Cascade reaction device and method for preparing aviation fuel by means of photoelectrocatalytic conversion of lignin

Abstract

Disclosed in the present invention are a cascade reaction device and method for preparing aviation fuel by means of photoelectrocatalytic conversion of lignin. The method comprises: placing lignin in a pretreatment reaction chamber filled with an alkaline solution, so that the lignin is fully dissolved; opening valves to enable a pretreated reaction liquid to flow into an anode chamber in a photoelectrocatalytic reaction chamber; using solar energy to drive a photoelectrocatalytic reaction at an anode; after sufficient reaction, enabling the reaction liquid in the anode chamber to flow into a temporary storage chamber, and subsequently, using a pump to transfer the reaction liquid in the temporary storage chamber into a cathode chamber; and after sufficient reaction, introducing the reaction liquid in the cathode chamber into a high-pressure reaction chamber by means of a pump, and enabling hydrogen generated in the cathode chamber to flow into a gas cylinder by means of a pipe for collection, so as to be supplied to the high-pressure reaction chamber, wherein the reaction liquid undergoes a hydrodeoxygenation reaction under the action of a catalyst in the high-pressure reaction chamber, and after sufficient reaction, the aviation fuel can be obtained. The present invention achieves an integrated cascade reaction for solar-driven conversion of lignin into aviation fuel.

Description

Cascade reaction device and method for preparing aviation fuel by photoelectrocatalytic conversion of lignin TECHNICAL FIELD

[0001] The application belongs to the field of aviation fuel preparation and relates to a lignin preparation aviation fuel technology, in particular to a cascade reaction device and method for preparing aviation fuel by photoelectrocatalytic conversion of lignin. BACKGROUND

[0002] Lignocellulosic biomass is considered an ideal material for preparing sustainable aviation fuel because of its wide source and low price. Among them, the rich cyclic structure of lignin becomes an effective raw material for preparing aromatic and naphthenic aviation fuel. Lignin often needs to be depolymerized into aromatic monomers before being subjected to hydrodeoxygenation to obtain aviation fuel due to its high polymer structure. In order to obtain long-chain products, coupling of carbon-carbon bonds is also required. At present, the whole process is often carried out under thermal catalytic conditions, and an external hydrogen source is required, which consumes a large amount of cost and limits subsequent development.

[0003] A method for synthesizing polycyclic alkanes from lignin-derived phenols by one-pot two-step method is disclosed in Chinese Patent No. CN117024238A. First, a hydrogenation catalyst is used to convert lignin-derived phenolic compounds into ketone compounds, and then the ketone compounds are prepared into aviation coal precursors through hydroxy aldehyde condensation reaction, and finally polycyclic alkanes are generated through complete hydrodeoxygenation.

[0004] A method for preparing aviation fuel from lignin derivatives is disclosed in Chinese Patent No. CN115746923A. The invention uses a heteropoly acid catalyst to carry out alkylation reaction of lignin phenolic derivatives and lignin aldehyde derivatives under solvent-free conditions to obtain tricyclic oxygen-containing fuel precursors, and finally form a variety of isomerized naphthenes through hydrodeoxygenation and isomerization reaction; the alkylation temperature is 60-100℃, and the reaction time is 0.5-6 hours.

[0005] A method for preparing polycyclic alkanes aviation kerosene from lignin-derived phenols and formaldehyde is disclosed in Chinese Patent No. CN116925804A. The invention causes phenolic compounds and formaldehyde derived from agricultural and forestry wastes to occur phenol-aldehyde condensation reaction under the action of solid acid to form aviation coal precursors, and then obtains polycyclic aviation kerosene through hydrodeoxygenation of a bifunctional catalyst; the molar ratio of phenolic compounds and formaldehyde is 0.5-10; the reaction temperature is 30-120℃, and the reaction time is 3-12 hours.

[0006] From the above prior art, it can be seen that, whether it is which process, the preparation of aviation fuel or aviation fuel precursor from lignin must go through hydrodeoxygenation, and hydrodeoxygenation needs to be carried out under high temperature and high pressure catalytic conditions, the energy consumption is very high, and hydrogen needs to be added, and the production and storage of hydrogen itself are also difficult, so the process is actually complex, and it is difficult to produce on a large scale and at a low cost.

[0007] A Chinese patent with publication number CN118416961A discloses a method for preparing aviation fuel using a multi-acid CuBTC supported Pd catalyst. The method uses a specific method to prepare a multi-acid Cu-BTC supported Pd catalyst, and uses H2, CO2 and lignin oil as raw materials to undergo coupling reaction. After the reaction is completed, the product is collected and purified by distillation to obtain aviation fuel. The method can realize the comprehensive utilization of biomass resources and carbon dioxide, and prepare aviation fuel by coupling reaction of carbon dioxide and lignin oil. Although the method provides coupling technology to improve the quality of aviation fuel, it does not solve the problem of high energy consumption of high temperature and high pressure hydrodeoxygenation reaction, and still needs to supply hydrogen from outside. The most important thing is that this technology is only a small batch of verification experiment in the laboratory, and each step is a non-continuous reaction in a reagent bottle. According to the embodiment, the injection rate of the main raw material lignin pyrolysis oil is only 0.1 mL / min, and only 6 mL is injected in one hour. It can only be called a trace experiment.

[0008] Therefore, a reaction device with low energy consumption is needed to convert lignin into aviation fuel at a low cost on a large scale to realize industrial production. SUMMARY

[0009] The purpose of the present application is to solve the problems in the prior art, and the present application aims to provide an integrated cascade reaction device and method for photoelectrocatalytic conversion of lignin to prepare aviation fuel.

[0010] Based on the above technical problems, the present application provides the following technical solutions:

[0011] On the one hand, the present application provides a cascade reaction device for photoelectrocatalytic conversion of lignin to prepare aviation fuel, comprising

[0012] A pretreatment system for dissolving lignin raw materials in an alkaline solution and performing preliminary depolymerization to obtain a lignin solution;

[0013] The photoelectrocatalysis system is used for photoelectrocatalysis reaction of lignin solution, depolymerization and coupling reaction of lignin; the photoelectrocatalysis system comprises an anode chamber, a cathode chamber and a transparent proton exchange membrane arranged between the two chambers, the anode chamber is provided with at least a light-transmitting window and a photocatalytic anode arranged at the light-transmitting window, and the photocatalytic anode is non-full light-shielding; the cathode chamber is provided with at least a photocatalytic cathode; the lignin depolymerization main reaction is carried out in the anode chamber through photoelectrocatalysis, and the coupling reaction and by-product hydrogen are generated in the cathode chamber through photoelectrocatalysis;

[0014] The hydrogenolysis reaction system is used for hydrogenolysis and thermal catalysis reaction of the reaction material treated by the photoelectrocatalysis system to prepare aviation fuel; and

[0015] The hydrogen collection system is connected with the cathode chamber of the photoelectrocatalysis system and the hydrogenolysis reaction system respectively, is used for collecting hydrogen generated by the cathode chamber temporarily, and supplies the hydrogenolysis reaction system to participate in hydrogenolysis and oxidation reaction.

[0016] Further, the cascade reaction device further comprises a liquid product collection system, the liquid product collection system is used for collecting the liquid product of the hydrogenolysis reaction system, a first reaction material temporary storage system is arranged between the photoelectrocatalysis system and the pretreatment reaction chamber, a second reaction material temporary storage system is arranged between the anode chamber and the cathode chamber, and a third reaction material temporary storage system is arranged between the cathode chamber and the hydrogenolysis reaction system.

[0017] Further, the pretreatment system comprises a pretreatment reaction chamber and a stirring mechanism for accelerating dissolution, and the pretreatment reaction chamber is further provided with a first valve for discharging.

[0018] Further, the photoelectrocatalysis system comprises a photoelectrocatalysis reaction chamber, the photoelectrocatalysis reaction chamber is divided into an anode chamber and a cathode chamber by a proton exchange membrane, and the photocatalytic cathode can receive residual light sequentially passing through the light-transmitting window, the photocatalytic anode and the proton exchange membrane.

[0019] Further, the photocatalytic anode comprises conductive glass integrally made with the light-transmitting window and a photocatalytic layer covered on the inner side of the conductive glass.

[0020] Further, the photocatalytic cathode comprises a silicon-based photoelectric cathode and a gallium nitride nanorod array covered on the silicon-based photoelectric cathode.

[0021] Further, the photoelectrocatalysis system further comprises a photovoltaic assembly for supplying power to the photocatalytic cathode and the photocatalytic anode.

[0022] Further, the second reaction material temporary storage system comprises a second reaction liquid temporary storage chamber and a first conveying pump, the second reaction liquid temporary storage chamber is connected with the anode chamber, and the first conveying pump is used for conveying the reaction liquid in the second reaction liquid temporary storage chamber to the cathode chamber;

[0023] The third reaction material temporary storage system includes a third reaction liquid temporary storage chamber connected to the cathode chamber and a second delivery pump for pressurizing the reaction liquid in the third reaction liquid temporary storage chamber and delivering it to the hydrogenolysis reaction system.

[0024] In another aspect, the present application provides a method for preparing aviation fuel by lignin conversion, using the above-mentioned cascade reaction device, comprising the following steps:

[0025] An alkaline solution is added to the pretreatment system, lignin raw material is dissolved in the alkaline solution, and preliminary depolymerization is carried out to obtain a lignin solution;

[0026] The lignin solution is introduced into the anode chamber, and the power is turned on, and the lignin is depolymerized under the photoelectrocatalysis of the photocatalytic anode;

[0027] The reaction product after depolymerization is introduced into the cathode chamber through the second reaction material temporary storage system, and under the action of the photocatalytic cathode, a coupling reaction is carried out and byproduct hydrogen is produced;

[0028] The reaction product after coupling reaction is introduced into the hydrogenolysis reaction system through the third reaction material temporary storage system for hydrothermal pyrolysis, and at the same time, the hydrogenolysis reaction system is supplied with hydrogen by the hydrogen gas collection system, and after the reaction is completed, aviation fuel product is obtained, and after purification, aviation fuel is obtained.

[0029] The present application places the alkaline solution required for the pretreatment reaction in the pretreatment reaction chamber, including potassium hydroxide solution and lignin; after sufficient dissolution, the pretreatment reaction liquid is sent to the anode chamber; the solar photovoltaic panel continuously stores electrical energy under sunlight; the controller drives the photoelectrocatalytic reaction using the electrical energy stored by the solar photovoltaic panel; the anode light window is irradiated by sunlight, and the reaction liquid is in full contact with the Fe2O3 photocatalyst coating; the silicon wafer absorbs the remaining wavelength of sunlight, and the reaction liquid after anode reaction is in full contact with the silicon wafer, and after photoelectrocatalytic reaction, liquid products and hydrogen are produced in the cathode chamber; the produced liquid products and hydrogen undergo hydrodeoxygenation reaction under the action of the catalyst in the high-pressure reaction chamber, thereby obtaining the final aviation fuel product, which is then collected and used for subsequent purification.

[0030] Compared with the prior art, the present application has the following advantages:

[0031] 1. Compared with traditional petroleum-based aviation fuel, this system utilizes abundant solar energy, lignin and water resources, not only reducing dependence on fossil fuels, but also significantly reducing carbon emissions in the production process, helping to promote the green development of the aviation industry, and contributing to the realization of global carbon neutralization.

[0032] 2. The introduction of photoelectrocatalytic technology enables efficient energy conversion and biomass conversion through mild reaction conditions and redox separation techniques. The cascade catalytic method further optimizes the conversion process and improves product selectivity. In particular, the synergistic effect of the anode and cathode photocatalysts enables the system to fully utilize each wavelength band of the solar spectrum, achieving efficient capture and utilization of full solar energy.

[0033] 3. The system uses a semi-automatic controller to simplify the operation process, reduce the demand for manpower, and ensure the efficiency and flexibility of the production process. The system relies entirely on solar energy to convert electrical energy, not only reducing energy costs, but also reducing environmental impact. This design not only improves the economic efficiency and sustainability of the system, but also provides an innovative and environmentally friendly solution for aviation fuel production, with great market potential and development prospects.

[0034] 4. The system minimizes the demand for external hydrogen sources through a self-sufficient strategy. By utilizing internal resources and optimizing the process, the system not only reduces raw material costs, but also reduces the environmental impact of the entire production process. This strategy enhances the economic efficiency and environmental friendliness of the system, while improving its adaptability to market fluctuations and long-term sustainability.

[0035] 5. The invention utilizes the characteristics of photoelectrocatalytic technology to separate depolymerization and coupling, using coupling to improve the quality of aviation fuel, and using the byproduct hydrogen from the coupling reaction as the hydrogen source for hydrogenation catalysis, making the hydrogen self-sufficient; creatively combining photoelectrocatalytic technology and hydrogenation deoxidation, achieving a synergistic effect, reducing production costs, and improving fuel quality. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 is a structural diagram of the cascade reaction device for photoelectrocatalytic lignin conversion to prepare aviation fuel in Example 1 of the invention.

[0037] Figure 2 is a cross-sectional schematic diagram of the cascade reaction device for photoelectrocatalytic lignin conversion to prepare aviation fuel in Example 1 of the invention.

[0038] Figure 3 is a schematic diagram of the external structure of the cascade reaction device for photoelectrocatalytic lignin conversion to prepare aviation fuel in Example 1 of the invention in the first state.

[0039] Figure 4 is a schematic diagram of the external structure of the cascade reaction device for photoelectrocatalytic lignin conversion to prepare aviation fuel in Example 1 of the invention in the second state.

[0040] Wherein, 100-preprocessing system, 1-preprocessing reaction chamber, 200-first reaction material temporary storage system, 2-first reaction liquid temporary storage chamber, 300-photoelectrocatalysis system, 3-photoelectrocatalysis reaction chamber, 31-anode chamber, 311-first liquid inlet hole, 312-first liquid outlet hole, 313-anode light window, 314-Fe2O3 photocatalyst coating, 32-cathode chamber, 321-second liquid inlet hole, 322-second liquid outlet hole, 323-first gas outlet hole, 324-photocatalytic cathode, 33-proton exchange membrane, 400-second reaction material temporary storage system, 4-second reaction liquid temporary storage chamber, 500-third reaction material temporary storage system, 5-third reaction liquid temporary storage chamber, 600-hydrogenolysis reaction system, 6-high pressure reaction chamber, 61-third liquid inlet hole, 62-third liquid outlet hole, 63-first gas inlet hole, 64-second gas inlet hole, 65-catalyst inlet, 700-hydrogen collection system, 7-hydrogen collection bottle, 800-liquid product collection system, 8-liquid product collection bottle, 9-solar photovoltaic panel, 10-first valve, 11-second valve, 12-third valve, 13-first pump, 14-fourth valve, 15-second pump, 16-first valve group, 17-second valve group, 18-fifth valve, 19-third valve group, 20-rotary bearing, 21-controller, 22-first door, 23-second door, 24-third door, 25-first glass window, 26-second glass window, 27-hydrogen supplement pipeline, 30-box type rack. DETAILED DESCRIPTION

[0041] The embodiments of the present application will be further described below in conjunction with the drawings and examples. The following examples are used to illustrate the present application, but cannot be used to limit the scope of the present application.

[0042] As shown in Figure 1, Example 1: the present application provides a cascade reaction device for preparing aviation fuel by photoelectrocatalytic conversion of lignin, comprising

[0043] The preprocessing system 100 is used for dissolving lignin raw material in an alkaline solution and performing preliminary depolymerization to obtain a lignin solution;

[0044] The photoelectrocatalysis system 300 is used for performing photoelectrocatalytic reaction on the lignin solution to perform depolymerization and coupling reaction on the lignin; the photoelectrocatalysis system 300 comprises an anode chamber 31, a cathode chamber 32, and a transparent proton exchange membrane 33 arranged between the two; the anode chamber 31 is provided with at least a light-transmitting window and a photocatalytic anode arranged at the light-transmitting window, and the photocatalytic anode is non-full light-shielding; the cathode chamber 32 comprises at least a photocatalytic cathode; the anode chamber 31 performs lignin depolymerization main reaction through photoelectrocatalysis, and the cathode chamber 32 performs coupling reaction through photoelectrocatalysis and generates by-product hydrogen;

[0045] a hydrogenolysis reaction system 600 for carrying out a hydrogen thermal catalytic reaction to prepare aviation fuel; and

[0046] a hydrogen collection system 700 connected with the cathode chamber 32 of the photoelectrocatalytic system 300 and the hydrogenolysis reaction system 600 respectively, for collecting and temporarily storing the hydrogen generated by the cathode chamber 32 and supplying the hydrogen to the hydrogenolysis reaction system 600 to participate in the hydrogenolysis oxidation reaction;

[0047] The cascade reaction device further comprises a liquid product collection system 800, and a first reaction material temporary storage system 200 is arranged between the photoelectrocatalytic system 300 and the pretreatment reaction chamber 1, a second reaction material temporary storage system 400 is arranged between the anode chamber 31 and the cathode chamber 32, and a third reaction material temporary storage system 500 is arranged between the cathode chamber 32 and the hydrogenolysis reaction system 600.

[0048] The pretreatment system 100 of the present application is the key first step of the whole process, which involves the initial depolymerization of lignin, a complex macromolecular substance, into smaller molecular fragments, and its conversion into a smaller molecular fragment, which is fully dissolved in an alkaline solution, providing convenience for subsequent catalytic reaction and energy conversion process; wherein the selection of the alkaline solution is important for the pretreatment process, which not only promotes the depolymerization of lignin molecules, but also helps to improve its solubility. Strong alkalis such as sodium hydroxide or potassium hydroxide can form salts with the acidic hydrogen in lignin, thereby weakening the intermolecular interaction force, making lignin molecules more easily dispersed and dissolved. The anode chamber 31 of the photoelectrocatalytic system 300 uses photoelectrocatalytic reaction to depolymerize the dissolved lignin solution, and is depolymerized into low-carbon aromatic hydrocarbons. After that, the reaction material is sent into the cathode chamber 32 by the second reaction material temporary storage system 400, and under the action of the photo-cathode, C-C coupling reaction is carried out to increase the carbon number, lignin is converted into high-density fuel precursor, and byproduct hydrogen is produced; after that, the reaction product after coupling reaction is introduced into the hydrogenolysis reaction system 600 by the third reaction material temporary storage system 500 to carry out hydrogenation pyrolysis, and at the same time, hydrogen gas is supplied to the hydrogenolysis reaction system 600 by using the hydrogen gas collection system 700, and after the reaction is completed, aviation fuel product is obtained, and after purification, aviation fuel is obtained. The hydrogenolysis reaction system 600 of the present application is a conventional hydrogenolysis catalytic technology in the prior art, and no technical improvement is made, so the related technical details are not described again. The present application utilizes the different characteristics of photoelectrocatalysis in different electrode reaction principles, and uses the photoelectrocatalytic anode to mainly carry out depolymerization reaction, in order to create conditions for subsequent hydrogenation catalysis; after that, the reaction material of the anode chamber 31 is sent to the cathode chamber 32 by the transfer action of the second reaction material temporary storage system 400, and the anode chamber 31 can receive new material, this process can be carried out intermittently, and the reaction material temporary storage system provides guarantee for the continuity of the reaction; the reaction material entering the cathode chamber 32 carries out C-C coupling reaction under the characteristics of cathode photoelectrocatalysis, in order to improve the density of the final fuel and achieve the purpose of improving the quality, and at the same time, the byproduct hydrogen gas of the cathode chamber 32 is collected by the hydrogen gas collection system 700 and supplied to the hydrogenolysis reaction system 600 for use, so that the whole reaction hydrogen is basically self-sufficient, greatly reducing the cost and improving the quality.

[0049] The core device of the pretreatment system 100 is the pretreatment reaction chamber 1, which is used to dissolve lignin with strong alkali such as sodium hydroxide or potassium hydroxide. In order to accelerate the dissolution process, the pretreatment reaction chamber 1 can be provided with a stirring mechanism, which can be a stirring paddle or a rotating pretreatment reaction chamber. For example, as shown in FIG. 2, the bottom of the pretreatment reaction chamber 1 is supported on a rack or platform (in this embodiment, a box-shaped rack 30) through a rotating bearing 20, and the pretreatment reaction chamber 1 is driven to rotate by a driving mechanism (not shown in FIG. 2) to achieve the purpose of stirring. A discharge port is provided at the bottom of the pretreatment reaction chamber 1, and a first valve 10 is provided on the discharge port. In order to adapt to the rotation of the pretreatment reaction chamber 1, the discharge port can be provided as a discharge pipe, and the first valve 10 is provided on the discharge pipe. The discharge pipe is inserted into the first reaction material temporary storage system 200 and does not directly contact the first reaction material temporary storage system 200. In order to meet the demand of alkali solution dissolving lignin, the inner wall of the pretreatment reaction chamber 1 is made of alkali-resistant material or provided with an alkali-resistant material coating (such as a metal oxide layer, etc.). In order to improve the stirring effect during rotation, the inner wall of the pretreatment reaction chamber 1 can be made into a net-like texture to improve the friction during stirring. In order to facilitate the addition of raw materials, the top of the pretreatment reaction chamber 1 can be provided with an openable first door 22, which can be directly provided on the top side wall of the pretreatment reaction chamber 1 or on the box-shaped rack 30. The specific position is not limited.

[0050] As shown in FIG. 2, the present application can also be provided with a first reaction material temporary storage system 200. Because the process of dissolving lignin with alkali solution is relatively slow, only completely dissolved lignin can obtain a higher reaction yield. Therefore, only the intermittent feeding method can obtain a completely dissolved lignin alkali solution. At this time, the first reaction material temporary storage system 200 needs to be set up for transfer, and the efficiency of lignin pretreatment can be improved through the temporary storage of the first reaction material temporary storage system 200. For example, the first reaction material temporary storage system 200 includes a first reaction liquid temporary storage chamber 2, the bottom of which is provided with a discharge port connected to the anode chamber 31, and a second valve 11 is provided on the discharge port for controlling the intermittent feeding of the anode chamber 31.

[0051] As shown in FIG. 2, the photoelectrocatalytic system 300 includes a photoelectrocatalytic reaction chamber 3, which is divided into an anode chamber 31 and a cathode chamber 32 by a proton exchange membrane 33. The light-transmitting window is located on the outer side (right side in FIG. 2) of the anode chamber 31 and can directly receive sunlight or specific wavelength catalytic light. The photo-catalytic cathode 324 is located on the inner side (left side in FIG. 2) of the cathode chamber 32 and can receive residual light that has passed through the light-transmitting window, the photo-catalytic anode, and the proton exchange membrane 33 in sequence.

[0052] As a preferred embodiment, the photo-catalytic anode comprises a conductive glass integrated with a light-transmitting window and a photo-catalytic layer covering the inner side of the conductive glass, the conductive glass forms an anode light window 313 with both conductive and light-transmitting functions; the photo-catalytic layer is a Fe2O3 photo-catalyst coating 314; the photo-catalytic anode can be designed as a detachable installation for easy replacement, and the specific detachable manner can be achieved by using the prior art, which is not the core of the present application.

[0053] For example, in order to meet the requirements of feeding and discharging of the anode chamber 31 and the cathode chamber 32, the top and bottom of the anode chamber 31 are respectively provided with a first liquid inlet hole 311 and a first liquid outlet hole 312; the first liquid inlet hole 311 is arranged corresponding to the second valve 11, and the first liquid outlet hole 312 corresponds to the second reaction material temporary storage system 400, and the first liquid outlet hole 312 is provided with a third valve 12; the bottom of the cathode chamber 32 is provided with a second liquid inlet hole 321 and a second liquid outlet hole 322, and the top of the cathode chamber 32 is provided with a first gas outlet hole 323, and the second liquid outlet hole 322 is provided with a fourth valve 14; the second liquid inlet hole 321 is connected with the outlet of the second reaction material temporary storage system 400, and the second liquid outlet hole 322 is connected with the inlet of the third reaction material temporary storage system 500; the discharging of the anode chamber 31 and the cathode chamber 32 is controlled by the third valve 12 and the fourth valve 14 respectively.

[0054] For example, as shown in FIG. 2, the photo-catalytic cathode 324 is arranged on the inner side opposite to the photo-catalytic anode, so that the photo-catalytic cathode 324 can also receive light; the photo-catalytic cathode 324 comprises a silicon-based photo-cathode and a gallium nitride nanorod array epitaxially grown on the silicon-based photo-cathode; the diameter of the gallium nitride nanorod is 5-50 nm, and the optimal diameter is about 10 nm; the length of the nanorod is 100-500 nm, and the optimal length is 200 nm; the silicon-based photo-cathode is an n+p-S structure silicon wafer; the gallium nitride nanorod array is grown on the n+p-S silicon wafer by using epitaxial technology; the strong solar energy absorption (~1.1 eV band gap) and large charge carrier mobility of Si are used to obtain a better photo-catalytic effect; the high aspect ratio of the GaN nanorod and the high electron mobility of the GaN nanorod are used to improve the electron release speed in the photo-catalytic process, thereby improving the photo-catalytic efficiency; in addition, the nanorod array limits the light reflection to the maximum, thereby enhancing the light absorption efficiency and further improving the photo-catalytic efficiency.

[0055] In order to improve the hydrogen production efficiency of the photo-catalytic cathode 324, the present application also provides a photo-catalytic cathode preparation method, which is as follows:

[0056] First, the Si wafer is polished, then n-type phosphorus dopant is spin-coated on the front side, p-type boron dopant is spin-coated on the back side, and annealing is performed at 900°C (in argon atmosphere). Then GaN nanowires are grown on the surface of the Si wafer by plasma-enhanced molecular beam epitaxy. The substrate temperature is 790°C, the plasma power is 350W, and the growth time is 15h, to obtain the photocatalytic cathode 324.

[0057] Exemplarily, as shown in FIG. 2, the second reaction material temporary storage system 400 includes a second reaction liquid temporary storage chamber 4 and a first pump 13, the top of the second reaction liquid temporary storage chamber 4 is provided with an inlet communicating with the first liquid outlet hole 312 at the bottom of the anode chamber 32, and the bottom of the second reaction liquid temporary storage chamber 4 is provided with an outlet connected with the inlet of the first pump 13; the sidewall of the second reaction liquid temporary storage chamber 4 is provided with a first glass window 25 or a liquid level meter, so as to observe the liquid level in the second reaction liquid temporary storage chamber 4.

[0058] Exemplarily, as shown in FIG. 2 and FIG. 3, the third reaction material temporary storage system 500 includes a third reaction liquid temporary storage chamber 5 and a second pump 15, the top of the third reaction liquid temporary storage chamber 5 is provided with an inlet communicating with the second liquid outlet hole 322 at the bottom of the cathode chamber 31, and the bottom of the third reaction liquid temporary storage chamber 5 is provided with an outlet connected with the inlet of the second pump 15; the sidewall of the third reaction liquid temporary storage chamber 5 is provided with a second glass window 26 or a liquid level meter, so as to observe the liquid level in the third reaction liquid temporary storage chamber 5.

[0059] Exemplarily, as shown in FIG. 2, the hydrogenolysis reaction system 600 includes a high-pressure reaction chamber 6, the bottom of the high-pressure reaction chamber 6 is provided with a third liquid inlet hole 61 and a third liquid outlet hole 62, the top is provided with a first gas inlet hole 63 and a second gas inlet hole 64, and the sidewall of the top is provided with a catalyst inlet 65; the third liquid inlet hole 61 is connected with the outlet of the second pump 15, the third liquid outlet hole 62 is connected with the liquid product collection system 800, and the fifth valve 18 is arranged on the third liquid outlet hole 62; it should be noted that the high-pressure reaction chamber 6 is actually a hydrogenation catalytic high-pressure reaction chamber commonly used in the prior art, which usually includes a heating device (not shown in FIG. 2), but the present application does not improve it, so it will not be described in detail.

[0060] It should be noted that generally, the hydrogen gas generated by the cathode chamber 32 is sufficient for the hydrogenolysis reaction system 600, but in the case of fluctuation of lignin raw material quality or production process, there is often a situation that the hydrogen gas is not enough, so a hydrogen supplement pipeline 27 is arranged, which is connected with the first gas inlet hole 63 for supplementing hydrogen.

[0061] As shown in Fig. 2, the hydrogen collection system 700 includes several hydrogen collection bottles 7 (3 in Fig. 2), each of which is provided with a valve at each end to form a first valve group 16 and a second valve group 17, wherein the first valve group 16 is connected to the first gas outlet hole 323 at the top of the cathode chamber 32 through a pipeline for collecting hydrogen, and the second valve group 17 is connected to the second gas inlet hole 64 at the top of the high-pressure reaction chamber 6 through a pipeline for supplying the collected hydrogen to the high-pressure reaction chamber 6 for reaction. Of course, if the pressure of the collected hydrogen is less than the pressure of the high-pressure reaction chamber 6, a pressure increasing device should also be provided in the hydrogen collection system 700 to increase the pressure of the hydrogen, and the setting position of the pressure increasing device is not limited as long as it can increase the pressure, which can be set at the first valve group 16 or the second valve group 17.

[0062] In order to facilitate the protection and management of the hydrogen collection bottles 7, a containing groove can be provided on the box-type rack 30, all the hydrogen collection bottles 7 are placed in the containing groove, and then an openable second door 23 is provided at the top of the containing groove to facilitate the taking, placing and replacing of the hydrogen collection bottles 7.

[0063] As shown in Fig. 2, the liquid product collection system 800 includes several liquid product collection bottles 8 (3 in Fig. 2), each of which is provided with a control valve to form a third valve group, which is connected to the fifth valve 18 at the bottom of the high-pressure reaction chamber 6 through a pipeline to control the discharge of the reaction liquid into each liquid product collection bottle 8 after the reaction in the high-pressure reaction chamber 6 is completed. In order to reduce energy consumption, the liquid product collection bottles 8 can be arranged at the bottom of the high-pressure reaction chamber 6, so that the reaction liquid can flow into the liquid product collection bottles 8 by gravity.

[0064] In order to facilitate the protection and management of the liquid product collection bottles 8, a containing groove can be provided first, as shown in Fig. 2, a side-opening containing groove is provided at the bottom of the left side of the box-type rack 30, all the liquid product collection bottles 8 are placed in the side-opening containing groove, and then an openable third door 24 is provided at the opening of the side of the containing groove to facilitate the taking, placing and replacing of the liquid product collection bottles 8.

[0065] As shown in Fig. 2, Fig. 3 and Fig. 4, in order to facilitate modular design, a box-type rack 30 can be provided, and the pretreatment system 100, the photoelectrocatalytic system 300, the hydrogenolysis reaction system 600, the hydrogen collection system 700, the first reaction material temporary storage system 200, the second reaction material temporary storage system 400 and the third reaction material temporary storage system 500 can be concentrated in the box-type rack 30 to realize highly integrated modular design, and a single box-type rack 30 is a complete cascade reaction device, and multiple cascade reaction devices can be used for large-scale batch production.

[0066] In order to improve energy saving, the application can also be provided with a photovoltaic assembly to power the electrodes of the photoelectrocatalytic system 300 with solar energy. Specifically, as shown in Figures 2, 3 and 4, the photovoltaic assembly includes at least several solar photovoltaic panels 9, which can be arranged on the top of the box-type rack 30, such as on the first door 22 and the second door 23, and the position is not limited. The electricity generated by the solar photovoltaic panels 9 is introduced to the photocatalytic cathode 324 and the photocatalytic anode through wires, respectively. Of course, a storage battery and a transformer can also be provided to obtain the required voltage, which can be achieved by using existing technology, and the application will not be described in detail.

[0067] In order to improve the degree of automation, the application can also be provided with a control system to control the voltage between the photocatalytic cathode 324 and the photocatalytic anode through the built-in controller 21. All valves can also be set as electric valves, and the control sequence can be set by the controller 21. The controller 21 is also used to set the reaction parameters in the high-pressure reaction chamber 6, so that each step of the reaction is automatically performed.

[0068] In this embodiment, renewable solar energy, lignin and water resources are used as raw materials, reducing dependence on fossil fuels, effectively reducing carbon emissions and promoting green transformation of the aviation industry. The system uses photoelectrocatalytic technology to achieve efficient energy and biomass conversion through mild conditions and cascade catalytic methods. The synergistic effect of the cathode and anode photocatalysts optimizes the capture and utilization of full-spectrum solar energy. The semi-automatic controller 21 simplifies the operation and reduces labor costs, while the self-sufficient strategy minimizes the demand for external hydrogen sources, reduces raw material and environmental costs, and improves economic efficiency and sustainability. This innovative solution has significant market potential and provides strong support for global carbon neutralization goals.

[0069] Embodiment 2

[0070] Embodiment 2 uses the cascade reaction device provided in Embodiment 1 to perform the method of integrated cascade reaction for photoelectrocatalytic lignin conversion to produce aviation fuel. Embodiment 2 specifically includes the following steps:

[0071] S1. In the pretreatment system 100, the first valve 10 below the pretreatment reaction chamber 1 is closed, the alkaline solution required for the pretreatment reaction is added to the pretreatment reaction chamber 1, and the lignin is put in. The controller 21 drives it to rotate at a uniform speed to ensure that the lignin is fully dissolved in the alkaline environment, preparing for subsequent photoelectrocatalytic conversion. After the pretreatment reaction is completed, the driving device is closed to stop the rotation of the pretreatment reaction chamber 1, and the first valve 10 and the second valve 11 are opened to make the pretreatment reaction liquid flow from the first reaction liquid temporary storage chamber 2 to the anode chamber 31; In subsequent reactions, the first reaction liquid temporary storage chamber 2 serves as a transfer mechanism to adjust the mismatch between the dissolution speed of the pretreatment reaction chamber 1 and the reaction speed of the anode chamber 31, so the volume of the first reaction liquid temporary storage chamber 2 relative to the anode chamber can be changed as needed.

[0072] S2. In the photoelectrocatalytic system 300, the photo-catalytic anode inside the anode light window 313 is irradiated by sunlight, and the photoelectrocatalytic reaction is driven by the electricity stored in the solar photovoltaic panel 9. After the reaction in the anode chamber 31 is completed, the third valve 12 and the first pump 13 are opened, and the reaction liquid flows into the cathode chamber 32 through the second reaction liquid temporary storage chamber 4. The photo-catalytic cathode 324 absorbs the remaining wavelength of sunlight, and the photoelectrocatalytic reaction is fully carried out. Then, the fourth valve 14 is opened, and the second pump 15 is used to push the reaction liquid to flow into the high-pressure reaction chamber 6 through the third reaction liquid temporary storage chamber 5. Subsequently, the first valve group 16 and the second valve group 17 are opened, and the hydrogen gas generated in the cathode chamber 32 flows into the high-pressure reaction chamber 6 through the hydrogen gas collection bottle 7. The functions of the second reaction liquid temporary storage chamber 4 and the third reaction liquid temporary storage chamber 5 are similar to those of the first reaction liquid temporary storage chamber 2, and they are used as transfer mechanisms to adjust the mismatch between the upstream and downstream reaction rates.

[0073] S3. In the hydrogenolysis reaction system 600, in order to prevent hydrogen deficiency, the external hydrogen source can supplement hydrogen to the high-pressure reaction chamber 6 through the first gas inlet hole 63. The catalyst inlet hole 65 is opened, and the catalyst is put into the high-pressure reaction chamber 6. Then, the catalyst inlet hole 65 is closed, and the controller 21 is used to set the reaction parameters in the high-pressure reaction chamber 6, so that the hydrogenation deoxidation reaction can proceed normally.

[0074] S4. In the product collection system, after the hydrogenation deoxidation reaction is completed, the fifth valve 18 and the third valve group 19 are opened, and the final product flows into the liquid product collection bottle 8. The unused hydrogen gas is collected in the hydrogen gas collection bottle 7.

[0075] S5. After all the reactions are completed, the first door 22, the second door 23, and the third door 24 are opened to clean the remaining impurities in the pretreatment reaction chamber 1, remove the unused hydrogen gas collection bottle 7, and remove the liquid product collection bottle 8 for subsequent purification.

[0076] It should be noted that during the first reaction, since the reaction in the photoelectrocatalytic reaction chamber 3 is linked, it is necessary to ensure that the cathode chamber 32 has materials to react. Therefore, two methods can be used to solve this problem. The first method is to pre-feed the alkaline solution into the cathode chamber 32, so that the photoelectrocatalytic reaction can be completed. The second method is that the first batch of reaction materials entering the anode chamber 31 does not react and is directly sent to the cathode chamber 32. When the anode chamber and the cathode chamber are both full of materials, the photo-catalytic reaction is started. However, in any case, the hydrogen in the hydrogenolysis reaction system 600 should be insufficient at the beginning of the reaction, so external hydrogen compensation is needed at the beginning of the reaction. After the reaction reaches equilibrium, there is no need to supplement external hydrogen.

[0077] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A cascade reaction device for photoelectrocatalytic lignin conversion to produce aviation fuel, characterized in that, The application relates to a system for preparing aviation fuel from lignin, which comprises the following parts: a pretreatment system for dissolving lignin raw materials in an alkaline solution and performing primary depolymerization to obtain a lignin solution; a photoelectrocatalysis system for performing photoelectrocatalysis reaction on the lignin solution to perform depolymerization and coupling reaction on the lignin; the photoelectrocatalysis system comprises an anode chamber, a cathode chamber and a transparent proton exchange membrane arranged between the two chambers, the anode chamber is provided with at least a light-transmitting window and a photocatalytic anode arranged at the light-transmitting window, the photocatalytic anode is non-full light-shielding; the cathode chamber is provided with at least a photocatalytic cathode; the lignin depolymerization main reaction is performed in the anode chamber through photoelectrocatalysis, and the coupling reaction and byproduct hydrogen are generated in the cathode chamber through photoelectrocatalysis; a hydrogenolysis reaction system for performing hydrogenation thermal catalysis reaction on the reaction materials treated by the photoelectrocatalysis system to prepare aviation fuel; and a hydrogen collection system connected with the cathode chamber of the photoelectrocatalysis system and the hydrogenolysis reaction system respectively, used for collecting the hydrogen generated by the cathode chamber temporarily and supplying the hydrogenolysis reaction system to participate in the hydrogenolysis oxidation reaction. The system further comprises a liquid product collection system used for collecting the liquid product of the hydrogenolysis reaction system, a first reaction material temporary storage system arranged between the photoelectrocatalysis system and the pretreatment reaction chamber, a second reaction material temporary storage system arranged between the anode chamber and the cathode chamber, and a third reaction material temporary storage system arranged between the cathode chamber and the hydrogenolysis reaction system. The pretreatment system comprises a pretreatment reaction chamber and a stirring mechanism for accelerating dissolution, and the pretreatment reaction chamber is further provided with a first valve for discharging. The photoelectrocatalysis system comprises a photoelectrocatalysis reaction chamber, which is divided into an anode chamber and a cathode chamber by a proton exchange membrane, and the photocatalytic cathode can receive residual light sequentially passing through the light-transmitting window, the photocatalytic anode and the proton exchange membrane. The photocatalytic anode comprises conductive glass integrated with the light-transmitting window and a photocatalytic layer covered on the inner side of the conductive glass.

2. The cascade reaction device for photoelectrocatalytic conversion of lignin to aviation fuel according to claim 1, characterized in that, The photocatalytic cathode comprises a silicon-based photoelectric cathode and a gallium nitride nanorod array covered on the silicon-based photoelectric cathode.

3. The cascade reaction device for photoelectrocatalytic conversion of lignin to aviation fuel according to claim 2, characterized in that, The photoelectrocatalysis system further comprises a photovoltaic assembly for supplying power to the photocatalytic cathode and the photocatalytic anode.

4. The cascade reaction device for photoelectrocatalytic conversion of lignin to aviation fuel according to claim 2, characterized in that, The second reaction material temporary storage system comprises a second reaction liquid temporary storage chamber connected with the anode chamber and a first conveying pump used for conveying the reaction liquid in the second reaction liquid temporary storage chamber to the cathode chamber.

5. The cascade reaction device for photoelectrocatalytic conversion of lignin to aviation fuel according to claim 2, characterized in that, The third reaction material temporary storage system comprises a third reaction liquid temporary storage chamber connected with the cathode chamber and a second conveying pump used for conveying the reaction liquid in the third reaction liquid temporary storage chamber to the hydrogenolysis reaction system after pressurization.

6. The cascade reaction device for photoelectrocatalytic conversion of lignin to aviation fuel according to claim 2, characterized in that, The hydrogenolysis reaction system comprises a hydrogen supplement pipeline and a product collection system.

7. The cascade reaction device for photoelectrocatalytic conversion of lignin to aviation fuel according to claim 2, characterized in that, The system comprises the following steps:

8. The cascade reaction device for photoelectrocatalytic conversion of lignin to aviation fuel according to claim 2, characterized in that, adding an alkaline solution into the pretreatment system, dissolving lignin raw materials in the alkaline solution and performing primary depolymerization to obtain a lignin solution; introducing the lignin solution into the anode chamber, connecting the power supply and performing depolymerization reaction on the lignin under the photoelectrocatalysis of the photocatalytic anode; 9. The cascade reaction device for photoelectrocatalytic conversion of lignin to aviation fuel according to claim 2, characterized in that, introducing the reaction product after the depolymerization reaction into the cathode chamber through the second reaction material temporary storage system, performing coupling reaction under the action of the photocatalytic cathode and generating byproduct hydrogen; and 10. A method for the conversion of lignin to aviation fuel, using the cascade reactor according to any one of claims 1 to 9, characterized in that, performing hydrogenation thermal catalysis reaction on the reaction materials treated by the photoelectrocatalysis system to prepare aviation fuel. ​ ​ ​ The reaction product after the coupling reaction is introduced into the hydrogenolysis reaction system by the third reaction material temporary storage system for hydrothermal cracking, and the hydrogenolysis reaction system is supplied with hydrogen by the hydrogen gas collection system, and the aviation fuel product is obtained after the reaction is completed, and the aviation fuel is obtained after purification.

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