Method for preparing porous carbon and hydrogen-rich synthesis gas by lignin pyrolysis carbonization

Abstract

The application discloses a method for preparing porous carbon and hydrogen-rich synthesis gas by lignin pyrolysis carbonization, and relates to the technical field of renewable energy conversion and utilization. First, waste lithium ion battery positive electrodes are crushed into fine particle samples, and then the positive electrode materials are mixed with lignin in a ratio of 5-15% to the lignin, and the mixture is uniformly mixed and then loaded into a dielectric barrier discharge reactor, and the reactor is placed in a vacuum tube furnace, and vacuum is drawn to a pressure of less than 0.1 Pa; the pyrolysis carbonization reaction is carried out at a reaction temperature of 700-900 DEG C and a discharge current of 100-300 mA; and the solid-phase product is centrifugally cleaned and dried to obtain the porous carbon. The lignin conversion effect is good, and the carbon, hydrogen and oxygen elements are maximally classified and utilized; the content of carbon elements in the obtained porous carbon is more than 95%, and the porous carbon has high specific surface and volume adsorption performance; the hydrogen-rich synthesis gas obtained has a H2 volume fraction of more than 42%, a CO volume fraction of more than 38%, and a total volume content of synthesis gas of more than 80%, and can be directly used as a gas fuel or a synthesis raw material.

Description

Technical Field

[0001] This invention relates to the field of renewable energy conversion and utilization technology, specifically a method for preparing porous carbon and hydrogen-rich syngas by lignin pyrolysis and carbonization. Background Technology

[0002] Porous carbon materials are novel materials with carbon as the main component and a highly developed pore structure. They are characterized by large specific surface area, strong mechanical properties, high chemical stability, and excellent physical properties (electrical conductivity, thermal conductivity, thermal stability, etc.). Currently, they are used in energy storage and conversion, gas storage and capture, catalysts and their supports, water purification, and other fields, and their application scale is increasing daily. Hydrogen-rich syngas refers to a syngas mainly composed of H2 and CO, where H2 can meet the requirements for the hydrogenation conversion of CO.

[0003] Lignin is considered an ideal carbon source for constructing porous carbon materials, with abundant reserves accounting for approximately 30% of the organic carbon in the biosphere. Lignin is mainly composed of three structural units: guaiacolylpropane, syringylpropane, and p-hydroxyphenylpropane, with a carbon content as high as 60%. It is characterized by high aromaticity, high calorific value, and abundant active sites. If lignin is used as a carbon source, and specific methods are employed to simultaneously produce hydrogen-rich syngas while preparing porous carbon materials, not only can the high-value utilization of lignin be maximized, but it can also more efficiently alleviate dependence on fossil fuels and the increasingly severe environmental problems.

[0004] Currently, methods for preparing porous carbon through lignin carbonization include activation, template methods, microwave methods, and hydrothermal methods. All methods require the addition of activators or templates, and the reaction temperature is within the range of 450-900℃. The resulting porous carbon exhibits significant differences in texture properties. Furthermore, lignin gasification for producing hydrogen-rich syngas typically requires high-pressure steam conditions to achieve higher carbon conversion rates, and higher reaction temperatures are necessary to obtain a higher proportion of H2.

[0005] Recently, low-temperature plasma gasification technology has become one of the focuses of researchers. Plasma technology based on dielectric barrier discharge has been applied to the gasification of waste biomass to produce syngas, bio-oil and biochar. The reaction generally requires an inert gas atmosphere (N2 or CO2). Energy is directly input into the chemical bonds of biomass macromolecules through dielectric barrier discharge to break the macromolecules. However, the discharge process of low-temperature plasma lacks the product regulation guidance type and belongs to disordered high-energy bond breaking and pyrolysis. It is suitable for the degradation of materials and small molecule gasification, but not very suitable for the preparation of porous carbon.

[0006] In recent years, with the continuous expansion of lithium-ion battery usage, lithium-ion batteries have been widely used in electrical equipment and the automotive industry. Therefore, the recycling and reuse of key materials from spent lithium-ion batteries has become increasingly urgent. Lithium-ion batteries mainly consist of four materials: positive electrode material, negative electrode material, separator, and electrolyte. Among these, the positive electrode material accounts for 30-40% of the cost of lithium-ion battery materials. It possesses unique structural characteristics and special physicochemical properties, playing a crucial role in lithium-ion batteries and directly leading the development of the lithium-ion battery industry. Currently, the recycling and reuse of positive electrode materials for lithium-ion batteries mainly focuses on the recycling and reuse of valuable metals within the positive electrode material. Simultaneously, some researchers use recycled positive electrode materials as additives or catalysts for biomass pyrolysis. However, the catalytic principle still relies primarily on the breaking and cleavage of chemical bonds such as CC, CO, and CH by traditional metal oxides or metal ions. The products contain many large-molecule liquefaction products (including aldehydes, ketones, phenols, and hydrocarbons), which are significantly insufficient in both porous carbon preparation and hydrogen-rich syngas production.

[0007] Therefore, it is necessary to invent a method for preparing porous carbon and hydrogen-rich syngas by pyrolysis carbonization of lignin to solve the above problems and shortcomings. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a method for preparing porous carbon and hydrogen-rich syngas through lignin pyrolysis carbonization, which solves the problem that the traditional method for preparing porous carbon and hydrogen-rich syngas through lignin pyrolysis carbonization is not very effective.

[0009] To achieve the above objectives, the present invention provides a method for preparing porous carbon and hydrogen-rich syngas through lignin pyrolysis and carbonization, comprising the following steps:

[0010] (1) The positive electrode of the lithium-ion battery is pulverized into powder, and the lignin is also made into powder;

[0011] (2) Add the positive electrode material to the lignin in a certain proportion, add an appropriate amount of distilled water, stir evenly at 80°C until the water is basically evaporated, and then transfer the mixture into a constant temperature drying oven and dry at 110°C for 2 hours for later use.

[0012] (3) The homogeneous mixture obtained in step (2) is packed into the dielectric barrier discharge reactor. The reactor is placed in a vacuum tube furnace, and after the vacuum is evacuated to <0.1 Pa, the vacuum pump is turned off and the pyrolysis carbonization reaction is carried out. The reaction ends when the pressure gauge reading no longer changes. When the reactor is cooled to room temperature, the vacuum pump is turned on to extract the gas phase product. After filtration and drying, the gas is collected in a gas collection bag. At the same time, the solid phase product is removed. After centrifugation, washing and drying, porous carbon is collected.

[0013] Furthermore, in step (1), the lithium-ion battery cathode refers to common lithium-ion battery cathode materials such as lithium titanate, lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium nickel cobalt aluminum oxide, and lithium nickel cobalt manganese oxide.

[0014] Furthermore, in step (1), the lithium-ion battery cathode powder has a particle size of 25-45 μm, and the lignin powder has a particle size of 75-100 μm.

[0015] Furthermore, in step (2), the mixing ratio of the positive electrode material and lignin is 5-15%.

[0016] Furthermore, in step (2), the medium barrier reactor is a coaxial cylindrical type with a discharge gap of 10 mm and a length of 100 mm. The barrier medium is quartz, with a stainless steel tube arranged in the center as a high-voltage electrode, and a copper mesh on the outside of the quartz medium as a low-voltage electrode. Quartz discs with vent holes and stainless steel tube support holes are arranged at both ends.

[0017] Furthermore, in step (3), the pyrolysis carbonization reaction temperature is 700-900℃ and the discharge current is 100-300mA.

[0018] This invention provides a method for preparing porous carbon and hydrogen-rich syngas through lignin pyrolysis and carbonization. Compared with the prior art, it has the following advantages:

[0019] This invention provides a method for preparing porous carbon and hydrogen-rich syngas by pyrolysis carbonization of lignin. In this method, the cathode of waste lithium-ion batteries is recycled; the lignin conversion effect is good, and the carbon, hydrogen and oxygen elements are maximized for separate utilization; the obtained porous carbon has a carbon content of more than 95% and has a high specific surface area adsorption performance; the obtained hydrogen-rich syngas has an H2 volume fraction of more than 42%, a CO volume fraction of more than 38%, and a total syngas volume content of more than 80%, which can be directly used as a gaseous fuel or a synthesis raw material. Attached Figure Description

[0020] Figure 1 This is a flowchart of the steps of the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Please see Figure 1This invention provides three embodiments: a method for preparing porous carbon and hydrogen-rich syngas by lignin pyrolysis and carbonization, specifically including the following embodiments:

[0023] Example 1

[0024] A method for preparing porous carbon and hydrogen-rich syngas by lignin pyrolysis carbonization includes the following steps:

[0025] (1) The lithium titanate was pulverized to a particle size of 25 μm and the lignin powder was 75 μm;

[0026] (2) Add lithium titanate to lignin at a mass ratio of 5%, add an appropriate amount of distilled water, stir evenly at 80°C until the water is basically evaporated, then transfer the mixture to a constant temperature drying oven and dry at 110°C for 2 hours for later use.

[0027] (3) The homogeneous mixture obtained in step (2) is packed into the dielectric barrier discharge reactor. The reactor is placed in a vacuum tube furnace and evacuated to <0.1 Pa. The vacuum pump is then turned off to carry out the pyrolysis carbonization reaction. The reaction temperature and discharge current are controlled at 700℃ and 100mA, respectively. The reaction ends when the pressure gauge reading no longer changes. When the reactor cools to room temperature, the vacuum pump is turned on to extract the gas phase product. After filtration and drying, the gas is collected in a gas collection bag. At the same time, the solid phase product is removed. After centrifugation, washing, and drying, porous carbon is collected.

[0028] Calculations showed that the solid-phase (porous carbon) yield from lignin pyrolysis carbonization was 38.65%, the gas-phase yield was 57.40%, and there was a 3.95% liquid-phase (mainly water) condensation loss. Using an EA 3000 elemental analyzer, the porous carbon was found to contain 95.80% carbon, 2.21% oxygen, and 1.99% other elements.

[0029] The specific surface area and porosity of porous carbon were analyzed by nitrogen adsorption-desorption testing using a Thermo Finnigan Sorptomatic 1990 analyzer. The specific surface area (S) of porous carbon was calculated using the BET method. BET ) and pore volume (V) BET The specific surface area of ​​the micropores (S) was calculated using the t-plot method. micro ) and pore volume (V) micro The results are shown in Table 1. The porous carbon material prepared by this invention has a high specific surface area and pore volume, and good adsorption performance, and can be further used as a purification / storage material.

[0030] Table 1 Properties of porous carbon textures obtained in Example 1

[0031]

[0032] The contents of H2, CO, CO2, and CH4 in the gaseous product were determined using an Agilent 7820 gas chromatograph, and the results are shown in Table 2. The gaseous product obtained by this invention has an H2 content of 42.50%, a CO content of 38.05%, and a total content of 80.55%, making it suitable for further use as a raw material in chemical synthesis. Furthermore, considering CH4 and other gaseous components, the combustible gas content is nearly 90%, making it suitable for use as a gaseous fuel.

[0033] Table 2 Composition of the gaseous products obtained in Example 1

[0034]

[0035] Example 2

[0036] A method for preparing porous carbon and hydrogen-rich syngas by lignin pyrolysis carbonization includes the following steps:

[0037] (1) The lithium iron phosphate was crushed to a particle size of 45 μm and the lignin powder was 100 μm.

[0038] (2) Add lithium iron phosphate to lignin at a mass ratio of 15%, add an appropriate amount of distilled water, stir evenly at 80°C until the water is basically evaporated, then transfer the mixture to a constant temperature drying oven and dry at 110°C for 2 hours for later use.

[0039] (3) The homogeneous mixture obtained in step (2) is packed into the dielectric barrier discharge reactor. The reactor is placed in a vacuum tube furnace and evacuated to <0.1 Pa. The vacuum pump is then turned off to carry out the pyrolysis carbonization reaction. The reaction temperature and discharge current are controlled at 900℃ and 300mA, respectively. The reaction ends when the pressure gauge reading no longer changes. When the reactor cools to room temperature, the vacuum pump is turned on to extract the gas phase product. After filtration and drying, the gas is collected in a gas collection bag. At the same time, the solid phase product is removed. After centrifugation, washing, and drying, porous carbon is collected.

[0040] Calculations showed that the solid-phase (porous carbon) yield from lignin pyrolysis carbonization was 33.03%, the gas-phase yield was 65.22%, and there was a 1.75% liquid-phase (mainly water) condensation loss. Using an EA 3000 elemental analyzer, the porous carbon was found to contain 97.50% carbon, 0.56% oxygen, and 1.94% other elements.

[0041] The specific surface area and porosity of porous carbon were analyzed by nitrogen adsorption-desorption testing using a Thermo Finnigan Sorptomatic 1990 analyzer. The specific surface area (S) of porous carbon was calculated using the BET method. BET ) and pore volume (V) BET The specific surface area of ​​the micropores (S) was calculated using the t-plot method. micro) and pore volume (V) micro The results are shown in Table 3. The porous carbon material prepared by this invention has a high specific surface area and pore volume, and good adsorption performance, and can be further used as a purification / storage material.

[0042] Table 3 Properties of porous carbon textures obtained in Example 2

[0043]

[0044] The contents of H2, CO, CO2, and CH4 in the gaseous products were determined using an Agilent 7820 gas chromatograph, and the results are shown in Table 4. The gaseous products obtained by this invention have an H2 content of 43.11%, a CO content of 39.82%, and a total content of 82.93%, making them suitable for further use as raw materials in chemical synthesis. Furthermore, including CH4 and other gaseous components, the combustible gas content exceeds 90%, making them suitable for use as gaseous fuels.

[0045] Table 4. Composition of the gaseous products obtained in Example 2

[0046]

[0047] Example 3

[0048] A method for preparing porous carbon and hydrogen-rich syngas by lignin pyrolysis carbonization includes the following steps:

[0049] (1) The lithium nickel cobalt manganese oxide (NCM532) was pulverized to a particle size of 35 μm, and the lignin powder had a particle size of 90 μm;

[0050] (2) Add NCM532 to lignin at a mass ratio of 10%, add an appropriate amount of distilled water, stir evenly at 80°C until the water is basically evaporated, then transfer the mixture to a constant temperature drying oven and dry at 110°C for 2 hours for later use.

[0051] (3) The homogeneous mixture obtained in step (2) is packed into the dielectric barrier discharge reactor. The reactor is placed in a vacuum tube furnace and evacuated to <0.1 Pa. The vacuum pump is then turned off to carry out the pyrolysis carbonization reaction. The reaction temperature and discharge current are controlled at 800℃ and 200mA, respectively. The reaction ends when the pressure gauge reading no longer changes. When the reactor cools to room temperature, the vacuum pump is turned on to extract the gas phase product. After filtration and drying, the gas is collected in a gas collection bag. At the same time, the solid phase product is removed. After centrifugation, washing, and drying, porous carbon is collected.

[0052] Calculations showed that the solid-phase (porous carbon) yield from lignin pyrolysis carbonization was 35.46%, the gas-phase yield was 62.40%, and there was an additional 2.14% liquid-phase (mainly water) condensation loss. The porous carbon, analyzed using an EA 3000 elemental analyzer, contained 96.89% carbon, 1.11% oxygen, and 2.05% other elements.

[0053] The specific surface area and porosity of porous carbon were analyzed by nitrogen adsorption-desorption testing using a Thermo Finnigan Sorptomatic 1990 analyzer. The specific surface area (S) of porous carbon was calculated using the BET method. BET ) and pore volume (V) BET The specific surface area of ​​the micropores (S) was calculated using the t-plot method. micro ) and pore volume (V) micro The results are shown in Table 1. The porous carbon material prepared by this invention has a high specific surface area and pore volume, and good adsorption performance, and can be further used as a purification / storage material.

[0054] Table 5 Properties of porous carbon textures obtained in Example 3

[0055]

[0056] The contents of H2, CO, CO2, and CH4 in the gaseous products were determined using an Agilent 7820 gas chromatograph, and the results are shown in Table 6. The gaseous products obtained by this invention have an H2 content of 44.10%, a CO content of 38.95%, and a total content of 83.05%, making them suitable for further use as raw materials in chemical synthesis. Furthermore, including CH4 and other gaseous components, the combustible gas content exceeds 90%, making them suitable for use as gaseous fuels.

[0057] Table 6. Composition of the gaseous products obtained in Example 3

[0058]

[0059] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0060] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for producing porous carbon and hydrogen-rich syngas from lignin pyrolysis carbonization, characterized in that, Includes the following steps: (1) The positive electrode of the lithium-ion battery is pulverized into powder, and the lignin is also in powder form; (2) Add the positive electrode material to the lignin in a certain proportion, add an appropriate amount of distilled water, stir evenly at 80°C until the water is basically evaporated, then transfer the mixture into a constant temperature drying oven and dry at 110°C for 2 hours for later use. (3) The homogeneous mixture obtained in step (2) is packed into the dielectric barrier discharge reactor. The reactor is placed in a vacuum tube furnace. After the vacuum is evacuated to <0.1Pa target pressure, the vacuum pump is turned off and the pyrolysis carbonization reaction is carried out. The reaction ends when the pressure gauge reading no longer changes. When the reactor is cooled to room temperature, the vacuum pump is turned on to extract the gas phase product. After filtration and drying, it enters the gas collection bag. At the same time, the solid phase product is removed. After centrifugation, washing and drying, porous carbon is collected. In step (1), the lithium-ion battery cathode powder has a particle size of 25-45µm and the lignin powder has a particle size of 75-100µm. In step (2), the mass ratio of the positive electrode material to lignin is 5-15%, the dielectric barrier discharge reactor is a coaxial cylindrical type with a discharge gap of 10 mm and a length of 100 mm, the barrier medium is quartz, a stainless steel tube is arranged in the center as a high-voltage electrode, a copper mesh is included on the outside of the quartz medium as a low-voltage electrode, and quartz discs with vent holes and stainless steel tube support holes are arranged at both ends. In step (3), the pyrolysis carbonization reaction temperature is 700-900℃ and the discharge current is 100-300mA.

2. The method of claim 1, wherein the lignin is pyrolyzed at a temperature of 300-600 °C in the presence of a catalyst to produce the porous carbon and the hydrogen-rich synthesis gas. In step (1), the positive electrode of the lithium-ion battery includes common positive electrode materials of lithium titanate, lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium nickel cobalt aluminum oxide, and lithium nickel cobalt manganese oxide.

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