Abstract

Catalytic pyrolysis behavior of synthesized microporous catalysts (conventional Zeolite Socony Mobil–5 (C-ZSM-5), highly uniform nanocrystalline ZSM-5 (HUN-ZSM-5) and β-zeolite), Mesoporous catalysts (highly hydrothermally stable Al-MCM-41 with accessible void defects (Al-MCM-41(hhs)), Kanemite-derived folded silica (KFS-16B) and well-ordered Al-SBA-15 (Al-SBA-15(wo)) were studied with waste polyethylene (PE) and polypropylene (PP) mixture which are the main constituents in municipal solid waste. All the catalysts were characterized by Brunauer-Emmett-Teller (BET), X-ray powder diffraction (XRD), and NH3-temperature programmed desorption (TPD). The results demonstrated that microporous catalysts exhibited high yields of gas products and high selectivity for aromatics and alkene, whereas the mesoporous catalysts showed high yields of liquid products with considerable amounts of aliphatic compounds. The differences between the microporous and mesoporous catalysts could be attributed to their characteristic acidic and textural properties. A significant amount of C2–C4 gases were produced from both types of catalysts. The composition of the liquid and gas products from catalytic pyrolysis is similar to petroleum-derived fuels. In other words, products of catalytic pyrolysis of plastic waste can be potential alternatives to the petroleum-derived fuels.

Highlights

  • Plastic materials have been extensively consumed by various industry sectors including packaging, household, construction, automobile, aerospace, and electronic [1] owing to their advantageous properties, such as light weight, good strength and durability, resistance to corrosion, excellent thermal and electrical insulation, versatility and low production costs

  • This paper presents an investigation of the catalytic performance of modified microporous catalysts and macroporous catalysts in pyrolysis of plastic waste

  • While other chemicals—Pluronic P123, cetyltrimethylammonium bromide (CTAB), tetraethylorthosilicate (TEOS), aluminum isopropoxide, tetrapropylammonium bromide, tetrapropylammonium hydroxide, phenylaminopropyltrimethoxysilane (PHAPTMS)—and other reagents used for synthesis of the other five catalysts were purchased from Sigma-Aldrich

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Summary

Introduction

Plastic materials have been extensively consumed by various industry sectors including packaging, household, construction, automobile, aerospace, and electronic [1] owing to their advantageous properties, such as light weight, good strength and durability, resistance to corrosion, excellent thermal and electrical insulation, versatility and low production costs. The use of incineration can significantly reduce the need for landfill space and energy can be recovered from plastic waste. Pyrolysis has been gaining increasing interest over the years as a promising alternative to landfill and incineration due to its ability to recover energy from plastic wastes in the form of valuable hydrocarbons (i.e., liquid hydrocarbon fuels, combustible gases and char) with low negative environmental impacts. Pyrolysis is able to treat heterogeneous and contaminated polymers without pre-sorting and complex pre-treatment. The downside of this technology is the broad distribution of its product in terms of carbon number. This is due to random scission of the polymer chains during pyrolysis. Pyrolysis temperature and time can be lowered considerably as compared with pure thermal cracking

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