A system, method and application for co-production of nitrogen-doped porous carbon and hydrogen-rich syngas

Abstract

The application discloses a system, a method and an application for co-production of nitrogen-doped porous carbon and hydrogen-rich synthesis gas. The system comprises a raw material molten salt assisted carbonization unit, a solid phase product activation and purification unit, a gas phase product cascade catalysis unit and a clean heat supply-waste heat recovery unit. The solid phase product activation and purification unit comprises, in sequence, a soaking device, a solid-liquid separation device, an impregnation premixing device, an activation chamber and a dust removal device. The gas phase product cascade catalysis unit comprises, in sequence, a catalytic impurity removal chamber and a catalytic reformer. The catalytic impurity removal chamber is provided with a denitrogenation catalytic layer and a decoking catalytic layer in sequence. Based on the above-mentioned system for co-production of nitrogen-doped porous carbon and hydrogen-rich synthesis gas, nitrogen-containing biomass raw materials (such as waste artificial board), solid-state chlorinated salt and an activating agent can be used as raw materials to prepare hydrogen-rich synthesis gas and nitrogen-doped porous carbon with excellent electrochemical performance, and full-component high-value utilization of the nitrogen-containing biomass raw materials can be realized.

Description

Technical Field

[0001] This invention relates to the field of biomass resource utilization technology, and in particular to a system, method and application for co-producing nitrogen-doped porous carbon and hydrogen-rich syngas. Background Technology

[0002] Waste engineered wood products are a major source of light industrial biomass waste generated by industries such as furniture manufacturing and construction decoration. These include materials such as particleboard, plywood, and fiberboard. From a physicochemical perspective, they contain over 80% lignocellulose and nitrogen-containing adhesives such as urea-formaldehyde resin, making them ideal raw materials for self-generated nitrogen-doped carbon materials. The rapid development of related industries during urbanization inevitably leads to a large amount of waste engineered wood products, and the "resource-environment" conflict has become a pressing issue for enterprises and a hot topic of widespread social concern.

[0003] Traditional disposal methods for waste wood-based panels include landfilling, stockpiling, incineration without boundaries, or direct-fired heating. While these methods can achieve some degree of disposal and added value, they generally have significant drawbacks: (1) high energy input and low economic benefits; (2) resin components are difficult to degrade, and adhesives leach out and cause pollution; (3) improper nitrogen treatment leads to serious pollution emissions. In recent years, the scientific and engineering communities have shifted their focus from extensive disposal methods to targeted, high-value utilization of all components of light industrial biomass waste such as waste wood-based panels. Based on their basic properties, they have proposed resource utilization strategies such as carbonization and gasification, aiming to open up channels for wood-based panels to generate fuels, adsorbents, and supercapacitor electrode materials. However, current carbonization technology still has some problems: on the one hand, nitrogen is volatilized in large quantities in the form of NH3 during conventional carbonization, resulting in low nitrogen retention in solid products and nitrogen-containing gaseous products that are prone to secondary pollution; on the other hand, the resulting carbon materials have underdeveloped pore structures and poor electrochemical performance, while the carbonization gaseous products have low hydrogen content and high tar content, resulting in limited overall value.

[0004] Therefore, there is an urgent need to develop a system and process for the directional thermal conversion of waste engineered wood products to co-produce nitrogen-doped porous carbon and hydrogen-rich syngas, so as to achieve efficient fixation of carbon and nitrogen elements and resource-based conversion of gaseous products. Summary of the Invention

[0005] The first aspect of the present invention is to provide a system for co-producing nitrogen-doped porous carbon and hydrogen-rich syngas.

[0006] The second objective of this invention is to provide a method for co-producing nitrogen-doped porous carbon and hydrogen-rich syngas.

[0007] The third aspect of this invention aims to provide a system and method for co-producing nitrogen-doped porous carbon and hydrogen-rich syngas, and its application in the preparation of hydrogen-rich combustible gas, hydrogen-rich syngas, supercapacitor electrode materials, adsorbent materials, and fuels.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A first aspect of the present invention provides a system for co-producing nitrogen-doped porous carbon and hydrogen-rich syngas, the system comprising: A raw material molten salt-assisted carbonization unit is used to mix and carbonize nitrogen-containing biomass raw materials with solid chloride salts. The raw material molten salt-assisted carbonization unit includes a premixing device and a medium-temperature carbonization furnace connected in sequence. The medium-temperature carbonization furnace is provided with a first outlet and a second outlet. The solid-phase product activation and purification unit is used to sequentially perform immersion washing, solid-liquid separation, activation and dust removal on the primary biochar-molten salt mixture generated by the medium-temperature carbonization furnace to obtain nitrogen-doped porous carbon; wherein, the solid-phase product activation and purification unit includes an immersion washing device, a solid-liquid separation device, an immersion premixing device, an activation chamber and a dust removal device connected in sequence, wherein the immersion washing device is connected to the second outlet of the medium-temperature carbonization furnace. A gas-phase product step-by-step catalytic unit is used to sequentially denitrify, decoke, and reform the crude gas generated by the medium-temperature carbonization furnace to obtain hydrogen-rich syngas. The gas-phase product step-by-step catalytic unit includes a catalytic purification chamber and a catalytic reformer connected in sequence. The catalytic purification chamber is provided with a denitrification catalytic layer and a decoke catalytic layer in sequence. The catalytic purification chamber is connected to the first outlet of the medium-temperature carbonization furnace.

[0009] The system for co-producing nitrogen-doped porous carbon and hydrogen-rich syngas of the present invention has at least the following beneficial effects: (1) In the system of the present invention, nitrogen-containing biomass raw materials and solid chloride salts are first fully premixed in a premixing device, and then carbonized in a medium-temperature carbonization furnace. The resulting primary biochar-molten salt mixture (containing a mixture of molten salt and nitrogen-doped biochar) is sent to the impregnation device of the solid product activation and purification unit through the second outlet of the medium-temperature carbonization furnace to remove the molten salt. It is then separated by a solid-liquid separation device, and the resulting solid phase (nitrogen-doped carbon) is sent to the impregnation premixing device to be mixed with an activator. After high-temperature activation and dust removal in the activation chamber and dust removal device, nitrogen-doped porous carbon is obtained. The gaseous products (such as crude gas) generated in the medium-temperature carbonization furnace are sent to the catalytic purification chamber of the gaseous product stepped catalytic unit through the first outlet. After being treated by the denitrification catalytic layer and the decoking catalytic layer, it enters the catalytic reformer. After reacting with calcium oxide, it is reformed to obtain hydrogen-rich synthesis gas.

[0010] (2) Based on thermochemical conversion technology, this system achieves the directional preparation of nitrogen-doped porous carbon and hydrogen-rich syngas, as well as the full-component high-value conversion of nitrogen-containing biomass raw materials (such as waste artificial boards) through molten salt-assisted carbonization coupling activation and a step-by-step catalysis strategy. In addition, the system adopts a modular unit design, and each unit can be flexibly adjusted according to the actual situation to adapt to various production scales.

[0011] (3) Since the carbonization of waste artificial boards produces nitrogen-containing pollutants (nitrogen-containing tar, NH3, HCN, etc.), this system adopts the step-by-step catalysis method of gas phase products. By designing a step-by-step catalytic unit for gas phase products, the crude gas is processed sequentially through the denitrification catalytic layer, the decoking catalytic layer and the catalytic reformer to convert it into hydrogen-rich syngas, thereby realizing the high-value harmless utilization of gas phase products.

[0012] In some embodiments of the present invention, the raw material molten salt-assisted carbonization unit further includes a material conveying device for conveying the raw material-molten salt mixture generated by the premixing device to the medium-temperature carbonization furnace.

[0013] In some embodiments of the present invention, the solid-liquid separation device is provided with a solid phase outlet and a liquid phase outlet, wherein the solid phase outlet is connected to the impregnation premixing device for feeding the separated nitrogen-doped carbon into the impregnation premixing device. The liquid phase outlet is connected to the immersion washing device and is used to send the separated liquid phase into the immersion washing device for reflux treatment.

[0014] In some embodiments of the present invention, the dust removal device includes a primary cyclone dust collector and a secondary cyclone dust collector.

[0015] In some embodiments of the present invention, the primary cyclone dust collector is provided with a first top discharge port and a first bottom discharge port, wherein the first top discharge port is connected to the secondary cyclone dust collector; and the first bottom discharge port is connected to the activation chamber. The secondary cyclone dust collector is provided with a second top discharge port and a second top and bottom discharge port. The second top discharge port is connected to the catalytic impurity removal chamber and is used to transport the denitrified gas to the catalytic impurity removal chamber for impurity removal.

[0016] In some embodiments of the present invention, the second top and bottom discharge ports are used to collect the nitrogen-doped porous carbon.

[0017] In some embodiments of the present invention, the denitrification catalyst layer comprises any one of dolomite, olivine, iron ore and red mud, and is used to denitrify the gas entering the catalytic purification chamber.

[0018] In some embodiments of the present invention, the decoking catalyst layer comprises a nickel-based active component catalyst for decoking the denitrified product.

[0019] In some embodiments of the present invention, the support for the nickel-based active component catalyst includes any one of Al2O3, porous biochar, and lignite coke.

[0020] Preferably, the nickel-based catalyst comprises Ni / Al2O3.

[0021] In some embodiments of the present invention, the catalytic reformer includes a cyclone dust removal chamber and a combustion chamber.

[0022] Preferably, the cyclone dust collector is provided with a first top discharge port, a second top discharge port, and a bottom discharge port; the second top discharge port is connected to the combustion chamber.

[0023] In some embodiments of the present invention, the system further includes a clean heating-waste heat recovery unit, which includes a clean heating device and a waste heat recovery device. The clean heating device includes an electric heating device and a combustion heating device; wherein the electric heating device is used to heat the medium-temperature carbonization furnace, the activation chamber, and the catalytic purification chamber; and the combustion heating device is used to heat the combustion chamber. The waste heat recovery device includes a first heat exchange device and a second heat exchange device; The first heat exchange device includes a first heater and a first cooler connected in sequence, forming a loop; wherein, the first cooler is disposed between the premixing device and the material pipeline of the medium-temperature carbonization furnace; the first heater is disposed between the medium-temperature carbonization furnace and the material pipeline of the immersion washing device; the heat transfer medium of the first heat exchange device is heat transfer oil. The second heat exchange device includes a second heater and a second cooler connected in sequence, forming a loop; wherein, the second cooler is disposed in the medium-temperature carbonization furnace and is used to provide a heat source; the second heater is disposed between the catalytic purification chamber and the material pipeline of the catalytic reformer; the heat transfer medium of the second heat exchange device is a molten sodium-potassium alloy.

[0024] In some embodiments of the present invention, the clean heating-waste heat recovery unit further includes a working fluid storage tank for storing the heat transfer working fluid. During operation, the heat transfer working fluid absorbs heat in the first heater of the first heat exchanger or the second heater of the second heat exchanger, causing its temperature to rise. This heat is then transferred to the first cooler of the first heat exchanger or the second cooler of the second heat exchanger to provide heat for preheating or carbonizing the raw material-molten salt mixture. After its temperature decreases, the heat transfer working fluid is circulated back to the first heater of the first heat exchanger or the second heater of the second heat exchanger, thereby completing the heat transfer and exchange.

[0025] Preferably, the working medium storage tank includes a first working medium storage tank and a second working medium storage tank, wherein: The first working fluid storage tank includes a first working fluid inlet and a first working fluid outlet. The first working fluid inlet is connected to the first heater of the first heat exchange device, and the first working fluid outlet is connected to the first cooler of the first heat exchange device.

[0026] The second working fluid storage tank includes a second working fluid inlet and a second working fluid outlet. The second working fluid inlet is connected to the second heater of the second heat exchange device, and the second working fluid outlet is connected to the second cooler of the second heat exchange device.

[0027] In some embodiments of the present invention, the system further includes a circulating pump assembly for driving the flow of materials or heat transfer fluids in the system.

[0028] In some embodiments of the present invention, the system further includes an automation control unit.

[0029] A second aspect of the present invention provides a method for co-producing nitrogen-doped porous carbon and hydrogen-rich syngas, which is carried out using the system described in the first aspect, and specifically includes the following steps: S1. Nitrogen-containing biomass raw materials are mixed with solid chloride salts and carbonized in the medium-temperature carbonization furnace to obtain primary biochar-molten salt mixture and crude fuel gas. S2. The primary biochar-molten salt mixture is sequentially washed, separated into solid and liquid, activated, and dedust-removed to obtain nitrogen-doped porous carbon. S3. The crude gas is subjected to denitrification, decoking and reforming treatment in sequence to obtain hydrogen-rich synthesis gas.

[0030] The co-production method of the present invention has at least the following beneficial effects: The molten salt-assisted carbonization activation method of this invention helps to construct the carbon skeleton and suppress the volatilization of nitrogen-containing components, and can significantly improve the solid phase yield (solid phase yield > 47%) and nitrogen content (about 3 wt.%) of the product; through stepwise catalysis of the gas phase product, denitrification, decoking and reforming of gas components can be achieved, converting the gas phase product into hydrogen-rich syngas, and completing the high-value utilization of all components of waste wood-based panels.

[0031] In some embodiments of the present invention, the nitrogen-containing biomass raw material includes waste engineered wood products.

[0032] In some embodiments of the present invention, the waste engineered wood includes any one of medium fiberboard, plywood, and particleboard.

[0033] In some embodiments of the present invention, the solid chloride salt includes at least one of zinc chloride, copper chloride, lithium chloride, cadmium chloride, potassium chloride-lithium chloride, sodium chloride-zinc chloride, and potassium chloride-zinc chloride; Solid chloride salts, as molten salt components, are mainly used to assist in carbonization. During the carbonization process, they can form a liquid phase to suppress nitrogen volatilization and promote the formation of carbon skeletons and participate in nitrogen fixation (especially the generation of highly active pyridine nitrogen).

[0034] In some embodiments of the present invention, the mass ratio of the nitrogen-containing biomass raw material to solid chloride salt is 0.2 to 5:1.

[0035] Preferably, the mass ratio of the nitrogen-containing biomass raw material to the solid chloride salt is 1:1, for example, it can be 0.2:1, 0.3:1, 0.5:1, 1:1, 2:1, 3:1 or 5:1, etc.

[0036] In some embodiments of the present invention, the carbonization temperature is 400~600 °C.

[0037] In some embodiments of the present invention, the immersion includes washing with a mixed solution of HCl and H2O2 or water.

[0038] In some embodiments of the present invention, the activation includes mixing the nitrogen-doped carbon obtained from the solid-liquid separation with an activator and treating it at 700~900 °C.

[0039] In some embodiments of the present invention, the mass ratio of the nitrogen-doped carbon to the activator is 0.2 to 5:1.

[0040] Preferably, the mass ratio of the nitrogen-doped carbon to the activator is 1:1. For example, it can be 0.2:1, 0.3:1, 0.5:1, 1:1, 2:1, 3:1 or 5:1, etc.

[0041] In some embodiments of the present invention, the activator includes at least one of potassium bicarbonate, potassium carbonate, sodium bicarbonate, and sodium carbonate.

[0042] Under the premise of stabilizing the carbon and nitrogen elements in molten salt, activators are used to create pores in nitrogen-doped carbon, forming more micropores and mesopores, which helps to improve the specific capacitance and rate performance of the product.

[0043] In some embodiments of the present invention, the temperature of the denitrification process is 700~900 ℃; preferably 800 ℃.

[0044] Preferably, the denitrification is performed using dolomite, and the amount added is 10% to 20% of the volatile matter mass.

[0045] In some embodiments of the present invention, the temperature of the decoking process is 600~800 ℃; preferably 700 ℃.

[0046] Preferably, the decoking process uses Ni / Al2O3 with a loading of 20 ± 2 wt.%.

[0047] In some embodiments of the present invention, the temperature of the reforming process is 500~700 ℃; preferably 600 ℃.

[0048] In some embodiments of the present invention, the reforming includes mixing and reacting the denitrified and decoked product (clean fuel gas) with calcium oxide.

[0049] A third aspect of the present invention provides the application of the system as described in the first aspect or the method as described in the second aspect in the preparation of high-value biogas, syngas feedstock, supercapacitor electrode materials, adsorbent materials, and fuel cell electrode materials.

[0050] Other features and advantages of the present invention will be set forth in the following description. Attached Figure Description

[0051] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 This is a schematic diagram of the system structure for the co-production of nitrogen-doped porous carbon and hydrogen-rich syngas according to the present invention. Figure 2 This is a schematic diagram of the dust removal device. Figure 3 This is a schematic diagram of the structure of the first heat exchange device; Figure 4 The results of the detection of elemental composition and yield of biochar produced by molten salt-mediated carbonization and conventional carbonization in this invention are shown, where a is the solid yield, b is the carbon retention efficiency, c is the nitrogen density ratio, and d is the nitrogen retention efficiency. Figure 5 The results show the comparison of nitrogen functional groups in biochar produced by molten salt-mediated carbonization and conventional carbonization in this invention. In the figure, a is the N1s XPS spectrum of FB-550, b is the N1s XPS spectrum of FB-CuCl2-550-1:1, and c is the relative content distribution of nitrogen-containing functional groups. Figure 6 The images show the microstructures of different biochar materials used in this invention, where ab represents FB-550; cd represents FB-CuCl2-550-1:1; ef represents FB-KHCO3-800; and gh represents FB-CuCl2 / KHCO3-800-1:1. Figure 7 The structural characteristics of different biochar materials of this invention are shown in the following figures: a is the nitrogen adsorption-desorption isotherm, b is the Barrett-Joyner-Halada (BJH) pore size distribution, and c is the Raman spectrum. Figure 8 The results show the electrochemical performance of different biochar materials of this invention, where a is 10 mV·s. 1 The CV curve is shown below, where b is 0.1 A·g. 1The GCD curves are shown below, c is the current density-specific capacitance curve, d is the Nyquist plot, and e is the GCD curve of FB-CuCl2 / KHCO3-800-1:1 at 5 A·g. 1 Coulomb efficiency and cycle performance under these conditions.

[0052] Figure 9 The percentage of nitrogen-containing components in the products after catalysis by different metal oxides; Figure 10 The percentage of nitrogen-containing components with and without nickel-based catalysts; Figure 11 This is a schematic diagram illustrating the regulation mechanism of syngas during reforming catalysis. Icon labels: Raw material molten salt auxiliary carbonization unit 100; premixing device 110; medium temperature carbonization furnace 120; first outlet 121; second outlet 122; Solid product activation and purification unit 200; washing device 210; solid-liquid separation device 220; solid phase outlet 221; liquid phase outlet 222; impregnation premixing device 230; activation chamber 240; dust removal device 250; primary cyclone dust collector 251; first top discharge port 2511; first bottom discharge port 2512; secondary cyclone dust collector 252; second top discharge port 2521; second top and bottom discharge ports 2522; Gas-phase product cascade catalytic unit 300; catalytic impurity removal chamber 310; denitrification catalytic layer 311; decoking catalytic layer 312; catalytic reformer 320; cyclone dust removal chamber 321; combustion chamber 322; fuel storage tank 323; collection chamber 324; Clean heating - waste heat recovery unit 400; first heat exchange device 410; second heat exchange device 420; 411 first heater; 412 first cooler; 413 first working fluid storage tank; 4131 first working fluid inlet; 4132 first working fluid outlet. Detailed Implementation

[0053] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0054] The terms "preferred," "more preferably," etc., used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.

[0055] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0056] In the description of this invention, the reference term "and / or" includes all and any combination of one or more of the associated listed items.

[0057] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0058] Example 1: System for co-producing nitrogen-doped porous carbon and hydrogen-rich syngas Reference Figure 1 As shown, the present invention provides a system for the directional thermal conversion of waste wood-based panels to co-produce nitrogen-doped porous carbon and hydrogen-rich syngas. The system consists of a raw material molten salt-assisted carbonization unit 100, a solid-phase product activation and purification unit 200, a gas-phase product step-by-step catalytic unit 300, and a clean heating-waste heat recovery unit 400.

[0059] (1) Raw material molten salt assisted carbonization unit The raw material molten salt-assisted carbonization unit 100 is used to mix nitrogen-containing biomass raw materials (such as waste artificial board raw materials) with solid chloride salts, and then carry out molten salt-assisted carbonization in the medium-temperature carbonization furnace 120 to realize the reconstruction of the biomass carbon skeleton and the retention of nitrogen elements, while generating primary biochar-molten salt mixture and crude fuel gas.

[0060] The aforementioned raw material molten salt-assisted carbonization unit 100 consists of a premixing device 110 and a medium-temperature carbonization furnace 120 connected in sequence. The premixing device 110 is used to mix nitrogen-containing biomass raw materials and solid chloride salts. Specifically, it can be any one of a conical mixer (such as a double-helix conical mixer), a V-type mixer, a ribbon mixer, or a drum mixer, preferably a conical mixer, which helps to uniformly mix waste artificial board raw material powder with solid chloride salts to obtain a raw material-molten salt mixture.

[0061] In some instances, the raw material molten salt-assisted carbonization unit 100 also includes a screw feeder for conveying the raw material-molten salt mixture obtained from the premixing unit 110 to the medium-temperature carbonization furnace 120, thereby achieving stable, continuous, and controllable material conveying.

[0062] The intermediate-temperature carbonization furnace 120 is a carbonization reactor operating at a moderate temperature (preferably 400-600 °C) and inert atmosphere. In this reactor, the raw material-molten salt mixture undergoes a molten salt-mediated carbonization reaction to generate a primary biochar-molten salt mixture (a mixture of molten salt and nitrogen-doped biochar) and crude fuel gas, achieving preliminary nitrogen fixation. The intermediate-temperature carbonization furnace 120 is equipped with a first outlet 121 and a second outlet 122. The first outlet 121 is connected to the catalytic purification chamber 310 of the gas phase product cascade catalytic unit 300 and is used to transport the crude fuel gas to the gas phase product cascade catalytic unit 300. The second outlet 122 is used to transport the primary biochar-molten salt mixture to the solid phase product activation and purification unit 200.

[0063] In some instances, the outer surface of the medium-temperature carbonization furnace 120 is also equipped with a resistance heating device (such as an electric heating jacket) to provide thermal energy for processes that require precise temperature control, such as carbonization, activation, and catalysis.

[0064] In the specific reaction, waste wood-based panels and solid chloride salt are fully premixed in a 1:1 ratio in a premixing device 110. The resulting raw material-molten salt mixture is then stably conveyed to a medium-temperature carbonization furnace 120 via a screw feeder. The mixture undergoes a medium-temperature carbonization reaction at a set temperature of 400-600 °C for 0.5-1.5 h. After the reaction is complete, a primary biochar-molten salt mixture and crude fuel gas are obtained. The resulting primary biochar-molten salt mixture is then conveyed to a solid-phase product activation and purification unit 200 via the second outlet 122 of the medium-temperature carbonization furnace 120.

[0065] (2) Solid-phase product activation and purification unit The solid product activation and purification unit 200 is used to activate and purify the primary biochar-molten salt mixture generated during the carbonization process. Then, through auxiliary steps such as immersion washing, centrifugal separation, and cyclone dust removal, nitrogen-doped porous carbon is prepared, and the carbon-containing tail gas generated is purified.

[0066] The aforementioned solid product activation and purification unit 200 is formed by sequentially connecting an immersion washing device 210 (such as an immersion water tank), a solid-liquid separation device 220 (such as a centrifugal filter), an impregnation premixing device 230 (such as an impregnation premixing tank), an activation chamber 240 (such as a high-temperature activation chamber), and a dust removal device 250. One end of the immersion washing device 210 is connected to the second outlet 122 of the medium-temperature carbonization furnace 120. It is a device used for wet leaching and washing of the primary biochar-molten salt mixture, with the purpose of removing soluble salts and impurities to obtain pure primary carbon material.

[0067] Solid-liquid separation device 220 is used to separate the solid and liquid phases of the product after treatment in the immersion water tank. It has a solid phase outlet and a liquid phase outlet. The solid phase outlet is connected to the impregnation premixing tank to feed the separated nitrogen-doped carbon into the premixing tank. The liquid phase outlet is connected to the immersion washing device 210 to feed the separated liquid phase into the immersion washing device 210 for reflux treatment. A filtrate tank 223 can also be installed in the passage between the liquid phase outlet and the immersion washing device 210. After solid-liquid separation, the liquid phase first enters the filtrate tank and is then transported to the immersion water tank for recycling; the solid phase (i.e., nitrogen-doped carbon) enters the impregnation premixing device 230 via a conveying device. The impregnation premixing device 230 is equipped with a stirring device to mix the nitrogen-doped carbon with an activator (such as KHCO3 or K2CO3), ensuring the activator is evenly distributed on the carbon skeleton to obtain a nitrogen-doped carbon-activator mixture for subsequent high-temperature activation treatment.

[0068] The activation chamber 240 is a reaction chamber that operates at high temperature (preferably 700~900 ℃). The nitrogen-doped carbon-activator mixture undergoes a chemical activation reaction here to generate a mixed gas containing porous carbon powder, i.e., carbon-containing tail gas.

[0069] like Figure 2 As shown, the cyclone dust collector 250 includes a primary cyclone dust collector 251 and a secondary cyclone dust collector 252. The primary cyclone dust collector 251 is provided with a first top discharge port 2511 and a first bottom discharge port 2512. The first bottom discharge port 2512 is connected to the high-temperature activation chamber 240 and is used to transport the larger solid particles in the carbon-containing tail gas, mainly carbon dust, i.e., large-particle high-temperature dust, to the high-temperature activation chamber 240 to re-participate in the activation reaction. The first top discharge port 2511 is connected to the secondary cyclone dust collector 252 and is used to transport the smaller solid particles in the carbon-containing tail gas to the secondary cyclone dust collector 252 for secondary dust removal. The secondary cyclone dust collector 252 is provided with a second top discharge port 2521 and a second top and bottom discharge port 2522. The second top discharge port 2521 is connected to the catalytic purification chamber 310 of the gas phase product step catalytic unit 300 and is used to transport carbon removal tail gas. The second top and bottom discharge port 2522 is used to collect nitrogen-doped porous carbon.

[0070] In the specific reaction, in the solid-phase product activation and purification unit 200, the primary biochar-molten salt mixture is transported to the immersion water tank through the second outlet 122 of the medium-temperature carbonization furnace 120 to remove the molten salt. Then, it is separated by a centrifugal filter to obtain nitrogen-doped carbon, which is then transported to an impregnation premixing tank and mixed with an activator (such as KHCO3 or K2CO3). After impregnation for 12 hours, a nitrogen-doped carbon-activator mixture is obtained. This mixture is then transported to the activation chamber 240 and activated at 700-900 °C for 1-2 hours to generate carbon-containing tail gas. After dust removal by a primary cyclone dust collector 250, the generated large-particle high-temperature dust is returned to the high-temperature activation chamber 240 for further reaction. The remaining gas is then dusted by a secondary cyclone dust collector 250 to obtain decarbonized tail gas and nitrogen-doped porous carbon. The decarbonized tail gas is then introduced into the catalytic purification chamber 310 for subsequent catalytic treatment.

[0071] (3) Gas-phase product cascade catalytic unit The gas phase product cascade catalytic unit 300 is used to perform cascade catalytic treatment on the gas phase products (i.e. crude fuel gas) generated by the raw material molten salt assisted carbonization unit 100. The gas undergoes denitrification, decoking, reforming and CO2 capture treatment in sequence to finally obtain hydrogen-rich syngas and realize the recycling of calcium oxide.

[0072] The gas-phase product cascade catalytic unit 300 includes a catalytic impurity removal chamber 310 and a catalytic reformer 320, with the catalytic impurity removal chamber 310 connected to the catalytic reformer 320. The catalytic impurity removal chamber 310 is sequentially equipped with a denitrification catalytic layer 311 and a decoking catalytic layer 312. The denitrification catalytic layer 311 can catalytically decompose pollutants (such as NH3) in the crude fuel gas at high temperatures; the decoking catalytic layer 312 is used to catalytically crack complex tar molecules in the crude fuel gas, converting them into smaller molecule gases to obtain clean fuel gas. The catalytic impurity removal chamber 310 and the activation chamber 240 are separated by a partition.

[0073] In some embodiments, the denitrification catalyst layer 311 can be made of materials such as dolomite, olivine, iron ore, or red mud. Dolomite is a natural mineral, mainly composed of CaMg(CO3)2, with a magnesium (MgO) content typically around 20%–22% and a calcium (CaO) content of approximately 30%–32%, and also contains small amounts of impurities such as iron, silicon, and aluminum. The number of denitrification catalyst layers 311 can be one, two, three, four, or five, preferably two layers. The decoking catalyst layer 312 can be made of materials such as Ni / Al2O3 or activated carbon, where Ni / Al2O3 refers to a catalyst with alumina as a support and nickel metal loaded on it. The number of denitrification catalyst layers 311 can be one, two, three, four, or five, preferably two layers. In the specific reaction, when the crude fuel gas generated by the molten salt-assisted carbonization unit 100 enters the catalytic purification chamber 310, it undergoes denitrification and decoking treatment sequentially through the denitrification catalyst layer 311 and the decoking catalyst layer 312. The catalytic purification chamber 310 can solve the complex purification problem of the coexistence of nitrogen oxides and tar in the gaseous products generated during the carbonization process. The absence of any link can easily lead to downstream catalyst poisoning or deactivation, system blockage, or a significant decrease in hydrogen yield and purity. The order and combination of the denitrification catalyst layer 311 and the decoking catalyst layer 312 are indispensable for the long-term stable operation of the system and the acquisition of high-quality hydrogen-rich syngas.

[0074] The catalytic reformer 320 includes a cyclone dust collector 321 and a combustion chamber 322, with the combustion chamber 322 connected to the cyclone dust collector 321. The catalytic reformer 320 is used to adjust the gas composition and increase the hydrogen concentration. When the clean fuel gas, after denitrification and decoking, enters the catalytic reformer 320, calcium oxide and water vapor are introduced into the reaction system. In the catalytic reforming stage, calcium oxide acts as a catalyst and CO2 adsorbent, promoting the water-gas shift reaction (the process of reacting carbon monoxide with water to produce carbon dioxide and hydrogen) and capturing CO2 in situ, thereby increasing the hydrogen yield. Water vapor, as a gasifying agent and reactant, is introduced into the catalytic reforming stage and can undergo a water-gas shift reaction with CO to increase hydrogen production. The combustion chamber 322 is used to decompose the calcium carbonate produced in the reaction back into calcium oxide for reuse in the catalytic reformer 320.

[0075] In some embodiments, the catalytic reformer 320 further includes a fuel storage tank 323 and a collection chamber 324. A combustion chamber 322 is connected to the fuel storage tank 323, and fuel is fed into the combustion chamber 322 through nozzles for combustion and energy supply. The collection chamber 324 is connected to the cyclone dust removal chamber 321 and the combustion chamber 322, and is used to collect calcium carbonate and send it to the combustion chamber 322 for re-decomposition into calcium oxide.

[0076] In some implementations, the resulting hydrogen-rich syngas can be used as a raw material to produce high-value-added chemicals such as green liquid fuels (diesel, gasoline), methanol, or acetic acid through downstream processes such as Fischer-Tropsch synthesis, methanol synthesis, or anaerobic fermentation.

[0077] In the specific reaction, when the crude fuel gas generated by the molten salt-assisted carbonization unit 100 enters the catalytic purification chamber 310, it undergoes nitrogen removal through the denitrification catalytic layer 311 (such as a dolomite bed) at a temperature of 800-900 °C. It then enters the decoking catalytic layer 312 (such as a Ni / Al2O3 layer) for decoking and purification at 700-800 °C, yielding clean fuel gas. This clean fuel gas then enters the catalytic reformer 320 along with calcium oxide powder and water vapor, ultimately producing hydrogen-rich syngas. Calcium oxide reacts to form calcium carbonate, which decomposes in the combustion chamber 322 to regenerate calcium oxide, facilitating recycling at the chemical chain level. The heat from the high-temperature flue gas generated in the combustion chamber 322 is also connected to the waste heat recovery network.

[0078] (4) Clean heating - waste heat recovery unit The Clean Heating - Waste Heat Recovery Unit 400 is responsible for optimizing, managing, recovering, and redistributing the energy flow of the entire system. It recovers the sensible heat of the high and medium temperature materials during the process through a heat exchange network, and uses it in stages to preheat the raw material-molten salt mixture entering the carbonization furnace and to heat the medium temperature carbonization reaction, thereby achieving efficient internal energy circulation and significantly reducing the overall energy consumption of the system.

[0079] The main structure of the clean heating-waste heat recovery unit 400 includes a waste heat recovery device and a clean heating device installed between various process flow pipelines. The waste heat recovery device includes a first heat exchanger 410 and a second heat exchanger 420 for heat exchange.

[0080] like Figure 3As shown, the first heat exchange device 410 includes a first heater 411 and a first cooler 412 connected in sequence, forming a loop. The first cooler 412 is located between the premixing device 110 and the material pipeline of the medium-temperature carbonization furnace 120, and the first heater 411 is located between the medium-temperature carbonization furnace 120 and the material pipeline of the rinsing water tank, for absorbing heat from the primary biochar-molten salt mixture. In some embodiments, the first heat exchange device 410 also includes a first working fluid storage tank 413, preferably a pressure vessel with an insulation layer, for storing and buffering the heat transfer working fluid to maintain system pressure stability. The first working fluid storage tank 413 has a first working fluid inlet 4131 and a first working fluid outlet 4132, wherein the first working fluid inlet 4131 is connected to the first heater 411, and the first working fluid outlet 4132 is connected to the first cooler 412. The residual heat in the primary biochar-molten salt mixture can be recovered through heat exchange between the first heater 411 and the first cooler 412 for preheating treatment of the raw material-molten salt mixture.

[0081] The second heat exchange device 420 includes a second heater 421 and a second cooler 422 connected in sequence, forming a loop. The second cooler 422 is located inside the medium-temperature carbonization furnace 120 to provide a heat source; the second heater 421 is located between the catalytic purification chamber 310 and the material pipeline of the catalytic reformer 320 to absorb heat. In some embodiments, the first heat exchange device 410 also includes a second working fluid storage tank, located between the pipelines of the second cooler 422 and the second heater 421, enabling efficient heat transfer via the heat transfer medium. Through heat exchange between the second heater 421 and the second cooler 422, heat from the clean fuel gas can be recovered, contributing to efficient heat utilization.

[0082] In some embodiments, the heat transfer medium used in the clean heating-waste heat recovery unit 400 is selected from high-boiling-point heat transfer oil, molten salt medium (such as sodium nitrate-potassium nitrate eutectic salt), or sodium-potassium alloy, which have high heat capacity, low viscosity, and chemical stability. Preferably, the heat transfer medium used in the first heat exchange device 410 is heat transfer oil; the heat transfer medium used in the second heat exchange device 420 is molten sodium-potassium alloy.

[0083] In some embodiments, the clean heating device includes an electric heating device and a combustion heating device; wherein the electric heating device is used to heat the medium-temperature carbonization furnace 120, the activation chamber 240 and the catalytic purification chamber 310; and the combustion heating device is used to heat the combustion chamber 322.

[0084] In some implementations, the startup and main energy input of each core reaction unit (such as the raw material molten salt-assisted carbonization unit 100, the solid-phase product activation and purification unit 200, and the gas-phase product cascade catalytic unit 300) can be achieved through electric heating or combustion heating. When electric heating is used, clean green electricity is used for power supply. After the system is running stably, the directional recovery and recycling network of sensible heat from crude gas and high-temperature solid-phase products helps to significantly reduce the consumption of external energy and achieve efficient and low-carbon operation. When combustion heating is used, natural gas combustion is used as the core high-temperature heat source, and heat pipes combined with heat transfer medium are used as efficient transport carriers. The reaction heat of the raw material molten salt-assisted carbonization unit 100 and the gas-phase product cascade catalytic unit 300 is actively collected, and the main combustion heat and recovered waste heat are directionally transported through a closed-loop path to the core energy-consuming units such as the medium-temperature carbonization furnace 120, the high-temperature activation chamber 240, and the catalytic reformer 320 as their main process heat sources.

[0085] In some embodiments, the system of the present invention further includes a circulating pump assembly, preferably a high-temperature and high-pressure pump, for driving the flow of materials or working fluids in a closed-loop circulation system.

[0086] In some embodiments, the system of the present invention also includes an automated control unit. By deploying a sensor network to collect data in real time and utilizing machine learning and model predictive control algorithms, real-time collaborative optimization and adaptive adjustment of key parameters such as molten salt addition, temperature of each catalyst bed, and steam injection rate are achieved to realize full automation of the production process, ensure stable product quality, dynamically respond to changes in external conditions, and maximize overall energy efficiency and economic benefits.

[0087] In summary, the system of this invention, based on thermochemical conversion technology, achieves the directional preparation of nitrogen-doped porous carbon and hydrogen-rich syngas through a molten salt-assisted carbonization coupled activation and a cascade catalysis strategy, thus realizing the high-value conversion of all components of waste engineered wood panels. Simultaneously, by integrating a waste heat recovery device, the system recovers waste heat generated in the medium- and high-temperature processes for use in other parts of the reaction for heating or material preheating, achieving cascaded energy utilization and significantly reducing system operating energy consumption. Furthermore, the system of this invention adopts a modular unit design, and each unit can be flexibly adjusted according to actual conditions to adapt to various production scales.

[0088] Example 2: Process for Co-producing Nitrogen-Doped Porous Carbon and Hydrogen-Rich Syngas This embodiment provides a process for co-producing nitrogen-doped porous carbon and hydrogen-rich syngas using waste fiberboard, which specifically includes the following steps.

[0089] (1) Raw material molten salt assisted carbonization First, the crushed and dried waste MDF raw material is fully premixed with solid copper chloride in a 1:1 ratio in a conical mixer. Then, this raw material-molten salt mixture is stably conveyed to a medium-temperature carbonization furnace 120 via a screw feeder, where a medium-temperature carbonization reaction is carried out at a set temperature of 550 ℃ for 1 h. After the reaction is complete, a primary biochar-molten salt mixture (a mixture of molten salt and nitrogen-doped biochar) and crude fuel gas are obtained. The primary biochar-molten salt mixture is discharged through the discharge system, while the crude fuel gas is sent to a cascade catalytic unit via a blower for subsequent reactions.

[0090] In some instances, solid copper chloride can be replaced by other solid chloride salts, such as zinc chloride, which are mainly used to form a liquid phase environment during carbonization to promote heat conduction, inhibit the volatilization of nitrogen-containing components, and participate in nitrogen fixation.

[0091] (2) Activation and purification of solid products The above-mentioned primary biochar-molten salt mixture is transported to a washing water tank (solvent is water) after passing through a heat exchange device to remove the molten salt, and then processed by a centrifugal filter. The centrifugation speed is 3000-4500 rpm and the centrifugation time is 15-25 min. The liquid phase after centrifugation is collected in a filtrate tank, and the solid phase (i.e., nitrogen-doped carbon) is transported to an impregnation premixing tank and mixed with activator KHCO3. After impregnation for 12 h, a nitrogen-doped carbon-activator mixture is obtained. The nitrogen-doped carbon-activator mixture is then transported to a high-temperature activation chamber 240 and activated continuously at 800 ℃ for 2 h to obtain carbon-containing tail gas.

[0092] The carbon-containing tail gas is transported to the primary cyclone dust collector 250 for dust removal. The generated large-particle high-temperature dust is returned to the high-temperature activation chamber 240 for further reaction. The remaining gas is passed into the secondary cyclone dust collector 250 for secondary dust removal, resulting in carbon-removed tail gas and nitrogen-doped porous carbon.

[0093] The decarbonized tail gas is passed into the catalytic purification chamber 310 for subsequent catalytic treatment.

[0094] (3) Gas-phase product step-by-step catalysis The crude fuel gas is fed into the catalytic purification chamber 310. After denitrification treatment through two layers of dolomite bed at 800 °C, it is further purified by decoking through two layers of Ni / Al2O3 bed at 700 °C to obtain clean fuel gas. Then, it is fed into the catalytic reformer 320 with calcium oxide powder and water vapor at a mass ratio of 0.35:1 and reacted at 600 °C. After impurity removal, the resulting gas is collected to obtain hydrogen-rich synthesis gas.

[0095] In this process, calcium oxide reacts to form calcium carbonate, which then decomposes at 900-1000 °C in combustion chamber 322, regenerating calcium oxide and thus contributing to the recycling of calcium carbonate at the chemical chain level.

[0096] Tests revealed that the aforementioned hydrogen-rich syngas mainly contains hydrogen (H2) and carbon monoxide (CO), with H2 accounting for over 60% of the volume.

[0097] Example 3: Experiment on the effects of molten salt-assisted carbonization and activation treatment on carbon materials One of the core innovations of this invention in the process of co-producing nitrogen-doped porous carbon and hydrogen-rich syngas lies in the molten salt-assisted carbonization and activation strategy. To objectively and quantitatively verify the technical effect of this strategy, this embodiment systematically tests and compares the performance of the biochar material prepared by the process in Example 2 above and the biochar material prepared by conventional methods. The specific preparation method of the biochar material is as follows: (1) Carbonized biochar FB-400 The preparation method of carbonized biochar FB-400 specifically includes the following steps: The crushed and dried waste fiberboard raw material is fed into the medium-temperature carbonization furnace 120 by a screw feeder and directly carbonized at a constant temperature of 400℃ for 1 hour to obtain a solid product. After cooling, carbonized biochar is obtained and labeled as FB-400.

[0098] (2) Carbonized biochar FB-550 The preparation method of carbonized biochar FB-550 specifically includes the following steps: The crushed and dried waste fiberboard raw material is fed into the medium-temperature carbonization furnace 120 by a screw feeder and directly carbonized at a constant temperature of 550℃ for 1 hour to obtain a solid product. After cooling, carbonized biochar is obtained and labeled as FB-550.

[0099] (3) Molten salt carbonized biochar FB-CuCl2-550-1:1 The preparation method of molten salt carbonized biochar FB-CuCl2-550-1:1 specifically includes the following steps: Take an appropriate amount of the primary biochar-molten salt mixture prepared in Example 2 above, wash it with water or a mixed acid solution (containing 1 MHCl and 1.2 M H2O2) to remove the influence of the salt, then wash it with water until neutral, and dry it to obtain molten salt carbonized biochar, labeled as FB-CuCl2-550-1:1, for later use.

[0100] (4) Activated porous carbon FB-KHCO3-800 The preparation method of activated porous carbon FB-KHCO3-800 specifically includes the following steps: Using FB-550 as a precursor, it was mixed with potassium bicarbonate at a mass ratio of 1:1 and impregnated for 12 hours. Then, it was chemically activated by maintaining a constant temperature of 800 °C for 1 hour. The activated solid was first washed with 0.1M HCl, then washed with water until neutral, and dried to obtain nitrogen-doped porous carbon material, labeled as FB-KHCO3-800.

[0101] (5) Molten salt carbonization-activated porous carbon FB-CuCl2 / KHCO3-800-1:1 The preparation method of molten salt carbonization-activated porous carbon FB-CuCl2 / KHCO3-800-1:1 specifically includes the following steps: The above FB-CuCl2-550-1:1 was mixed with potassium bicarbonate at a mass ratio of 1:1 and impregnated for 12 hours. Then, it was chemically activated by maintaining a constant temperature of 800℃ for 1 hour. After activation, the solid was first washed with 0.1M HCl, then washed with water until neutral, and dried to obtain molten salt carbonized-activated porous carbon, labeled as FB-CuCl2 / KHCO3-800-1:1.

[0102] The following is a detailed analysis of the elemental composition and yield of the five biochar materials mentioned above, including microstructure observation, pore structure parameter determination, carbon structure order analysis, and electrochemical energy storage performance testing: 1. Elemental composition and yield To quantitatively verify the effectiveness of the molten salt-assisted carbonization activation strategy of this invention in improving element fixation efficiency and product yield, an elemental analyzer (Vario EL cube, Elementar, German) was used to test the performance of FB-400, FB-550, FB-CuCl2-550-1:1, FB-KHCO3-800, and FB-CuCl2 / KHCO3-800-1:1. The solid yield was calculated as the percentage of the final solid product mass to the initial raw material mass.

[0103] Test results as follows Figure 4 As shown, in conventional carbonization, with increasing carbonization temperature, the solid yield decreases from approximately 32.8% for FB-400 to 27.4% for FB-550, the nitrogen density ratio decreases by 20.1% simultaneously, and the nitrogen retention efficiency decreases from 32.4% to 25.9%, indicating carbon loss issues. However, molten salt-mediated carbonization of FB-CuCl2-550-1:1 achieves a solid yield of 47.0%, a nitrogen density ratio increase of 19.8%, and a nitrogen retention efficiency of 53.1%, representing increases of 71.5%, 19.8%, and 105% respectively compared to FB-550, and even improvements compared to FB-400. This suggests that molten salt-assisted carbonization can suppress carbon and nitrogen volatilization caused by temperature increases through liquid coating.

[0104] Furthermore, the nitrogen content and solid yield of biochar FB-CuCl2 / KHCO3-800-1:1 obtained by molten salt-assisted carbonization activation were compared with those of directly activated FB-KHCO3-800 without molten salt pretreatment. The results are shown in Table 1.

[0105] Table 1:

[0106] The nitrogen content and solids yield of FB-CuCl2 / KHCO3-800-1:1 reached 2.9 wt.% and 30.9%, respectively, which were 1.6 wt.% and 11.6% higher than those of FB-KHCO3-800 directly activated without molten salt pretreatment. Correspondingly, the nitrogen retention rate was also significantly improved (from 6.0% to 21.5%, an increase of 258.3%).

[0107] The above results indicate that by adding the molten salt carbonization step, nitrogen volatilization and excessive decomposition of the carbon skeleton in the early stage of pyrolysis of the precursor can be effectively suppressed, providing a nitrogen-rich and stable precursor for subsequent activation, thereby achieving higher nitrogen retention and carbon yield in a synergistic manner.

[0108] 2. Elemental chemical state analysis In this experiment, the chemical state of nitrogen on the surface of the biochar materials FB-550, FB-CuCl2-550-1:1, FB-KHCO3-800 and FB-CuCl2 / KHCO3-800-1:1 prepared above was analyzed by X-ray photoelectron spectroscopy (XPS, ESCALAB 250Xi spectrometer).

[0109] The results of FB-550 and FB-CuCl2-550-1:1 are as follows Figure 5 As shown, molten salt-assisted carbonization can significantly regulate and optimize the form of nitrogen.

[0110] Furthermore, peak fitting was performed on the N 1s spectrum of the molten salt carbonized-activated porous carbon FB-CuCl2 / KHCO3-800-1:1. The results showed that the relative content of pyridine nitrogen (N-6), which has excellent pseudocapacitive activity, was as high as 51.75%. In contrast, the proportion of pyridine nitrogen in the conventional process product (FB-KHCO3-800) without molten salt pretreatment was only 35.63%.

[0111] The above results demonstrate that the molten salt-assisted carbonization step of this invention not only effectively preserves nitrogen, but more importantly, guides the directional transformation of nitrogen species into the more electrochemically active pyridine nitrogen form, increasing its enrichment level by approximately 45% compared to conventional processes. This atomic-scale optimization of chemical state provides a fundamental structural explanation for the material's superior rate performance and significant pseudocapacitive contribution.

[0112] 3. Microscopic morphological observation The microstructure of the biochar materials FB-550, FB-CuCl2-550-1:1, FB-KHCO3-800 and FB-CuCl2 / KHCO3-800-1:1 prepared above was observed using scanning electron microscopy (SEM).

[0113] SEM characterization image as follows Figure 6 As shown, the morphology of the four biochars differs significantly due to the processing conditions. The material treated with conventional carbonization (such as FB-550) exhibits fragmented, striped structures and particle agglomeration characteristics, which is the result of the initial crushing of the lignocellulose raw material after pyrolysis. The material prepared by molten salt-assisted carbonization (such as FB-CuCl2-550-1:1) is further crushed, with increased bulk density and a flaky structure. This may be related to the fact that molten CuCl2 accelerates the decomposition of lignocellulose components through liquid-phase reaction.

[0114] Furthermore, the activated porous carbon FB-KHCO3-800 exhibits more thorough structural fragmentation, presenting as short segments and forming significant honeycomb-like pores. This may be related to the etching effect of CO2 and H2O released by the high-temperature decomposition of KHCO3 on the carbon material. The biochar FB-CuCl2 / KHCO3-800-1:1 obtained by molten salt-assisted carbonization activation retains the fragmented morphology brought about by molten salt-assisted carbonization, while the surface porosity is significantly improved and the microcrack density is increased, reflecting the synergistic etching effect of CuCl2-induced fragmentation and KHCO3 decomposition products.

[0115] The above results indicate that melt-assisted treatment helps accelerate the decomposition of lignocellulose components, and combined with activation treatment, it can further significantly improve surface porosity and increase microcrack density.

[0116] 4. Determination of pore structure parameters In this experiment, the pore structure of the biochar materials FB-550, FB-CuCl2-550-1:1, FB-KHCO3-800 and FB-CuCl2 / KHCO3-800-1:1 prepared above was quantitatively analyzed using a nitrogen adsorption-desorption tester (ASAP 2020 adsorption instrument) with BET method and BJH model.

[0117] The test results are shown in Table 2.

[0118] Table 2:

[0119] The results show that both conventional and molten salt-assisted carbide products exhibit tens to hundreds of times increases in specific surface area and total pore volume after activation. Specifically, the specific surface area of ​​FB-CuCl2 / KHCO3-800-1:1 reaches 1151.05 m². 2 ·g 1 The total pore volume is 0.4730 cm³. 3 · g 1 The average pore size is 1.64 nm, and its adsorption isotherm exhibits typical Type IV characteristics with a significant hysteresis loop, confirming that the material is rich in mesopores. Although its specific surface area is slightly lower than that of the untreated control sample (FB-KHCO3-800, 1254.59 m²), it is still relatively stable. 2 ·g 1 However, both belong to the same order of magnitude of high specific surface area carbon materials. In addition, it is worth noting that FB-CuCl2 / KHCO3-800-1:1 has a significantly higher nitrogen content (2.9 wt.% vs. ~1.3 wt.%) and a better distribution of nitrogen species. While ensuring sufficient ion adsorption / transport channels, it achieves a simultaneous improvement in the density and mass of active sites (nitrogen species), which lays a key structural foundation for the material's excellent comprehensive electrochemical performance.

[0120] 5. Carbon structural order analysis This experiment analyzed the microstructure of the biochar materials FB-550, FB-CuCl2-550-1:1, FB-KHCO3-800, and FB-CuCl2 / KHCO3-800-1:1 prepared above using a laser miniature Raman spectrometer. The following tests were performed under 532 nm laser excitation.

[0121] The results are as follows Figure 7 As shown, molten salt-assisted carbonization and activation treatment can achieve synergistic control of the concentration of carbon framework defects and the degree of graphitization. All samples are within the range of ~1360 cm⁻¹. 1 (D peak, corresponding to sp³ carbon / defect / disordered structure) and ~1580 cm⁻¹ 1 A characteristic peak appears at (G peak, corresponding to sp² graphitized carbon). Among them, the I peak of the molten salt carbonization intermediate (FB-CuCl2-550-1:1) is... D / I GThe intensity ratio of 2.24 indicates that the molten salt environment, while promoting nitrogen doping, also introduces a large number of structural defects. After activation with KHCO3, the ID / IG value of the final product (FB-CuCl2 / KHCO3-800-1:1) decreases to 1.99, while its G peak full width at half maximum (FWHM) decreases and the peak shape becomes sharper. In contrast, the single conventional carbonization activation product FB-KHCO3-800 or the conventional carbonization product FB-550 pathway exhibits a lower degree of disorder (Ig). D / I G The values ​​(1.83 and 1.95 respectively) are relatively low, indicating that their carbon skeleton defect concentration is limited.

[0122] The above results further confirm that the subsequent activation process, while creating pores, promotes the transformation of some disordered carbon into an ordered graphite microcrystalline structure through the high-temperature annealing effect. This achieves an optimized balance between defect sites that can provide pseudocapacitive activity and conductive graphite networks that ensure rapid electron transport, revealing the intrinsic reason why the material has both high reactivity and excellent rate performance from the microcrystalline structure level.

[0123] 6. Electrochemical energy storage performance testing (1) Cyclic voltammetry test: The above-mentioned biochar material was tested using cyclic voltammetry, and its cyclic voltammetric curve is shown below. Figure 8 As shown in Figure a, the results indicate that the activated FB-CuCl2 / KHCO3-800-1:1 and FB-KHCO3-800 exhibit nearly rectangular CV curves, suggesting that their energy storage mechanism is dominated by electric double-layer capacitance (EDLC). Simultaneously, the weak redox peaks observed in the 1.2–1.8 V potential range confirm that nitrogen functional groups (especially pyridine and pyrrole nitrogen) introduce significant pseudocapacitive contributions. In contrast, the unactivated nitrogen-doped biochar FB-550 and FB-CuCl2-550-1:1 exhibit irregular CV curve shapes and weak capacitive response.

[0124] (2) Specific capacitance test results: The above-mentioned biochar material was tested using a constant current charge-discharge method, and the results are as follows: Figure 8 As shown in Figure b, the activated porous carbon material FB-CuCl2 / KHCO3-800-1:1 and FB-KHCO3-800 at 0.1 A g are compared. 1 At current density, the specific capacitance reaches approximately 220 F g. 1 In contrast, the specific capacitance of unactivated nitrogen-doped biochar FB-550 is extremely low (<5.2 F g) compared to FB-CuCl2-550-1:1. 1 ).

[0125] Furthermore, it is worth noting that FB-CuCl2-550-1:1, which has a high nitrogen content (4.3%) but extremely underdeveloped pores, also exhibits negligible specific capacitance (0.7 F g). - ¹), which directly proves that a well-developed porous structure is an indispensable physical basis for obtaining high specific capacitance.

[0126] (3) Ratio performance: The results of the rate performance test are as follows: Figure 8 As shown in Figure c, the results demonstrate that the material exhibits excellent capacity retention at high current densities. At 50 A·g - ¹ At extremely high current densities, the specific capacitance of FB-CuCl2 / KHCO3-800-1:1 prepared by the integrated molten salt carbonization-activation process still remains at 37.28 F·g. - ¹, significantly superior to the control material FB-KHCO3-800 (9.86 F·g) without molten salt pretreatment. - ¹). This superior performance is mainly attributed to the higher nitrogen content (2.9%) of FB-CuCl2 / KHCO3-800-1:1 and the significantly enriched pyridine nitrogen configuration (accounting for 51.75% of nitrogen species), which effectively enhances the kinetics of the fast Faraday reaction at high rates.

[0127] (4) Electrochemical impedance analysis: The above-mentioned biochar materials were analyzed by electrochemical impedance spectroscopy, and the results are as follows: Figure 8 As shown in Figure d, among all activated and unactivated samples, FB-KHCO3-800 exhibits the lowest equivalent series resistance (ESR, 11.7 Ω), followed by FB-CuCl2 / KHCO3-800-1:1 (12.8 Ω). The ESR is negatively correlated with the graphitic nitrogen (NQ) content in the material, indicating that graphitic nitrogen effectively enhances the electronic conductivity of the material. Furthermore, FB-CuCl2 / KHCO3-800-1:1 exhibits a distinct semi-circular arc in the mid-to-high frequency region, corresponding to its significant pseudocapacitive charge transfer process.

[0128] (5) Long-term cycling stability test: The above-mentioned biochar material was tested using a battery cycle performance tester. The long-term cycle test results are as follows: Figure 8 As shown in Figure e, the results are displayed at 5 A·g 1After 8000 charge-discharge cycles at a current density, the FB-CuCl2 / KHCO3-800-1:1 electrode maintained a specific capacitance of 97.32% and a coulombic efficiency close to 100%. This excellent cycling stability stems from the synergistic effect of the material's hierarchical porous and robust carbon framework and optimized and stable nitrogen functional groups (N-5 / N-6 provide activity, NQ ensures conductivity), ensuring structural integrity and reversible reactions during long-term cycling.

[0129] The above results indicate that molten salt-assisted carbonization and activation treatment helps to improve the electrochemical energy storage performance of biochar materials.

[0130] Example 4: Experiment on the effect of stepwise catalytic process on gas-phase products This example analyzes the composition and catalytic effect of the hydrogen-rich syngas obtained by the above method, as detailed below: 1. Raw gas composition analysis The crude fuel gas before entering the catalytic converter was comprehensively analyzed by thermogravimetric analysis-Fourier transform infrared spectroscopy (TG-FTIR), and the tar content was determined by condensation, weighing, and then coupled with gas chromatography-mass spectrometry (GC / MS). The results are shown in Table 3.

[0131] Table 3:

[0132] The test results showed that the crude gas composition was dominated by carbon oxides, with CO2 (46.5%) and CO (22.1%) accounting for nearly 70% combined, forming the main carbon source basis for subsequent catalytic reforming. Simultaneously, the gas contained a certain proportion of light hydrocarbon components (6.3%) and a small amount of aromatic hydrocarbons (0.6%). The former is an important precursor for hydrogen production during reforming, while the latter is a key precursor leading to catalyst coking. Notably, the hydrogen concentration in the crude gas composition was extremely low (0.1%), directly indicating the necessity of increasing hydrogen production through catalytic reforming. Furthermore, nitrogenous contaminants (2.9%) and high levels of tar precursors (24.8%) were clearly detected, fully demonstrating the indispensability of the "denitrification-decoking-reforming" staged catalytic process in this system.

[0133] 2. Denitrification performance evaluation To quantitatively evaluate the denitrification performance of dolomite catalysts, this experiment analyzed the content of key nitrogen-containing components such as NH3, HCN, and N2 in the pyrolysis products and calculated their proportions relative to the total nitrogen in the raw materials. In the experiment, NH3 was absorbed by 0.1 mol / L sulfuric acid solution and then determined spectrophotometrically; HCN was absorbed by 0.2 mol / L sodium hydroxide solution and then determined spectrophotometrically; N2 in the gas phase was collected together with other gases, the total volume was first measured using a wet flow meter, and then qualitative and quantitative analysis was performed using a gas chromatograph equipped with a thermal conductivity detector (TCD).

[0134] The results are as follows Figure 9 As shown, the use of dolomite catalysts enables more efficient and comprehensive synergistic removal of nitrogen pollutants. Compared with the conditions without a catalyst, the composite system composed of CaO, Al2O3, and Fe2O3 in dolomite exhibits a synergistic effect: it not only significantly inhibits the formation of NH3 and HCN (reducing the NH3-N content to approximately 10%, but also HCN...) (N decreased to about 1%), while promoting the directional conversion of nitrogen to N2.

[0135] 3. Analysis of descorching effect H2 and N2 in gaseous products under catalyst-free and catalyst-containing (e.g., Ni / Al2O3) conditions were analyzed using a GC / TCD detector, and carbon-containing gases were analyzed using a GC / FID detector. Total organic carbon and total nitrogen in light tar were analyzed using a TOC-TN analyzer.

[0136] Analysis results as follows Figure 10 As shown, the gas phase components contain a high amount of tar under catalyst-free conditions; however, with the Ni / Al2O3 catalyst, nitrogen-containing products are highly selectively converted into N2 (accounting for over 70%), while the proportions of other nitrogen-containing components such as NH3 and tar are reduced to almost 0, indicating a better tar removal effect.

[0137] 4. Analysis of the effects of reorganization Based on the fact that calcium oxide can absorb carbon dioxide from syngas, it alters the water-gas shift reaction (CO + H2O). The thermodynamic equilibrium of CO2+H2 causes the reaction equilibrium to continuously shift towards hydrogen production, which helps to effectively increase hydrogen production.

[0138] A schematic diagram of the syngas regulation mechanism during reforming catalysis is shown below. Figure 11 As shown, under optimized conditions of 650~700 ℃, based on the catalytic reforming effect of CaO, the hydrogen gas fraction in the product gas can be significantly increased from 30%~40% in traditional gasification to 60~80%, while reducing the CO2 concentration to 5%~15%.

[0139] In summary, this invention provides a system and application for the co-production of nitrogen-doped porous carbon and hydrogen-rich syngas. Specifically, this invention provides a system and process for the directional thermal conversion of waste engineered wood products to co-produce nitrogen-doped porous carbon and hydrogen-rich syngas, which has at least the following advantages: (1) High-value utilization of all components of waste materials is realized. This invention achieves high-value utilization and directional migration and full recovery of the core components in waste wood-based panels by using a system for the co-production of nitrogen-doped porous carbon and hydrogen-rich syngas through directional thermal conversion: converting the lignocellulose carbon skeleton into high-performance nitrogen-doped porous carbon; fixing and regulating the nitrogen element in the urea-formaldehyde resin adhesive into electrochemical active sites for carbon materials; and simultaneously converting the crude gas generated during carbonization into hydrogen-rich syngas through a stepwise catalytic process. This invention solves the technical problems of low lignocellulose conversion efficiency and large-scale volatilization loss of nitrogen element during conventional carbonization, as well as the generation of tar and nitrogen-containing pollutants (NH3, HCN, etc.), resulting in a double burden on resources and the environment.

[0140] (2) Deep integration and tiered utilization of energy flow are achieved. In traditional biomass thermochemical conversion systems, each unit—crushing, drying, pyrolysis, and activation—operates independently, relying on external electricity or fuel for all energy input. A large amount of waste heat from medium- and low-temperature processes is directly discharged due to the difficulty in matching, resulting in high overall system energy consumption. In contrast, the system process of this invention relies on tiered utilization of energy and tiered catalytic units for gaseous products. The high-temperature activation gas is internally circulated within the system to maintain the thermal balance of the unit itself and reduce external functional requirements. The gaseous heat energy output from the medium-temperature catalytic purification stage is directionally supplied to the molten salt carbonization unit through a heat exchange device as its core reaction heat source. The waste heat of the biochar-molten salt mixture in the raw material molten salt auxiliary carbonization unit is used for preheating the raw materials. This invention achieves closed-loop, tiered utilization of process waste heat within the system, thereby significantly reducing dependence on external energy sources.

[0141] (3) The biochar obtained based on the system and process of this invention has excellent electrochemical performance. This invention optimizes the microstructure of nitrogen-doped porous carbon through molten salt-assisted carbonization activation technology, thereby improving electrochemical performance such as specific capacity, rate performance and cycle stability.

[0142] (4) Deep purification and high-value conversion of gaseous products are achieved. The integrated denitrification, decoking, and reforming cascade catalytic unit of this invention, through front-end dolomite denitrification catalysis, mid-stage nickel-based catalyst decoking catalysis, and end-stage CaO reforming catalysis and in-situ CO2 capture, directionally regulates the gas composition, significantly increases the hydrogen concentration, and produces high-purity, high-value-added hydrogen-rich syngas. This process not only converts pollutants into clean energy, but also elevates the value of gaseous products from "low-grade fuel" to a value that can be used as clean energy or chemical raw materials, achieving a high degree of unity between environmental and economic benefits.

[0143] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A system for co-producing nitrogen-doped porous carbon and hydrogen-rich syngas, characterized in that, The system includes: A raw material molten salt-assisted carbonization unit (100) is used to mix and carbonize nitrogen-containing biomass raw materials with solid chloride salts. The raw material molten salt-assisted carbonization unit (100) includes a premixing device (110) and a medium-temperature carbonization furnace (120) connected in sequence. The medium-temperature carbonization furnace (120) is provided with a first outlet (121) and a second outlet (122). The raw material molten salt-assisted carbonization unit (100) also includes a material conveying device for conveying the raw material-molten salt mixture generated by the premixing device (110) to the medium-temperature carbonization furnace (120). A solid-phase product activation and purification unit (200) is used to sequentially impregnate, separate solids and liquids, activate, and remove dust from the primary biochar-molten salt mixture generated by the medium-temperature carbonization furnace (120) to obtain nitrogen-doped porous carbon. The solid-phase product activation and purification unit (200) includes an impregnation device (210), a solid-liquid separation device (220), an impregnation premixing device (230), an activation chamber (240), and a dust removal device (250) connected in sequence. The impregnation device (210) is connected to the medium-temperature carbonization furnace (120). The second outlet (122) of the warm carbonization furnace (120) is connected; the solid-liquid separation device (220) is provided with a solid phase outlet (221) and a liquid phase outlet (222), wherein the solid phase outlet (221) is connected to the impregnation premixing device (230) and is used to send the separated nitrogen-doped carbon into the impregnation premixing device (230); the liquid phase outlet (222) is connected to the washing device (210) and is used to send the separated liquid phase into the washing device (210) for reflux treatment; A gas-phase product cascade catalytic unit (300) is used to sequentially denitrify, decoke and reform the crude gas generated by the medium-temperature carbonization furnace (120) to obtain hydrogen-rich syngas; the gas-phase product cascade catalytic unit (300) includes a catalytic purification chamber (310) and a catalytic reformer (320) connected in sequence, wherein the catalytic purification chamber (310) is sequentially provided with a denitrification catalytic layer (311) and a decoke catalytic layer (312); the catalytic purification chamber is connected to the first outlet (121) of the medium-temperature carbonization furnace (120).

2. The system according to claim 1, characterized in that, The dust removal device (250) includes a primary cyclone dust collector (251) and a secondary cyclone dust collector (252). The primary cyclone dust collector (251) is provided with a first top discharge port (2511) and a first bottom discharge port (2512), wherein the first top discharge port (2511) is connected to the secondary cyclone dust collector (252); and the first bottom discharge port (2512) is connected to the activation chamber (240). The secondary cyclone dust collector (252) is provided with a second top discharge port (2521) and a second top and bottom discharge port (2522). The second top discharge port (2521) is connected to the catalytic impurity removal chamber (310) and is used to transport the denitrified gas to the catalytic impurity removal chamber (310) for impurity removal.

3. The system according to claim 1, characterized in that, The denitrification catalyst layer (311) comprises any one of dolomite, olivine, iron ore and red mud, and is used to denitrify the crude fuel gas entering the catalytic purification chamber (310); And / or, the decoking catalyst layer (312) contains a nickel-based active component catalyst for decoking the denitrified product.

4. The system according to claim 3, characterized in that, The support for the nickel-based active component catalyst includes any one of Al2O3, porous biochar, and lignite coke.

5. The system according to claim 3, characterized in that, The catalytic reformer (320) includes a cyclone dust removal chamber (321) and a combustion chamber (322).

6. The system according to claim 5, characterized in that, The cyclone dust removal chamber (321) is provided with a first top discharge port, a second top discharge port and a bottom discharge port; the second top discharge port is connected to the combustion chamber (322).

7. The system according to any one of claims 1 to 6, characterized in that, The system also includes a clean heating-waste heat recovery unit (400), which includes a clean heating device and a waste heat recovery device; The clean heating device includes an electric heating device and a combustion heating device; the electric heating device is used to heat the medium-temperature carbonization furnace (120), the activation chamber (240) and the catalytic purification chamber (310); the combustion heating device is used to heat the combustion chamber (322); The waste heat recovery device includes a first heat exchange device (410) and a second heat exchange device (420). The first heat exchange device (410) includes a first heater (411) and a first cooler (412) connected in sequence, the first heater (411) and the first cooler (412) forming a loop; wherein, the first cooler (412) is disposed between the premixing device (110) and the material pipeline of the medium-temperature carbonization furnace (120); the first heater (411) is disposed between the medium-temperature carbonization furnace (120) and the material pipeline of the immersion device (210); the heat transfer medium of the first heat exchange device (410) is heat transfer oil; The second heat exchange device (420) includes a second heater (421) and a second cooler (422) connected in sequence, the second heater (421) and the second cooler (422) forming a loop; wherein, the second cooler (422) is disposed in the medium-temperature carbonization furnace (120) to provide a heat source; the second heater (421) is disposed between the catalytic purification chamber (310) and the material pipeline of the catalytic reformer (320); the heat transfer medium of the second heat exchange device (420) is a molten sodium-potassium alloy.

8. A method for co-producing nitrogen-doped porous carbon and hydrogen-rich syngas, characterized in that, The method is performed using the system described in any one of claims 1 to 7, and includes the following steps: S1. Nitrogen-containing biomass raw materials are mixed with solid chloride salts and carbonized in the medium-temperature carbonization furnace (120) to obtain primary biochar-molten salt mixture and crude fuel gas; S2. The primary biochar-molten salt mixture is sequentially washed, separated into solid and liquid, activated, and dedust-removed to obtain nitrogen-doped porous carbon. S3. The crude gas is subjected to denitrification, decoking and reforming treatment in sequence to obtain hydrogen-rich synthesis gas.

9. The method according to claim 8, characterized in that, The nitrogen-containing biomass raw materials include waste engineered wood products; And / or, the solid chloride salt includes at least one of zinc chloride, copper chloride, lithium chloride, cadmium chloride, potassium chloride-lithium chloride, sodium chloride-zinc chloride, and potassium chloride-zinc chloride; And / or, the carbonization treatment temperature is 400~600 ℃; And / or, the activation includes mixing the nitrogen-doped carbon obtained from the solid-liquid separation with any one of the activators potassium carbonate, potassium bicarbonate, sodium carbonate and sodium bicarbonate, and treating it at 700~900 °C. And / or, the temperature of the denitrification process is 700~900 ℃; And / or, the temperature of the decoking process is 600~800 ℃; And / or, the temperature of the reforming process is 500~700 ℃; And / or, the reforming includes mixing and reacting the decoking product with calcium oxide and water vapor.

10. The method according to claim 9, characterized in that, The solid chloride salt is zinc chloride or copper chloride.

11. The application of the system as described in any one of claims 1 to 7 or the method as described in any one of claims 8 to 10 in the preparation of high-value biogas, syngas feedstock, supercapacitor electrode materials, adsorbent materials, and fuel cell electrode materials.

Images