Term of Award

Spring 2020

Degree Name

Master of Science in Applied Engineering (M.S.A.E.)

Document Type and Release Option

Thesis (restricted to Georgia Southern)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Department

Department of Mechanical Engineering

Committee Chair

Prakashbhai Bhoi

Committee Member 1

David Calamas

Committee Member 2

Marcel Ilie

Abstract

Biomass-based pyrolytic oil exhibits a lower calorific value and contains oxygenated compounds, which need to be minimized to upgrade the biofuel quality. In addition, approximately 50% of the world’s current bioplastics are composed of similar chemicals found in traditional plastics, which are not biodegradable. Because of the lack of a suitable environment, bioplastics and recyclable plastics breach their designated waste chain and accumulate in landfills. To prevent these plastics from littering the ocean, alternative solutions are necessary. The overall goal of this research is to study the effects of the co-pyrolysis ratio of pinewood to high-density polyethylene (HDPE) plastic in order to reduce the oxygenated compounds and to improve the quality of pyrolysis oil. In this research, a double-column staged reactor was fabricated whereby the pine biomass to HDPE plastic ratio was varied between 0/100, 25/75, 50/50, 75/25, and 100/0 at 450℃, 500℃, and 550℃. A Zeolitic-based ZSM-5 catalyst was used with the feedstock at a ratio of 1:1, which cracked the heavy molecules into gasoline-range liquid hydrocarbons with a higher calorific value. Virgin HDPE was used for the co-pyrolytic feedstock. In addition, virgin low-density polyethylene; virgin polylactic acid; and waste plastics such as HDPE grocery bags, polyethylene terephthalate water bottles, and compostable bioplastic bags were investigated for the comparison with virgin HDPE. Virgin HDPE produced 30.54% liquid pyrolysis oil with a calorific value of 40.38 MJ/Kg and a selectivity of above 90% toward gasoline-range aromatic hydrocarbons at 500℃. Comparatively, at 500℃, pinewood offered 26.27% liquid pyrolysis oil yield with a heating value of 30.13 MJ/Kg and a gasoline selectivity of 69.30%. The addition of HDPE in the co-pyrolytic feed increased the hydrogen/carbon effective (H/Ceff) ratio and the gasoline selectivity simultaneously. The gasoline selectivity was also increased from 68.87% to 76.31% for 100% pine sawdust when the experimental temperature was increased from 450℃ to 550℃ with an H/Ceff of 0.029. However, for HDPE of above 50% or an H/Ceff ratio above 0.989, gasoline selectivity was above 90% at 450℃ and 500℃. Mixed plastics also demonstrated a liquid yield of 17.35% and the calorific value was 42.68 MJ/Kg with a gasoline selectivity of above 90%. Moreover, pyrolysis oil from both virgin and waste HDPE has shown a significantly higher selectivity toward C9 hydrocarbons. Among C9 hydrocarbons, cumene is used in gasoline as an octane booster. The gas contains (C1–C5) range hydrocarbons and typically consists of alkanes and alkenes, which are important from the point of view of the high calorific value of gaseous fuel. Therefore, the catalytic co-pyrolysis of pine and plastics has shown significant potential for improving the bio-oil quality of gasoline-range hydrocarbon fuels, and, in particular, HDPE has increased the quantity and quality of pyrolysis oil simultaneously.

Research Data and Supplementary Material

No

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