Conversion of pyrolytic non-condensable gases from polypropylene co-polymer into bamboo-type carbon nanotubes and high-quality oil using biochar as catalyst.

The conversion of low-value plastic waste into high-value products such as carbon nanomaterial is of recent interest. In the current study, the non-condensable pyrolysis gases, produced from Polypropylene Copolymer (PPC) feedstock, was converted into bamboo-type carbon nanotubes (BCNTs) through catalytic chemical vapour deposition using biochar. Experiments were conducted in a three-zone furnace fixed bed reactor, where PPC was pyrolysed in the second zone and carbon nanotubes (CNTs) growth was eventuated in the third zone. The effects of different growth temperatures (500, 700, 900 °C) and biochar particle sizes (nanoparticle as well as 0-100 and 100-300 µm) were investigated to optimise the production of hydrogen and the yield of carbon nanotubes on the biochar surface. Biochar samples used in the synthesis of CNTs were obtained from the pyrolysis of saw dust at 700 °C in a muffle furnace. Analyses performed by using Scanning electron microscopy, Transmission electron microscopy, X-ray diffraction, and Raman spectroscopy techniques suggested that the best crystalline structure of CNTs were obtained at 900 °C with nano-sized biochar as a catalyst. The strong gas-solid contact and void fraction of nano-sized particles enhances the diffusion-precipitation mechanism, leading to the growth of CNTs. The nano-sized biochar increased hydrogen production at 900 °C and reduced the polycyclic aromatic hydrocarbons content in oil to only 1%, which is advantageous for further utilisation. Therefore, the production of high-value CNTs from waste plastic using low-cost biochar catalyst can be a sustainable approach in the management of waste plastic while participating in the circular economy.

Reaction of carbon tetrachloride with methane in a non-equilibrium plasma at atmospheric pressure, and characterisation of the polymer thus formed.

In this paper we focus on the development of a methodology for treatment of carbon tetrachloride utilising a non-equilibrium plasma operating at atmospheric pressure, which is not singularly aimed at destroying carbon tetrachloride but rather at converting it to a non-hazardous, potentially valuable commodity. This method encompasses the reaction of carbon tetrachloride and methane, with argon as a carrier gas, in a quartz dielectric barrier discharge reactor. The reaction is performed under non-oxidative conditions. Possible pathways for formation of major products based on experimental results and supported by quantum chemical calculations are outlined in the paper. We elucidate important parameters such as carbon tetrachloride conversion, product distribution, mass balance and characterise the chlorinated polymer formed in the process.