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Example 2
A mixture obtained by mixing 100 parts by mass of granular coal pitch having a softening point of 280° C. as an organic material with 0.9 part by mass of tris(2,4-pentanedionato)iron(III) (metal species: Fe) was fed into a melt extruder, where it was melted and mixed at a melting temperature of 320° C., and spun at a discharge rate of 16 g/min to obtain a pitch fiber. The pitch fiber was subjected to an infusibilization treatment by heating for 54 minutes, to 354° C. from ambient temperature in the air at a rate of 1 to 30° C./minute, to obtain an infusibilized pitch fiber as an activated carbon precursor. The iron (Fe) content in the activated carbon precursor was 0.11% by mass.
The activated carbon precursor was activated by conducting a heat treatment at an atmospheric temperature of 950° C. for 40 minutes, while continuously introducing a gas having a CO2 concentration of 100% by volume into an activation furnace, to obtain an activated carbon of Example 2. In the activated carbon, the pore volume A of pores with a size of 1.0 nm or less was 0.396 cc/g, the pore volume B of pores with a size of 3.0 nm or more and 3.5 nm or less was 0.016 cc/g, the iron content was 0.251% by mass, and the average fiber diameter was 13.6 μm.
Granular coal pitch having a softening point of 280° C. as an organic material was fed into a melt extruder, where it was melted and mixed at a melting temperature of 320° C., and spun at a discharge rate of 20 g/min, to obtain a pitch fiber. The pitch fiber was subjected to an infusibilization treatment by heating for 54 minutes, to 354° C. from ambient temperature in the air at a rate of 1 to 30° C./minute, to obtain an infusibilized pitch fiber as an activated carbon precursor. The iron content in the activated carbon precursor was 0% by mass.
The activated carbon precursor was activated by conducting a heat treatment at an atmospheric temperature of 875° C. for 40 minutes, while continuously introducing a gas having an H2O concentration of 100% by volume into an activation furnace, to obtain an activated carbon of Comparative Example 2. In the activated carbon, the pore volume A of pores with a size of 1.0 nm or less was 0.401 cc/g, the pore volume B of pores with a size of 3.0 nm or more and 3.5 nm or less was 0.000 cc/g, the iron content was 0% by mass, and the average fiber diameter was 16.7 μm.
Example 6
A mixture obtained by mixing 100 parts by mass of granular coal pitch having a softening point of 280° C. as an organic material with 0.3 part by mass of tris(acetylacetonato)yttrium was fed into a melt extruder, where it was melted and mixed at a melting temperature of 320° C., and spun at a discharge rate of 20 g/min to obtain a pitch fiber. The pitch fiber was subjected to an infusibilization treatment by heating for 54 minutes, to 354° C. from ambient temperature in the air at a rate of 1 to 30° C./minute, to obtain an infusibilized pitch fiber as an activated carbon precursor. The yttrium content in the activated carbon precursor was 0.06% by mass.
The activated carbon precursor was activated by conducting a heat treatment at an atmospheric temperature of 950° C. for 60 minutes, while continuously introducing a gas having a CO2 concentration of 100% by volume into an activation furnace, to obtain an activated carbon of Comparative Example 6. In the activated carbon, the pore volume A of pores with a size of 1.0 nm or less was 0.429 cc/g, the pore volume B of pores with a size of 3.0 nm or more and 3.5 nm or less was 0.000 cc/g, the yttrium content was 0.15% by mass, and the fiber diameter was 18.2 μm.
Example 11
Alternative feedstocks to caking coals were explored as source materials for carbon foam. In one series of experiments, a foaming pitch derived from non-caking coal prepared as described above was used as a feedstock.
90 g of foaming pitch with a particle size range of 30-50 mesh was weighed and transferred to a 250 mL beaker and 15 g of a flux agent composed of high fructose corn syrup and recycled coal volatiles as described previously was added. The contents were mixed for a period of time until the mixture was homogeneous. The foaming mixture was loaded into a crucible and converted into carbon foam using microwave radiation at 20% power for 5 min. The foam was covered with a ceramic lid and calcined in one step in a non-oxidizing environment as described previously.
A thin layer of a graphene-type compound was found on the lid of the crucible after this experiment, showing that the method can provide an additional carbon species from vapors expelled during the heat treatment and calcination processes disclosed herein. Examples of graphene-type layers formed on carbon foams can be seen in
Example 12
In some experiments, larger samples having compositions similar to those described previously (i.e., containing coal powder, high fructose corn syrup, and graphite) but with a top surface area of approximately 1 square foot were prepared. Coal flux mixtures were prepared using a commercial mixer. A square sample container 1 foot on each side was constructed and a large-chamber microwave with rotating coil was obtained for these experiments. Several samples of this size were manufactured successfully using the heating protocols described previously. The container used for large-scale foam production as well as an example large piece of foam are seen in
It will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.
Example 6
Samples containing high fructose corn syrup as an additional agent but lacking a conductive carbon compound were prepared as described above. Samples containing high fructose corn syrup as well as 1% by weight or 5% by weight graphite were also prepared. Samples containing 1% by weight graphite reached the required temperatures more easily and thus formed green foam more quickly, and a similar increase was also seen for samples containing 5% by weight graphite, regardless of whether high volatile or low volatile bituminous coal was used. Results were similar for different coal particle sizes (20-35 mesh, 35-60 mesh, 60-100 mesh, and >100 mesh) as well as for different microwave power levels, with the largest impact of increasing graphite concentration on foam formation time at low power levels. A 1000 W microwave was used for most experiments.
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