(27b) Thermogravimetric Analysis of Bio-Oils and Upgraded Products

Biomass can be converted to liquid products through thermochemical processing such as pyrolysis and hydrothermal liquefaction. This bio-oil, after catalytic upgrading to remove reactive oxygenated species, can be used to produce fuel products and commodity chemicals. A key metric for fuel product composition and quality is the boiling point range or distillation curve. Determining the applicability of bio-oil and upgraded products as fuels requires knowledge of distillation curves. Standard distillation methods used to characterize petroleum products can be applied to bio-derived fuels; however, these methods require relatively large sample volumes that may not be available from lab scale research reactors. Although gas chromatography (GC) based simulated distillation methods that require small sample volumes exist for petroleum products, these are not applicable to bio-oils containing oxygenated compounds. Thermogravimetry (TG) is well suited for determining boiling temperatures of oxygenated bio-oils using small sample sizes. TG based micro-distillation data indicate bio-oil reactivity at high temperatures and thus provide a rapid determination of the extent of removal of reactive species. This paper discusses TG micro-distillation methodology for bio-oils and comparison to GC based simulated distillation. Both methods are applied to pyrolysis and hydrothermal liquefaction products as well as upgraded products with three levels of oxygen removal. These data highlight the impact of oxygenated compounds on GC simulated distillation data as well as the use of TG data to indicate removal of reactive compounds.