Cellulose-based fibers were developed in the 1960s for aerospace applications and at that time became the first carbon fibers produced commercially. Though they are not as strong as PAN-based fibers they have many advantages, such as abundant resources of the precursor, and are a naturally occurring polysaccharide. But since they consist of D-glucose monomer units joined by 1-4 glucosidic bonds, forming an ether linkage by the elimination of water (one molecule may include up to ten thousand units), these ether linkages together with hydrogen bonds between different units make cellulose relatively stiff and hard to dissolve. They are not soluble in the most common solvents, which leads to extremely difficult processing of cellulose. On the other hand, their derivatives, such as cellulose acetates, are much easier to handle with spinning processes [54]. Cellulose acetates are common esters of cellulose. They are synthesized by reacting cellulose with acetic anhydride or acetic acid in the presence of sulfuric acid. The acetylation makes cellulose more soluble in organic solvents, making it more suitable to produce films from cellulose triacetate. The degree of substitution affects the solubility of cellulose acetate and hence determines the options for further processing for different applications. For example, cellulose acetate with degree of substitution of 2–2.5 is soluble in acetone, dioxane or methyl acetate, while celluloses with higher degree of acetylation are soluble in dichloromethane.
3.7 Summary
Catalysts are known to play an important role in chemical transformations and reactions as they increase the speed of a reaction, lower the activation energy for the reaction, act as a facilitator and bring the reactive species together more effectively, and create a higher yield of one species when two or more products are formed. Recently, nanocatalysts have begun being used because nanomaterials are more effective than conventional catalysts due to their extremely small size and very high surface area-to-volume ratio. Moreover, at the nanoscale, unique properties are found which are not present in their macroscopic counterparts. Hence, for synthesis of CNF, consideration of use of nanocatalyst is very important. In this chapter different types of catalysts and their various preparation methods were presented. Finally, synthesis of carbon nanofiber (CNF) using nanocatalysts were discussed with special emphasis.
References
1. Liu, Z., Gan, L.M., Hong, L., Chen, W., Lee, J.Y., Carbon-supported Pt nanoparticles as catalysts for proton exchange membrane fuel cells. J. Power Sources, 139, 73, 2005.
2. Solsona, B., Graham, J.H., Tomas, G., Taylor, S.H., Supported gold catalysts for the total oxidation of alkanes and carbon monoxide. New J. Chem., 6, 2004.
3. Singh, S.B. and Tandon, P.K., Catalysis: A Brief Review on Nano-Catalyst. J. Energy Chem. Eng., 2, 3, 106–115, 2014.
4. Gupta, V., M.S. thesis, Dept. of Chemical and Materials Engineering, Univ, of Cincinnati, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1136846342
5. Rodriguez-Manzo, J.A., Terrones, M., Terrones, H., Kroto, H.W., Sun, L., Banhart, F., In situ nucleation of carbon nanotubes by the injection of carbon atoms into metal particles. Nat. Nanotechnol., 2, 307–311, 2007.
6. Sharon, M. and Sharon, M., Carbon Nano Forms and Application, McGraw Hill, USA, 2010.
7. Menezes, W.G., Zielasek, Thiel, V.K., Hartwig, A., Bäumer, M., Effect of particle size, composition and support on catalytic activity of AuAg nanoparticles prepared in reverse block copolymer micelles as nanoreactors. J. Catal., 299, 222–231, 2013.
8. Cheng, Y., Zheng, Y., Wang, Y., Bao, F., Qin, Y., Synthesis and magnetic properties of nickel ferrite nano-octahedra. J. Solid-State Chem., 178, 2394–2397, 2005.
9. Xu, H., Zeng, L., Xing, S., Xian, Y., Jin, L., Microwave- irradiated synthesized platinum nanoparticles/carbon nanotubes for oxidative determination of trace Arsenic (III). Electrochem. Commun., 10, 551–554, 2010.
10. Men, Y., Higuchi, M., Yamamoto, K., Synthesis of DPA dendron encapsulated gold clusters with metal-assembling function. Sci. Technol. Adv. Mater., 7, 2, 139–144, 2006.
11. Cheney, B.A., Lauterbach, J.A., Chen, J.G., Reverse micelle synthesis and characterization of supported Pt/Ni bimetallic catalyst on ℷAl2O3 Appl. Catal. A: Gen., 394, 41–47, 2011.
12. Oza, G., Pandey, S., Mewada, A., Sharon, M., Extracellular biosynthesis of gold nanoparticles using Salmonella typhi. Der Chimica Sinica, 3, 5, 1041–46, 2012. (ISSN: 0976–8505).
13. Oza, G., Pandey, S., Sharon, M., Extra cellular bio-synthesis of gold nanoparticles using Escherichia coli and deciphering the role of lactate dehydrogenase using LDH knockout E.coli. J. At. Mol., 2, 4, 301–311, 2012. ISSN–2277–1247.
14. Mewada, A., Pandey, S., Oza, G., Shah, R., Thakur, M., Gupta, A., Sharon, M., A novel report on assessing pH dependent role of nitrate reductase on green biofabrication of gold nanoplates and nanocubes, J. Bionanosci., 7, 2, 174–180, 2013.
15. Chen, D., Rønning, M., Tøtdal, B., Vrålstad, T., Ochoa-Fernández, E., Holmen, A., Large- scale synthesis of carbon nanofiber on Ni-Fe-Al hydrotalcite derived catalysts:II: Effect of Ni/Fe composition on CNF synthesis from ethylene and carbon monoxide. Appl. Catal. A, 338, 147–158, 2008.
16. Narayanan, K.B. and Sakthivel, N., Synthesis and characterization of nanogold composite using cylindrocldium floridanum and heterogenous catalysis in the degradation of 4-nitrphenol. J. Hazard. Mater., 189, 519–525, 2011.
17. Pandey, S., Mewada, A., Thakur, M., Shinde, S., Shah, R., Oza, G., Sharon, M., Synthesis and Cetrifugal Separation of Fluorescent Carbon Dots at Room Temperature. J. Nanosci., 2013, 2013. (ISSN: 2356–749X).
18. Pandey, S., Oza, G., Gupta, A., Shah, R., Sharon, M., Sharon, The possible involvement of nitrate reductase from Aspargus racemosus in biosynthesis of gold nanoparticles. M Eur. J. Exp. Biol., 2, 3, 475–483, 2012.
19. Thakur, M., Pandey, S., Mewada, A., Shah, R., Oza, G., Sharon, M., Spectrochim. Acta Part A Mol. Biomol. Spectrosc., 109, 344–347, 2013.
20. Malik, R., Garg, T., Goyal, A.K., Rath, G., Polymeric nanofibers: targeted gastro-retentive drug delivery systems. J. Drug Target., 23, 2, 24, 2014.
21. Ahmad, N., Sharma, S., Singh, V.N., Shamsi, Fatma, S.F.A., Mehta, B.F., Biosynthesis of silver nanoparticles from Desmodium triflorum: A novel approach towards weed utilization. Biotechnol. Res. Int., 2011, 454090, 8, 2011.
22. Panigrahi, S., Kundu, S., Ghosh, S., Nath, S., Pal, T., General method of synthesis for metal nanoparticles. J. Nanopart. Res., 6, 4, 411–414, 2004.
23. Mude, N., Ingle, A., Gade, A., Rai, M., Synthesis of Silver nanoparticles using Callus extract of Carica papaya- A first Report. J. Plant Biochem. Biotechnol., 18, 83–86, 2009.
24. Dizaj, S.M., Lotfipour, F., Barzegar-Jalali, M., Antimicrobial activity of the metals and metal oxide nanoparticles. Mater. Sci. Eng. C, 44, 278–284, 2014.
25. Endo, M., Kenji, T., Susumu, I., Kiyoharu, K., Minoru, S., Kroto, H.W., The production and structure of pyrolytic carbon nanotubes. J. Phys. Chem. Solids, 54, 12, 1841–1848, 1993.
26.
