System and method for preparing olefin through oxygen-free dehydrogenation of light alkane through micro photocatalysis

Abstract

The invention relates to a system and a method for preparing olefin by anaerobic dehydrogenation of light alkane through micro photocatalysis, and belongs to the technical field of photocatalysis energy conversion, the system comprises a reaction atmosphere regulation and control system, a photocatalysis reaction-catalyst regeneration circulation system, a gas switching system and a product detection system which are communicated in sequence; the photocatalytic reaction-catalyst regeneration cycle system comprises a plurality of groups of light sources and quartz reactors, the quartz reactors are used for loading a catalyst and quartz sand, and the reaction atmosphere regulation and control system is used for conveying atmosphere into the quartz reactors. And the gas switching system is used for transmitting a product of the quartz reactor to the product detection system. According to the system and the method disclosed by the invention, the alternate synergistic circulation of the photo-catalytic alkane anaerobic dehydrogenation reaction and the catalyst in-situ regeneration is realized, and the continuous flow alkane anaerobic dehydrogenation high-selectivity olefin preparation reaction and the catalyst rapid in-situ regeneration are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of photocatalytic energy conversion, and in particular to a system and method for producing olefins by micro-photocatalytic oxygen-free dehydrogenation of low-carbon alkanes. Background Art

[0002] The traditional route for converting alkanes to olefins is to subject crude oil or naphtha to high-temperature steam cracking and thermal catalytic cracking. The reaction conditions are relatively harsh and have the characteristics of high cost and high energy consumption. In addition, the high temperature causes the catalyst to easily deposit carbon, thereby reducing the catalytic efficiency. In recent years, photocatalytic technology has shown great vitality in the dehydrogenation of alkanes (including aerobic dehydrogenation and anaerobic dehydrogenation). Light can reduce the energy barrier of the rate-limiting step of the catalytic reaction, or change the adsorption and desorption behavior of the reaction intermediates on the catalyst surface, thereby changing the reaction selectivity. Therefore, compared with thermal catalysis, the catalyst can show higher activity and ideal selectivity under solar-driven conditions, fundamentally reducing energy consumption and production costs.

[0003] Generally, the process of catalytic dehydrogenation of low-carbon alkanes into olefins of the same carbon requires the participation of O2 and the generation of water to complete the periodic reaction cycle. However, the aerobic dehydrogenation of alkanes with the participation of molecular oxygen can easily lead to over-oxidation of alkanes or product olefins, that is, the combustion of alkanes and olefins to generate CO, CH4 or CO2, which greatly reduces the yield and selectivity of the target product olefins; at the same time, the aerobic dehydrogenation reaction of alkanes releases a large amount of heat, which can easily lead to reactor runaway; furthermore, due to the flammability of alkane-oxygen mixtures, conventional oxygen co-feed catalytic systems have serious safety hazards and require expensive air separation devices to provide oxygen on site.

[0004] Compared with aerobic dehydrogenation, the oxygen-free dehydrogenation of alkanes can effectively inhibit over-oxidation and improve the selectivity of product olefins; however, the oxygen-free dehydrogenation of alkanes faces serious problems such as catalyst carbon deposition and catalyst sintering under high temperature conditions, which makes the catalyst easily deactivated. In addition, alkanes can also react with the lattice oxygen of metal oxide catalysts to partially oxidize on the catalyst surface, avoiding the direct participation of oxygen in the alkane oxidative dehydrogenation reaction process, which reduces production costs and improves the safety of the reaction system.

[0005] Using the lattice oxygen of oxides to catalyze the anaerobic dehydrogenation of low-carbon alkanes under anaerobic and light conditions can significantly improve the selectivity of olefins with the same carbon number. However, due to the uninterrupted participation in the oxidative dehydrogenation reaction, the lattice oxygen of the catalyst is gradually consumed, resulting in catalyst deactivation.

[0006] In view of the above-mentioned technical phenomena, the inventors have invented a micro-continuous photocatalytic dehydrogenation of low-carbon alkanes to olefins - catalyst in-situ regeneration system and method to achieve an efficient cycle of low-carbon alkane oxygen-free dehydrogenation reaction and catalyst in-situ regeneration. Summary of the invention

[0007] The object of the present invention is to provide a system and method for micro-photocatalytic oxygen-free dehydrogenation of light alkanes to produce olefins, so as to realize an efficient cycle of oxygen-free dehydrogenation reaction of light alkanes and in-situ regeneration of catalysts.

[0008] The present invention provides a micro-photocatalytic system for oxygen-free dehydrogenation of low-carbon alkanes to olefins, which adopts the following technical solution: A micro photocatalytic system for oxygen-free dehydrogenation of low-carbon alkanes to olefins, comprising a reaction atmosphere control system, a photocatalytic reaction-catalyst regeneration circulation system, a gas switching system and a product detection system which are sequentially connected and arranged; The photocatalytic reaction-catalyst regeneration circulation system includes a light source and a quartz reactor, and the light source and the quartz reactor are arranged in multiple groups. The quartz reactor is used to load the catalyst and quartz sand, the reaction atmosphere control system is used to transport the atmosphere into the quartz reactor, and the gas switching system is used to transmit the product of the quartz reactor to the product detection system.

[0009] Preferably, the reaction atmosphere control system comprises at least one set of first valve bodies, and the first valve bodies are any one of a three-way valve, a four-way valve or a six-way valve; The gas switching system includes at least one set of second valve bodies, and the second valve bodies are any one of three-way valves, four-way valves or six-way valves.

[0010] Preferably, when the photocatalytic reaction-catalyst regeneration circulation system includes two groups of quartz reactors, the reaction atmosphere control system includes a group of first valve bodies, the gas switching system includes a group of second valve bodies, and the light source is arranged above each group of quartz reactors; A group of valve ports of the first valve body is used to deliver alkane dehydrogenation reaction gas to a group of quartz reactors, and a group of valve ports of the second valve body delivers alkane oxygen-free dehydrogenation reaction products to a product detection system; Another group of valve ports of the first valve body is used to deliver air to another group of quartz reactors for reducing the catalysts in the quartz reactors.

[0011] Preferably, when the photocatalytic reaction-catalyst regeneration circulation system includes three groups of quartz reactors, the reaction atmosphere control system includes two groups of first valve bodies, the gas switching system includes two groups of second valve bodies, and the light source is provided in multiple groups, and the multiple groups of light sources are respectively arranged above each group of quartz reactors; One set of valve ports of the two sets of the first valve bodies is used to deliver alkane dehydrogenation reaction gas to a set of quartz reactors, and one set of valve ports of the two sets of the second valve bodies delivers alkane oxygen-free dehydrogenation reaction products to a product detection system; One group of valve ports of the two groups of the first valve bodies is used to deliver argon gas into one group of quartz reactors for purging the quartz reactors; One group of valve ports of the two groups of the first valve bodies is used to transport air into one group of quartz reactors for reducing the catalyst in the quartz reactors.

[0012] Preferably, the quartz reactor includes any one of a serpentine reactor, an elliptical reactor or a rectangular reactor.

[0013] Preferably, the light source is any one of a xenon lamp, a mercury lamp or an LED lamp.

[0014] Preferably, the product detection system comprises either gas chromatography or liquid chromatography.

[0015] The present invention also provides a method for preparing olefins by micro-photocatalytic oxygen-free dehydrogenation of low-carbon alkanes, which uses the above-mentioned system for preparing olefins by micro-photocatalytic oxygen-free dehydrogenation of low-carbon alkanes, comprising the following steps: S1. Connecting the reaction atmosphere control system, the photocatalytic reaction-catalyst regeneration circulation system, the gas switching system and the product detection system end to end in sequence, wherein the quartz reactor in the photocatalytic reaction-catalyst regeneration circulation system is loaded with catalyst and quartz sand, and a light source is arranged above each group of quartz reactors; S2, turning on the light source, opening a group of valve ports of the first valve body, introducing alkane dehydrogenation reaction gas into a group of quartz reactors to carry out a photocatalytic alkane dehydrogenation reaction gas dehydrogenation reaction, opening a group of valve ports of the second valve body to transport the product of the photocatalytic alkane dehydrogenation reaction gas dehydrogenation reaction to the product detection system for online analysis, and at the same time, opening another group of valve ports of the first valve body to introduce air into another group of quartz reactors, and opening another group of valve ports of the second valve body to exhaust the air in the other group of quartz reactors; S3, 10 minutes later, the first valve body and the second valve body in the reaction atmosphere control system and the gas switching system are switched simultaneously, a group of valve ports of the first valve body conveys air to the quartz reactor where the photocatalytic alkane dehydrogenation reaction gas dehydrogenation reaction is completed to perform in-situ regeneration of the catalyst, and a group of valve ports of the second valve body is used to exhaust the air of the quartz reactor where the photocatalytic alkane dehydrogenation reaction gas dehydrogenation reaction is completed; another group of valve ports of the first valve body conveys alkane dehydrogenation reaction gas to another group of quartz reactors to perform photocatalytic alkane dehydrogenation reaction gas dehydrogenation reaction, and another group of valve ports of the second valve body conveys the product of the photocatalytic alkane dehydrogenation reaction gas dehydrogenation reaction to the product detection system for online analysis; S4. After 10 minutes, repeat steps S2 and S3, and repeat the cycle.

[0016] Preferably, the quartz reactors in step S1 include at least two groups.

[0017] Preferably, the catalyst in step S1 is any one of a CuO catalyst and a MnCo2O4 catalyst; The quartz sand in step S1 is 40-60 mesh; The mass ratio of the catalyst to quartz sand is 1:(1-2).

[0018] In summary, the present invention includes the following beneficial technical effects: 1. The reaction atmosphere system in the system of the present application is used to control the atmosphere of the photocatalytic low-carbon alkane oxygen-free dehydrogenation reaction and the in-situ regeneration of the photocatalyst, that is, through the reaction atmosphere control system, the alkane dehydrogenation reaction gas and the catalyst regeneration gas are alternately fed into different quartz reactors through gas pipelines to complete the photocatalytic reaction or the in-situ regeneration of the catalyst. The gas switching system controls the alkane oxygen-free dehydrogenation reaction product to continuously perform online analysis to determine the photocatalytic reaction efficiency, product selectivity and catalyst stability, and realize continuous flow photocatalytic alkane dehydrogenation to olefins. The present application realizes the alternating synergistic cycle of photocatalytic alkane oxygen-free dehydrogenation reaction and catalyst in-situ regeneration, does not require the replacement of the photocatalyst, does not use an additional catalyst regeneration device, and avoids repeated disassembly and installation of the quartz reactor, which is convenient for practical use, improves the photocatalytic efficiency, and realizes the continuous flow alkane oxygen-free dehydrogenation reaction with high selectivity to olefins and the rapid in-situ regeneration of the catalyst.

[0019] 2. The method in the present application includes regulating the atmosphere delivered to the photocatalytic reaction-catalyst in-situ regeneration circulation system through a reaction atmosphere control system, and the atmosphere enters multiple groups of quartz reactors through the reaction atmosphere control system to achieve alternating and coordinated circulation of photocatalytic anaerobic dehydrogenation of alkanes to olefins and in-situ regeneration of catalysts (or introducing gas pipelines and reactors in an inert gas purge device); through a product control system, the alkane product is continuously fed into a product detection system for online analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic structural diagram of a micro-photocatalytic system for oxygen-free dehydrogenation of low-carbon alkanes to olefins in Example 1 of the present invention.

[0021] Figure 2 It is a schematic structural diagram of a micro-photocatalytic system for oxygen-free dehydrogenation of low-carbon alkanes to olefins in Example 2 of the present invention.

[0022] Figure 3 It is a schematic diagram of the photocatalytic CuO ethane dehydrogenation performance in Example 1 of the present invention.

[0023] Figure 4 It is a schematic diagram of the photocatalytic MnCo2O4 propane dehydrogenation performance in Example 2 of the present invention.

[0024] Explanation of the accompanying drawings: 1. Reaction atmosphere control system; 11. First valve body; 2. Photocatalytic reaction-catalyst regeneration circulation system; 21. Quartz reactor; 22. Light source; 3. Gas switching system; 31. Second valve body; 4. Product detection system. DETAILED DESCRIPTION

[0025] The following is combined with the embodiments and the attached Figure 1-4 The present invention is described in further detail.

[0026] The present invention provides a micro-photocatalytic system for the oxygen-free dehydrogenation of low-carbon alkanes to olefins. Figure 1 and Figure 2 , including a reaction atmosphere control system 1, a photocatalytic reaction-catalyst regeneration circulation system 2, a gas switching system 3 and a product detection system 4 which are connected in sequence; the reaction atmosphere control system 1 is used to control the atmosphere to the photocatalytic reaction-catalyst regeneration circulation system 2, the photocatalytic reaction-catalyst regeneration circulation system 2 is used for photocatalytic reaction or in-situ regeneration of the catalyst, and the gas switching system 3 is used to control the continuous delivery of the alkane oxygen-free dehydrogenation reaction products to the product detection system 4 for online analysis, so as to determine the photocatalytic reaction efficiency, product selectivity and catalyst stability, and realize continuous flow photocatalytic dehydrogenation of alkanes to olefins.

[0027] Reference Figure 1 and Figure 2 The photocatalytic reaction-catalyst regeneration circulation system 2 includes a light source 22 and a quartz reactor 21. The quartz reactor 21 in this embodiment is an existing conventional device. The quartz reactor 21 includes any one of a serpentine reactor, an elliptical reactor or a rectangular reactor for loading the catalyst and quartz sand to enhance the contact area between the catalyst and the alkane dehydrogenation reaction gas. The catalyst can be any one of transition metal oxide semiconductors. The catalyst in this embodiment is preferably any one of CuO catalyst and MnCo2O4 catalyst. The light source 22 irradiates the quartz reactor 21. The light source 22 in the embodiment is any one of a xenon lamp, a mercury lamp or an LED lamp; the reaction atmosphere control system 1 is used to transport the atmosphere into the quartz reactor 21 so that the anaerobic dehydrogenation reaction of alkanes is carried out in the quartz reactor 21. The light source 22 and the quartz reactor 21 are provided in multiple groups. The specific number of the light source 22 and the quartz reactor 21 in this embodiment is determined according to experiments; the gas switching system 3 is used to transmit the product passing through the quartz reactor 21 to the product detection system 4. The product detection system 4 includes any one of gas chromatography or liquid chromatography. The product detection system 4 in this embodiment is a gas chromatography-mass spectrometer.

[0028] Reference Figure 1 and Figure 2The reaction atmosphere control system 1 includes at least one first valve body 11, which is any one of a three-way valve, a four-way valve or a six-way valve; the gas switching system 3 includes at least one second valve body 31, which is any one of a three-way valve, a four-way valve or a six-way valve.

[0029] Reference Figure 1 In this embodiment, two groups of quartz reactors 21 are provided, and a light source 22 is provided above each group of quartz reactors 21; the reaction atmosphere control system 1 includes a group of first valve bodies 11, and the first valve bodies 11 in this embodiment are selected as four-way valves, and the gas switching system 3 includes a group of second valve bodies 31, and the second valve bodies 31 in this embodiment are selected as four-way valves. A group of valve ports of the first valve body 11 is used to deliver alkane dehydrogenation reaction gas to a group of quartz reactors 21, and a group of valve ports of the second valve body 31 delivers the alkane oxygen-free dehydrogenation reaction product to the product detection system 4; and another group of valve ports of the first valve body 11 is used to deliver air to another group of quartz reactors 21 for reducing the catalyst in another group of quartz reactors 21, and another group of valve ports of the second valve body 31 is used to exhaust the air in the quartz reactor 21.

[0030] Reference Figure 2 In this embodiment, three groups of quartz reactors 21 are provided, and two groups of light sources 22 are provided. The two groups of light sources 22 are respectively located above each group of quartz reactors 21; the reaction atmosphere control system 1 includes two groups of first valve bodies 11, and the first valve bodies 11 in this embodiment are selected as six-way valves. The gas switching system 3 includes two groups of second valve bodies 31, and the second valve bodies 31 in this embodiment are selected as four-way valves. The two groups of valve ports respectively located in the two groups of first valve bodies 11 are connected to convey the alkane dehydrogenation reaction gas to one of the groups of quartz reactors 21, and the two groups of valve ports respectively located in the two groups of second valve bodies 31 are connected to convey the alkane oxygen-free dehydrogenation reaction product to the product detection system 4; the second groups of valve ports respectively located in the two groups of first valve bodies 11 are connected to convey argon gas to the second group of quartz reactors 21 for purging the quartz reactors 21, and a group of valve ports of the second valve body 31 discharges the purge gas; the third groups of valve ports respectively located in the two groups of first valve bodies 11 are connected to convey air to the third group of quartz reactors 21 for reducing the catalyst in the quartz reactors 21, and a group of valve ports of the second valve body 31 discharges the air in the third group of quartz reactors 21.

[0031] The present invention also provides a method for preparing olefins by the anaerobic dehydrogenation of low-carbon alkanes through micro-photocatalysis, which adopts the system for preparing olefins by the anaerobic dehydrogenation of low-carbon alkanes through the micro-photocatalysis.

[0032] Test Example 1 A method for using a micro-photocatalytic low-carbon alkane dehydrogenation system to produce olefins, referring to Figure 1 and Figure 3 , including the following steps: S1, the reaction atmosphere control system 1, the photocatalytic reaction-catalyst regeneration circulation system 2, the gas switching system 3 and the product detection system 4 are connected end to end in sequence, the reaction atmosphere control system 1 in this test example includes a group of first valve bodies 11, the first valve body 11 is selected as a four-way valve, the photocatalytic reaction-catalyst regeneration circulation system 2 includes two groups of quartz reactors 21, the quartz reactors 21 are loaded with 0.15g catalyst and 0.2g quartz sand, the catalyst is selected as CuO catalyst, the quartz sand is 40-60 mesh, the light source 22 is arranged above each group of quartz reactors 21, the light source 22 adopts an LED lamp with a wavelength of 365nm, and the position of the light source 22 is adjusted so that it converges directly above the quartz reactor 21, and the gas switching system 3 includes a group of second valve bodies 31, and the second valve body 31 is selected as a four-way valve; S2, turn on the light source 22, open the two groups of valve ports of the first valve body 11, under the action of the airflow, one group of valve ports of the first valve body 11 is used to pass alkane dehydrogenation reaction gas into one group of quartz reactors 21. The alkane dehydrogenation reaction gas in this test example is ethane, and the photocatalytic alkane dehydrogenation reaction gas dehydrogenation reaction is carried out in the quartz reactor 21. The second valve body 31 is opened. A group of valve ports connected to the output end of the quartz reactor 21 is opened to transport the product of the photocatalytic alkane dehydrogenation reaction gas dehydrogenation reaction to the product detection system 4 for online analysis (i.e., A1→A2→R1→C1→C2→GCMS); at the same time, another group of valve ports of the first valve body 11 is passing air into another group of quartz reactors 21 to reduce the catalyst in the other group of quartz reactors 21. The second valve body 31 is opened. Another group of valve ports connected to the quartz reactor 21 is opened to exhaust the air in the other group of quartz reactors 21 (i.e., A3→A4→R2→C3→C4); S3, 10 minutes later, the first valve body 11 and the second valve body 31 in the reaction atmosphere control system 1 and the gas switching system 3 are switched simultaneously, a group of valve ports of the first valve body 11 conveys air to the quartz reactor 21 where the dehydrogenation reaction of the photocatalytic alkane dehydrogenation reaction gas is completed to perform in-situ regeneration of the catalyst, and a group of valve ports of the second valve body 31 is used to exhaust the air of the quartz reactor 21 where the dehydrogenation reaction of the photocatalytic alkane dehydrogenation reaction gas is completed; another group of valve ports of the first valve body 11 conveys alkane dehydrogenation reaction gas to another group of quartz reactors 21 to perform dehydrogenation reaction of the photocatalytic alkane dehydrogenation reaction gas, and another group of valve ports of the second valve body 31 conveys the product of the dehydrogenation reaction of the photocatalytic alkane dehydrogenation reaction gas to the product detection system 4 for online analysis; S4. After 10 minutes, repeat steps S2 and S3, and repeat the cycle.

[0033] In this test example, the first valve body 11 is marked as A, and the four groups of valve ports of the first valve body 11 are marked as A1, A2, A3, and A4; the two groups of reactors are marked as R1 and R2 respectively; the second valve body 31 is marked as B, and the four groups of valve ports of the second valve body 31 are marked as B1, B2, B3, and B4; the product detection system 4 is marked as GCMS.

[0034] Test Example 2 A method for using a micro-photocatalytic low-carbon alkane dehydrogenation system to produce olefins, referring to Figure 2 and Figure 4 , including the following steps: S1, the reaction atmosphere control system 1, the photocatalytic reaction-catalyst regeneration circulation system 2, the gas switching system 3 and the product detection system 4 are connected end to end in sequence, the reaction atmosphere control system 1 in this test example includes two groups of first valve bodies 11, the two groups of first valve bodies 11 are selected as six-way valves, the photocatalytic reaction-catalyst regeneration circulation system 2 includes three groups of quartz reactors 21, the quartz reactors 21 are loaded with 0.2g catalyst and 0.2g quartz sand, the catalyst is selected as MnCo2O4 catalyst, the quartz sand is 40-60 mesh, the light source 22 is arranged above each group of quartz reactors 21, the light source 22 uses a full-band light source, in this test example, it is a 300 W xenon lamp, the position of the light source 22 is adjusted so that it converges directly above the quartz reactor 21, the gas switching system 3 includes two groups of second valve bodies 31, the second valve body 31 is selected as a four-way valve; S2, turn on the light source 22, open the three valve ports of the two groups of first valve bodies 11, under the action of the airflow, the first valve ports of the two groups of first valve bodies 11 are connected to the first group of quartz reactors 21 to introduce propane, and the photocatalytic alkane dehydrogenation reaction gas dehydrogenation reaction is carried out in the quartz reactor 21, and the valve ports of the two groups of second valve bodies 31 connected to the output end of the first group of quartz reactors 21 are opened to transport the product of the photocatalytic alkane dehydrogenation reaction gas dehydrogenation reaction to the product detection system 4 for online analysis (i.e., A2→A1→B1→B2→R1→C2→C1→D1→D2→GCMS); at the same time, the second valve ports of the two groups of first valve bodies 11 are feeding the second group of quartz reactors 2 1, argon is introduced into the second group of quartz reactors 21 to purge, and a group of valve ports of the second valve body 31 connected to the second group of quartz reactors 21 is opened to discharge the argon in the second group of quartz reactors 21 (i.e., A4→A3→B3→B4→R2→C4→C3); at the same time, the third groups of valve ports of the two groups of first valve bodies 11 are introducing air into the third group of quartz reactors 21 to reduce the catalyst in the third group of quartz reactors 21, and the valve ports of the second valve body 31 connected to the third group of quartz reactors 21 are opened to discharge the air in the third group of quartz reactors 21 (i.e., A6→A5→B5→B6→R3→D3→D4); S3, 10 minutes later, switch one of the first valve bodies 11 and the second valve body 31 to introduce air into the first quartz reactor 21 for catalyst reduction (i.e. A6→A1→B1→B2→R1→C2→C3); introduce propane into the second quartz reactor 21 for photocatalytic propane oxygen-free dehydrogenation reaction, and then pump the product into the product detection system 4 for online analysis through the gas switching system 3 (i.e. A2→A3→B3→B4→R2→C4→C1→D1→D2→GC); introduce argon into the third quartz reactor 21 for purging (i.e. A4→A5→B5→B6→R3→C2→C4→D3); S4, 10 minutes later, switch one group of the first valve body 11 and the second valve body 31 to the default state, and switch the other group of the first valve body 11 and the second valve body 31, introduce argon into the first group of reactors for purging (i.e. A4→A3→B3→B2→R1→C2→C1→D1→D4); introduce air into the second group of reactors for catalyst reduction (i.e. A6→A5→B5→B4→R2→C4→C3); introduce propane into the third group of reactors for photocatalytic propane oxygen-free dehydrogenation reaction (i.e. A1→A1→B1→B6→R3→D3→C2→GCMS); S5. After 10 minutes, switch another set of the first valve body 11 and the second valve body 31 to the default state, repeat the operations of step S2, step S3 and step S4, and perform multiple cycle reactions.

[0035] In this test example, the two groups of first valve bodies 11 are marked as A and B respectively, the four groups of valve ports of A are marked as A1, A2, A3, A4, A5, A6, and the four groups of valve ports of B are marked as A1, A2, A3, A4, A5, B6; the three groups of reactors are marked as R1, R2, R3; the two groups of second valve bodies 31 are marked as C and D respectively, the four groups of valve ports of C are marked as C1, C2, C3, C4, and the four groups of valve ports of D are marked as D1, D2, D3, D4; the product detection system 4 is marked as GCMS.

[0036] The above are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A micro-photocatalytic system for oxygen-free dehydrogenation of low-carbon alkanes to olefins, characterized in that: It comprises a reaction atmosphere control system (1), a photocatalytic reaction-catalyst regeneration circulation system (2), a gas switching system (3) and a product detection system (4) which are connected in sequence; The photocatalytic reaction-catalyst regeneration circulation system (2) comprises a light source (22) and a quartz reactor (21), wherein the light source (22) and the quartz reactor (21) are provided in multiple groups, the quartz reactor (21) is used to load the catalyst and quartz sand, the reaction atmosphere control system (1) is used to transport the atmosphere into the quartz reactor (21), and the gas switching system (3) is used to transmit the product of the quartz reactor (21) to the product detection system (4).

2. A micro photocatalytic system for oxygen-free dehydrogenation of low-carbon alkanes to olefins according to claim 1, characterized in that: The reaction atmosphere control system (1) comprises at least one first valve body (11), wherein the first valve body (11) is any one of a three-way valve, a four-way valve or a six-way valve; The gas switching system (3) comprises at least one set of second valve bodies (31), wherein the second valve bodies (31) are any one of a three-way valve, a four-way valve or a six-way valve.

3. A micro photocatalytic system for oxygen-free dehydrogenation of low-carbon alkanes to olefins according to claim 2, characterized in that: In a state where the photocatalytic reaction-catalyst regeneration circulation system (2) includes two groups of quartz reactors (21), the reaction atmosphere control system (1) includes a group of first valve bodies (11), the gas switching system (3) includes a group of second valve bodies (31), and the light source (22) is arranged above each group of quartz reactors (21); A group of valve ports of the first valve body (11) is used to transport alkane dehydrogenation reaction gas into a group of quartz reactors (21), and a group of valve ports of the second valve body (31) transports alkane oxygen-free dehydrogenation reaction products to a product detection system (4); Another group of valve ports of the first valve body (11) is used to transport air into another group of quartz reactors (21) for reducing the catalyst in the quartz reactors (21).

4. The micro photocatalytic system for oxygen-free dehydrogenation of low-carbon alkanes to olefins according to claim 2, characterized in that: In a state where the photocatalytic reaction-catalyst regeneration circulation system (2) includes three groups of quartz reactors (21), the reaction atmosphere control system (1) includes two groups of first valve bodies (11), the gas switching system (3) includes two groups of second valve bodies (31), and a plurality of groups of light sources (22) are provided, and the plurality of groups of light sources (22) are respectively provided above each group of quartz reactors (21); One set of valve ports of the two sets of the first valve bodies (11) is used to transport alkane dehydrogenation reaction gas into a set of quartz reactors (21), and one set of valve ports of the two sets of the second valve bodies (31) transports alkane oxygen-free dehydrogenation reaction products to a product detection system (4); A group of valve ports of the two groups of the first valve bodies (11) is used to deliver argon gas into a group of quartz reactors (21) for purging the quartz reactors (21); One set of valve ports of the two sets of the first valve bodies (11) is used to transport air into one set of quartz reactors (21) for reducing the catalyst in the quartz reactors (21).

5. The micro photocatalytic system for oxygen-free dehydrogenation of low-carbon alkanes to olefins according to claim 1, characterized in that: The quartz reactor (21) comprises any one of a serpentine reactor, an elliptical reactor or a rectangular reactor.

6. The micro photocatalytic system for oxygen-free dehydrogenation of low-carbon alkanes to olefins according to claim 1, characterized in that: The light source (22) is any one of a xenon lamp, a mercury lamp or an LED lamp.

7. The micro photocatalytic system for oxygen-free dehydrogenation of low-carbon alkanes to olefins according to claim 1, characterized in that: The product detection system (4) includes either gas chromatography or liquid chromatography.

8. A method for preparing olefins by micro-photocatalytic oxygen-free dehydrogenation of low-carbon alkanes, characterized in that: The system for producing olefins by dehydrogenation of low-carbon alkanes using a micro-photocatalytic method as claimed in any one of claims 1 to 7 comprises the following steps: S1, connecting the reaction atmosphere control system (1), the photocatalytic reaction-catalyst regeneration circulation system (2), the gas switching system (3) and the product detection system (4) end to end in sequence, wherein the quartz reactor (21) in the photocatalytic reaction-catalyst regeneration circulation system (2) is loaded with a catalyst and quartz sand, and a light source (22) is arranged above each group of quartz reactors (21); S2, turning on the light source (22), opening a group of valve ports of the first valve body (11), introducing alkane dehydrogenation reaction gas into a group of quartz reactors (21) to carry out a photocatalytic alkane dehydrogenation reaction gas dehydrogenation reaction, opening a group of valve ports of the second valve body (31) to transport the product of the photocatalytic alkane dehydrogenation reaction gas dehydrogenation reaction to the product detection system (4) for online analysis, and at the same time, opening another group of valve ports of the first valve body (11) to introduce air into another group of quartz reactors (21), and opening another group of valve ports of the second valve body (31) to exhaust the air in the other group of quartz reactors (21); S3. After 10 minutes, the first valve body (11) and the second valve body (31) in the reaction atmosphere control system (1) and the gas switching system (3) are switched simultaneously. A group of valve ports of the first valve body (11) transports air into the quartz reactor (21) where the photocatalytic alkane dehydrogenation reaction gas dehydrogenation reaction is completed to perform in-situ regeneration of the catalyst. A group of valve ports of the second valve body (31) is used to exhaust the air in the quartz reactor (21) where the photocatalytic alkane dehydrogenation reaction gas dehydrogenation reaction is completed. Another group of valve ports of the first valve body (11) transports alkane dehydrogenation reaction gas into another group of quartz reactors (21) to perform a photocatalytic alkane dehydrogenation reaction gas dehydrogenation reaction. Another group of valve ports of the second valve body (31) transports the product of the photocatalytic alkane dehydrogenation reaction gas dehydrogenation reaction to the product detection system (4) for online analysis. S4. After 10 minutes, repeat steps S2 and S3, and repeat the cycle.

9. The method of micro-photocatalytic oxygen-free dehydrogenation of low-carbon alkanes to olefins according to claim 8, characterized in that: The quartz reactor (21) in step S1 comprises at least two groups.

10. The method of micro photocatalytic oxygen-free dehydrogenation of low-carbon alkanes to olefins according to claim 8, characterized in that: The catalyst in step S1 is any one of a CuO catalyst and a MnCo2O4 catalyst; The quartz sand in step S1 is 40-60 mesh; The mass ratio of the catalyst to quartz sand is 1:(1-2).

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