Catalytic Pyrolysis of LDPE Plastic Wastes over Mortar Cement Catalyst

Abstract:

A CaO based catalyst synthesized from mortar previously used in construction was chosen for pyrolysis of LDPE plastic waste. The samples were calcined at temperatures of 500 and 800 °C for comparison purpose. After calcination, two mixed oxides were obtained, denoted as catalyst A and B. The chemical composition of the metal oxide catalysts and the liquid products of the pyrolysis were characterized by X-ray Fluorescence (XRF) and Simulated Distillation - Gas Chromatography (SD-GC), respectively. The XRF analysis indicated that the catalyst, reformed from the mortar cement, consisted of CaO, silica (silicon dioxide, SiO₂) and alumina (aluminium (III) oxide, Al₂O₃) as the main constituents, though, the composition of each compound differed because of the influence of calcination temperature. Catalyst A had 41.96% of CaO, 4.27% of Al₂O₃ and 30.82% of SiO₂ when the catalyst B had 37.04% of CaO, 2.38% of Al₂O₃ and 37.31% of SiO₂. The amount of CaO in the catalyst B was found to be less in catalyst A. The catalyst A gave higher percentage yield of naphtha oil (48±1.14%v/v), compared to catalyst B (21±1.26%v/v). The performance of this catalyst (A) towards the pyrolysis of plastic wastes was compared to commercial grade ZSM-5 and FCC catalysts. It was found that the catalyst A, CaO based catalyst, reformed from the mortar cement, gave the highest yield of naphtha oil (48±1.14%v/v) compared to ZSM-5 (26±1.52%v/v) and FCC (16±1.09%v/v). The optimum operating temperature for the pyrolysis was found at 410 °C (in the temperature range 370 °C to 450 °C) and the optimum catalyst (A) composition was 0.3 %w/w of mortar cement catalyst in LDPE. This optimum condition gave 86.67± 0 %w/w of liquid, 12.49± 0.24 %w/w of gas and 0.84± 0.24 %w/w of solid. The catalyst A showed the best performance amongst all the catalysts towards the pyrolysis process of plastic wastes.

• Periodical: Advanced Materials Research (Volumes 931-932)
• Pages: 47-51
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.931-932.47
• Online since: May 2014
• Authors: Veeranuch Srakeaw*, Siriporn Yodjai, Unalome Wetwatana
• Keywords: Mortar Cement Catalyst, Plastic Waste, Pyrolysis

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