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ARS Home » Northeast Area » Wyndmoor, Pennsylvania » Eastern Regional Research Center » Sustainable Biofuels and Co-products Research » Research » Publications at this Location » Publication #414438

Research Project: Chemical Conversion of Biomass into High Value Products

Location: Sustainable Biofuels and Co-products Research

Title: Production of sustainable aviation fuel additives through selective hydrogenation of pyrolyzate from waste polystyrene

Author
item PRAJAPATI, RAVINDRA - University Of Illinois
item ZABOROWSKI, E - University Of Illinois
item LU, HONG - University Of Illinois
item RAJAGOPALAN, NANDAKISHORE - University Of Illinois
item Sharma, Brajendra
item Moser, Bryan
item KUMAR, NALIN - University Of Illinois

Submitted to: ACS Sustainable Chemistry & Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/9/2024
Publication Date: 12/18/2024
Citation: Prajapati, R., Zaborowski, E., Lu, H., Rajagopalan, N., Sharma, B.K., Moser, B.R., Kumar, N. 2024. Production of sustainable aviation fuel additives through selective hydrogenation of pyrolyzate from waste polystyrene. ACS Sustainable Chemistry & Engineering. 13(1):212-219. https://doi.org/10.1021/acssuschemeng.4c06748.
DOI: https://doi.org/10.1021/acssuschemeng.4c06748

Interpretive Summary: The aviation industry contributes 2% of anthropogenic greenhouse gas emissions, therefore sustainable aviation fuels (SAF) will be needed to achieve significant reductions in aviation emissions. Post-consumer waste plastic is experiencing a significant increase resulting in a large amount ending up in the environment. One of the waste plastics, polystyrene, has a very low rate of recycling. One of the ways to utilize this waste polystyrene is by converting it into an additive for the SAF. This research discusses the depolymerization of waste polystyrene to styrene through low-temperature catalytic pyrolysis followed by hydrogenation to ethylbenzene, which has been shown to have potential as an additive to improve the properties of SAF. This approach could be extended to a mixture of biomass/plastic to utilize and convert waste generated in agricultural fields to fuels and chemicals and will also provide a way for the farmers to generate value-added products from the plastic waste generated on farms.

Technical Abstract: As one of the fastest-growing transportation sectors, the aviation industry contributes 2% of anthropogenic greenhouse gas emissions. In the forthcoming decades, the integration of sustainable aviation fuels will play a pivotal role in achieving significant reductions in aviation emissions. The production of waste plastic on a global scale is experiencing a significant increase. Unfortunately, the rate of recycling waste polystyrene is less than 1%. However, there is hope in improving the rate of recycling certain plastic types such as through the pyrolysis of polystyrene, which shows promise in producing petrochemicals and alternative fuel streams. This study focuses on a two-step process that selectively converts styrene into ethylbenzene. The main objective of this process is to develop SAF additives from pyrolysis of polystyrene. To compare and control the results, virgin polystyrene was analyzed alongside waste polystyrene samples. The pyrolysis study of virgin polystyrene involved the use of three different catalysts: CaO, SAPO-11, and ASA. These catalysts were tested at temperatures of 375°C and 400 degree C to screen for the most effective catalyst and optimize the process parameters. The liquid pyrolysis oil was then analyzed using various techniques such as GC-FID, GC-MS, NMR, viscometry, and refractometry to determine its composition and physicochemical properties. The results showed that the CaO catalyst produced the highest amount of liquid oil at 400 degree C. The pyrolysis of waste polystyrene was carried out using the CaO catalyst at 400°C and underwent similar characterization. The resulting pyrolysis oil was then hydroprocessed using a Pd/C/Zeolite-13x catalyst. The cutting-edge slurry phase dual catalyst illustrated a conversion efficiency of over 97% for styrene to ethylbenzene. The hydroprocessed oil was then distilled into ethylbenzene. The blending of ethylbenzene was carried out with commercial SAF oil and fuel properties of the resulting SAF oil were compared with commercial aviation fuel. The SAF12 showed almost similar fuel properties to the reference oil.