Catalytic Pyrolysis of Plastic Waste: Moving Toward Pyrolysis Based Biorefineries

Rashid Miandad,Asad S Aburiazaiza,Mohammad Rehan,Mohammad A Barakat,Iqbal M I Ismail,Hizbullah Khan,Jeya Dhavamani,Abdul-Sattar Nizami,Ali Hassanpour,Jabbar Gardy

doi:10.3389/fenrg.2019.00027

Rashid Miandad, Asad S Aburiazaiza + Show 8 more

Open Access

https://doi.org/10.3389/fenrg.2019.00027

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Abstract

Pyrolysis based biorefineries have great potential to convert wastes such as plastic and biomass waste into energy and other valuable products to achieve maximum economic and environmental benefits. In this study, the catalytic pyrolysis of different types of plastics waste (PS, PE, PP, and PET) as single or mixed in different ratios in the presence of modified natural zeolite (NZ) catalysts in a small pilot scale pyrolysis reactor was carried out. The NZ was modified by thermal activation (TA-NZ) at 550°C and acid activation (AA-NZ) with HNO3 to enhance its catalytic properties. The catalytic pyrolysis of PS produced the highest liquid oil (70 and 60%) than PP (40 and 54%) and PE (40 and 42%) using TA-NZ and AA-NZ catalysts respectively. The gas chromatography-mass spectrometry (GC-MS) analysis of oil showed a mixture of aromatics, aliphatic and other hydrocarbon compounds. The TA-NZ and AA-NZ catalysts showed a different effect on the wt.% of catalytic pyrolysis products and liquid oil chemical composition, with AA-NZ showing higher catalytic activity than TA-NZ. FT-IR results showed clear peaks of aromatic compounds in all liquid oil samples with some peaks of alkanes that further confirmed the GC-MS results. The liquid oil has higher heating values (HHV) range of 41.7-44.2 MJ/kg, close to conventional diesel. Therefore, it has the potential to be used as an alternative source of energy and as transportation fuel after refining/ blending with conventional fuels.

Highlights

Plastic waste production and consumption is increasing at an alarming rate, with the increase of the human population, rapid economic growth, continuous urbanization, and changes in life style
The plastic waste used as the feedstock in the catalytic pyrolysis process was collected from Jeddah and included grocery bags, disposable juice cups and plates, and drinking water bottles, which consist of polyethylene (PE), polypropylene (PP) polystyrene (PS), and polyethylene terephthalate (PET) plastics, respectively
The selection of these plastic materials was made based on the fact that they are the primary source of plastic waste produced in Kingdom of Saudi Arabia (KSA)

Summary

Introduction

Plastic waste production and consumption is increasing at an alarming rate, with the increase of the human population, rapid economic growth, continuous urbanization, and changes in life style. The short life span of plastic accelerates the production of plastic waste on a daily basis. The global plastic production was estimated at around 300 million tons per year and is continuously increasing every year (Miandad et al, 2016a; Ratnasari et al, 2017). Catalytic Pyrolysis of Plastic Waste countries, open or landfill disposal is a common practice for plastic waste management (Gandidi et al, 2018). The disposal of plastic waste in landfills provide habitat for insects and rodents, that may cause different types of diseases (Alexandra, 2012). Pyrolysis is a common technique used to convert plastic waste into energy, in the form of solid, liquid and gaseous fuels

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