Production process for producing activated carbon for wood sugar with caramel decoloration function by using physical activation method

Abstract

The invention belongs to the technical field of activated carbon production, and particularly relates to a production process for producing activated carbon with a caramel decoloring function for wood sugar by using a physical activation method. The method comprises the following steps that S1, raw material screening and pretreatment are conducted, specifically, high-quality wood with the water content being 10%-15% is selected and cut into wood chips with the length being 5-10 cm, the width being 3-5 cm and the thickness being 1-2 cm, and then the wood chips are dried at the temperature of 100-120 DEG C till the water content is lower than 5%; through optimized process steps, especially a unique activation process, the activated carbon has rich micropore and mesopore structures and has higher adsorption capacity on caramel pigment, the caramel decolorization rate is remarkably increased, the requirement of the sugar industry for high-quality activated carbon can be met, and the high caramel decolorization performance is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of activated carbon production, and relates to a production process for producing activated carbon for xylene sugar with caramel decolorization function by using a physical activation method. Background Art

[0002] Activated carbon is a porous adsorption material with a highly developed pore structure and a huge specific surface area. It is widely used in many fields such as food, medicine, and environmental protection. In the sugar industry, activated carbon with efficient caramel decolorization function is needed to remove impurities such as pigments in sugar solution to improve the purity and quality of sugar.

[0003] There are some shortcomings in the traditional production process of activated carbon for xylose. For example, the caramel decolorization rate of activated carbon produced by some processes is not high, which cannot meet the increasingly high quality requirements of sugar production; some processes cause great pollution to the environment during the production process, or have low production efficiency and high cost. Physical activation is one of the common methods for producing activated carbon, but the existing physical activation method still has room for improvement in the selection of activators and control of process parameters when producing activated carbon for xylose, so as to obtain activated carbon products with better performance.

[0004] In order to overcome the shortcomings of the existing technology, people have proposed various solutions through continuous exploration. For example, a Chinese patent discloses a method for preparing activated carbon from lignocellulose residues [application number: 202410510272.X], which is to dry the lignocellulose residues after pretreatment and enzymatic saccharification in the lignocellulose-based lactic acid production process, and then obtain activated carbon through carbonization and cesium carbonate activation. However, this solution still has the defects of low activated carbon caramel decolorization rate, low production efficiency and high cost in production. Summary of the invention

[0005] The purpose of the present invention is to solve the above problems and provide a production process of xylene activated carbon with caramel decolorization function by physical activation method.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A production process for producing activated carbon for xylitol with caramel decolorization function by physical activation method comprises the following steps:

[0008] S1: Raw material screening and pretreatment: Select high-quality wood with a moisture content of 10%-15%, cut it into wood chips with a length of 5-10cm, a width of 3-5cm, and a thickness of 1-2cm, and then dry it at a temperature of 100-120°C until the moisture content is less than 5%;

[0009] S2: Carbonization treatment: The pretreated wood chips are placed in a carbonization furnace, the temperature is raised from room temperature to 400-500°C at a heating rate of 5-10°C / min, and carbonized at this temperature for 2-3 hours to obtain a carbonized material;

[0010] S3: Physical activation: placing the carbonized material in an activation furnace, introducing a mixed gas consisting of water vapor and carbon dioxide in a volume ratio of 1:2-3:2 as an activator, activating at a temperature of 850-950° C. for 1-3 hours, and the flow rate of the mixed gas is 0.5-1.5 L / min;

[0011] S4: Pickling treatment: The activated product is cooled to room temperature, and then soaked in a 5%-10% hydrochloric acid solution for 2-4 hours, with a liquid-to-solid ratio of the hydrochloric acid solution to the product being 5:1-10:1 (L / kg) to remove impurities;

[0012] S5: Water washing and drying: The acid-washed product is repeatedly washed with deionized water until the pH value of the washing liquid is 6-7, and then dried at a temperature of 120-150° C. for 3-5 hours to obtain activated carbon for xylose.

[0013] In the above-mentioned production process of activated carbon for xylitol with caramel decolorization function by physical activation, in the step S1, the high-quality wood is one of birch, poplar or pine.

[0014] In the above-mentioned production process of activated carbon for xylene sugar with caramel decolorization function by physical activation method, in the step S2, the pressure in the carbonization furnace is controlled at -0.05 MPa to -0.03 MPa.

[0015] In the above-mentioned production process of xylose activated carbon with caramel decolorization function by physical activation method, in the S3 step, a staged heating method is adopted in the activation furnace, firstly the temperature is raised from room temperature to 600-700°C at a heating rate of 8-12°C / min, maintained for 30-60 minutes, and then raised to 850-950°C at a heating rate of 5-8°C / min for activation.

[0016] In the above-mentioned production process of xylose activated carbon with caramel decolorization function by physical activation method, in the step S3, before the mixed gas is introduced, nitrogen is first introduced into the activation furnace for displacement, so that the oxygen content in the furnace is less than 0.5%.

[0017] In the above-mentioned production process of xylene activated carbon with caramel decolorization function by physical activation, in the step S4, ultrasonic assistance is used during the soaking process, the ultrasonic frequency is 20-40kHz, and the power is 100-300W.

[0018] In the above-mentioned production process of xylene activated carbon with caramel decolorization function by physical activation method, in the step S5, countercurrent washing is used for water washing, and vacuum drying is used during the drying process, and the vacuum degree is controlled at -0.08MPa to -0.06MPa.

[0019] In the above-mentioned production process of xylene activated carbon with caramel decolorization function by physical activation method, a post-treatment step is also included, in which the dried activated carbon is heat-treated at a temperature of 300-400°C for 2-3 hours, and air is introduced during the heat treatment process with an air flow rate of 0.2-0.5L / min.

[0020] In the above-mentioned production process of activated carbon for xylose with caramel decolorization function by physical activation, after step S1, the wood chips are subjected to steam explosion treatment with a steam pressure of 2-3 MPa and a holding time of 3-5 minutes.

[0021] In the above-mentioned production process of xylene activated carbon with caramel decolorization function by physical activation, after step S2, the carbonized material is ball-milled for 1-2 hours and the ball-to-material ratio is 10:1-20:1.

[0022] Compared with the prior art, the advantages of the present invention are:

[0023] 1. The present invention optimizes the process steps, especially the unique activation process, so that the activated carbon has rich micropores and mesopore structures, has a stronger adsorption capacity for caramel pigment, and significantly improves the caramel decolorization rate, which can meet the demand of the sugar industry for high-quality activated carbon and achieve high caramel decolorization performance.

[0024] 2. The present invention adopts physical activation method, which reduces the use and discharge of chemical reagents compared with some chemical activation methods, and is more environmentally friendly. At the same time, reasonable process parameter setting reduces energy consumption, improves production efficiency, reduces production costs, and is environmentally friendly and energy-saving.

[0025] 3. The present invention adopts physical activation method, which reduces the use and discharge of chemical reagents compared with some chemical activation methods, and is more environmentally friendly. At the same time, reasonable process parameter setting reduces energy consumption, improves production efficiency, reduces production costs, and stabilizes product quality.

[0026] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with the accompanying drawings.

[0029] Example 1

[0030] like Figure 1 As shown, a production process for producing activated carbon for xylose with caramel decolorization function by physical activation method includes the following steps: S1: raw material screening and pretreatment: select birch with a moisture content of 12%, cut it into wood chips with a length of 6 cm, a width of 4 cm, and a thickness of 1.5 cm, and then dry it at a temperature of 110°C to a moisture content of 4%.

[0031] S2: Carbonization treatment: The pretreated wood chips are placed in a carbonization furnace, and the temperature is raised from room temperature to 450°C at a heating rate of 8°C / min, and carbonized at this temperature for 2.5 hours. The pressure in the carbonization furnace is controlled at -0.04MPa to obtain a carbonized material.

[0032] S3: Physical activation: Place the carbonized material in an activation furnace, introduce a mixed gas consisting of water vapor and carbon dioxide in a volume ratio of 1:1.5 as an activator, and activate at 900°C for 2 hours. The flow rate of the mixed gas is 1L / min. The activation furnace adopts a staged heating method, firstly raising the temperature from room temperature to 650°C at a heating rate of 10°C / min, maintaining for 45 minutes, and then raising the temperature to 900°C at a heating rate of 6°C / min for activation. Before introducing the mixed gas, nitrogen is introduced into the activation furnace for replacement to make the oxygen content in the furnace less than 0.5%.

[0033] S4: pickling treatment: the activated product was cooled to room temperature, and then soaked in 8% hydrochloric acid solution for 3 hours, the liquid-solid ratio of hydrochloric acid solution to product was 8:1 (L / kg), and ultrasonic assistance was used during the soaking process, the ultrasonic frequency was 30kHz, and the power was 200W.

[0034] S5: Water washing and drying: The acid-washed product is repeatedly washed with deionized water until the pH value of the washing solution is 6.5, and then dried at 130°C for 4 hours. The water washing adopts a countercurrent washing method, and the drying process adopts vacuum drying, and the vacuum degree is controlled at -0.07MPa.

[0035] Post-treatment step: The dried activated carbon was heat treated at 350°C for 2.5 hours. Air was introduced during the heat treatment process with an air flow rate of 0.3 L / min.

[0036] Performance test: After testing, the activated carbon caramel decolorization rate produced in this embodiment reached more than 95%, and the specific surface area was 1200m 2 / g, the iodine adsorption value is 1000mg / g, and various performance indicators are excellent, meeting the requirements of the sugar industry for high-quality activated carbon for wood sugar.

[0037] Example 2

[0038] Combination Figure 1 As shown, the difference from Example 1 is that S1: raw material screening and pretreatment: select pine wood with a moisture content of 10%, cut it into wood chips with a length of 5 cm, a width of 3 cm, and a thickness of 1 cm, and then dry it at a temperature of 100°C to a moisture content of 3%.

[0039] S2: Carbonization treatment: The pretreated wood chips are placed in a carbonization furnace, and the temperature is raised from room temperature to 400°C at a heating rate of 5°C / min, and carbonized at this temperature for 3 hours. The pressure in the carbonization furnace is controlled at -0.05MPa to obtain a carbonized material.

[0040] S3: Physical activation: Place the carbonized material in an activation furnace, introduce a mixed gas consisting of water vapor and carbon dioxide in a volume ratio of 2:2 as an activator, and activate at a temperature of 850°C for 3 hours. The flow rate of the mixed gas is 0.5L / min. The activation furnace adopts a staged heating method, firstly raising the temperature from room temperature to 600°C at a heating rate of 8°C / min, maintaining for 60 minutes, and then raising the temperature to 850°C at a heating rate of 5°C / min for activation. Before introducing the mixed gas, nitrogen is introduced into the activation furnace for displacement to make the oxygen content in the furnace less than 0.5%.

[0041] S4: pickling treatment: the activated product was cooled to room temperature, and then soaked in a 5% hydrochloric acid solution for 4 hours, the liquid-solid ratio of the hydrochloric acid solution to the product was 5:1 (L / kg), and ultrasonic assistance was used during the soaking process, the ultrasonic frequency was 20kHz, and the power was 100W.

[0042] S5: Water washing and drying: The acid-washed product is repeatedly washed with deionized water until the pH value of the washing solution is 6, and then dried at 120°C for 5 hours. The water washing adopts a countercurrent washing method, and the drying process adopts vacuum drying, and the vacuum degree is controlled at -0.08MPa.

[0043] Post-treatment step: The dried activated carbon was heat treated at 300°C for 3 hours. Air was introduced during the heat treatment with an air flow rate of 0.2 L / min.

[0044] Performance test: The activated carbon caramel decolorization rate produced in this embodiment reaches 93%, and the specific surface area is 1100m 2 / g, and the iodine adsorption value is 950mg / g, which also has good performance and can be used in the sugar industry.

[0045] Example 3

[0046] Combination Figure 1 As shown, the difference from Examples 1 and 2 is that S1: raw material screening and pretreatment: select poplar wood with a moisture content of 15%, cut it into wood chips with a length of 10 cm, a width of 5 cm, and a thickness of 2 cm, and then dry it at a temperature of 120°C to a moisture content of 2%.

[0047] S2: Carbonization treatment: The pretreated wood chips are placed in a carbonization furnace, and the temperature is raised from room temperature to 500°C at a heating rate of 10°C / min, and carbonized at this temperature for 2 hours. The pressure in the carbonization furnace is controlled at -0.03MPa to obtain a carbonized material.

[0048] S3: Physical activation: Place the carbonized material in an activation furnace, introduce a mixed gas consisting of water vapor and carbon dioxide in a volume ratio of 3:2 as an activator, and activate at a temperature of 950°C for 1 hour. The flow rate of the mixed gas is 1.5L / min. The activation furnace adopts a staged heating method, firstly raising the temperature from room temperature to 700°C at a heating rate of 12°C / min, maintaining for 30 minutes, and then raising the temperature to 950°C at a heating rate of 8°C / min for activation. Before introducing the mixed gas, nitrogen is introduced into the activation furnace for replacement to make the oxygen content in the furnace less than 0.5%.

[0049] S4: pickling treatment: the activated product was cooled to room temperature, and then soaked in a 10% hydrochloric acid solution for 2 hours, the liquid-solid ratio of the hydrochloric acid solution to the product was 10:1 (L / kg), and ultrasonic assistance was used during the soaking process, the ultrasonic frequency was 40kHz, and the power was 300W.

[0050] S5: Water washing and drying: The acid-washed product is repeatedly washed with deionized water until the pH value of the washing solution is 7, and then dried at 150°C for 3 hours. The water washing adopts a countercurrent washing method, and the drying process adopts vacuum drying, and the vacuum degree is controlled at -0.06MPa.

[0051] Post-treatment step: The dried activated carbon was heat treated at 400°C for 2 hours. Air was introduced during the heat treatment process with an air flow rate of 0.5 L / min.

[0052] Performance test: The activated carbon caramel decolorization rate produced in this embodiment reaches 96%, and the specific surface area is 1300m 2 / g, and the iodine adsorption value is 1050mg / g, showing good performance advantages.

[0053] The present invention uses a mixed gas composed of water vapor and carbon dioxide in a specific ratio (1:2-3:2) as an activator. Compared with the traditional single activator or activators in different ratios, it can more effectively form a rich and suitable pore structure on the surface of activated carbon. This unique activator combination has been verified by a large number of experiments to significantly improve the adsorption capacity of activated carbon for caramel pigment, which is one of the key factors for improving the caramel decolorization function of the product, and is innovative in the activator.

[0054] Through heating rate and temperature control: During the carbonization and activation process, the heating rate and temperature are precisely controlled. For example, during carbonization, the temperature is raised to 400-500℃ at a heating rate of 5-10℃ / min, and during activation, the temperature is raised in stages, first at a heating rate of 8-12℃ / min from room temperature to 600-700℃, and then at a heating rate of 5-8℃ / min to 850-950℃ after a period of time. This precise temperature control method is conducive to the gradual formation and optimization of the pore structure of activated carbon. Compared with the traditional simple heating method, it can produce activated carbon with a more reasonable pore structure and better adsorption performance, and achieve optimization of process parameters.

[0055] During the carbonization and activation process, time and pressure are also precisely controlled. The carbonization time is 2-3 hours, and the pressure is controlled at -0.05MPa to -0.03MPa; the activation time is 1-3 hours, and the mixed gas flow rate is 0.5-1.5L / min. The synergistic effect of these parameters makes the preparation process of activated carbon more scientific and reasonable, further improves the product quality, and achieves precise control of time and pressure.

[0056] Ultrasonic waves are introduced into the pickling process with a frequency of 20-40kHz and a power of 100-300W. Ultrasonic waves can accelerate the reaction between hydrochloric acid and impurities, more thoroughly remove impurities such as metal ions in activated carbon, and improve product purity, which is rarely used in traditional activated carbon production processes.

[0057] Ultrasonic waves are introduced into the pickling process with a frequency of 20-40kHz and a power of 100-300W. Ultrasonic waves can accelerate the reaction between hydrochloric acid and impurities, more thoroughly remove impurities such as metal ions in activated carbon, and improve product purity, which is rarely used in traditional activated carbon production processes.

[0058] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways without departing from the spirit of the present invention.

Claims

1. A production process for producing activated carbon for xylose with caramel decolorization function by physical activation method, characterized in that: The following steps are involved: S1: Raw material screening and pretreatment: Select high-quality wood with a moisture content of 10%-15%, cut it into wood chips with a length of 5-10cm, a width of 3-5cm, and a thickness of 1-2cm, and then dry it at a temperature of 100-120°C until the moisture content is less than 5%; S2: Carbonization treatment: The pretreated wood chips are placed in a carbonization furnace, the temperature is raised from room temperature to 400-500°C at a heating rate of 5-10°C / min, and carbonized at this temperature for 2-3 hours to obtain a carbonized material; S3: Physical activation: placing the carbonized material in an activation furnace, introducing a mixed gas consisting of water vapor and carbon dioxide in a volume ratio of 1:2-3:2 as an activator, activating at a temperature of 850-950° C. for 1-3 hours, and the flow rate of the mixed gas is 0.5-1.5 L / min; S4: Pickling treatment: The activated product is cooled to room temperature, and then soaked in a 5%-10% hydrochloric acid solution for 2-4 hours, with a liquid-to-solid ratio of the hydrochloric acid solution to the product being 5:1-10:1 (L / kg) to remove impurities; S5: Water washing and drying: The acid-washed product is repeatedly washed with deionized water until the pH value of the washing liquid is 6-7, and then dried at a temperature of 120-150° C. for 3-5 hours to obtain activated carbon for xylose.

2. The production process of activated carbon for xylose with caramel decolorization function by physical activation method according to claim 1, characterized in that: In the step S1, the high-quality wood is one of birch, poplar or pine.

3. The production process of activated carbon for xylose with caramel decolorization function by physical activation method according to claim 1, characterized in that: In the step S2, the pressure in the carbonization furnace is controlled within a range of -0.05 MPa to -0.03 MPa.

4. The production process of activated carbon for xylose with caramel decolorization function by physical activation method according to claim 1, characterized in that: In the step S3, the activation furnace is heated in stages, firstly from room temperature to 600-700°C at a heating rate of 8-12°C / min, maintained for 30-60 minutes, and then heated to 850-950°C at a heating rate of 5-8°C / min for activation.

5. The production process of activated carbon for xylose with caramel decolorization function by physical activation method according to claim 1, characterized in that: In the step S3, before the mixed gas is introduced, nitrogen is introduced into the activation furnace for replacement, so that the oxygen content in the furnace is less than 0.5%.

6. The production process of activated carbon for xylose with caramel decolorization function by physical activation method according to claim 1, characterized in that: In the step S4, ultrasonic wave is used to assist the immersion process, and the ultrasonic wave frequency is 20-40kHz and the power is 100-300W.

7. The production process of activated carbon for xylose with caramel decolorization function by physical activation method according to claim 1, characterized in that: In the step S5, the water washing adopts a countercurrent washing method, and vacuum drying is adopted in the drying process, and the vacuum degree is controlled at -0.08MPa to -0.06MPa.

8. The production process of activated carbon for xylose with caramel decolorization function by physical activation method according to claim 1, characterized in that: The method also includes a post-treatment step, in which the dried activated carbon is heat-treated at a temperature of 300-400° C. for 2-3 hours, and air is introduced during the heat treatment process with an air flow rate of 0.2-0.5 L / min.

9. The production process of activated carbon for xylose with caramel decolorization function by physical activation method according to claim 1, characterized in that: After the step S1, the wood chips are subjected to steam explosion treatment, with a steam pressure of 2-3 MPa and a holding time of 3-5 minutes.

10. The production process of activated carbon for xylose with caramel decolorization function by physical activation method according to claim 1, characterized in that: After the step S2, the carbonized material is subjected to ball milling treatment, the ball milling time is 1-2 hours, and the ball-to-material ratio is 10:1-20:1.

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