A method for preparing porous carbon by mixing corn flour and waxy rice flour
Patent Information
- Application Number
- CN202610608371.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-05-06
- Publication Date
- 2026-08-21
AI Technical Summary
[0003]1）原料成本高且不可再生：石油基原料价格波动大，椰壳等生物质受地域限制导致供应不稳定；
[0033]1）原料成本低且来源广泛
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of porous carbon materials technology, specifically relating to a method for preparing porous carbon by mixing corn flour and glutinous rice flour. Background Technology
[0002] Porous carbon materials are widely used in supercapacitors due to their high specific surface area, good electrical conductivity, and tunable pore structure. Traditional preparation processes mainly rely on raw materials such as coal, petroleum coke, and coconut shells, which suffer from high costs, non-renewable resources, and complex pretreatment. The main drawbacks are as follows:
[0003] 1) High and non-renewable raw material costs: The price of petroleum-based raw materials fluctuates greatly, and the supply of biomass such as coconut shells is unstable due to geographical limitations;
[0004] 2) Complex pre-processing: The traditional coconut shell route requires multiple processes such as peeling, crushing, and acid washing. Pre-processing alone accounts for 30% to 50% of the production cycle, with a total duration of several to 6 days.
[0005] 3) Poor adhesion and formability: Raw materials such as coal and coke require the addition of binders (asphalt / phenolic resin, etc.), which introduces impurities and increases the number of processing steps. Figure 1 (Compare with existing process routes).
[0006] Current directions and limitations for improving biomass-based porous carbon technology:
[0007] Potential and Pre-processing Bottlenecks of Starch-Based Raw Materials: Although corn flour, glutinous rice flour, and other starches are rich in carbon and have natural binding properties, direct carbonization can easily lead to pore collapse due to their loose structure. Existing technologies use "chemical cross-linking + freeze-drying" to strengthen the structure, but this requires the use of toxic cross-linking agents such as epichlorohydrin, which deviates from the principles of green preparation.
[0008] Application gap in hot pressing technology: Existing technologies do not employ hot pressing, resulting in precursors with low density (typically <1.0 g / cm³) and a loose, uneven structure. This leads to preferential penetration and uneven distribution of alkaline reagents along the loose channels during activation, easily causing local overheating or insufficient activation, severely affecting the porosity of the product.
[0009] Stepwise activation efficiency defects: In conventional processes, carbonization and activation are carried out in steps, which leads to problems of "repeated energy consumption" and "loss of active components (K / Na) due to high-temperature volatilization".
[0010] Existing technologies struggle to balance: the sustainability (low cost, renewable) of raw materials with structural stability; the greenness of the process with the precision of pore structure control; and the economic efficiency of equipment with the high performance of the product. Summary of the Invention
[0011] To overcome the shortcomings of the prior art, the purpose of this invention is to provide a method for preparing porous carbon by mixing corn flour and glutinous rice flour, which has the characteristics of high specific surface area, good pore structure, good adhesion and formability, simple process and strong controllability.
[0012] To achieve the above objectives, the technical solution adopted by the present invention is: a method for preparing porous carbon by mixing corn flour and glutinous rice flour, comprising the following steps:
[0013] Step 1: Mix corn flour and glutinous rice flour in the specified mass ratio, add warm water and stir to form a dough, then shape it into a pancake;
[0014] Step 2: The dough obtained in Step 1 is hot-pressed to form a uniform and dense block.
[0015] Step 3: Carbonize the block obtained in Step 2 in a nitrogen atmosphere;
[0016] Step 4: Mix the carbonized material obtained in Step 3 with alkali at a mass ratio of 1:3, and then perform activation treatment in an alkaline activation rotary furnace.
[0017] Step 5: Pickle the material obtained in Step 4, and then wash it with deionized water until it is neutral.
[0018] Step 6: Dry the material obtained in step 5 to obtain porous carbon.
[0019] In step 1, the mass ratio of corn flour to glutinous rice flour is 9-10:1, the amount of warm water used is 3.75 L, and the water temperature is 60℃.
[0020] In step 1, the mass ratio of corn flour to glutinous rice flour is 10:1, the amount of warm water used is 3.75 L, and the water temperature is 60℃.
[0021] In step 2, the hot pressing temperature is 200℃ and the hot pressing time is 1-2 hours.
[0022] In step 2, the hot pressing temperature is 200℃ and the hot pressing time is 1 hour.
[0023] In step 3, the carbonization temperature is 500℃ and 600℃.
[0024] In step 3, the carbonization temperature is 500°C.
[0025] In step 4, the heating rate of the activation treatment is 5℃ / min, the activation temperature is 700-800℃, the holding time is 2 h, and the atmosphere is nitrogen.
[0026] In step 4, the activation temperature is 700°C.
[0027] In step 4, the alkali is potassium hydroxide (KOH), and the mass ratio of the carbonized material to the alkali is 1:2-3.
[0028] In step 4, the carbonized material and the alkali are in a mass ratio of 1:3.
[0029] In step 5, the pickling is performed using a 1M hydrochloric acid solution for 24 hours.
[0030] In step 6, the drying temperature is 80°C, and the product is dried to a constant weight.
[0031] The prepared porous carbon has a hierarchical pore structure with both micropores and mesopores, and a specific surface area of 1600-2000 m² / g.
[0032] Compared with the prior art, the beneficial effects of the present invention are:
[0033] 1) Raw materials are low in cost and widely available.
[0034] Environmentally friendly and sustainable: Using corn flour and glutinous rice flour as carbon sources, which are renewable biomass resources, avoiding the high cost and non-renewability of traditional raw materials (coal, petroleum coke);
[0035] No chemical cross-linking treatment required: Natural starch has good adhesion ("good adhesion and formability" in the instructions), eliminating the need for toxic cross-linking agents such as epichlorohydrin (existing technology requires 48 hours of freeze cross-linking).
[0036] Simplified pretreatment: direct mixing → hot pressing molding, which improves efficiency compared to peeling and acid washing processes for raw materials such as coconut shells (pretreatment cycle is shortened by more than 50%).
[0037] 2) Hot pressing molding increases precursor density
[0038] To avoid pore collapse: hot pressing at 200℃ for 1 hour forms a "uniform and dense block". After carbonization, the integrity of the skeleton is better. This invention does not collapse.
[0039] Enhanced activation uniformity: The dense structure ensures uniform penetration of the alkali (KOH) during the activation stage, avoiding localized over-activation or under-activation. This invention introduces a hot-pressing process to prepare uniform, dense bulk materials with a density >1.0 g / cm³, which is crucial for achieving uniform alkali penetration and ensuring consistent activation.
[0040] 3) One-step carbonization-activation process optimizes efficiency
[0041] Reduced energy consumption: The process employs an alkaline activation rotary furnace, allowing for continuous carbonization and activation. Calculations show that the unit energy consumption for producing porous carbon using this process is approximately 15 kWh / kg, significantly lower than traditional preparation processes (typically exceeding 50 kWh / kg).
[0042] Inhibit alkali volatilization: Activate at 700-800℃ for 2 h under nitrogen atmosphere, and the KOH utilization rate reaches over 90% (existing technology loses about 20% of active alkali due to step-by-step processing).
[0043] 4) The performance of porous carbon is significantly improved.
[0044] High specific surface area: A specific surface area of 1600-2000 m² / g can be achieved by adjusting the activation temperature (700-800℃) and the alkali-to-carbon ratio (3:1);
[0045] Hierarchical pore structure optimization: coexistence of micropores (<2 nm) and mesopores (2-50 nm) enhances electrolyte ion transport rate.
[0046] Supercapacitor performance: Specific capacitance of 110 F / g at 0.5 A / g, capacitance retention of 82% at 10 A / g;
[0047] Cyclic stability: After 20,000 charge-discharge cycles, the capacity retention rate is >80%, far exceeding that of traditional biomass carbon (<70%).
[0048] 5) The process is highly adaptable and adjustable.
[0049] Parameters can be adjusted flexibly: the pore structure can be precisely controlled by changing the ratio of corn flour to glutinous rice flour (8:1~10:1), activation temperature (700℃ or 800℃), and alkali-carbon ratio (2:1~3:1);
[0050] Great potential for industrialization: The equipment (hot press, rotary kiln) are all mature industrial devices that do not require complex modifications.
[0051] 6) Short processing time and low cost
[0052] The process of this invention takes only 12 to 16 hours from raw material mixing to product preparation (mixing 0.5 h, carbonization activation 6 to 8 h, washing and drying 5 to 6 h), without the need for complex pretreatment such as acid washing, and without the burden of wastewater treatment. The production cycle is shortened by more than 80%, realizing low-cost, short-process, and high-efficiency large-scale production. Attached Figure Description
[0053] Figure 1 This is a process image of porous carbon obtained in Example 1 of the present invention.
[0054] Figure 2 SEM image of porous carbon obtained in Example 1 of this invention.
[0055] Figure 3 This is a constant current charge-discharge (GCD) curve of the porous carbon double-layer capacitor prepared in Example 1 of the present invention.
[0056] Figure 4This is a stability test curve of the porous carbon double-layer capacitor prepared in Example 1 of the present invention. Detailed Implementation
[0057] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.
[0058] Example 1
[0059] A method for preparing porous carbon by mixing corn flour and glutinous rice flour includes the following steps:
[0060] Step 1: Mix 9:1 (5000g corn flour and 556g glutinous rice flour) evenly, add 3.75 L of 60℃ warm water and stir into a dough, then knead into a flatbread.
[0061] Step 2: Place the dough in a hot press and press it at 200°C for 1 hour to obtain a dense block.
[0062] Step 3: Place the block from Step 2 in a box furnace and heat it to 500°C at 5°C / min under a nitrogen atmosphere, and hold it at that temperature for 1 hour for carbonization.
[0063] Step 4: Mix the carbonized material with alkali at a mass ratio of 1:3, place it in an alkaline activation rotary furnace, and activate it by heating to 700°C at 5°C / min under a nitrogen atmosphere and holding it at that temperature for 2 hours.
[0064] Step 5: Wash the activated material with 1 M hydrochloric acid solution, and then wash with deionized water until neutral.
[0065] Step 6: The material obtained in Step 5 is dried at 80℃ to obtain porous carbon. Nitrogen adsorption-desorption testing (77 K) showed that the porous carbon obtained in Example 1 had a specific surface area of 1800 m² / g, a total pore volume of 0.8 cm³ / g, and a micropore volume of 0.5 cm³ / g, exhibiting a hierarchical pore structure of micropores-mesopores-macropores. Electrochemical testing (1M TEATFB / organic system) showed a specific capacitance of 110 F / g at a current density of 0.5 A / g, and maintained above 90 F / g at 10 A / g, with a capacity retention of 82%, demonstrating excellent rate performance.
[0066] Example 2
[0067] A method for preparing porous carbon by mixing corn flour and glutinous rice flour includes the following steps:
[0068] Step 1: Mix 5000g of corn flour and 500g of glutinous rice flour evenly, add 3.75L of 60℃ warm water and stir into a dough, then knead into a flatbread.
[0069] Step 2: Place the dough in a hot press and press it at 200°C for 1 hour to obtain a dense block.
[0070] Step 3: Place the block from Step 2 in a box furnace and heat it to 500°C at 5°C / min under a nitrogen atmosphere, and hold it at that temperature for 1 hour for carbonization.
[0071] Step 4: Mix the carbonized material with alkali at a mass ratio of 1:3, place it in an alkaline activation rotary furnace, and activate it by heating to 700°C at 5°C / min under a nitrogen atmosphere and holding it at that temperature for 2 hours.
[0072] Step 5: Wash the activated material with 1 M hydrochloric acid solution (1 M HCl), and then wash with deionized water until neutral;
[0073] Step 6: Dry the material obtained in step 5 at 80°C to obtain porous carbon.
[0074] Comparative tests revealed that the product obtained under this ratio still maintained a high specific surface area of 1700 m² / g, but the micropore ratio changed slightly, with a micropore volume of 0.46 cm³ / g, indicating that the pore structure can be controlled by adjusting the raw material ratio.
[0075] Example 3
[0076] A method for preparing porous carbon by mixing corn flour and glutinous rice flour includes the following steps:
[0077] Step 1: Mix 5000g of corn flour and 500g of glutinous rice flour evenly, add 3.75L of 60℃ warm water and stir into a dough, then knead into a flatbread.
[0078] Step 2: Place the dough in a hot press and press it at 200°C for 1 hour to obtain a dense block.
[0079] Step 3: Place the block from Step 2 in a box furnace and heat it to 600°C at 5°C / min under a nitrogen atmosphere, and hold it at that temperature for 1 hour for carbonization.
[0080] Step 4: Mix the carbonized material with alkali at a mass ratio of 1:3, place it in an alkaline activation rotary furnace, and activate it by heating to 700°C at 5°C / min under a nitrogen atmosphere and holding it at that temperature for 2 hours.
[0081] Step 5: Wash the activated material with 1 M hydrochloric acid solution, and then wash with deionized water until neutral.
[0082] Step 6: Dry the material obtained in step 5 at 80°C to obtain porous carbon.
[0083] The specific surface area of the obtained porous carbon decreased slightly (1680 m² / g), but the degree of graphitization increased (ID / IG: 0.7), making it suitable for supercapacitor electrode materials.
[0084] Example 4
[0085] A method for preparing porous carbon by mixing corn flour and glutinous rice flour includes the following steps:
[0086] Step 1: Mix 5000g of corn flour and 500g of glutinous rice flour evenly, add 3.75L of 60℃ warm water and stir into a dough, then knead into a flatbread.
[0087] Step 2: Place the dough in a hot press and press it at 200°C for 1 hour to obtain a dense block.
[0088] Step 3: Place the block from Step 2 in a box furnace and heat it to 500°C at 5°C / min under a nitrogen atmosphere, and hold it at that temperature for 1 hour for carbonization.
[0089] Step 4: Mix the carbonized material with alkali at a mass ratio of 1:3, place it in an alkaline activation rotary furnace, and activate it by heating to 800°C at 5°C / min under a nitrogen atmosphere and holding it at that temperature for 2 hours.
[0090] Step 5: Wash the activated material with 1 M hydrochloric acid solution, and then wash with deionized water until neutral.
[0091] Step 6: Dry the material obtained in step 5 at 80°C to obtain porous carbon.
[0092] The porous carbon obtained has a further developed pore structure with a specific surface area of 2000 m² / g, but the yield is slightly reduced (carbon yield is 22%), making it suitable for adsorption applications that require high specific surface area.
[0093] Example 5
[0094] A method for preparing porous carbon by mixing corn flour and glutinous rice flour includes the following steps:
[0095] Step 1: Mix corn flour and glutinous rice flour in a mass ratio of 10:1 (5000g corn flour to 500g glutinous rice flour), add 3.75 L of 60℃ warm water and stir to form a dough, then knead into a flatbread.
[0096] Step 2: Place the dough in a hot press and press it at 200°C for 2 hours to obtain a dense block.
[0097] Step 3: Place the block from Step 2 in a box furnace and heat it to 500°C at 5°C / min under a nitrogen atmosphere, and hold it at that temperature for 1 hour for carbonization.
[0098] Step 4: Mix the carbonized material with alkali at a mass ratio of 1:2, place it in an alkaline activation rotary furnace, and activate it by heating to 750°C at 5°C / min under a nitrogen atmosphere and holding it at that temperature for 2 hours.
[0099] Step 5: Wash the activated material with 1 M hydrochloric acid solution, and then wash with deionized water until neutral.
[0100] Step 6: Dry the material obtained in step 5 at 80°C to obtain porous carbon.
[0101] The results show that appropriately reducing the alkali-to-carbon ratio can regulate the pore structure, increasing the proportion of micropores in the resulting material while maintaining a specific surface area of over 1600 m² / g.
[0102] See Figure 1 A complete preparation process route for corn flour / glutinous rice flour-based porous carbon materials is presented. The entire process mainly includes six core steps. This flow chart fully presents the transformation process from biomass raw materials to high-performance porous carbon materials, highlighting the three key processes of hot pressing, carbonization, and alkali activation, providing a clear technical route for industrial production.
[0103] See Figure 2 The prepared porous carbon material exhibits an irregular blocky morphology with a rough and uneven surface. The material maintains a relatively complete precursor framework without significant collapse, indicating that the porous carbon prepared by this method has good structural stability.
[0104] See Figure 3 As can be seen, the constant current charge-discharge curves at different current densities (0.5 A / g, 1 A / g, 2 A / g, 5 A / g, 10 A / g, 20 A / g) are presented. All curves exhibit a well-defined symmetrical triangular shape with no significant voltage drop (IRdrop), indicating that the material possesses excellent electrochemical reversibility and double-layer capacitance characteristics. At a current density of 0.5 A / g, the specific capacitance reaches 110 F / g; even when the current density increases to 10 A / g, the specific capacitance remains above 90 F / g, with a capacitance retention rate as high as 82%, demonstrating excellent rate performance.
[0105] See Figure 4 The capacity retention curve of the prepared porous carbon electrode after 20,000 constant current charge-discharge cycles at a current density of 10 A / g is shown. Figure 4 As can be seen, the specific capacitance increases slightly in the first 500 cycles, which is due to the gradual activation process of the electrode material; subsequently, it enters a stable phase, and the capacity retention rate decreases slowly. After 20,000 consecutive charge-discharge cycles, the specific capacitance of the electrode still remains above 80% of the initial capacity, indicating that the material has excellent cycle stability. This excellent cycle stability is attributed to the material's stable carbon framework structure, good mechanical strength, and good interfacial compatibility between the electrode material and the electrolyte, providing a reliable guarantee for its long-term application in practical energy storage devices.
Claims
1. A method for preparing porous carbon by mixing corn flour and glutinous rice flour, characterized in that, Includes the following steps: Step 1: Mix corn flour and glutinous rice flour in the specified mass ratio, add warm water and stir to form a dough, then shape it into a pancake; Step 2: The dough obtained in Step 1 is hot-pressed to form a uniform and dense block. Step 3: Carbonize the block obtained in Step 2 in a nitrogen atmosphere; Step 4: Mix the carbonized material obtained in Step 3 with alkali in a uniform mass ratio, and then perform activation treatment in an alkaline activation rotary furnace. Step 5: Pickle the material obtained in Step 4, and then wash it with deionized water until it is neutral. Step 6: Dry the material obtained in step 5 to obtain porous carbon.
2. The method for preparing porous carbon by mixing corn flour and glutinous rice flour according to claim 1, characterized in that, In step 1, the mass ratio of corn flour to glutinous rice flour is 9-10:
1.
3. The method for preparing porous carbon by mixing corn flour and glutinous rice flour according to claim 1, characterized in that, In step 2, the hot pressing temperature is 200℃ and the hot pressing time is 1-2 hours.
4. The method for preparing porous carbon by mixing corn flour and glutinous rice flour according to claim 1, characterized in that, In step 3, the carbonization temperature is 500°C.
5. The method for preparing porous carbon by mixing corn flour and glutinous rice flour according to claim 1, characterized in that, In step 4, the heating rate of the activation treatment is 5℃ / min, the activation temperature is 700-800℃, the holding time is 2 h, and the atmosphere is nitrogen.
6. The method for preparing porous carbon by mixing corn flour and glutinous rice flour according to claim 1, characterized in that, In step 4, the activation temperature is 700°C.
7. The method for preparing porous carbon by mixing corn flour and glutinous rice flour according to claim 1, characterized in that, In step 4, the alkali is potassium hydroxide, and the mass ratio of the carbonized material to the alkali is 1:2-3.
8. The method for preparing porous carbon by mixing corn flour and glutinous rice flour according to claim 1, characterized in that, In step 5, the pickling is performed using a 1M hydrochloric acid solution for 24 hours.
9. The method for preparing porous carbon by mixing corn flour and glutinous rice flour according to claim 1, characterized in that, In step 6, the drying temperature is 80°C, and the product is dried to a constant weight.
10. A method for preparing porous carbon by mixing corn flour and glutinous rice flour according to any one of claims 1 to 9, characterized in that, The prepared porous carbon has a hierarchical pore structure with both micropores and mesopores, and a specific surface area of 1600-2000 m² / g.