(679a) Remediation of Biomass Pyrolysis Oil Distillate Residues Using Solvent Liquefaction

Fast pyrolysis of biomass produces organic bio-oils, which can be refined into finished hydrocarbon fuels. While we have shown that distilling oils with relatively low oxygen (<15 wt%) produces useful residues, some residues prove more difficult for use in applications requiring high purity, such as carbon anodes. Residues from protein-containing biomasses like spirulina contain high levels of nitrogen (> 10 wt%), which interfere with product purity and quality. Some residues emanate from lighter oils with low fixed carbon content, which limits the potential yield of solid co-products. Herein we will discuss liquefaction screening studies performed on distillate residues from various bio-oil types produced by tail-gas reactive pyrolysis: 1) Spirulina bio-oil 2) switchgrass bio-oil and 3) switchgrass bio-oil phenolic fraction. A variety of solvents and additive combinations (including formic acid, ethanol, NaOH, and Al(OTf)₃) were explored for each residue. Microreactors were assembled using Swagelok union fittings and pressure-resistant plugs, and we conducted reactions in parallel at 320 ^oC for 1 hr. GC-MS results indicated preferential liquefaction occurred in some solvents over others, depending on the residue examined. Spirulina-based residue was more effectively depolymerized in ethanol, producing esterified fatty acids. Aqueous media was more effective for other residues, producing one-ring phenolics. Using optimized results from microreaction experiments, we will also discuss scaled-up experiments in a 100 mL pressurized Parr reactor.