Biobased tar pitch produced from biomass pyrolysis oils

Authors: Elkasabi, Yaseen; Mullen, Charles; Strahan, Gary; Wyatt, Victor

Submitted to: Fuel
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/13/2022
Publication Date: 3/1/2022
Citation: Elkasabi, Y.M., Mullen, C.A., Strahan, G.D., Wyatt, V.T. 2022. Biobased tar pitch produced from biomass pyrolysis oils. Fuel. https://doi.org/10.1016/j.fuel.2022.123300.
DOI: https://doi.org/10.1016/j.fuel.2022.123300

Interpretive Summary: In order to produce aluminum metal, factories use a carbon brick that is electrically conductive. This carbon brick is made by mixing and baking at high temperatures different carbon materials together. Since these materials are made from heavy petroleum, the aluminum production also makes greenhouse gases and contributes to global warming. To make this whole process more environmentally friendly, we created carbon material substitutes that come from plants. We use a high temperature process to convert the plant matter into an oil, and that oil gets refined and heated into the desired carbon material. Overall, we improved the chemical properties of these materials, compared with past efforts to make these materials from plant sources.

Technical Abstract: Petroleum-based carbon solid materials, such as petcoke and coal tar pitch, have decreased in quality and/or availability due to various factors, such as the declining elemental quality of crude oil and the push towards environmental sustainability. Coal tar pitch acts as a binder in smelting anodes for aluminum production, which contributes significantly to the fossil-based CO2 production globally. In an effort to reduce the carbon footprint of these processes, we synthesized a renewable biopitch based on biomass pyrolysis. In comparison to previous studies on biopitch, we utilized pyrolysis bio-oils with reduced oxygen content (<15%). Guayule and switchgrass biomasses served as the biomass of choice, and their bio-oils underwent continuous distillation. Solid residues underwent extraction to remove toluene insolubles, and the remaining fraction underwent heat treatment to ~380 oC. While both the residues and pitches contained trace amounts of quinoline insolubles (QI), the pitch toluene insolubles (TI) amounted to 32 – 54 wt%. Coking values exceeded 43 wt% for both pitches, making them feasible for anode utilization.