路连接混合瓶,所述混合瓶通过管路连接原位真空反应仓的进气口,所述真空单元通过管路连接原位真空反应仓的进气口,所述光照单元设置于电子顺磁共振波谱仪前端可拆卸窗口前面,所述温控单元通过管路连接电子顺磁共振波谱仪。通过本发明的系统可在测试过程中加光、通气、变温、真空等原位反应条件下材料的实时监测。此外,测试条件与实际反应相匹配的同时,还可在本发明的系统上设计极端反应来验证实验猜想。(The invention discloses an in-situ vacuum reaction system for dynamically detecting defects, which comprises an electron paramagnetic resonance spectrometer, an in-situ vacuum reaction bin, an air path unit, a vacuum unit, an illumination unit, a temperature control unit and a mixing bottle, wherein the in-situ vacuum reaction bin is arranged in a detection cavity of the electron paramagnetic resonance spectrometer, the air path unit is connected with the mixing bottle through a pipeline, the mixing bottle is connected with an air inlet of the in-situ vacuum reaction bin through a pipeline, the vacuum unit is connected with an air inlet of the in-situ vacuum reaction bin through a pipeline, the illumination unit is arranged in front of a detachable window at the front end of the electron paramagnetic resonance spectrometer, and the temperature control unit is connected with the electron paramagnetic resonance spectrometer through a pipeline. The system of the invention can be used for monitoring the materials in real time under the in-situ reaction conditions of light addition, ventilation, temperature change, vacuum and the like in the test process. In addition, extreme reactions can be designed on the system of the present invention to verify experimental guesses while the test conditions are matched to the actual reaction.)

1. The utility model provides an in situ vacuum reaction system for dynamic detection defect, its characterized in that, includes electron paramagnetic resonance spectrometer, in situ vacuum reaction storehouse, gas circuit unit, vacuum unit, illumination unit, control by temperature change unit, mixing bottle, the in situ vacuum reaction storehouse is placed to electron paramagnetic resonance spectrometer's detection cavity is inside, the gas circuit unit passes through the tube coupling mixing bottle, the mixing bottle passes through the air inlet of tube coupling in situ vacuum reaction storehouse, the air inlet of vacuum unit through tube coupling in situ vacuum reaction storehouse, the illumination unit sets up in electron paramagnetic resonance spectrometer front end can dismantle before the window, the control by temperature change unit passes through tube coupling electron paramagnetic resonance spectrometer.

2. The in-situ vacuum reaction system for dynamically detecting defects according to claim 1, wherein: the in-situ vacuum reaction bin comprises a quartz reaction tube, a connecting part, an air inlet pipeline, a stainless steel pipeline, an a valve, a b valve and a composite vacuum gauge, wherein the connecting part is connected with the lower end of the stainless steel pipeline, the lower end of the connecting part is connected with the quartz reaction tube through threads, the outer wall of the air inlet pipeline, the stainless steel pipeline, the connecting part and the inner wall of the quartz reaction tube form an exhaust pipeline, and the a valve, the b valve and the composite vacuum gauge are connected with the stainless steel pipeline.

3. The in-situ vacuum reaction system for dynamically detecting defects according to claim 2, wherein: the quartz reaction tube has an outer diameter of 5-10mm and an inner diameter of 4-9 mm.

4. The in-situ vacuum reaction system for dynamically detecting defects according to claim 3, wherein: the length of the quartz reaction tube is 90-110 mm.

5. The in-situ vacuum reaction system for dynamically detecting defects according to claim 2, wherein: the outer diameter of the connecting portion is 20 mm.

6. The in-situ vacuum reaction system for dynamically detecting defects according to claim 5, wherein: the length of the connecting portion is 66 mm.

7. The in-situ vacuum reaction system for dynamically detecting defects according to claim 2, wherein: the air inlet pipeline is made of polyformaldehyde.

8. The in-situ vacuum reaction system for dynamically detecting defects according to claim 7, wherein: the length of the air inlet pipeline is 150-200 mm.

9. The in-situ vacuum reaction system for dynamically detecting defects according to claim 1, wherein: the vacuum unit consists of a secondary pump.

10. The in-situ vacuum reaction system for dynamically detecting defects according to claim 9, wherein: the secondary pump comprises a mechanical pump and a molecular pump.

Technical Field

The invention belongs to the technical field of material detection, and relates to an in-situ vacuum reaction system for dynamically detecting defects.

Background

The defects not only can regulate and control the microstructure and the macroscopic appearance of catalytic performance of the catalyst, but also can provide active centers for adsorption and activation of molecules. The surface active center, the reactive species, and the surface structure are also changed during the reaction process along with the transition of the defects from the static system to the dynamic system. However, the commonly used defect characterization techniques and means, including the electron mirror type and the spectrum type, also mainly remain in the static analysis of the catalyst defects before and after the reaction. For the dynamic in-situ identification approach, although partial in-situ detection approaches have been reported, a general method for defect characterization is still lacking. Limited by the limitations of in situ detection methods that match actual reaction processes, understanding the nature of the defect variations is a significant challenge.

In recent years, as a common active center in the reaction process, the dynamic change of defects in the catalytic reaction process is gradually confirmed by experts at home and abroad, and the reversible change of the defects is also listed as a research focus. The surface state in the reaction process is different from the state presented by material characterization, and the in-situ characterization data of the catalytic reaction process needs to be acquired to deeply understand the reaction process. Although real sites, action modes and dynamic changes of defects are gradually concerned in the reaction process, observed phenomena and understanding are preliminary, the detection conditions of an in-situ means for acquiring defect signals are extreme, for example, an in-situ TEM and an in-situ SEM need to detect under a vacuum condition, the conditions are not consistent with the actual reaction conditions, the real-time changes of material defects in the reaction process cannot be accurately reflected, the method is limited by the limitation of an in-situ detection method matched with the actual reaction process, and the essential understanding of the defect changes is a great challenge. Understanding the fundamental rules and deep microscopic mechanisms of the physical and chemical transformation processes of defect changes is still insufficient, and breaking through the limitations of the existing research still faces huge challenges.

An electron paramagnetic resonance spectrometer (EPR) can observe the electron behaviors (dynamics) in molecules and analyze various microscopic phenomena by identifying an electron environment, is widely applied to the research on the aspects of catalytic reaction mechanisms, crystal defects and the like, and can realize the qualitative and quantitative analysis of the defects. However, the bruke electron paramagnetic resonance spectrometer can only realize the analysis of the defects under temperature change and light addition, and the detection of the defects still has limitations.

Disclosure of Invention

The invention aims to solve the defects in the prior art and provides an in-situ vacuum reaction system for dynamically detecting defects.

In order to achieve the purpose, the invention adopts the technical scheme that:

the utility model provides an in situ vacuum reaction system for dynamic detection defect, includes electron paramagnetic resonance spectrometer, in situ vacuum reaction storehouse, gas circuit unit, vacuum unit, illumination unit, temperature control unit, mixing bottle, the in situ vacuum reaction storehouse is placed to electron paramagnetic resonance spectrometer's detection cavity is inside, the gas circuit unit passes through the tube coupling mixing bottle, the mixing bottle passes through the air inlet in tube coupling in situ vacuum reaction storehouse, the air inlet in vacuum unit through tube coupling in situ vacuum reaction storehouse, the illumination unit sets up in electron paramagnetic resonance spectrometer front end can dismantle the window preceding, the temperature control unit passes through tube coupling electron paramagnetic resonance spectrometer.

Further, the in-situ vacuum reaction bin comprises a quartz reaction tube, a connecting part, an air inlet pipeline, a stainless steel pipeline, a valve a, a valve b and a composite vacuum gauge, wherein the connecting part is connected with the lower end of the stainless steel pipeline, the lower end of the connecting part is connected with the quartz reaction tube through threads, an exhaust pipeline is formed by the outer wall of the air inlet pipeline, the stainless steel pipeline, the connecting part and the inner wall of the quartz reaction tube, and the valve a, the valve b and the composite vacuum gauge are connected with the stainless steel pipeline.

Furthermore, the outer diameter of the quartz reaction tube is 5-10mm, and the inner diameter is 4-9 mm.

Further, the length of the quartz reaction tube is 90-110 mm.

Further, the outer diameter of the connecting portion is 20 mm.

Further, the length of the connecting portion is 66 mm.

Further, the air inlet pipeline is made of polyformaldehyde.

Further, the length of the air inlet pipeline is 150-200 mm.

Further, the vacuum unit consists of a secondary pump.

Further, the secondary pump comprises a mechanical pump and a molecular pump.

Compared with the prior art, the invention has the following advantages and beneficial effects:

the in-situ vacuum reaction system for dynamically detecting the defects is improved based on the conventional Bruker EMX nano electron paramagnetic resonance spectrometer and is realized by additionally arranging an in-situ vacuum reaction bin, an air path unit, a vacuum unit, an illumination unit, a temperature control unit, a mixing bottle and the like. The system of the invention can be used for monitoring the materials in real time under the in-situ reaction conditions of light addition, ventilation, temperature change, vacuum and the like in the test process. In addition, extreme reactions can be designed on the system of the present invention to verify experimental guesses while the test conditions are matched to the actual reaction.

Drawings

FIG. 1 is a schematic diagram of an in-situ vacuum reaction system for dynamically detecting defects according to the present invention;

FIG. 2 is a schematic structural view of an in-situ vacuum reaction chamber according to the present invention;

FIG. 3 is a diagram of TiO with different initial defects₂The material is a real-time defect signal change condition diagram tested by utilizing in-situ EPR under the conditions of photocatalytic adsorption, reaction and lamp turn-off.

Detailed Description

In order to make the objects, technical problems to be solved, and technical solutions of the present invention clearer, the present invention is further described below with reference to the accompanying drawings and specific embodiments.

FIG. 1 is a schematic structural diagram of an in-situ vacuum reaction system for dynamically detecting defects of the present invention, which comprises an electron paramagnetic resonance spectrometer (1), an in-situ vacuum reaction chamber (2), a gas path unit (3), a vacuum unit (4), an illumination unit (5), a temperature control unit (6), and a mixing bottle (7), an in-situ vacuum reaction chamber (2) is arranged in a detection cavity of the electron paramagnetic resonance spectrometer (1), the gas circuit unit (3) is connected with a mixing bottle (7) through a pipeline, the mixing bottle (7) is connected with a gas inlet of the in-situ vacuum reaction bin (2) through a pipeline, the vacuum unit (4) is connected with the air inlet of the in-situ vacuum reaction bin (2) through a pipeline, the illumination unit (5) is arranged in front of a detachable window at the front end of the electron paramagnetic resonance spectrometer (1), the temperature control unit (6) is connected with the electron paramagnetic resonance spectrometer (1) through a pipeline.

The in-situ vacuum reaction system for dynamically detecting the defects is improved based on the conventional Bruker EMX nano electron paramagnetic resonance spectrometer (1) and is realized by additionally arranging an in-situ vacuum reaction bin (2), an air path unit (3), a vacuum unit (4), an illumination unit (5), a temperature control unit (6), a mixing bottle (7) and the like.

As shown in fig. 2, the in-situ vacuum reaction chamber (2) includes a quartz reaction tube (21), a connection part (22), an air inlet pipeline (23), a stainless steel pipeline (24), an a valve (25), a b valve (26), and a composite vacuum gauge (27).

The quartz reaction tube has an outer diameter of 5-10mm, an inner diameter of 4-9mm and a length of 90-110 mm. Can be disassembled, the upper end is provided with a thread sealing port, and the screw can be screwed down to realize vacuum and low pressure resistance. The detachable quartz reaction tube is convenient for sample changing, and a sample is placed in the electron paramagnetic resonance spectrometer after being placed. The quartz reaction tube is light-permeable, so that the test of materials under the condition of light addition of the illumination unit in the reaction process can be realized, and the quartz reaction tube does not influence the experimental result. In order to ensure that the gas is fully contacted with the sample, the gas is directly introduced into the bottom of the quartz reaction tube, quartz wool is added into the quartz reaction tube, and then the sample is placed, so that the aeration in the reaction process and the test of the material under the vacuum condition can be realized. The air inlet pipe in the quartz reaction tube is a soft rubber tube with moderate hardness.

The connecting portion has an outer diameter of 20mm and a length of 66 mm. The bearing function is realized, and the material is polyformaldehyde (other high molecular polymers can be used, and the bearing material is non-magnetic). The in-situ vacuum reaction chamber is matched with an instrument matching bayonet of the electron paramagnetic resonance spectrometer, and the connecting part is connected with the electron paramagnetic resonance spectrometer under the connection of the instrument matching bayonet. The connecting part and the lower end of the stainless steel pipeline are welded by stainless steel and cannot be disassembled, and the lower end of the stainless steel pipeline is connected with the quartz reaction tube by threads.

The gas inlet pipeline introduces gas into the in-situ vacuum reaction bin, and the gas inlet pipeline is made of polyformaldehyde (other high molecular polymers can be used and the gas inlet pipeline is nonmagnetic) and has the length of 150-200 mm. The upper end flange valve ensures vacuum connection, and the lower end is slightly longer than the connecting part and is connected with the soft rubber tube to extend into the bottom of the quartz reaction tube. The middle bulge of the gas inlet pipeline is used for flange valve connection, and the outer diameter of the part, which is lower than the flange valve, of the gas inlet pipeline is smaller than the inner diameters of the stainless steel pipeline, the connecting part and the quartz reaction tube. The outer wall of the air inlet pipeline, the stainless steel pipeline, the connecting part and the inner wall of the quartz reaction tube form an exhaust pipeline.

The valve a is connected with a stainless steel pipeline, one end of the valve a is a vacuum pumping port, the vacuum pumping port is connected with a secondary vacuum pump (a mechanical pump and a molecular pump), and the connection mode is stainless steel screw connection, so that low vacuum in the reaction bin is ensured. The pump port end pipeline is connected with low vacuum silicon, and the quantity of the pump port end pipeline in the system can reach 10^-4～10^-5pa。

The valve b is also connected with a stainless steel pipeline, an air outlet is formed in one end of the valve b and used for discharging reaction tail gas, the valve b is connected with an airflow display device through a pipeline, and a stainless steel screw of the air outlet is screwed.

The composite vacuum gauge is also connected with the stainless steel pipeline, and the vacuum detection range can be switched spontaneously according to actual conditions. In addition, a mode in which low vacuum silicon and high vacuum silicon are separately detected may be used. And when the reading number of the low-vacuum silicone is stabilized at about 0.5Pa, opening the high-vacuum silicone grease detection reactor to detect the high vacuum degree.

The gas circuit unit is connected with the gas circuit unit through a gas inlet of the in-situ vacuum reaction bin and used for distributing gas for the in-situ vacuum reaction bin.

The vacuum unit consists of a secondary pump, and comprises a mechanical pump and a molecular pump, wherein the mechanical pump primarily pumps air to low vacuum, and then the molecular pump pumps the air to a high vacuum environment. The vacuum of the in-situ vacuum reaction bin and the whole gas circuit can be realized, the mutual interference of gas components to a test environment is eliminated, and the detection of an instrument under the vacuum condition can be realized.

The illumination unit is an external unit, and a window is arranged at the front end of the electron paramagnetic resonance spectrometer and can be detached. The front panel of the instrument is disassembled, and the lamp can be extended into the instrument to realize the light adding condition during detection. However, it should be noted that if it is necessary to reach deep into the instrument, it is made of a non-magnetic material, otherwise, it is only allowed to turn on the light outside the instrument.

The temperature control unit is connected with the electron paramagnetic resonance spectrometer through a pipeline, and the temperature control unit can be used for realizing real-time monitoring of the material under the in-situ reaction condition of temperature change in the testing process of the electron paramagnetic resonance spectrometer.

The in-situ vacuum reaction system for dynamically detecting the defects can realize the following functions:

1. and simulating photocatalytic test conditions.

Placing the test sample in the in-situ vacuum reaction chamber. And (4) closing the valve a and closing the vacuum silicone grease. And placing the catalytic sample in an instrument cavity of an electron paramagnetic resonance spectrometer. And (4) closing the valve b, opening the valve a and the sample inlet valve, opening the secondary pump to carry out vacuum treatment on the sample to remove adsorbed substances on the surface of the material, and simultaneously removing adsorbed atmosphere molecules in the pipeline. Then, the vacuum unit is closed, the atmosphere is introduced from the gas inlet, and the valve b is opened when the low vacuum silicon shows normal pressure. And after gas is normally introduced, the external illumination unit is opened, so that the catalyst change under the reaction condition can be monitored in real time.

2. And (5) testing under vacuum conditions.

And placing the catalytic sample in an instrument cavity of an electron paramagnetic resonance spectrometer. And (4) closing the valve b, opening the valve a and the injection port valve, and opening the secondary vacuum pump. After the material is pumped to low vacuum, the external illumination unit is turned on, and the influence of the light source on the material under the vacuum condition can be monitored in real time.

3. Real-time monitoring of the reaction process can be achieved by using a design device. FIG. 3 is a diagram of TiO with different initial defects₂The material utilizes a real-time defect signal change situation diagram tested by in-situ EPR under the conditions of photocatalytic adsorption, reaction and lamp turn-off, as shown in figure 3, and the defect content is dynamically changed in the whole photocatalytic reaction process. Adsorption process in the first 15 minutes, catalyst defectsThe content is slightly reduced, which means that the adsorption of molecules on surface defects inhibits the generation of partial defect signals; however, after switching on, the content of defects increases substantially instantaneously; after the lamp was turned off, the defect concentration of the catalyst was restored to the initial state with disappearance of the excitation source. These findings are based on the in situ vacuum reaction chamber design.

It will be appreciated by those of ordinary skill in the art that the embodiments described herein are intended to assist the reader in understanding the principles of the invention and are to be construed as being without limitation to such specifically recited embodiments and examples. Those skilled in the art, having the benefit of this disclosure, may effect numerous modifications thereto and changes may be made without departing from the scope of the invention in its broader aspects.