A mass spectrometry ionization source device for online monitoring of catalytic reactions

Abstract

The present invention belongs to the technical field of mass spectrometers, specifically a mass spectrometry ionization source device for online monitoring of catalytic reactions. The catalytic reactor is sealedly connected to the ionization source cavity. The top of the catalytic reactor is open and filled with a catalyst. The bottom of the catalytic reactor is connected to a reaction gas source for introducing reaction gas. A heating device is wrapped around the outside of the catalytic reactor. A vacuum ultraviolet lamp, an ion repeller electrode, a curtain electrode, and an aperture electrode are all placed inside the ionization source cavity. The ion repeller electrode, the curtain electrode, and the aperture electrode are arranged in sequence along the direction of light emission from the vacuum ultraviolet lamp. The top of the catalytic reactor is located between the ion repeller electrode and the curtain electrode and is located in the light emitted by the vacuum ultraviolet lamp. The catalytic reactor mass spectrometry interface designed by the present invention can prevent secondary reactions of short-lived catalytic reaction intermediates, ensure the efficiency and effectiveness of detecting active intermediate products, and successfully achieve online monitoring of complex species systems in catalytic reactions.

Description

Technical Field

[0001] The invention belongs to the technical field of mass spectrometers, in particular to a mass spectrometer ionization source device for online monitoring of catalytic reactions. Background Art

[0002] Catalytic reactions often involve surface intermediates on the catalyst, and some also involve unstable gas-phase intermediates such as free radicals and alkyl hydroperoxides. Online detection of gas-phase intermediates is crucial for fundamentally understanding the reaction mechanisms of these catalytic reactions, designing efficient catalyst structures, and optimizing reactors. However, due to the lack of conventional detection technologies, this has long been a challenge.

[0003] Mass spectrometry technology has the characteristics of being able to simultaneously detect various species in the system, including ions, atoms, and free radicals, with high sensitivity in detecting ion species and relatively easy identification of unknown species. However, the interface between the catalytic reactor and the mass spectrometer requires special design. Summary of the Invention

[0004] In view of the above-mentioned problems existing in catalytic reactions, the object of the present invention is to provide a mass spectrometry ionization source device for online monitoring of catalytic reactions.

[0005] The object of the present invention is achieved through the following technical solutions:

[0006] The present invention comprises a catalytic reactor, an ionization source cavity, a vacuum ultraviolet lamp, an ion repeller electrode, a curtain electrode, a hole electrode, a heating device and a time-of-flight mass spectrometer;

[0007] The catalytic reactor is sealed and connected to the ionization source cavity. The top of the catalytic reactor is open and filled with a catalyst. The bottom of the catalytic reactor is connected to the reaction gas source for introducing the reaction gas. The heating device is wrapped around the outside of the catalytic reactor.

[0008] The vacuum ultraviolet lamp, ion repeller electrode, curtain electrode and aperture electrode are all placed inside the ion source cavity, and the ion repeller electrode, curtain electrode and aperture electrode are arranged in sequence along the light emission direction of the vacuum ultraviolet lamp. The top of the catalytic reactor is located between the ion repeller electrode and the curtain electrode and is located on the light emitted by the vacuum ultraviolet lamp.

[0009] The ion repeller electrode is a flat plate structure with a through hole in the middle; the curtain electrode and the hole electrode are both conical structures with a through hole in the middle;

[0010] The optical axis of the light emitted by the vacuum ultraviolet lamp is coaxial with the through holes on the ion repeller electrode, the curtain electrode and the aperture electrode;

[0011] The aperture electrode is connected to a time-of-flight mass spectrometer.

[0012] Wherein: the winding length of the heating device is greater than the filling depth of the catalyst.

[0013] The catalytic reactor is a hollow quartz tube, which is sealed and connected to the ionization source cavity through an O-ring. The top center of the quartz tube is opened, and the catalyst is filled in the top of the quartz tube. Quartz wool is provided in the quartz tube at the bottom of the catalyst, and the catalyst is fixed by the quartz wool.

[0014] The axial center line of the catalytic reactor is perpendicular to the emission direction of the vacuum ultraviolet lamp light. The top opening of the catalytic reactor is close to the curtain electrode and lower than the through hole on the curtain electrode.

[0015] The heating device is a wound resistance wire or a ceramic heating ring, and the heating temperature range is room temperature to 1000°C.

[0016] The side wall of the ionization source cavity is connected to a mechanical pump or a molecular pump, and the mechanical pump or the molecular pump is located just above the opening of the catalytic reactor. The cavity pressure range of the ionization source cavity is 0.001-1000Pa.

[0017] There is no back-blowing gas or back-blowing gas between the curtain electrode and the hole electrode. The back-blowing gas is helium and / or argon with a flow rate ranging from 0 to 20 L / min.

[0018] The vacuum ultraviolet lamp is a gas discharge lamp light source, a laser light source or a synchrotron radiation light source.

[0019] The through holes on the ion repeller electrode, the curtain electrode and the hole electrode are all circular holes and are all opened in the middle.

[0020] The advantages and positive effects of the present invention are:

[0021] The catalytic reactor mass spectrometry interface designed in the present invention can avoid secondary reactions of short-lived catalytic reaction intermediates, ensure the efficiency and effectiveness of active intermediate product detection, and successfully realize online monitoring of complex species systems in catalytic reactions. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of the present invention;

[0023] Figure 2 It is the test result diagram of the present invention;

[0024] Among them: 1 is a catalytic reactor, 2 is an ionization source cavity, 3 is a vacuum ultraviolet lamp, 4 is an ion repeller electrode, 5 is a curtain electrode, 6 is a hole electrode, 7 is a reaction gas, 8 is a catalyst, 9 is quartz wool, 10 is a heating device, 11 is an O-ring, 12 is a mechanical pump or a molecular pump, 13 is a back-blowing gas, and 14 is a time-of-flight mass spectrometer. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with the accompanying drawings.

[0026] like Figure 1 As shown, the present invention includes a catalytic reactor 1, an ionization source cavity 2, a vacuum ultraviolet lamp 3, an ion repeller electrode 4, a curtain electrode 5, an aperture electrode 6, a heating device 10 and a time-of-flight mass spectrometer 14. The catalytic reactor 1 is sealed and connected to the ionization source cavity 2. The top of the catalytic reactor 1 is opened and filled with a catalyst 8. The bottom of the catalytic reactor 1 is connected to the reaction gas source for introducing the reaction gas 7. The heating device 10 is wrapped around the outside of the catalytic reactor 1. The vacuum ultraviolet lamp 3, the ion repeller electrode 4, the curtain electrode 5 and the aperture electrode 6 are all placed inside the ionization source cavity 2. The aperture electrode 6 of this embodiment is arranged on the cavity wall of the ionization source cavity 2. The ion repeller electrode 4, the curtain electrode 5 and the aperture electrode 6 are arranged in sequence along the light emission direction of the vacuum ultraviolet lamp 3. The top of the catalytic reactor 1 is located between the ion repeller electrode 4 and the curtain electrode 5 and is on the light emitted by the vacuum ultraviolet lamp 3.

[0027] The ion repeller electrode 4 of this embodiment is a flat plate structure with a circular through hole in the middle; the curtain electrode 5 and the hole electrode 6 of this embodiment are both conical structures with a circular through hole in the middle; the optical axis of the light emitted by the vacuum ultraviolet lamp 3 is coaxial with the through holes in the middle of the ion repeller electrode 4, the curtain electrode 5 and the hole electrode 6; the hole electrode 6 is connected to the time-of-flight mass spectrometer 14.

[0028] The catalytic reactor 1 of this embodiment is a hollow quartz tube, sealed to the ionization source chamber 2 via an O-ring 11. A central opening is located at the top of the quartz tube, filled with a catalyst 8. Quartz wool 9 is located within the quartz tube below the catalyst 8, securing the catalyst 8 therein. The axial centerline of the catalytic reactor 1 is perpendicular to the direction of light emission from the vacuum ultraviolet lamp 3. The opening at the top of the catalytic reactor 1 is located adjacent to the curtain electrode 5 and lower than the through-hole in the middle of the curtain electrode 5.

[0029] The heating device 10 of this embodiment is a wound resistance wire or a ceramic heating ring, and the heating temperature range is room temperature to 1000° C. The winding length of the heating device 10 is greater than the filling depth of the catalyst 8 .

[0030] The side wall of the ionization source cavity 2 of this embodiment is connected to a mechanical pump or molecular pump 12, which is located directly above the top opening of the catalytic reactor 1. The cavity pressure of the ionization source cavity 2 ranges from 0.001 Pa to 1000 Pa.

[0031] In this embodiment, there is no or a back-blowing gas 13 between the curtain electrode 5 and the aperture electrode 6 . The back-blowing gas 13 is helium and / or argon, and the flow rate range is 0-20 L / min.

[0032] The vacuum ultraviolet lamp 3 of this embodiment is a gas discharge lamp light source, a laser light source or a synchrotron radiation light source.

[0033] The time-of-flight mass spectrometer 14 of this embodiment is prior art and will not be described in detail here.

[0034] Experimental example

[0035] The reaction gas 7 introduced into the bottom of the catalytic reactor 1 is a mixture of H2 and N2 with a mixing ratio of 3:1. The catalyst 8 is a graphene-confined single-atom iron catalyst. GK (Reference: Ziquan Chen; Yihan Ye; Tao Peng; Chenxin Wu; Haiyang Li; Xiulian Pan; Xinhe Bao; Iron-Single Sites Confined by Graphene Lattice for Ammonia Synthes is under Mild Conditions, ACS Catalysis, 2023, 13: 14385-14394.), the heating temperature of the heating device 10 is 300°C, the gas pressure in the ionization source cavity 2 is controlled to 0.3 Pa by a mechanical pump or a molecular pump 12, no backblowing gas 13 is passed between the curtain electrode 5 and the aperture electrode 6, and the vacuum ultraviolet lamp 3 is a gas discharge lamp light source.

[0036] Catalyst 8 is heated at 300°C to produce ammonia synthesis reaction, generating product NH3. The reaction intermediate N2H2 and product NH3 are ionized into ions under photoionization conditions and enter the time-of-flight mass spectrometer 14 for detection. The detection results are as follows: Figure 2 shown.

Claims

1. A mass spectrometry ionization source device for online monitoring of catalytic reactions, characterized by: It comprises a catalytic reactor (1), an ionization source cavity (2), a vacuum ultraviolet lamp (3), an ion repeller electrode (4), a curtain electrode (5), a hole electrode (6), a heating device (10) and a time-of-flight mass spectrometer (14); The catalytic reactor (1) is sealedly connected to the ionization source cavity (2); the top end of the catalytic reactor (1) is open and filled with a catalyst (8); the bottom end of the catalytic reactor (1) is connected to a reaction gas source for introducing reaction gas (7); and the heating device (10) is wound around the outside of the catalytic reactor (1); The vacuum ultraviolet lamp (3), the ion repeller electrode (4), the curtain electrode (5) and the aperture electrode (6) are all placed inside the ion source cavity (2); the ion repeller electrode (4), the curtain electrode (5) and the aperture electrode (6) are arranged in sequence along the light emission direction of the vacuum ultraviolet lamp (3); the top of the catalytic reactor (1) is located between the ion repeller electrode (4) and the curtain electrode (5), and is located on the light emitted by the vacuum ultraviolet lamp (3); The ion repeller electrode (4) is a flat plate structure with a through hole in the middle; the curtain electrode (5) and the hole electrode (6) are both conical structures with a through hole in the middle; The optical axis of the light emitted by the vacuum ultraviolet lamp (3) is coaxial with the through holes on the ion repeller electrode (4), the curtain electrode (5) and the hole electrode (6); The aperture electrode (6) is connected to a time-of-flight mass spectrometer (14); The top opening of the catalytic reactor (1) is close to the curtain electrode (5) and lower than the through hole on the curtain electrode (5); Back-blowing gas (13) is passed between the curtain electrode (5) and the hole electrode (6), and the back-blowing gas (13) is helium and / or argon, with a flow rate ranging from 0 to 20 L / min.

2. The mass spectrometry ionization source device for online monitoring of catalytic reactions according to claim 1, characterized in that: The winding length of the heating device (10) is greater than the filling depth of the catalyst (8).

3. The mass spectrometry ionization source device for online monitoring of catalytic reactions according to claim 1, characterized in that: The catalytic reactor (1) is a hollow quartz tube, the quartz tube is sealed and connected to the ionization source cavity (2) via an O-ring (11), the top center of the quartz tube is opened, the catalyst (8) is filled in the top of the quartz tube, and quartz wool (9) is provided in the quartz tube at the bottom of the catalyst (8), and the catalyst (8) is fixed by the quartz wool (9).

4. The mass spectrometry ionization source device for online monitoring of catalytic reactions according to claim 1, characterized in that: The axial centerline of the catalytic reactor (1) is perpendicular to the light emission direction of the vacuum ultraviolet lamp (3).

5. The mass spectrometry ionization source device for online monitoring of catalytic reactions according to claim 1, characterized in that: The heating device (10) is a wound resistance wire or a ceramic heating ring, and the heating temperature range is room temperature to 1000°C.

6. The mass spectrometry ionization source device for online monitoring of catalytic reactions according to claim 1, characterized in that: The side wall of the ionization source cavity (2) is connected to a mechanical pump or a molecular pump (12), and the mechanical pump or the molecular pump (12) is located directly above the opening of the catalytic reactor (1). The cavity pressure range of the ionization source cavity (2) is 0.001 to 1000 Pa.

7. The mass spectrometry ionization source device for online monitoring of catalytic reactions according to claim 1, characterized in that: The vacuum ultraviolet lamp (3) is a gas discharge lamp light source, a laser light source or a synchrotron radiation light source.

8. The mass spectrometry ionization source device for online monitoring of catalytic reactions according to claim 1, characterized in that: The through holes on the ion repeller electrode (4), the curtain electrode (5) and the hole electrode (6) are all circular holes and are all opened in the middle.

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