阅读说明：本技术 一种用于低磁场下仲氢诱导极化装置及方法 (Para-hydrogen induced polarization device and method used in low magnetic field ) 是由 王伟宇 徐君 邓风 于 2020-05-18 设计创作，主要内容包括：本发明公开了一种用于低磁场下仲氢诱导极化装置,包括仲氢进气通道、保护气体进气通道和反应气体进气通道,仲氢进气通道、保护气体进气通道和反应气体进气通道的出气端均分别与第六直通阀一端和第七直通阀一端连接,第七直通阀另一端与反应器的进口端连接,反应器的出口端与第四单向阀的进端连接,反应器位于加热炉内,加热炉与加热炉控制器连接,第四单向阀的出端通过采样进气管与反应采样管连接,高斯计设置在反应器的出口端附近,高斯计与磁场强度显示仪连接。本发明还公开了一种用于低磁场下仲氢诱导极化方法。本发明结构简单,控制操作简便,实现高效的极化产生及稳定的极化核磁谱图信号采集。(The invention discloses a para-hydrogen induced polarization device used in a low magnetic field, which comprises a para-hydrogen inlet channel, a protective gas inlet channel and a reaction gas inlet channel, wherein the gas outlet ends of the para-hydrogen inlet channel, the protective gas inlet channel and the reaction gas inlet channel are respectively connected with one end of a sixth straight-through valve and one end of a seventh straight-through valve, the other end of the seventh straight-through valve is connected with the inlet end of a reactor, the outlet end of the reactor is connected with the inlet end of a fourth one-way valve, the reactor is positioned in a heating furnace, a heating furnace is connected with a heating furnace controller, the outlet end of the fourth one-way valve is connected with a reaction sampling pipe through a sampling gas inlet pipe, a gaussmeter is arranged near the outlet end of the reactor, and the gaussmeter is connected with a magnetic. The invention also discloses a para-hydrogen induced polarization method under a low magnetic field. The invention has simple structure, simple and convenient control and operation, and realizes efficient polarization generation and stable polarization nuclear magnetic spectrum signal acquisition.)

1. A para-hydrogen induced polarization device used under low magnetic field comprises a para-hydrogen inlet channel, and is characterized by also comprising a protective gas inlet channel and a reaction gas inlet channel,

the outlet ends of the parahydrogen inlet channel, the protective gas inlet channel and the reaction gas inlet channel are respectively connected with one end of a sixth straight-through valve (18) and one end of a seventh straight-through valve (19), the other end of the seventh straight-through valve (19) is connected with the inlet end of a reactor (20), the outlet end of the reactor (20) is connected with the inlet end of a fourth one-way valve (21), the reactor (20) is positioned in a heating furnace (23), the heating furnace (23) is connected with a heating furnace controller (24), the outlet end of the fourth one-way valve (21) is connected with one end of a sampling gas inlet pipe, the other end of the sampling gas inlet pipe penetrates through a sealing plug at the opening of the reaction sampling pipe (22) and extends to the bottom of the reaction sampling pipe (22), one end of a sampling gas outlet pipe penetrates through the opening of the reaction sampling pipe (22) and extends to the top of the sealing plug of the reaction sampling pipe (22), and a gauss, the gaussmeter (26) is connected with a magnetic field intensity display instrument (25).

2. A para-hydrogen induced polarization device under low magnetic field as claimed in claim 1, wherein the para-hydrogen gas inlet channel comprises a first pressure gauge (1), a first through valve (2), a first one-way valve (3), a first gas purifier (4) and a first mass flow controller (5), one end of the first through valve (2) is the gas inlet end of the para-hydrogen gas inlet channel and is provided with the first pressure gauge (1), the other end of the first through valve (2) is connected with the gas inlet end of the first one-way valve (3), the outlet end of the first one-way valve (3) is connected with the gas inlet end of the first gas purifier (4), the gas outlet end of the first gas purifier (4) is connected with one end of the first mass flow controller (5), and the other end of the first mass flow controller (5) forms the gas outlet end of the para-hydrogen gas inlet channel.

3. The para-hydrogen induced polarization device under the low magnetic field according to claim 2, wherein the protective gas inlet channel comprises a second pressure gauge (6), a second straight-through valve (7), a second one-way valve (8), a second gas purifier (9), a second mass flow controller (10) and a third straight-through valve (11), one end of the second straight-through valve (7) is an inlet end of the protective gas inlet channel and is provided with the second pressure gauge (6), the other end of the second straight-through valve (7) is connected with an inlet end of the second one-way valve (8), an outlet end of the second one-way valve (8) is connected with one end of the third straight-through valve (11) through the second gas purifier (9) and the second mass flow controller (10) in sequence, and the other end of the third straight-through valve (11) forms an outlet end of the protective gas inlet channel.

4. The para-hydrogen induced polarization device for the low magnetic field according to claim 3, wherein the reaction gas inlet channel comprises a third pressure gauge (12), a fourth straight-through valve (13), a third one-way valve (14), a third gas purifier (15), a third mass flow controller (16) and a fifth straight-through valve (17), one end of the fourth straight-through valve (13) forms the gas inlet end of the reaction gas inlet channel and is provided with the third pressure gauge (12), the other end of the fourth straight-through valve (13) is connected with the inlet end of the third one-way valve (14), the outlet end of the third one-way valve (14) is connected with one end of the fifth straight-through valve (17) through the third gas purifier (15) and the third mass flow controller (16) in sequence, and the other end of the fifth straight-through valve (17) forms the gas outlet end of the reaction gas inlet channel.

5. A para-hydrogen induced polarization device under low magnetic field according to claim 4, wherein the first check valve (3), the second check valve (8) and the third check valve (14) are all in one-way conduction from inlet to outlet.

6. A method for para-hydrogen induced polarization under low magnetic field, which uses the para-hydrogen induced polarization device under low magnetic field of claim 5, comprising the following steps:

step 1, placing a reaction catalyst in a reactor (20), and adjusting the placing position of the reactor (20) until a magnetic field intensity display instrument (25) displays that the detected magnetic field intensity is 1-100G;

step 2, connecting a parahydrogen gas path to a first straight-through valve (2), connecting a protective gas path to a second straight-through valve (7), connecting a fourth straight-through valve (13) to a reaction gas path, starting the first straight-through valve (2), the second straight-through valve (7), a third straight-through valve (11), the fourth straight-through valve (13), a fifth straight-through valve (17) and a seventh straight-through valve (19), closing the sixth straight-through valve (18), introducing protective gas for purging when the flow rate of the second mass flow controller (10) is 200 and 300sccm, and simultaneously starting a heating furnace controller (24) to adjust the temperature of a heating furnace (23) to a reaction target temperature of 50-500 ℃;

and 3, after the heating furnace (23) reaches the target temperature for 10 minutes, closing the second mass flow controller (10), introducing parahydrogen gas at the flow rate of 0-300sccm into the first mass flow controller (5), introducing reaction gas at the flow rate of 0-300sccm into the third mass flow controller (16), and triggering magnetic resonance sampling after 10-20 seconds until the magnetic resonance sampling is finished.

Technical Field

The invention relates to the technical field of magnetic resonance spectrograms, in particular to a para-hydrogen induced polarization device used in a low magnetic field and a para-hydrogen induced polarization method used in the low magnetic field. The method is suitable for the nuclear magnetic resonance polarization of a gas-solid reaction system under a low magnetic field environment by taking parahydrogen gas as a polarization source.

Background

Nuclear Magnetic Resonance (NMR) technology can provide key information on material composition, molecular structure and related kinetics, is a very important research method and analysis means, and is widely applied to various fields such as biology, chemistry, medicine, physics and the like. The nuclear magnetic signal intensity is in direct proportion to the nuclear spin energy level distribution number difference in the static magnetic field, and the nuclear spin energy level distribution number difference in the conventional static magnetic field is only 10-5 orders of magnitude, so the intrinsic sensitivity of nuclear magnetic resonance is low, the acquisition of the nuclear magnetic signal is very difficult, and the deeper application of the nuclear magnetic resonance is restricted to a certain extent. By utilizing Para-hydrogen Induced Polarization technology (Para-hydrogen Induced Polarization), nuclear magnetic observation object molecules are combined with Para-hydrogen molecules, so that the particle layout number difference on different energy levels is improved by orders of magnitude, namely, the original thermal equilibrium state is reached to a Polarization state, signals can be enhanced by 4-5 orders of magnitude, the strength of NMR signals is greatly improved, and the problem of sensitivity is solved.

Among para-hydrogen induced polarization techniques, low field polarization techniques (ALTADENA) are one of the main methods for obtaining polarization enhancement. The method takes para-hydrogen molecules as a polarization source, and performs an addition reaction on the para-hydrogen molecules and asymmetric reactants under the condition of a low magnetic field, breaks the original symmetry under the condition of keeping spin coupling among hydrogen atoms, and simultaneously quickly transfers the para-hydrogen molecules to a high magnetic field environment to trigger in-situ acquisition of a nuclear magnetic resonance spectrogram so as to obtain polarization enhancement of nuclear magnetic signals. In the process, the addition reaction of parahydrogen molecules and asymmetric reactants needs to be carried out under a specific low magnetic field, and the parahydrogen molecules are rapidly transferred to a high magnetic field environment for observation after the reaction, so a parahydrogen induced polarization device under the low magnetic field is needed. At present, no corresponding device design is available at home to meet the requirements, no commercial design is available at foreign countries to meet the requirements, the existing parahydrogen induced polarization device under low magnetic field has poor design stability, the low magnetic field strength under addition reaction cannot be determined, and the rapid transfer of an observed object after reaction is difficult to meet, so that a polarization signal is lost, the signal strength is reduced, and meanwhile, an instrument device is heavy and cannot meet the application requirements under a specific environment.

Disclosure of Invention

The present invention is directed to the above problems of the prior art, and provides a para-hydrogen induced polarization device under low magnetic field, which can generate polarization signal under low magnetic field; determining the magnetic field intensity in the low-magnetic-field reaction process, and using the magnetic field intensity for fitting calculation and spectrogram processing; the rapid sample transfer is realized, and the continuity of polarization generation and nuclear magnetic signal acquisition is met; the device has simple structure, simple and convenient control operation and easy maintenance.

The invention also aims to provide a para-hydrogen induced polarization method under low magnetic field, which is used together with a para-hydrogen induced polarization device under low magnetic field to realize polarization generation and collection under low magnetic field condition in a gas-solid reaction system.

In order to achieve the purpose, the invention adopts the following technical measures:

a para-hydrogen induced polarization device used under low magnetic field comprises a para-hydrogen inlet channel, a protective gas inlet channel and a reaction gas inlet channel,

the outlet ends of the parahydrogen inlet channel, the protective gas inlet channel and the reaction gas inlet channel are respectively connected with one end of a sixth straight-through valve and one end of a seventh straight-through valve, the other end of the seventh straight-through valve is connected with the inlet end of a reactor, the outlet end of the reactor is connected with the inlet end of a fourth one-way valve, the reactor is positioned in a heating furnace, the heating furnace is connected with a heating furnace controller, the outlet end of the fourth one-way valve is connected with one end of a sampling gas inlet pipe, the other end of the sampling gas inlet pipe penetrates through a sealing plug at the opening of the reaction sampling pipe and extends to the bottom of the reaction sampling pipe, one end of a sampling gas outlet pipe penetrates through a sealing plug at the opening of the reaction sampling pipe and extends to the top of the reaction sampling pipe.

The parahydrogen inlet channel comprises a first pressure gauge, a first direct-current valve, a first one-way valve, a first gas purifier and a first mass flow controller, wherein one end of the first direct-current valve is an inlet end of the parahydrogen inlet channel and is provided with the first pressure gauge, the other end of the first direct-current valve is connected with an inlet end of the first one-way valve, an outlet end of the first one-way valve is connected with an inlet end of the first gas purifier, an outlet end of the first gas purifier is connected with one end of the first mass flow controller, and the other end of the first mass flow controller forms an outlet end of the parahydrogen inlet channel.

The protective gas inlet channel comprises a second pressure gauge, a second straight-through valve, a second one-way valve, a second gas purifier, a second mass flow controller and a third straight-through valve, one end of the second straight-through valve is an inlet end of the protective gas inlet channel and is provided with the second pressure gauge, the other end of the second straight-through valve is connected with an inlet end of the second one-way valve, an outlet end of the second one-way valve is connected with one end of the third straight-through valve sequentially through the second gas purifier and the second mass flow controller, and the other end of the third straight-through valve forms an outlet end of the protective gas inlet channel.

The reaction gas inlet channel comprises a third pressure gauge, a fourth straight-through valve, a third one-way valve, a third gas purifier, a third mass flow controller and a fifth straight-through valve, wherein one end of the fourth straight-through valve forms a gas inlet end of the reaction gas inlet channel and is provided with the third pressure gauge, the other end of the fourth straight-through valve is connected with a gas inlet end of the third one-way valve, an outlet end of the third one-way valve is connected with one end of the fifth straight-through valve sequentially through the third gas purifier and the third mass flow controller, and the other end of the fifth straight-through valve forms a gas outlet end of the reaction gas inlet channel.

The first one-way valve, the second one-way valve and the third one-way valve are all in one-way conduction from the inlet end to the outlet end.

The device can purify the feed gas, realize the low-magnetic-field polarization generation, determine the magnetic field intensity and ensure the continuity of the polarization generation and the nuclear magnetic signal acquisition.

Wherein, the reactor is a key part of a para-hydrogen induced polarization device under a low magnetic field. The key of the low-field transfer polarization technology of para-hydrogen induced polarization is that para-hydrogen and reaction molecules are subjected to addition reaction in a low-magnetic field environment, then the para-hydrogen is rapidly transferred to a high-magnetic field environment to induce polarization generation, and nuclear magnetic signal spectrogram acquisition is triggered. As shown in fig. 2, para-hydrogen molecule reacts with reactant under low field to form AB system, then the product is rapidly transferred to high magnetic field, the AB system is changed into AX system by increasing field intensity, the layout number of single energy level in alpha beta or beta alpha energy level is increased, polarization enhancement is obtained, and nuclear magnetic signal is in absorption and emission line type. The reactor is made of stainless steel materials, and can complete the reaction process of parahydrogen molecules and reactants under the condition of low magnetic field. The gaussmeter and the magnetic field intensity display instrument are key parts for low magnetic field intensity detection, magnetic field intensity information in the addition reaction process is obtained by detecting the magnetic field intensity at the outlet of the reactor, and the magnetic field intensity information is applied to nuclear magnetic resonance spectrogram processing and simulation calculation. The reaction sampling tube is a key part for collecting a polarization spectrogram. The reaction sampling tube is made of glass material, can be directly placed in the magnet, has the diameter of 5mm or 10mm, can be directly loaded in most conventional nuclear magnetic probes, enlarges the application range of the invention, ensures the loading of a sample with the maximum volume and improves spectrogram signals. The transparent tube wall structure made of glass material is also helpful for observing the condition of the internal sample.

Compared with the existing device, the device is additionally provided with a reactor which can be used for low-magnetic field reaction, so that parahydrogen molecules and reactants react under a low field to form an AB spin system; a gaussmeter is added, the intensity of the magnetic field of the reactor can be detected, and the method can be applied to nuclear magnetic resonance spectrogram processing and simulation calculation; the material and the size of the reaction sampling tube are determined, so that the reaction sampling tube can be suitable for more nuclear magnetic resonance spectrometers while ensuring more samples to be loaded, and the applicability of the device is improved; the purification pretreatment of the gas path gas flow is increased, the service life of the parahydrogen induced polarization device under low magnetic field is prolonged, and the maintenance cost is reduced; the multi-gas path input design is added, the multi-gas path access expansion can be met, and the expansibility of the parahydrogen induced polarization device under a low magnetic field is improved; the key gas path is additionally provided with a one-way valve design to prevent hydrogen, reaction gas and mixingThe gas is refluxed and mixed, so that the stability and reliability of the parahydrogen induced polarization device under a low magnetic field are improved. Fig. 3 shows a polarization spectrum signal obtained by a para-hydrogen induced polarization apparatus under a low magnetic field at a magnetic field strength of 25G using alumina supporting palladium and copper bimetallic as a carrier and propylene as a target polarization molecule in an actual use case. As can be seen from fig. 2, the polarization signal line type is representative of the absorption and emission line type. As can be seen in FIG. 3, H_aAnd H_bTo newly add proton¹All signals of the H NMR spectrum are polarization signals, H_aTo absorb linear form, H_bIs of the emission line type. Meanwhile, the spectrogram has better resolution, which shows that the device can stably and reliably obtain low-field in-situ polarization based on the para-hydrogen induced polarization technology under the actual application condition, and the quality of the spectrogram is good.

A para-hydrogen induced polarization method for use in low magnetic fields, comprising the steps of:

step 1, placing a reaction catalyst in a reactor, and simultaneously adjusting the placing position of the reactor until a magnetic field intensity display instrument displays that the detected magnetic field intensity is 1-100G;

step 2, connecting a first straight-through valve to a parahydrogen gas path, connecting a second straight-through valve to a protective gas path, connecting a fourth straight-through valve to a reaction gas path, opening the first straight-through valve, the second straight-through valve, the third straight-through valve, the fourth straight-through valve, the fifth straight-through valve and the seventh straight-through valve, closing the sixth straight-through valve, introducing protective gas for purging at the flow rate of 200 plus sccm of a second mass flow controller, and simultaneously opening a heating furnace controller to adjust the temperature of the heating furnace to the reaction target temperature of 50-500 ℃;

and 3, closing the second mass flow controller after the heating furnace reaches the target temperature for 10 minutes, introducing parahydrogen gas at the flow rate of 0-300sccm into the first mass flow controller, introducing reaction gas at the flow rate of 0-300sccm into the third mass flow controller, and triggering magnetic resonance sampling after 10-20 seconds until the magnetic resonance sampling is finished.

In the method, the step 1 is a key step for determining the intensity of the reaction magnetic field, and can help an instrument to adjust to the target magnetic field intensity; step 2 is a key step of setting hydrogenation reaction conditions, and can realize the setting of reaction temperature; and step 3 is a key step of polarization generation and signal acquisition, and can realize the addition reaction of para-hydrogen molecules and reactant molecules under the condition of a low magnetic field and quickly transfer the para-hydrogen molecules into a magnet for measurement. Compared with the prior art, the application method is simple to operate, flexible in scheme, capable of meeting the requirement of magnetic field regulation, fast in polarization and capable of meeting various actual observation systems.

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

1. the parahydrogen induced polarization device under the low magnetic field has simple structure, high stability and convenient manufacture and maintenance;

2. the reactor is provided with a gaussmeter, and the actual field intensity of the reaction can be adjusted by changing the position of the reactor, so that the reactor is more stable and accurate;

3. the heating furnace is arranged, so that the requirements of different addition reaction temperatures can be met, and the applicability is good;

4. the reaction sampling tube has fixed size, can be applied to most nuclear magnetic resonance probes, and has good practicability;

5. realizing the polarization generation of a target product with a constant speed by a mass flow controller;

6. the multi-gas-path test expansion is realized by controlling the straight-through valve;

7. the device is simple to operate, and after the device is connected with an upper air source, only the through valve and the mass flow controller are controlled to be opened and closed.

Drawings

Fig. 1 is a schematic diagram of a para-hydrogen induced polarization device for use in low magnetic fields.

FIG. 2 is a diagram of the principle of low-field polarization and polarization signals of para-hydrogen induced polarization.

FIG. 3 is a spectrum of a low-field polarization nuclear magnetic signal experimentally measured in an actual system.

In the figure: 1-a first pressure gauge (selectable model: WIKA Cl.1.6), 2-a first through valve (selectable model: SSC-723K 2), 3-a first one-way valve (selectable model: SSC-113), 4-a first gas purifier (selectable model: Dalianripril scientific and technological instrument-1, JY-4), 5-a first mass flow controller (selectable model: Qixinhuachuang D07), 6-a second pressure gauge (selectable model: WIKA Cl.1.6), 7-a second through valve (selectable model: Skansu SS-723K2), 8-a second one-way valve (selectable model: Skanhuachuang SS-113), 9-a second gas purifier (selectable model: JY-1, JY-4), 10-a second mass flow controller (selectable model: Qixinhuachuang D07), 11-third straight-through valve (selectable model: Sichuan bear SS-723K2), 12-third pressure gauge (selectable model: WIKA Cl.1.6), 13-fourth straight-through valve (selectable model: Sichuan bear SS-723K2), 14-third one-way valve (selectable model: Sichuan bear SS-113), 15-third gas purifier (selectable model: Dalianripril scientific and technological instrument JY-1, JY-4), 16-third mass flow controller (selectable model: Qixinhuachuang D07), 17-fifth straight-through valve (selectable model: Sichuan bear SS-723K2), 18-sixth straight-through valve (selectable model: Sichuan bear SS-723K2), 19-seventh straight-through valve (selectable model: Sichuan bear SS-723K2), 20-reactor (commercially available or steel tube self-made), 21-fourth one-way valve (selectable model: Sichuan bear SS-113), and optional model: Sichuan bear SS-723K2, 22-reaction sampling tube (purchased from market or made by glass tube), 23-heating furnace (purchased from market), 24-heating furnace controller (purchased from market), 25-magnetic field intensity display instrument (optional model: TUNKIATD8620), and 26-gauss meter (optional model: TUNKIATD 8620).

Detailed description of the preferred embodiments

The present invention will be described in further detail with reference to examples for the purpose of facilitating understanding and practice of the invention by those of ordinary skill in the art, and it is to be understood that the present invention has been described in the illustrative embodiments and is not to be construed as limited thereto.