| 摘要(英) |
The objective of this research is to achieve a high specific surface area (>3000 m2/g) that was observed in some commercial activated carbons, and at the same time able to modify the distribution of micropores and super-micropores.
The biomass-sucrose was chosen as the raw material for activated carbon in this research. The precursor was made by the hydrothermal carbonization of sucrose into sub-micron to tens of micron carbonaceous particles or their aggregates. The precursor was then directly chemically activated with KOH at high temperature in tubular furnace, or activated after further carbonization in dry nitrogen. Activated carbon powders with very high specific surface area were obtained.
The following operation variables were also studied; (1) the benefit of adding ammonium bicarbonates during the hydrothermal carbonization step. (2) The necessity of dry carbonization after the hydrothermal step and the proper temperature for such step. (3) The activation temperature, the soaking method and the amount of KOH activator used. The products were analyzed with FTIR, SEM, XRD, ASAP, ICP-AES and iodine adsorption.
We conclude that the proper process steps for producing high specific surface area activated carbon at high yield were (1) hydrothermal carbonization with the addition of ammonium bicarbonates, (2) dry carbonization at 450 °C, and (3) Chemical activation at 800 °C with KOH/C ratio of 4. The yield of our best activated carbon was 10.3 wt%, based on the amount of sucrose employed. The total pore volume was 1.517 cm3/g, and the specific surface area reached 3280 m2/g. 88.4% of the pore volume was contributed by micropores and the average pore size was 1.84 nm. The only problem was the incomplete removal of KOH, which amounted to 3.8 wt% of potassium in the final product. Therefore, although our product had a higher specific surface area than the commercial AX-21 sample, the iodine number was lower. We believe that by increasing the activation time or holding the activation temperature at 400 °C for 2 hours, such problems may be resolved.
|
| 參考文獻 |
(1) Titirici MM, Thomas A, Antonietti M. Back in the black: hydrothermal carbonization of plant material as an efficient chemical process to treat the CO2 problem? New Journal of Chemistry 2007; 31(6): 787-9.
(2) Wang Q, Li H, Chen LQ, Huang XJ. Monodispersed hard carbon spherules with uniform nanopores. Carbon 2001; 39(14): 2211-4.
(3) Wang Q, Li H, Chen L, Huang X. Novel spherical microporous carbon as anode material for Li-ion batteries. Solid State Ionics 2002 Dec; 152-153: 43-50.
(4) Sun XM, Li YD. Colloidal carbon spheres and their core/shell structures with noble-metal nanoparticles. Angewandte Chemie-International Edition 2004; 43(5): 597-601.
(5) Titirici MM, Antonietti M, Baccile N. Hydrothermal carbon from biomass: a comparison of the local structure from poly- to monosaccharides and pentoses/hexoses. Green Chemistry 2008; 10(11): 1204-12.
(6) Li SH, Wang EB, Tian CG, Mao BD, Kang ZH, Li QY, et al. Jingle-bell-shaped ferrite hollow sphere with a noble metal core: Simple synthesis and their magnetic and antibacterial properties. Journal of Solid State Chemistry 2008; 181(7): 1650-8.
(7) Joo JB, Kim P, Kim W, Kim J, Kim ND, Yi J. Simple preparation of hollow carbon sphere via templating method. Current Applied Physics 2008; 8(6): 814-7.
(8) Wan Y, Min YL, Yu SH. Synthesis of silica/carbon-encapsulated core-shell spheres: Templates for other unique core-shell structures and applications in in situ loading of noble-metal nanoparticles. Langmuir 2008; 24(9): 5024-8.
(9) Cui XJ, Antonietti M, Yu SH. Structural effects of iron oxide nanoparticles and iron ions on the hydrothermal carbonization of starch and rice carbohydrates. Small 2006; 2(6): 756-9.
(10) Pietrzak R, Nowicki P, Wachowska H. The influence of oxidation with nitric acid on the preparation and properties of active carbon enriched in nitrogen. Applied Surface Science 2009 Jan 1; 255(6): 3586-93.
(11) Cao Q, Xie KC, Lv YK, Bao WR. Process effects on activated carbon with large specific surface area from corn cob. Bioresource Technology 2006; 97(1): 110-5.
(12) Qiao WM, Ling LC, Zha QF, Liu L. Preparation of a pitch-based activated carbon with a high specific surface area. Journal of Materials Science 1997; 32(16): 4447-53.
(13) Diaz-Teran J, Nevskaia DM, Fierro JLG, Lopez-Peinado AJ, Jerez A. Study of chemical activation process of a lignocellulosic material with KOH by XPS and XRD. Microporous and Mesoporous Materials 2003 Jun 19; 60(1-3): 173-81.
(14) Lillo-Rodenas MA, Cazorla-Amoros, Linares-Solano. Understanding chemical reactions between carbons and NaOH and KOH: An insight into the chemical activation mechanism. Carbon 2003 Feb; 41(2): 267-75.
(15) Lozano-Castello D, Lillo-Rιenas MA, Cazorla-Amoros, Linares-Solano. Preparation of activated carbons from Spanish anthracite: I. Activation by KOH. Carbon 2001 Apr; 39(5): 741-9.
(16) Burg P, Fydrych P, Cagniant D, Nanse G, Bimer J, Jankowska A. The characterization of nitrogen-enriched activated carbons by IR, XPS and LSER methods. Carbon 2002 Aug; 40(9): 1521-31.
(17) Yue-Yan Lin. Size control of monodispersed colloidal carbon spherules. 2008.
(18) Ramos-Fernandez JM, Martinez-Escandell M, Rodriguez-Reinoso F. Production of binderless activated carbon monoliths by KOH activation of carbon mesophase materials. Carbon 2008 Feb; 46(2): 384-6.
(19) Ruiz V, Blanco C, Santamaria R, Ramos-Fernandez JM, Martinez-Escandell M, Sepulveda-Escribano A, et al. An activated carbon monolith as an electrode material for supercapacitors. Carbon 2009; 47(1): 195-200.
(20) MEGA-CARBON COMPANY. Nature Gas Storage with Bonded Carbon. 2009.
|
[Endnote RIS 格式]
[相關文章]
[文章引用]
[完整記錄]
[館藏目錄]
[檢視]
plurk
funp
live
udn
HD
myshare
netvibes
friend
youpush
delicious
baidu
Google bookmarks
del.icio.us
hemidemi
facebook
twitter
google
reddit