Micro-channel reactor for generating hydrogen peroxide through direct reaction of hydrogen and oxygen

Abstract

The invention discloses a micro-channel reactor for directly reacting hydrogen and oxygen to generate hydrogen peroxide. The micro-channel reactor comprises a reaction cavity, a gas channel, an inlet pipe, an outlet pipe, a reaction diffusion layer and a gas-liquid mixed-flow pump, a reaction diffusion layer is arranged in the middle of the reaction cavity, the reaction diffusion layer divides the reaction cavity into a first chamber and a second chamber, and gas channels are arranged in the first chamber or the second chamber; a catalyst for generating hydrogen peroxide through hydrogen-oxygen reaction is loaded in the reaction diffusion layer; the fluid in the gas channel enters the first chamber and the second chamber and then is diffused to the reaction diffusion layer through the gas channel for reaction; the first cavity and the second cavity are each provided with an inlet pipe, and the first cavity and the second cavity are each provided with an outlet pipe. According to the reactor, hydrogen and oxygen are respectively introduced from two sides, so that the explosion danger of gas is greatly reduced, and the reaction safety is improved; the product can enter the chamber to react again, so that the effect of accumulating the concentration of the product is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of microchannel reactor devices, and more particularly to a microchannel reactor for directly reacting hydrogen and oxygen to generate hydrogen peroxide. Background Art

[0002] The chemical industry plays a pivotal role in my country's national economy and is a pillar of its economy. For nearly a century, driven by the enormous economic benefits of scale, the chemical industry has tended toward large-scale development. This has led to significant equipment investment and long construction cycles, as well as persistent challenges such as severe environmental pollution, high energy consumption, and safety concerns. Therefore, accelerating the transformation and upgrading of the chemical industry toward high-end, green, and intelligent development remains a long and arduous task. Greening is a key policy for sustainable development. Its essence lies in developing green chemistry. This involves continuously overcoming technological challenges, developing high-end, green products, and developing green technologies with independent intellectual property rights, thereby developing green products (Garcia-Serna J, Perez-Barrigon L, Cocero M J. New trends for design towards sustainability in chemical engineering: Green engineering [J]. Chemical Engineering Journal, 2007, 133(1-3): 7-30.), (Geng Z, Li H, Zhu Q, et al. Production prediction and energy-saving model based on Extreme Learning Machine integrated ISM-AHP: Application in complex chemical processes [J]. Energy, 2018, 160: 898-909.). Oxidation is one of the most important reaction types in the chemical industry. As a typical green oxidant, hydrogen peroxide (H2O2) is of great significance for its efficient and green synthesis. At present, the demand for H2O2 in papermaking and textiles, chemical synthesis, sewage treatment, etc. still dominates (Lewis RJ, Hutchings G J. Recent Advances in the Direct Synthesis of H2O2[J]. Chemcatchem, 2019, 11(1): 298-308.).

[0003] Currently, most companies in my country use the traditional fixed-bed process to produce H2O2. However, large-scale production of this process can lead to problems such as poor heat transfer in the hydrogenation tower, severe localized over-hydrogenation and low overall hydrogenation efficiency, as well as catalyst agglomeration and high working fluid loss. These issues are difficult to fundamentally address. Therefore, the production of high-quality H2O2 remains a technical obstacle that the industry urgently needs to address.

[0004] In 1914, the first patent for the direct synthesis of H2O2 from hydrogen and oxygen was published. This patent reported that H2O2 could be directly synthesized by passing hydrogen and oxygen (gas phase) into a liquid medium (liquid phase) containing a palladium catalyst (solid phase) (Henkel H, Weber W. Manufacture of hydrogen peroxid[Z]. US. 1914). This method, to distinguish it from photocatalysis and electrocatalysis, is referred to as a thermocatalytic method. Designed to replace the then-current method of synthesizing H2O2 through electrolysis of ammonium sulfate, the thermocatalytic method attracted considerable attention upon its publication. However, due to persistent safety concerns, research progress was slow, sometimes even stagnant. Entering the 21st century, the concept of green development has garnered widespread attention. As a quinone-based green oxidant, H2O2 saw increasing demand for its application. However, the currently used anthraquinone method for producing H2O2 has also been questioned due to its environmental concerns and high energy consumption. Consequently, the direct synthesis of H2O2 from hydrogen and oxygen has once again become a hot topic and a frontier of research.

[0005] Direct synthesis of H2O2 from hydrogen and oxygen has the highest theoretical atomic utilization rate and is also the simplest method for producing H2O2. It has the advantages of being green and environmentally friendly, requiring low equipment investment, and having a simple process. Therefore, it is considered to be one of the most promising green alternatives to the anthraquinone method. It can produce H2O2 in an economical, efficient, and ready-to-use manner (Edwards JK, Solsona B, NEN, et al. Switching Off Hydrogen Peroxide Hydrogenation in the Direct Synthesis Process[J]. Science, 2009, 323(5917):1037-1041.;Freakley SJ, He Q, Harrhy JH, et al. Palladium-tin catalysts for the direct synthesis of H2O2 with high selectivity[J]. Science, 2016, 351(6276):965-968.;Ouyang L, Da GJ, Tian PF, et al. Insight into active sites of Pd–Au / TiO2 catalysts in hydrogen Peroxide synthesis directly from H2 and O2 [J]. Journal of Catalysis, 2014, 311: 129-136.) meets the needs of most end-use applications for low-concentration H2O2. However, due to the involvement of multiple side reactions, which are more thermodynamically favorable, the production efficiency and selectivity of H2O2 are not high. In addition, because hydrogen and oxygen have the risk of explosion in a wide range of ratios (4-96%), large amounts of inert gas are often added for dilution for safety reasons, which inevitably reduces production efficiency. Although the use of high pressure can increase production efficiency, it also increases the reaction risk.

[0006] Therefore, developing a reactor to improve the safety of the direct reaction of hydrogen and oxygen to synthesize hydrogen peroxide and designing a catalyst with high selectivity remains a major challenge facing the direct reaction of hydrogen and oxygen to synthesize H2O2. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a microchannel reactor for the direct reaction of hydrogen and oxygen to produce hydrogen peroxide. This reactor has excellent mass transfer and micro-mixing properties. Hydrogen and oxygen are introduced separately from two sides, greatly reducing the risk of gas explosion and improving reaction safety. By combining it with a gas-liquid mixed flow pump, the product can enter the chamber for further reaction, achieving the effect of cumulative product concentration.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows :

[0009] A microchannel reactor for directly reacting hydrogen and oxygen to generate hydrogen peroxide, comprising:

[0010] Reaction chamber, gas channel, inlet pipe, outlet pipe, reaction diffusion layer and gas-liquid mixed flow pump;

[0011] A reaction diffusion layer is provided in the middle of the reaction chamber, the reaction diffusion layer separating the reaction chamber into a first chamber and a second chamber, a gas channel is provided in the first chamber or the second chamber; and the reaction diffusion layer carries a catalyst for the hydrogen-oxygen reaction to generate hydrogen peroxide; after the fluid in the gas channel enters the first chamber and the second chamber, it diffuses from the gas channel to the reaction diffusion layer and reacts;

[0012] The first chamber and the second chamber are both provided with an inlet pipe, and the first chamber and the second chamber are also both provided with an outlet pipe;

[0013] The inlet pipe is connected to the outlet of the gas-liquid mixed flow pump through a pipeline, and is also connected to an external raw gas source through a pipeline;

[0014] The outlet pipe is communicated with the inlet of the gas-liquid mixed flow pump through a pipeline.

[0015] As an embodiment, in the reaction chamber, the gas ratio of the raw gas source hydrogen to oxygen is 1:0.5-1:10.

[0016] As an embodiment, the reaction temperature in the reaction chamber is -10°C-20°C.

[0017] As an embodiment, the rotation speed of the gas-liquid mixed flow pump is 1 rpm-200 rpm.

[0018] As an embodiment, the catalyst loading amount of the reaction diffusion layer is: 1mg-50mg.

[0019] As an embodiment, the gas channel is a detachable structure.

[0020] Any range described in the present invention includes the end value and any numerical value between the end values ​​and any sub-range formed by the end value or any numerical value between the end values.

[0021] Unless otherwise specified, all raw materials in the present invention can be purchased commercially, and the equipment used in the present invention can adopt conventional equipment in the relevant field or refer to the existing technology in the relevant field.

[0022] Compared with the prior art, the present invention has the following beneficial effects :

[0023] 1) High safety: In a conventional microchannel reactor, hydrogen and oxygen need to be mixed in the microchannel before reacting. First, the amount of gas that can be introduced into the mixture is small, and the reactants are few, resulting in a low product yield. Second, direct mixing of hydrogen and oxygen is prone to explosion, which is not very safe. The microreactor of the present invention separates the chambers for the hydrogen and oxygen reactions, thereby avoiding direct mixing and contact between hydrogen and oxygen, improving safety.

[0024] 2) High product concentration; in the present invention, since the microchannel reactor is combined with the gas-liquid mixed flow pump device, the product can enter the reaction chamber again for reaction through the action of the gas-liquid mixed flow pump after flowing out of the reaction device, and the product concentration is accumulated twice, thereby improving the yield.

[0025] 3) The product concentration is controllable; the present invention adopts a method of combining a microchannel reactor with a gas-liquid mixed flow pump, which means that the reaction can be terminated at any time during the reaction process by stopping the gas supply or stopping the gas-liquid mixed flow pump, thereby controlling the product concentration. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0027] Figure 1 This is a schematic structural diagram of a microchannel reactor for direct reaction of hydrogen and oxygen to generate hydrogen peroxide according to the present invention;

[0028] Figure 2 This is an exploded view of the reaction chamber of the present invention;

[0029] Figure 3 This is a data graph showing the relationship between the loading amount of catalyst A and the concentration of hydrogen peroxide at different gas-liquid mixed flow pump speeds in the production of hydrogen peroxide by direct reaction of hydrogen and oxygen using the device of the present invention in Example 1;

[0030] Figure 4 This is a data graph showing the relationship between the rotation speed of the gas-liquid mixed flow pump and the concentration of hydrogen peroxide at different loading amounts of catalyst A in the production of hydrogen peroxide by direct reaction of hydrogen and oxygen using the device of the present invention in Example 2;

[0031] Figure 5 This is a data graph showing the relationship between the loading amount of catalyst B and the concentration of hydrogen peroxide at different gas-liquid mixed flow pump speeds in the production of hydrogen peroxide by direct reaction of hydrogen and oxygen using the device of the present invention in Example 3;

[0032] Figure 6 This is a data graph showing the relationship between the rotation speed of the gas-liquid mixed flow pump and the concentration of hydrogen peroxide at different loading amounts of catalyst B in the direct reaction of hydrogen and oxygen to produce hydrogen peroxide using the device of the present invention in Example 4. DETAILED DESCRIPTION

[0033] In order to more clearly illustrate the present invention, the present invention is further described below in conjunction with preferred embodiments and accompanying drawings. Similar components in the accompanying drawings are represented by the same reference numerals. It should be understood by those skilled in the art that the following detailed description is illustrative rather than restrictive and should not be used to limit the scope of protection of the present invention.

[0034] The accompanying drawings illustrate various cross-sectional views of embodiments disclosed herein. These figures are not drawn to scale; for clarity, some details are exaggerated and some details may be omitted. The shapes, relative sizes, and positional relationships of the various regions and layers shown in the figures are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art may design regions / layers with different shapes, sizes, and relative positions based on actual needs.

[0035] See also Figure 1 and Figure 2 As shown, as one aspect of the present invention, a microchannel reactor for directly reacting hydrogen and oxygen to generate hydrogen peroxide comprises:

[0036] Reaction chamber 10, gas channel 20, inlet pipe 30, outlet pipe 40, reaction diffusion layer 50 and gas-liquid mixed flow pump 60;

[0037] A reaction diffusion layer 50 is provided in the middle of the reaction chamber 10. The reaction diffusion layer 50 separates the reaction chamber 10 into a first chamber 11 and a second chamber 12. A gas channel 20 is provided in each of the first chamber 11 and the second chamber 12. The reaction diffusion layer 50 carries a catalyst for the reaction of hydrogen and oxygen to produce hydrogen peroxide. After the fluid in the gas channel 20 enters the first chamber 11 and the second chamber 12, it diffuses from the gas channel 20 to the reaction diffusion layer 50 and reacts.

[0038] The first chamber 11 and the second chamber 12 are both provided with an inlet pipe 30, and the first chamber 11 and the second chamber 12 are also both provided with an outlet pipe 40; the reaction chamber 10 is used for the occurrence of the reaction and the flow of gas and liquid;

[0039] The inlet pipe 30 is connected to the outlet of the gas-liquid mixed flow pump through a pipeline, and is also connected to an external raw gas source through a pipeline;

[0040] The outlet pipe 40 is connected to the inlet of the gas-liquid mixed flow pump 60 through a pipeline.

[0041] The inlet pipe 30 is used to introduce the raw gas and the reaction liquid mixture respectively;

[0042] The outlet pipe 40 is used for the outflow of the mixture of unreacted raw materials and the reaction liquid;

[0043] The gas channel 20 is used for the flow of gas-liquid mixture or raw gas in the microchannel reactor;

[0044] The gas-liquid mixed flow pump 60 is used to transport the gas-liquid mixture.

[0045] The working principle of the present invention is as follows:

[0046] The raw gas hydrogen and oxygen enter the gas channels 20 in the first chamber 11 and the second chamber 12 from the inlet pipes 20 on the left and right sides, respectively, and then diffuse from the gas channels 20 to the reaction diffusion layer 50. In the reaction diffusion layer 50, the hydrogen and oxygen encounter the hydrogen peroxide catalyst and react to produce hydrogen peroxide. The hydrogen peroxide permeates from the reaction diffusion layer 50 into both the first chamber and the second chamber.

[0047] The hydrogen gas and reaction liquid on the left are transported to the gas-liquid mixed flow pump 60 through the outlet pipe 40;

[0048] The oxygen and reaction liquid on the right side are also delivered to the gas-liquid mixed flow pump 60 through the outlet pipe 40;

[0049] The reaction liquid mixture in the gas-liquid mixed flow pump 60 is transported to the gas channels 20 of the first chamber 11 and the second chamber 12 through pipelines respectively;

[0050] The microchannel reactor of the present invention is designed as a two-sided reaction chamber, with each chamber equipped with a separate gas channel. Hydrogen and oxygen can circulate on one side through the inlet and outlet pipes. After the reaction gas and liquid enter the chamber, they diffuse along the gas channel to the reaction diffusion layer. Hydrogen and oxygen react with the catalyst in the diffusion layer and flow out through the gas channel into the product bottle. The H2O2 in the product bottle is then pumped into the inlet pipe by a gas-liquid mixed flow pump and enters the next reaction cycle.

[0051] In this microreactor, hydrogen and oxygen enter the reaction chamber separately through gas channels, then diffuse through the reaction diffusion layer to react in the catalyst, avoiding direct mixing of hydrogen and oxygen and greatly improving reaction safety. Furthermore, the two chambers of this microreactor are open, meaning that the catalyst in the diffusion layer can be reused within a stable timeframe. This improves catalyst utilization efficiency, unlike traditional bonded microreaction channels that only allow for single reactions. Furthermore, the products can participate in the next reaction, achieving cumulative product concentration and controlling product concentration.

[0052] According to certain embodiments of the present invention, in the reaction chamber, the gas ratio of hydrogen and oxygen as the raw gas sources is 1:0.5-1:10; including but not limited to the gas ratio of hydrogen and oxygen is 1:1-1:10, or 1:1-1:9, or 1:1-1:8, or 1:1-1:7, or 1:1-1:6, or 1:1-1:5, or 1:1-1:4, or 1:1-1:3, or 1:1-1:2, or 1:1-1:0.5; preferably, the gas ratio of hydrogen and oxygen is 1:1.

[0053] According to certain embodiments of the present invention, the reaction temperature in the reaction chamber is -10°C-20°C, and the reaction temperature includes but is not limited to -10°C-0°C, or -10°C-1°C, or -10°C-2°C, or -10°C-3°C, or -5°C-0°C, or -5°C-1°C, or -5°C-2°C, or -5°C-3°C, or -5°C-0°C, or 0°C-1°C, or 0°C-2°C, or 0°C-3°C, or 0°C-4°C, or 0°C-5°C, or 0°C-6°C, or 0°C-7°C, or 0°C-8°C, or 0°C-9°C, or 0°C-10°C, or 10°C-15°C, or 10°C-20°C; more preferably, the reaction temperature in the reaction chamber is 10°C. According to certain embodiments of the present invention, the speed of the gas-liquid mixed flow pump is 1rpm-200rpm. The rotational speed includes but is not limited to 1-5rpm, or 1-10rpm, or 1-15rpm, or 1-20rpm, or 1-25rpm, or 1-30rpm, or 1-35rpm, or 1-40rpm, or 1-45rpm, or 1-50rpm, or 1-55rpm, or 1-60rpm, or 1-65rpm, or 1-70rpm, or 1-75rpm, or 1-80rpm, or 1-85rpm, or 1-90rpm, or 1-95rpm, or 1-100rpm, or 50-110rpm, or 50-120rpm, or 50-130rpm, or 50-140rpm, or 50-150rpm, or 50-160rpm, or 50-170rpm, or 50-180rpm, or 50-190rpm, or 50-200rpm; preferably, the rotational speed of the gas-liquid mixed flow pump is 60rpm.

[0054] According to certain embodiments of the present invention, the catalyst loading of the reaction diffusion layer is 1 mg-50 mg, including but not limited to 1 mg-5 mg, or 1 mg-6 mg, or 1 mg-7 mg, or 1 mg-8 mg, or 1 mg-9 mg, or 1 mg-10 mg, or 5 mg-10 mg, or 5 mg-15 mg, or 5 mg-20 mg, or 5 mg-25 mg, or 5 mg-30 mg, or 5 mg-35 mg, or 5 mg-40 mg, or 5 mg-45 mg, or 5 mg-50 mg; more preferably, the catalyst loading is 25 mg.

[0055] According to some embodiments of the present invention, the gas channel is a detachable structure.

[0056] Example 1

[0057] like Figure 1 and Figure 2 As shown, the microchannel reactor of the present invention is used to directly react hydrogen and oxygen to produce hydrogen peroxide. The experimental conditions and experimental process are as follows:

[0058] Experimental conditions: the temperature in the reaction chamber was 0-2°C; pure water was used as the reaction liquid; the ratio of hydrogen to oxygen introduced was 1:1, and the initial concentration was 20 ml / min.

[0059] Experimental process: Under different gas-liquid mixed flow pump speeds of 5, 10, 25, 50, 100, 150, and 200 rpm, the loading amount of catalyst PdPtRuRhAu was changed to 5, 10, 20, 30, 40, and 50 mg respectively; the concentration of product hydrogen peroxide was recorded, and the relationship between the loading amount of catalyst PdPtRuRhAu and the concentration of hydrogen peroxide at different gas-liquid mixed flow pump speeds was obtained, as shown in the figure. Figure 3 shown.

[0060] Example 2

[0061] The microchannel reactor of the present invention is used to produce hydrogen peroxide by direct reaction of hydrogen and oxygen. The experimental conditions and experimental process are as follows:

[0062] Experimental conditions: the temperature in the reaction chamber was 0-2°C; pure water was used as the reaction liquid; the ratio of hydrogen to oxygen introduced was 1:1, and the initial concentration was 20 ml / min.

[0063] Experimental process: When the loading amount of catalyst A is 5, 10, 20, 30, 40, and 50 mg respectively, the speed of the gas-liquid mixed flow pump is changed to 5, 10, 25, 50, 100, 150, and 200 rpm respectively; the concentration of the product hydrogen peroxide is recorded, and the relationship between the speed of the gas-liquid mixed flow pump and the concentration of hydrogen peroxide is obtained, as shown in FIG. Figure 4 shown.

[0064] Example 3

[0065] The microchannel reactor of the present invention is used to produce hydrogen peroxide by direct reaction of hydrogen and oxygen. The experimental conditions and experimental process are as follows:

[0066] Experimental conditions: the temperature in the reaction chamber was 0-2°C; pure water was used as the reaction liquid; the ratio of hydrogen to oxygen introduced was 1:1, and the initial concentration was 20 ml / min.

[0067] Experimental process: Under different gas-liquid mixed flow pump speeds of 5, 10, 25, 50, 100, 150, and 200 rpm, the loading amount of catalyst PdPtAgSnAu was changed to 5, 10, 20, 30, 40, and 50 mg respectively; the concentration of product hydrogen peroxide was recorded, and the relationship between the loading amount of catalyst PdPtAgSnAu and the concentration of hydrogen peroxide at different gas-liquid mixed flow pump speeds was obtained, as shown in the figure. Figure 5 shown.

[0068] Example 4

[0069] The microchannel reactor of the present invention is used to produce hydrogen peroxide by direct reaction of hydrogen and oxygen. The experimental conditions and experimental process are as follows:

[0070] Experimental conditions: the temperature in the reaction chamber was 0-2°C; pure water was used as the reaction liquid; the ratio of hydrogen to oxygen introduced was 1:1, and the initial concentration was 20 ml / min.

[0071] Experimental process: When the loading amount of catalyst PdPtAgSnAu is 5, 10, 20, 30, 40, 50 mg respectively, the speed of gas-liquid mixed flow pump is changed to 5, 10, 25, 50, 100, 150, 200 rpm respectively; the concentration of product hydrogen peroxide is recorded, and the relationship between the speed of gas-liquid mixed flow pump and the concentration of hydrogen peroxide is obtained, such as Figure 6 shown.

[0072] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications based on the above description are possible. It is not possible to enumerate all embodiments here. Any obvious variations or modifications arising from the technical solution of the present invention remain within the scope of protection of the present invention.

Claims

1. A microchannel reactor for direct reaction of hydrogen and oxygen to produce hydrogen peroxide, characterized in that: include: Reaction chamber, gas channel, inlet pipe, outlet pipe, reaction diffusion layer and gas-liquid mixed flow pump; A reaction diffusion layer is provided in the middle of the reaction chamber, the reaction diffusion layer separating the reaction chamber into a first chamber and a second chamber, a gas channel is provided in the first chamber or the second chamber; and the reaction diffusion layer carries a catalyst for the hydrogen-oxygen reaction to generate hydrogen peroxide; after the fluid in the gas channel enters the first chamber and the second chamber, it diffuses from the gas channel to the reaction diffusion layer and reacts; The first chamber and the second chamber are both provided with an inlet pipe, and the first chamber and the second chamber are also both provided with an outlet pipe; The inlet pipe is connected to the outlet of the gas-liquid mixed flow pump through a pipeline, and is also connected to an external raw gas source through a pipeline; The outlet pipe is communicated with the inlet of the gas-liquid mixed flow pump through a pipeline.

2. The microchannel reactor according to claim 1, wherein: In the reaction chamber, the gas ratio of the raw gas source hydrogen to oxygen is 1:0.5-1:

10.

3. The microchannel reactor according to claim 1, wherein: The reaction temperature in the reaction chamber is -10°C-20°C.

4. The microchannel reactor according to claim 1, wherein: The rotation speed of the gas-liquid mixed flow pump is 1 rpm-200 rpm.

5. The microchannel reactor according to claim 1, wherein: The catalyst loading amount of the reaction diffusion layer is 1 mg to 50 mg.

6. The microchannel reactor according to claim 1, wherein: The gas channel is a detachable structure.

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