CN103397404A - Method for increasing specific surface area of wooden active carbon fiber - Google Patents

Abstract

The invention provides a method for increasing the specific surface area of woody activated carbon fibers. The process steps of the method include performing pre-oxidation treatment on woody carbon fiber precursors, and then activating the obtained pre-oxidized silks to obtain woody activated carbon fibers. Compared with the woody activated carbon fiber prepared without preoxidation treatment, the specific surface area of the woody activated carbon fiber prepared by the method of the invention is significantly improved, the method of the invention is convenient to operate, has low energy consumption, and has good industrial application prospect.

Description

A method for increasing the specific surface area of woody activated carbon fibers

technical field

The invention relates to the field of chemical fibers, in particular to a wood activated carbon fiber whose specific surface area is improved through pre-oxidation treatment and a preparation method thereof. the

Background technique

Activated Carbon Fiber (ACF) is a newly emerging adsorption material. As a new type of adsorption functional material, it can be widely used in environmental purification, catalyst carrier, electrode material, etc. Compared with activated carbon, it has It is known as one of the most advanced environmental protection materials in the 21st century due to its small diameter, high specific surface area, large adsorption capacity, and fast adsorption and desorption speed. At present, the raw materials for the preparation of activated carbon fibers are mainly petrochemical products. Although the prepared products have excellent adsorption properties, due to the increasing shortage of petroleum resources, the activated carbon fibers are not sustainable. Today, when energy greening is highly advocated, how to prepare wood-based activated carbon fibers to replace activated carbon fibers made from petrochemical resources has become an important issue. the

At present, the core technology of activated carbon fiber is mainly in the hands of foreign monopoly enterprises, especially Japan and the United States, and special activated carbon fiber products with different raw material bases and different adsorption properties have been developed. Activated carbon fiber and its products have entered the stage of industrialization and practical application in developed countries such as Japan and the United States, while China's activated carbon fiber is basically still in the stage of research, development and testing, and has not yet been able to start varieties with industrialization value. It needs to be further improved. the

Woody biomass resources are renewable, and the rich cellulose and lignin contained in them are good raw materials for preparing activated carbon fibers. A large amount of waste wood and wood processing residues can be used as raw materials for activated carbon fibers. Using wood and other biomass resources as the precursor raw materials of activated carbon fibers can realize the sustainable utilization of activated carbon fiber raw materials and reduce the production cost of activated carbon fibers, which has great strategic significance in environmental protection and resource reserves. the

At present, internationally, in order to increase the specific surface area of wood-based activated carbon fibers and improve their adsorption properties, generally by changing the activation parameters, such as increasing the activation temperature, prolonging the activation time, and increasing the concentration of activators. However, these methods are cumbersome to operate, and require high activation temperature, resulting in high energy consumption, and are not suitable for the requirements of a conservation-minded society. Therefore, there is an urgent need for a method for increasing the specific surface area of woody activated carbon fibers that is easy to operate and low in energy consumption. the

Contents of the invention

The purpose of the present invention is to provide a method for increasing the specific surface area of wood activated carbon fibers. the

Another object of the present invention is to provide a wood activated carbon fiber with high specific surface area. the

A kind of method that the present invention improves wood activated carbon fiber specific surface area, comprises the following steps:

(1) The wood liquefied product undergoes spinning solution synthesis, melt spinning and solidification processes to prepare wood liquefied raw silk, and pre-oxidizes the raw silk to prepare pre-oxidized silk;

(2) Activate the pre-oxidized silk to obtain woody activated carbon fiber. the

Through the technical means known to those skilled in the art, the wood liquefaction is synthesized through spinning solution, melt spinning and solidification process to prepare wood liquefaction precursor silk, and this method has been disclosed in Chinese patent CN102719935A. the

Among them, the pre-oxidation treatment of step (1) is to put the raw silk into the pre-oxidation furnace, fix the two ends of the raw silk, and let air flow in, the air flow rate is 0.2-0.6m ³ /h, first heat up, then cool down, stop the air flow Into the air, take out the pre-oxidized silk

In the above step (1), the heating rate is 0.5-1°C/min, the temperature is raised to 200-280°C, kept for 40-80min, and then lowered to room temperature, the air is stopped, and the pre-oxidized wire is taken out. the

Wherein, the mass of the precursor put into the pre-oxidation furnace in step (1) is 1-2g. the

Preferably, the air flow rate is 0.6m ³ /h, and the heating rate is 1°C/min.

Preferably, the quality of the precursor put into the pre-oxidation furnace is 1.5g. the

In the step (1), heat to 280° C. and keep it warm for 60 minutes, then cool down to room temperature, stop feeding air, and take out the pre-oxidized wire. the

In the step (2) of the inventive method, the activation treatment step is as follows:

Under the protection of inert gas or nitrogen, the pre-oxidized silk is activated. The activation temperature is 650-910°C. The activator used is water vapor. The flow rate of water vapor is 3.9-7.1g/min, and the activation time is 30-60min. Wood activated carbon fiber. the

Preferably, in the activation treatment step, the water vapor flow rate is 4.84 g/min, and the activation time is 60 min. the

The wood activated carbon fiber prepared by the method of the present invention is also within the protection scope of the present invention. the

The present invention improves the method for wood activated carbon fiber, in step (1), the process parameter of pre-oxidation step is as follows:

Put 1-2g raw silk into the pre-oxidation furnace, fix both ends with clips, turn on the air generating pump to let in a certain amount of air, the air flow rate is 0.2-0.6m ³ /h, and the heating rate is 0.5-1℃/min , heated to 200-280°C for 40-80min, then lowered to room temperature, turned off the air generating pump, and took out the pre-oxidized wire.

Through a large number of experiments, combined with the results, the inventor found that in step (1), not only the selection of the pre-oxidation temperature range is a key factor, but also the quality of the original silk, the air flow rate and the heating rate have a great influence on the oxidation process. If the temperature is insufficient, the raw silk is added too much, and the heating rate is too slow, the oxidation degree of the obtained product is obviously insufficient, the adsorption and desorption capacity is poor, and the specific surface area is small. It cannot meet the technical requirements, let alone meet the needs of large-scale production. Within the range of conditions for the preoxidation according to the invention, very good results can be achieved. the

For the process parameters of the step (2) of the inventive method, specifically as follows:

The pre-oxidized silk is activated under the protection of nitrogen, the activation temperature is 650-910°C, the activator used is water vapor, the flow rate is 3.9-7.1g/min, and the activation time is 30-60min to obtain woody activated carbon fiber. the

Preferably, the method for improving woody activated carbon fiber specific surface area of the present invention is:

1) Preparation of pre-oxidized silk: the wood liquefied product undergoes spinning solution synthesis, melt spinning and solidification process to obtain the original silk of wood liquefied product, and then puts 1.5g of the original silk into the pre-oxidation furnace, and clamps at both ends Fix it, turn on the air generating pump to feed a certain amount of air, the air flow rate is 0.6m ³ /h, the heating rate is 1°C/min, heat to 280°C and keep it for 60min, then cool down to room temperature, turn off the air generating pump, and take out the pre-oxidized wire .

2) Activate the pre-oxidized silk under the protection of nitrogen. The activation temperature is 910°C. The activator used is water vapor, the flow rate is 4.84g/min, and the activation time is 60 minutes. The specific surface area of activated carbon fiber reached 3068m ² /g, and the total pore volume reached 1.728cc/g.

The woody activated carbon fiber that the inventive method obtains has larger specific surface area, and, owing to being fibrous, can be woven into various forms such as cloth, belt, felt to use, certain flexibility is provided for engineering application, thereby solved many problems Problems that granular activated carbon cannot solve. the

In addition, through the special treatment method of the present invention, pre-oxidation is carried out first, and then activated, so that the obtained woody activated carbon fiber has excellent physical and chemical properties, the specific surface area is greatly increased, and the adsorption and desorption capabilities are improved. The surface chemical structure and physical adsorption characteristics are widely used in environmental protection, electronics, medical hygiene, chemical industry and other fields. Moreover, the method of the invention is easy to operate, has low energy consumption, and has good industrial application prospects. the

Description of drawings

Fig. 1 is a comparison chart of nitrogen adsorption-desorption curves between the pre-oxidation treatment group and the control group in Example 1. Wherein, the relative pressure is the ratio of the partial pressure of nitrogen to the saturated vapor pressure of nitrogen at the temperature of liquid nitrogen. the

Fig. 2 is a comparison chart of nitrogen adsorption-desorption curves between the pre-oxidation treatment group and the control group in Example 2. the

Fig. 3 is the comparison chart of the nitrogen adsorption-desorption curves of the pre-oxidation treatment group and the control group in Example 3. the

Fig. 4 is a comparison chart of nitrogen adsorption-desorption curves between the pre-oxidation treatment group and the control group in Example 4. the

Fig. 5 is a comparison chart of nitrogen adsorption-desorption curves between the pre-oxidation treatment group and the control group in Example 5. the

Fig. 6 is a comparison chart of nitrogen adsorption-desorption curves between the pre-oxidation treatment group and the control group in Example 6. the

Detailed ways

The following examples further illustrate the content of the present invention, but should not be construed as limiting the present invention. Without departing from the spirit and essence of the present invention, any modifications or substitutions made to the methods, steps or conditions of the present invention fall within the scope of the present invention. the

Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. In the examples, the raw materials added are commercially available conventional raw materials unless otherwise specified. the

Embodiment 1 improves the method (1) of wood activated carbon fiber

The wood liquefied product undergoes the synthesis of spinning solution, melt spinning and solidification process to obtain the raw silk of the wood liquefied product (see Chinese patent CN102719935A for the method), then put 1.5g of the raw silk into the pre-oxidation furnace, and fix the two ends with clips , turn on the air generator pump to feed air with a flow rate of 0.6m ³ /h, heat up at a rate of 1°C/min, heat to 200°C and keep it warm for 60 minutes, then cool down to room temperature, turn off the air generator pump, and take out the pre-oxidized wire. Repeat the above steps to prepare 5g of pre-oxidized silk, and then activate it at 650°C under the protection of nitrogen. The activator used is water vapor, the flow rate is 4.84g/min, and the activation time is 60min to obtain woody activated carbon fiber. At the same time, a control group was set up, which was a group in which the precursors were directly activated without pre-oxidation treatment, and the parameters of the activation steps were the same as those of the pre-oxidation treatment group.

According to the nitrogen adsorption-desorption curve figure obtained by the Autosorb-iQ nitrogen adsorption instrument provided by Quantachrome Instrument Company, the specific surface area of the woody activated carbon fiber obtained by the present embodiment measured by the multi-point BET method is 701 m ² /g, compared with the control group ( Without pre-oxidation treatment), the specific surface area of wood activated carbon fibers (665m ² /g) increased by 5.4%, as shown in Figure 1. The total pore volume measured by the nitrogen capacity corresponding to the highest point of the relative pressure of the nitrogen adsorption curve reached 0.385/g, which was 3.2% higher than that of the control group (without pre-oxidation treatment) with a total pore volume of 0.373cc/g.

Embodiment 2 improves the method (2) of wood activated carbon fiber

The wood liquefied product undergoes spinning solution synthesis, melt spinning and solidification processes to obtain the raw silk of the wood liquefied product, then puts 1.5g of the raw silk into the pre-oxidation furnace, fixes both ends with clips, and turns on the air generating pump to feed Air with a flow rate of 0.6m ³ /h and a heating rate of 1°C/min, heated to 280°C and kept for 60 minutes, then lowered to room temperature, turned off the air generating pump, and took out the pre-oxidized wire. Repeat the above steps to prepare 5g of pre-oxidized silk, and then activate it at 650°C under the protection of nitrogen. The activator used is water vapor, the flow rate is 4.84g/min, and the activation time is 40min to obtain woody activated carbon fiber. At the same time, a control group was set up, which was a group in which the precursors were directly activated without pre-oxidation treatment, and the parameters of the activation steps were the same as those of the pre-oxidation treatment group.

According to the nitrogen adsorption-desorption curve obtained by the Autosorb-iQ nitrogen adsorption instrument provided by Quantachrome Instruments, the specific surface area of the woody activated carbon fiber obtained in this embodiment measured by the multi-point BET method is ^779m / g (Without pre-oxidation treatment) the specific surface area of 665m ² /g wood activated carbon fiber increased by 17.1%, see Figure 2. The total pore volume measured by the nitrogen capacity corresponding to the highest point of the relative pressure of the nitrogen adsorption curve reached 0.480cc/g, which was 28.7% higher than that of the control group (without pre-oxidation treatment) with a total pore volume of 0.373cc/g.

Embodiment 3 improves the method (3) of wood activated carbon fiber

The wood liquefied product undergoes the synthesis of spinning solution, melt spinning and solidification process to obtain the raw silk of the wood liquefied product, then puts 1g of the raw silk into the pre-oxidation furnace, fixes both ends with clamps, and turns on the air to generate the pump to flow in The air is 0.2m ³ /h, the heating rate is 0.5°C/min, heated to 240°C and kept for 40min, then lowered to room temperature, the air generating pump is turned off, and the pre-oxidized wire is taken out. Repeat the above steps to obtain 4.5g of pre-oxidized silk, and then activate it at 800°C under the protection of nitrogen. The activator used is water vapor, the flow rate is 7.1g/min, and the activation time is 30min to obtain woody activated carbon fiber. . At the same time, a control group was set up, which was the group that directly activated the protofilament without pre-oxidation treatment, and the parameters of the activation steps were the same as those of the pre-oxidation treatment group.

According to the nitrogen adsorption-desorption curve figure obtained by the Autosorb-iQ nitrogen adsorption instrument provided by Quantachrome Instrument Company, the specific surface area of the woody activated carbon fiber of the present embodiment measured by the multi-point BET method is 969m ² /g, compared with the control group ( Without pre-oxidation treatment) the specific surface area of woody activated carbon fibers (871m ² /g) increased by 11.3%, as shown in Figure 3. The total pore volume measured by the nitrogen capacity corresponding to the highest point of the relative pressure of the nitrogen adsorption curve reached 0.453cc/g, which was 4.4% higher than that of the control group (without pre-oxidation treatment) with a total pore volume of 0.434cc/g.

Embodiment 4 improves the method (4) of wood activated carbon fiber

The wood liquefied product undergoes the synthesis of spinning solution, melt spinning and solidification process to obtain the raw silk of the wood liquefied product, then puts 2g of the raw silk into the pre-oxidation furnace, fixes both ends with clips, and turns on the air to generate the flow of the pump The air is 0.6m ³ /h, the heating rate is 1°C/min, heated to 240°C and kept for 60min, then lowered to room temperature, the air generating pump is turned off, and the pre-oxidized wire is taken out. Repeat the above steps to prepare 5g of pre-oxidized silk, and then activate it at 910°C under the protection of helium. The activator used is water vapor, the flow rate is 4.84g/min, and the activation time is 60min to obtain woody activated carbon fiber. . At the same time, a control group was set up, which was a group in which the precursors were directly activated without pre-oxidation treatment, and the parameters of the activation steps were the same as those of the pre-oxidation treatment group.

According to the nitrogen adsorption-desorption curve figure obtained by the Autosorb-iQ nitrogen adsorption instrument provided by Quantachrome instrument company, the specific surface area of the wood activated carbon fiber obtained by using the multi-point BET method is measured to be 2877m ² /g, compared with the control group (not After pre-oxidation treatment), the specific surface area of woody activated carbon fibers (2592m ² /g) increased by 11.0%, as shown in Figure 4. The total pore volume measured by the nitrogen capacity corresponding to the highest point of the relative pressure of the nitrogen adsorption curve reached 1.476cc/g, which was 12.4% higher than that of the control group (without pre-oxidation treatment) with a total pore volume of 1.313cc/g.

Embodiment 5 improves the method (5) of wood activated carbon fiber

The wood liquefied product undergoes spinning solution synthesis, melt spinning and solidification processes to obtain the raw silk of the wood liquefied product, then puts 1.5g of the raw silk into the pre-oxidation furnace, fixes both ends with clips, and turns on the air generating pump to feed Air with a flow rate of 0.6m ³ /h and a heating rate of 1°C/min, heated to 280°C and kept for 60 minutes, then lowered to room temperature, turned off the air generating pump, and took out the pre-oxidized wire. Repeat the above steps to prepare 4g of pre-oxidized silk, and then activate it at 910°C under the protection of helium. The activator used is water vapor, the flow rate is 4.84g/min, and the activation time is 60min to obtain woody activated carbon fiber. . At the same time, a control group was set up, which was a group in which the precursors were directly activated without pre-oxidation treatment, and the parameters of the activation steps were the same as those of the pre-oxidation treatment group.

According to the nitrogen adsorption-desorption curve obtained by the Autosorb-iQ nitrogen adsorption instrument provided by Quantachrome Instruments, the specific surface area of the woody activated carbon fiber measured by the multi-point BET method is 3068m ² /g, which is higher than that of the control group (without pre-oxidation treatment). ) The specific surface area of woody activated carbon fibers was 2592m ² /g, which increased by 18.4%, as shown in Figure 5. The total pore volume measured by the nitrogen capacity corresponding to the highest point of the relative pressure of the nitrogen adsorption curve reached 1.728cc/g, which was 31.6% higher than that of the control group (without pre-oxidation treatment) with a total pore volume of 1.313cc/g.

Embodiment 6 improves the method (6) of wood activated carbon fiber

The wood liquefied product undergoes the synthesis of spinning solution, melt spinning and solidification process to obtain the raw silk of the wood liquefied product (see Chinese patent CN102719935A for the method), then put 1.5g of the raw silk into the pre-oxidation furnace, and fix the two ends with clips , turn on the air generator pump to feed air with a flow rate of 0.6m ³ /h, heat up at a rate of 0.5°C/min, heat to 240°C and keep it warm for 60 minutes, then cool down to room temperature, turn off the air generator pump, and take out the pre-oxidized wire. Repeat the above steps to obtain 4.5g pre-oxidized silk, and then activate it at 910°C under the protection of nitrogen. The activator used is water vapor, the flow rate is 3.9g/min, and the activation time is 50min to obtain woody activated carbon fiber. . At the same time, a control group was set up, which was a group in which the precursors were directly activated without pre-oxidation treatment, and the parameters of the activation steps were the same as those of the pre-oxidation treatment group.

According to the nitrogen adsorption-desorption curve figure obtained by the Autosorb-iQ nitrogen adsorption instrument provided by Quantachrome Instrument Company, the specific surface area of the woody activated carbon fiber obtained by the present embodiment measured by the multi-point BET method is 2731m ² /g, compared with the control group ( Without pre-oxidation treatment), the specific surface area of wood activated carbon fibers (2592m ² /g) increased by 5.4%, as shown in Figure 6. The total pore volume measured by using the nitrogen capacity corresponding to the highest point of the relative pressure of the nitrogen adsorption curve reached 1.361cc/g, which was 3.7% higher than that of the control group (without pre-oxidation treatment) with a total pore volume of 1.313cc/g.

Claims (10)

1. a method that improves wooden activated carbon fiber specific area, is characterized in that, comprises the following steps:

(1) timber liquefied matter, through synthetic, melt spinning and the curing process of spinning solution, makes the timber liquefied matter precursor, and precursor, by pre-oxidation treatment, is prepared preoxided thread;

(2) preoxided thread is made activation processing, obtain wooden activated carbon fiber.

2. the method for claim 1, is characterized in that, the pre-oxidation treatment of step (1) is that precursor is put into pre-oxidation furnace, and the precursor two ends are fixed, and pass into air, and air mass flow is 0.2-0.6m ³/ h, first heat up, then lower the temperature, and stops passing into air, takes out preoxided thread.

3. method as claimed in claim 2, is characterized in that, heating rate is 0.5-1 ℃/min, is warming up to 200-280 ℃, is down to room temperature after insulation 40-60min, stops passing into air, takes out preoxided thread.

4. method as claimed in claim 2, is characterized in that, the quality of putting into the precursor of pre-oxidation furnace is 1-2g.

5. method as claimed in claim 2, is characterized in that, air mass flow is 0.6m ³/ h, heating rate are 1 ℃/min.

6. method as claimed in claim 2, is characterized in that, it is characterized in that, the quality of putting into the pre-oxidation furnace precursor is 1.5g.

7. method as claimed in claim 2, is characterized in that, in described step (1), is heated to be down to room temperature after 280 ℃ of insulation 60min, stops passing into air, takes out preoxided thread.

8. the method for claim 1, is characterized in that, in described step (2), the activation processing step is as follows:

Under inert gas or nitrogen protection, preoxided thread is made activation processing, activation temperature is 650-910 ℃, and the activator that uses is water vapour, and steam rates is 3.9～7.1g/min, and soak time is 30-60min, obtains wooden activated carbon fiber.

9. method as claimed in claim 8, is characterized in that, steam rates is 4.84g/min, and soak time is 60min.

10. the wooden activated carbon fiber for preparing of the arbitrary described method of claim 1-9.

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