Department of Chemical Engineering, Visvesvaraya National Institute of Technology, Nagpur, 440010, India.
Amity School of Engineering and Technology, Amity University, Jaipur, 303002, India.
J Environ Manage. 2024 Aug;366:121881. doi: 10.1016/j.jenvman.2024.121881. Epub 2024 Jul 16.
Coal ash containing significant amount of SiO and AlO is utilized as a catalyst substrate for carbon nanotubes (CNTs) synthesis. Three different types of catalysts were made by impregnating coal ash with cobalt, iron, and nickel. These catalysts were used to produce CNTs through pyrolysis of waste polypropylene followed by chemical vapor deposition. The influence of catalyst type and reaction temperature (700, 800 and 900 °C) on CNTs yield and its quality was studied in detail. The produced CNTs were characterized by thermogravimetric analysis (TGA), Raman scattering and electron microscopes (FESEM and HRTEM). The TGA results revealed that the Ni catalyst produced CNTs with highest yield (266 %) compared to those synthesized over and Fe (96 %) and Co (95 %). However, the yield of the CNTs from all three metal impregnated coal ash based catalysts was found to have decreased with increase in reaction temperature. The thermal stability of CNTs obtained over different catalysts followed the order of Fe (570 °C) > Ni (550 °C) > Co (530 °C). Further, the Raman analysis demonstrated that the produced CNTs over different catalysts showed increasing degree of graphitization with the rise in reaction temperature. Additionally, the I/I ratios indicated that CNTs produced from Fe catalyst showed highest degree of graphitization followed by Co and Ni. FESEM and HRTEM analysis showed that the coal ash based catalysts produced multiwalled CNTs and the diameter of the CNTs was increasing with the rise in catalysis temperature. Therefore, co-utilization of coal ash and waste plastic for production of high value CNTs can be a sustainable approach to waste management while actively contributing in circular economy.
含有大量 SiO 和 AlO 的煤灰被用作合成碳纳米管 (CNT) 的催化剂载体。通过浸渍煤灰中的钴、铁和镍，制备了三种不同类型的催化剂。这些催化剂用于通过废聚丙烯的热解随后进行化学气相沉积来生产 CNT。详细研究了催化剂类型和反应温度（700、800 和 900°C）对 CNT 产率及其质量的影响。通过热重分析（TGA）、拉曼散射和电子显微镜（FESEM 和 HRTEM）对所制备的 CNT 进行了表征。TGA 结果表明，与在 Co（95%）和 Fe（96%）上合成的 CNT 相比，Ni 催化剂产生的 CNT 产率最高（266%）。然而，发现所有三种金属浸渍煤灰基催化剂制备的 CNT 产率都随反应温度的升高而降低。不同催化剂上获得的 CNT 的热稳定性遵循 Fe（570°C）>Ni（550°C）>Co（530°C）的顺序。此外，拉曼分析表明，不同催化剂上制备的 CNT 随反应温度的升高显示出越来越高的石墨化程度。此外，I/I 比表明，Fe 催化剂制备的 CNT 显示出最高的石墨化程度，其次是 Co 和 Ni。FESEM 和 HRTEM 分析表明，煤灰基催化剂制备的多壁 CNT 直径随催化温度的升高而增加。因此，煤灰和废塑料的共同利用来生产高价值的 CNT 可以是一种可持续的废物管理方法，同时积极为循环经济做出贡献。
