Mass spectrum ionization source device for catalytic reaction on-line monitoring

Abstract

The invention belongs to the technical field of mass spectrum analyzers, and particularly relates to a catalytic reaction on-line monitoring mass spectrum ionization source device, a catalytic reactor is hermetically connected with an ionization source cavity, the top end of the catalytic reactor is provided with a hole and is filled with a catalyst, the bottom end of the catalytic reactor is connected with a reaction gas source and is used for introducing reaction gas, and the ionization source cavity is provided with a gas inlet; the heating device is wound outside the catalytic reactor; the vacuum ultraviolet lamp, the ion repulsion electrode, the curtain electrode and the hole electrode are all placed in the ionization source cavity, the ion repulsion electrode, the curtain electrode and the hole electrode are sequentially arranged in the light emitting direction of the vacuum ultraviolet lamp, and the top of the catalytic reactor is located between the ion repulsion electrode and the curtain electrode and located on light emitted by the vacuum ultraviolet lamp. The mass spectrum interface of the catalytic reactor designed by the invention can avoid secondary reaction of a short-life catalytic reaction intermediate, ensure the efficiency and effectiveness of active intermediate product detection, and successfully realize on-line monitoring of a catalytic reaction complex species system.

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 of catalysts, and some also involve unstable gas-phase intermediates such as free radicals and alkyl hydroperoxides. Online detection of gas-phase intermediates is of great significance for fundamentally understanding the reaction mechanism of related catalytic reactions, designing efficient catalyst structures, and optimizing reactors. However, due to the lack of conventional detection technology, 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, high sensitivity in detecting ion species, and relatively easy to judge 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 objective of the present invention is achieved through the following technical solutions:

[0006] The 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 a reaction gas source for introducing reaction gas. The heating device is wound 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 hole 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 control body through an O-ring. The top center of the quartz tube has a hole, the catalyst is filled in the top of the quartz tube, and quartz wool is arranged 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, and 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 directly above the opening of the catalytic reactor. The cavity pressure range of the ionization source cavity is 0.001-1000Pa.

[0017] There is no or a back-blowing gas between the curtain electrode and the hole electrode, and 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] Wherein: 1 is a catalytic reactor, 2 is an ion 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 a reaction gas source for introducing a reaction gas 7. 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 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 emitting 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.

[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 hole 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, which is sealed and connected to the ionization source control body 2 through an O-ring 11. The top center of the quartz tube has a hole, and the catalyst 8 is filled in the top of the quartz tube. Quartz wool 9 is arranged in the quartz tube at the bottom of the catalyst 8, and the catalyst 8 is fixed by the quartz wool 9. The axial center line of the catalytic reactor 1 is perpendicular to the light emission direction of the vacuum ultraviolet lamp 3, and the top hole of the catalytic reactor 1 is close 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 a molecular pump 12, and the mechanical pump or the molecular pump 12 is located just above the top opening of the catalytic reactor 1. The cavity pressure range of the ionization source cavity 2 is 0.001-1000Pa.

[0031] In this embodiment, there is no or a back-blowing gas 13 between the curtain electrode 5 and the hole electrode 6 . The back-blowing gas 13 is helium and / or argon, and the flow rate range is 0 to 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 a 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, the mixing ratio of which is 3:1, and the catalyst 8 is a graphene-confined single-atom iron catalyst. GK (Reference: Ziquan Chen; Yihan Ye; Tao Peng; Chenxin Wu; Haiyang Li; Xiu ian 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 be 0.3 Pa by a mechanical pump or a molecular pump 12, there is no backblowing gas 13 between the curtain electrode 5 and the hole electrode 6, and the vacuum ultraviolet lamp 3 is a gas discharge lamp light source.

[0036] Catalyst 8 undergoes ammonia synthesis reaction under heating conditions at 300°C to generate 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 in that: 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 a 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).

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 control body (2) via an O-ring (11), the top center of the quartz tube has a hole, the catalyst (8) is filled in the top of the quartz tube, and quartz wool (9) is arranged 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), and 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).

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 from 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 gas pressure range of the ionization source cavity (2) is 0.001-1000 Pa.

7. The mass spectrometry ionization source device for online monitoring of catalytic reactions according to claim 1, characterized in that: There is or there is back-blowing gas (13) between the curtain electrode (5) and the hole electrode (6); the back-blowing gas (13) is helium and / or argon, and the flow rate range is 0 to 20 L / min.

8. 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.

9. 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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