Thermal Chemical Conversion of High-Density Polyethylene for the Production of Valuable Carbon Nanotubes Using Ni/AAO Membrane Catalyst

Xiaotong Liu,Jun Huang,Hongman Sun,Dipesh Patel,Chunfei Wu

doi:10.1021/acs.energyfuels.7b03160

Abstract

Thermal chemical conversion of waste plastics for syngas production is a promising alternative method for the management of waste plastics. However, one of the challenges of facilitating the deployment of this technology is the low economic benefit of waste-plastic recycling. By producing a high-value carbon nanotubes (CNTs) byproduct, an interesting alternative solution is provided. To further enhance the quality of CNTs produced from catalytic thermal chemical conversion of waste plastics, a template-based catalyst (Ni/anodic aluminum oxide, AAO) is proposed in this work. In addition, reaction temperature, Ni content and water injection were studied for their influences on the formation of CNTs on Ni/AAO using a two-stage fixed bed reactor. Various analytical methods, e.g., scanning electronic microscopy (SEM) and X-ray diffraction (XRD), were used to evaluate the performance of catalyst in relation to the production of CNTs. The results show that a higher loading of Ni on AAO resulted in the formation ...

Highlights

In 2015, approximately 3.7 million tonnes of plastics waste was produced in the UK 1
Wu et al 16 reported that an increase in the ratio of catalysts to plastics from 0.5 to 2 and a gasification temperature of 700 °C could improve the quality of carbon nanotubes (CNTs) in relation to the purity
It was noted that gas and liquid product that were produced as part of this work were not analysed, as the main aim of the research work was to investigate the influence of template catalyst on the production of CNTs in relation to the quality of CNTs

Summary

Introduction

In 2015, approximately 3.7 million tonnes of plastics waste was produced in the UK 1. In this work Ni-based AAO catalysts were investigated to produce CNTs from pyrolysis/gasification of waste plastics aiming to generate high quality CNTs with uniform distributions of diameters. The effect of gasification temperature, steam injection and the content of Ni on AAO membrane were studied in relation to their influence on the growth of CNTs. It was noted that gas and liquid product that were produced as part of this work were not analysed, as the main aim of the research work was to investigate the influence of template catalyst on the production of CNTs in relation to the quality of CNTs. 2.3 Sample characterizations A high resolution scanning electron microscope (SEM) Stereoscan 360 and a transmission electron microscope (TEM) JEOL 2010 were used to analyse the morphologies of the fresh catalysts. Around 5 mg reacted Ni/AAO catalysts was placed inside the TGA (TA Instruments, SDT-Q600), which was heated from room temperature up to 800 °C with an air flow rate of 100 mL min-1

Role of AAO membrane substrate 8

Production of CNTs 10

Findings

Conclusions