Submitted to: Separation and Purification Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/11/2023
Publication Date: 3/16/2023
Citation: Elkasabi, Y.M., Jones, K.C., Mullen, C.A., Strahan, G.D., Wyatt, V.T. 2023. Spinning band distillation of biomass pyrolysis-oil phenolics to produce pure phenol. Separation and Purification Technology. https://doi.org/10.1016/j.seppur.2023.123603.
Interpretive Summary: Many chemicals that are used on a day-to-day basis are made from crude oil. However, these chemicals tend to fetch a higher selling price than gasoline and jet fuel. So to make fuels from plants, we also need to make these common chemicals from plants, ideally together with fuels made from plants. Phenol is one such chemical; it is used to make plastics, drugs, and other common products. Currently, making phenol alongside biofuels in significant amounts has proven difficult. We have found a way to convert agricultural wastes directly into phenol; we also can purify the phenol from the other chemicals produced, using advanced tools for separating chemicals.
Technical Abstract: Competitive pricing for biofuels will require the coproduction of biobased products and chemicals to improve the economic outlook of biorefineries. Phenolics have been eyed due to their natural abundance in bio-oils relative to petroleum, as well as their potential profit margins. In bio-oils, the wide product distribution (especially phenolics) prevents meaningful separation. We’ve shown previously that bio-oils of relatively low oxygen (< 15 wt%) from advanced pyrolysis processes can be distilled and/or extracted, producing a fraction rich in phenol and cresols. We utilized a spinning band column distillation system, designed to perform at 200 theoretical plates. Catalytic (HZSM-5) pyrolysis bio-oils from switchgrass biomass first underwent extraction directly, producing a phenolic fraction and a hydrocarbon fraction. Subsequently, the phenolic fraction underwent a preliminary flash distillation ahead of spinning band distillation, in order to remove residues. Spinning band distillation resulted in fractions with more than ~80 wt% phenol (the balance o-cresol), which can be purified by recrystallization in pentane. Both GC/MS and NMR indicate phenol crystals were obtained at ~ 90 - 92 wt% purity. To complete the biorefinery concept, the hydrocarbon fraction was distilled to obtain a fuel product and heavy polyaromatic residues. The residues were thermally treated to produce bio-pitch.