Thermal chemical conversion of plastics waste for production of carbon nanotubes
Dr Xuebin Ke X.Ke@hull.ac.uk
With continuous growth for more than 50 years, global plastics production increased to 336 million tonnes in 2016, and over 27 million tonnes of post-consumer plastic wastes were produced. Waste management is necessary to minimise the plastic waste in order to reduce their negative impacts. Catalytic-pyrolysis of plastic waste provides an environmental friendly and economic method to produce valuable products such as H2rich syngas and carbon nanotubes (CNTs). Recently, CNTs attract a great interest and have been widely explored due to the excellent and unique chemical, mechanical, thermal and physical properties. However, the quality and quantity of CNTs produced from waste plastics need to be improved. The quality of CNTs can significantly affect and limit their applications. The aim of this research is to improve the quantity and quantity of CNTs by developing efficient catalysts. Four groups of different catalysts (Ni/Fe-based; Ni/AAO, Ni/ceramic, and Ni/sphere) have been investigated in relation to their performance on the production of CNTs from catalytic gasification of waste polypropylene, using a two-stage fixed-bed reaction system. The influences of reaction parameters for each group of catalysts on product yields and the production of CNTs in terms of morphology have been studied using a range of techniques; gas chromatography (GC); X-ray diffraction (XRD); temperature programme oxidation (TPO); scanning electron microscopy (SEM); transmission electron microscopy (TEM). It was found reaction temperature, catalytic particle size, steam addition, and catalytic metal content have significant effect on CNTs production. The particular optimum of each parameter for different catalysts could contribute to the enhancement of the quality and quantity of CNTs. For example, the optimum reaction temperature for Ni/AAO was suggested at 700oC, because the catalyst might not be activated at 600 °C, which produced a low yield of CNTs. However, a reaction temperature of 800 °C resulted in a low yield of CNTs. In addition, the results indicated that a higher loading of Ni on AAO resulted in the formation of metal particles with various sizes, thus leading to the production of non-uniform CNTs. Carbon deposition was also found decreasing with an increase of steam injection, but the quality of CNTs formation in relation to the uniform of CNTs seemed to be improved in the presence of steam. For Fe/Ni-based catalysts study, the results show that the Fe-based catalysts, in particular with large particle size (about 80 nm), produced the highest yield of hydrogen (25.60 mmol H2g-1plastic) and the highest yield of carbons (29 wt.%), as well as the largest fraction of graphite carbons (as obtained from TPO analysis of the reacted catalyst). Both Fe-and Ni-based catalysts with larger metal particles produced higher yield of hydrogen compared with the catalysts with smaller metal particles, respectively.
Liu, X. (2018). Thermal chemical conversion of plastics waste for production of carbon nanotubes. (Thesis). University of Hull. Retrieved from https://hull-repository.worktribe.com/output/4223301
|Publication Date||Nov 1, 2018|
|Deposit Date||Aug 5, 2021|
|Publicly Available Date||Feb 23, 2023|
|Additional Information||Department of Chemistry, The University of Hull|
© 2018 Liu, Xiaotong. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder.