High-performance wooden activated carbon for solvent recovery and preparation method thereof

Abstract

The invention discloses high-performance wooden activated carbon for solvent recovery and a preparation method of the high-performance wooden activated carbon, and belongs to the technical field of phosphoric acid method activated carbon. The preparation method comprises the following steps: mixing a biological material, an absorbent and phosphoric acid, and granulating to obtain granules; wherein the absorbent is a material with high specific heat capacity; then introducing air to activate the granules; and then cooling to room temperature, washing and recovering phosphoric acid, and drying to obtain the high-performance wooden activated carbon. A certain amount of high-specific-heat-capacity material is added as an absorbent during preparation of the wooden activated carbon, so that heat released by self-heat release of the activated carbon in the adsorption process can be absorbed, the temperature rise amplitude is reduced, spontaneous combustion caused by too fast local temperature rise of an activated carbon bed layer is prevented, and meanwhile, the performance of the activated carbon is not affected.

Description

Technical Field

[0001] The present invention belongs to the technical field of phosphoric acid activated carbon, and particularly relates to a high-performance wood activated carbon for solvent recovery and a preparation method thereof. Background Art

[0002] The pore structure of wood activated carbon is more developed than that of coal-based activated carbon. In addition to having abundant micropores, it also has a certain proportion of mesopores. The pores of coal-based activated carbon are mainly micropores, and the proportion of mesopores is extremely small. When activated carbon adsorbs organic solvents, the micropores determine the adsorption capacity, and the mesopores determine the adsorption rate. The more developed the mesopores are, the faster the adsorption rate is. And the self-heating phenomenon will become more obvious with the increase of the adsorption rate, which is likely to cause local overheating of the activated carbon bed and spontaneous combustion, thereby leading to equipment damage and affecting the normal operation of production. In severe cases, it may even cause fires and explosions, resulting in casualties and property losses.

[0003] Currently, the commonly used solutions mainly include the following several: (1) Initial passivation treatment: Use low-concentration organic solvent gas to pass into the adsorption bed, allowing the activated carbon to adsorb and desorb at low concentration, and repeatedly adsorb and desorb at low concentration for more than ten cycles, so that the activated carbon reaches passivation, thereby stabilizing and decreasing the adsorption rate.

[0004] (2) Install on-line monitoring equipment for waste gas components to monitor the types and concentrations of chemical substances in the waste gas in real time, and promptly discover and handle abnormal situations.

[0005] (3) Install temperature sensors in the activated carbon adsorption device to monitor the temperature change of the bed layer in real time. Once the temperature is found to rise abnormally, cooling measures should be taken in a timely manner, such as increasing the cooling air volume, spraying cooling, etc.

[0006] However, these methods all start from the outside and do not improve the activated carbon itself, so it is impossible to avoid the spontaneous combustion of wood activated carbon at the root. How to provide a high-performance wood activated carbon for solvent recovery that is not prone to spontaneous combustion has become an urgent problem to be solved at present. Summary of the Invention

[0007] The technical problem to be solved by the present invention is: how to prepare a preparation method of a high-performance wood activated carbon for solvent recovery that is not prone to spontaneous combustion.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is: a preparation method of a high-performance wood activated carbon for solvent recovery, comprising the following steps: S1. Mix a biological material, an absorbent, and phosphoric acid, and then granulate to obtain columnar materials; wherein, the absorbent is a material with a high specific heat capacity; S2. Introduce air to activate the columnar material. S3. Cool the columnar material obtained in S2 to room temperature, wash and recover phosphoric acid, and dry to obtain high-performance wood-based activated carbon.

[0009] The beneficial effects of the present invention are as follows: By adding a certain amount of high specific heat capacity material as an absorbent during the preparation of wood-based activated carbon, the present invention can absorb the heat released by the self-exothermic heat during the adsorption process of activated carbon, reduce the amplitude of temperature rise, prevent local overheating of the activated carbon bed layer and cause spontaneous combustion, and at the same time does not affect the performance of the activated carbon. The obtained wood-based activated carbon still has good performance when used for solvent recovery. Specific Embodiments

[0010] To illustrate the technical content, achieved objectives and effects of the present invention in detail, the following is described in conjunction with embodiments.

[0011] A preparation method of high-performance wood-based activated carbon for solvent recovery includes the following steps: S1. Mix a biological material, an absorbent and phosphoric acid, and then granulate to obtain a columnar material; Wherein, the absorbent is a high specific heat capacity material; S2. Introduce air to activate the columnar material; S3. Cool the columnar material obtained in S2 to room temperature, wash and recover phosphoric acid, and dry to obtain high-performance wood-based activated carbon.

[0012] As can be seen from the above description, the beneficial effects of the present invention are as follows: The preparation method provided by the present invention mixes a high specific heat capacity material and a biological material with phosphoric acid, and uses the phosphoric acid method to prepare activated carbon. The preparation method has few steps and a simple process. Without a special activator or a special gas atmosphere, activated carbon for solvent recovery that can absorb the heat released by the self-exothermic heat during the adsorption process of activated carbon, is not prone to spontaneous combustion and has good performance can be prepared.

[0013] Furthermore, the biological material is a carbon-containing biological material commonly used for preparing activated carbon, such as wood powder, wood chips, sawdust, wood shavings, coconut shells, palm shells, fruit shells, etc.

[0014] Furthermore, the mass ratio of the biological material, the absorbent and phosphoric acid is 1:0.2 - 0.5:1 - 2.

[0015] The absorbent is at least one of glass micro-powder, quartz micro-powder and ceramic micro-powder. Preferably, the mass ratio of glass micro-powder, quartz micro-powder and ceramic micro-powder is 1:0.3 - 0.5:0.1 - 0.2.

[0016] Further, the washing can be carried out with chlorine-free water or by boiling with clean water. Compared with washing with chlorine-free water at normal temperature multiple times, boiling with clean water has a better washing effect. However, restricted by conditions such as energy and equipment, washing with chlorine-free water at normal temperature can still be used to obtain high-performance wood-based activated carbon.

[0017] Further, granulation can be achieved by extrusion with a granulator followed by cutting, or by first preparing rod-shaped or strip-shaped materials with a granulator and then pre-drying and dispersing them into columnar materials.

[0018] Further, the particle size of the absorbent is 300 - 400 mesh. The particle size of the absorbent can also be greater than 300 mesh, but the smaller the particle size, the smaller the impact on the performance of the activated carbon, and the better the heat absorption effect.

[0019] Further, the mixing is carried out in a kneader at a temperature of 170 - 240 °C for 1 - 2 h. During the kneading (mixing) process, ensuring a certain temperature and time can not only ensure the full mixing of the raw materials but also cause the biomass materials to undergo ripening transformation and generate plasticity.

[0020] Further, during the activation treatment in S2, the temperature is raised from room temperature to 500 - 700 °C at a heating rate of 3 - 8 °C / min. A relatively slow heating rate is maintained during the activation process to control the development of the pore structure, avoid non-uniform activation, and avoid the formation of excessive micropores.

[0021] Further, the activation treatment is carried out in a rotary kiln with a rotation speed of 15 - 20 rpm. Conducting the activation in a rotary kiln can ensure uniform activation, obtain products with uniform quality, and at the same time enable continuous production and improve production efficiency.

[0022] Further, the moisture content of the granular material used for activation treatment is 25 - 35%. The granular material for activation treatment should ensure a certain moisture content and cannot be too low, which is crucial for the formation of high adsorption performance of the activated carbon and the composition of the pore structure.

[0023] In the present invention, for the pores of the activated carbon, the pore diameter of the macropores is greater than 50 nm, the pore diameter of the mesopores is 2 - 50 nm, and the pore diameter of the micropores is less than 2 nm.

[0024] Example 1 of the present invention is as follows: A preparation method of high-performance wood-based activated carbon for solvent recovery, comprising the following steps: S1. Mix wood powder, absorbent, and phosphoric acid in a kneader at a mass ratio of 1:0.2:1; the mixing temperature in the kneader is 200 °C and the time is 1.5 h; the absorbent is 400-mesh glass micro-powder; S2. Use a plunger granulator to produce columnar materials with a diameter of 4 mm and a length of 100 - 150 mm. S3. Pre - dry the columnar materials in an oven until the moisture content is 30%, and the pre - drying temperature is 180 °C. S4. Break up the pre - dried columnar materials into granular materials with a length of 3 - 5 mm. S5. Load the granular materials obtained in S4 into a rotary kiln for activation, introduce air, the rotation speed of the rotary kiln is 20 rpm, slowly heat up to 650 °C, and the heating rate is 5 °C / min. S6. After the activation is completed, cool to room temperature, boil with clear water, recover phosphoric acid, and dry in an oven at 150 °C until the moisture content < 5% to obtain high - performance wood - based activated carbon.

[0025] Example two of the present invention is as follows: A preparation method of high - performance wood - based activated carbon for solvent recovery, comprising the following steps: S1. Mix the biological material, absorbent and phosphoric acid in a kneader according to a mass ratio of 1:0.5:2; the mixing temperature in the kneader is 240 °C and the time is 1 h; the biological material is wood powder and coconut shell; the absorbent is 300 - mesh glass micro - powder and 300 - mesh quartz micro - powder with a mass ratio of 1:0.5. S2. Use a plunger granulator to produce columnar materials with a diameter of 3 mm and a length of 100 - 150 mm. S3. Pre - dry the columnar materials in an oven until the moisture content is 32%, and the pre - drying temperature is 150 °C. S4. Break up the pre - dried columnar materials into granular materials with a length of 3 - 5 mm. S5. Load the granular materials obtained in S4 into a rotary kiln for activation, introduce air, the rotation speed of the rotary kiln is 18 rpm, slowly heat up to 700 °C, and the heating rate is 4 °C / min. S6. After the activation is completed, cool to room temperature, boil with clear water, recover phosphoric acid, and dry in an oven at 150 °C until the moisture content < 5% to obtain high - performance wood - based activated carbon.

[0026] Example three of the present invention is as follows: A preparation method of high - performance wood - based activated carbon for solvent recovery, comprising the following steps: S1. Mix the biological material, absorbent and phosphoric acid in a kneader according to a mass ratio of 1:0.3:1.5; the mixing temperature in the kneader is 170 °C and the time is 2 h; the biological material is sawdust and wood shavings; the absorbent is 300 - mesh glass micro - powder and 300 - mesh ceramic micro - powder with a mass ratio of 1:0.2. S2. Use a plunger granulator to produce columnar materials with a diameter of 2 mm and a length of 100 - 150 mm. S3. Pre-dry the columnar pellets in an oven until the moisture content reaches 28%, and the pre-drying temperature is 200°C; S4. Break up the pre-dried columnar pellets into pellets with a length of 3 - 5 mm; S5. Load the pellets obtained in S4 into a rotary kiln for activation, introduce air, the rotational speed of the rotary kiln is 15 rpm, slowly heat up to 600°C, and the heating rate is 3°C / min; S6. After the activation is completed, cool to room temperature, boil with clear water, recover phosphoric acid, and dry in an oven at 150°C until the moisture content < 5% to obtain high-performance wood-based activated carbon.

[0027] Example 4 of the present invention is as follows: A preparation method of high-performance wood-based activated carbon for solvent recovery, comprising the following steps: S1. Mix wood powder, absorbent, and phosphoric acid in a kneader at a mass ratio of 1:0.4:1.2; the mixing temperature in the kneader is 220°C and the time is 1.2 h; the absorbent is 400-mesh glass micro-powder, 400-mesh quartz micro-powder, and 400-mesh ceramic micro-powder with a mass ratio of 1:0.5:0.1; S2. Use a plunger granulator to form columnar pellets with a diameter of 4 mm and a length of 100 - 150 mm; S3. Pre-dry the columnar pellets in an oven until the moisture content reaches 30%, and the pre-drying temperature is 160°C; S4. Break up the pre-dried columnar pellets into pellets with a length of 3 - 5 mm; S5. Load the pellets obtained in S4 into a rotary kiln for activation, introduce air, the rotational speed of the rotary kiln is 20 rpm, slowly heat up to 500°C, and the heating rate is 8°C / min; S6. After the activation is completed, cool to room temperature, boil with clear water, recover phosphoric acid, and dry in an oven at 150°C until the moisture content < 5% to obtain high-performance wood-based activated carbon.

[0028] Example 5 of the present invention is as follows: The difference between Example 5 and Example 1 is that the absorbent is 400-mesh quartz micro-powder.

[0029] Example 6 of the present invention is as follows: The difference between Example 6 and Example 1 is that the absorbent is 400-mesh ceramic micro-powder.

[0030] Example 7 of the present invention is as follows: The difference between Example 7 and Example 1 is that the absorbent is 400-mesh glass micro-powder, 400-mesh quartz micro-powder, and 400-mesh ceramic micro-powder with a mass ratio of 1:0.3:0.2.

[0031] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is only that steam is introduced instead of air during activation.

[0032] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is only that carbon dioxide is introduced instead of air during activation.

[0033] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is only that no absorbent is added, and an equal amount of biological material is used instead of the absorbent.

[0034] The activated carbons obtained from Example 1 and Comparative Examples 1 to 3 were subjected to performance tests. The test standards were ASTM D5228, GB / T19587 - 2004, etc. The results are shown in Table 1.

[0035] Table 1

[0036] In summary, the preparation method provided by the present invention can significantly increase the ignition point of the obtained activated carbon by adding glass micro-powder, quartz micro-powder or ceramic micro-powder as an endothermic agent, avoiding the problem of spontaneous combustion during use. Moreover, for the change of the activation object, the activation process is reasonably adjusted, so that the obtained activated carbon has good adsorption and desorption properties.

[0037] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent transformation made using the content of the specification of the present invention, or directly or indirectly applied in the relevant technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A method for preparing high-performance wood activated carbon for solvent recovery, characterized in that: The following steps are involved: S1. Mixing a biomaterial, an absorbent and phosphoric acid, and then granulating to obtain a granulate; wherein the absorbent is a material with a high specific heat capacity; S2, introducing air to activate the pellets; S3. Cool the pellets obtained in S2 to room temperature, wash and recover the phosphoric acid, and dry to obtain high-performance wood activated carbon.

2. The preparation method according to claim 1, characterized in that: The mass ratio of the biomaterial, the absorbent and the phosphoric acid is 1:0.2-0.5:1-2.

3. The preparation method according to claim 1, characterized in that: The absorbent is at least one of glass micropowder, quartz micropowder and ceramic micropowder.

4. The preparation method according to claim 1, characterized in that: The particle size of the absorbent is 300-400 meshes.

5. The preparation method according to claim 1, characterized in that: The mixing temperature is 170~240℃ and the mixing time is 1~2h.

6. The preparation method according to claim 1, characterized in that: During the activation treatment in S2, the temperature is raised from room temperature to 500~700°C.

7. The preparation method according to claim 6, characterized in that: The heating rate is 3~8℃ / min.

8. The preparation method according to claim 1, characterized in that: The activation treatment is carried out in a rotary kiln, and the rotation speed of the rotary kiln is 15-20 rpm.

9. The preparation method according to claim 1, characterized in that: The moisture content of the granular material used for activation treatment is 25~35%.

10. A high performance wood activated carbon for solvent recovery, characterized in that: The method is prepared according to any one of claims 1 to 9.

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