(133b) Transportation Fuels from Renewable Biomass Sources: Opportunities and Challenges

The production of liquid transportation fuels from biomass in an efficient and cost-effective way is a primary focus of the US DOE. Conversion of wood and other agricultural residual feedstocks through a liquefaction method, such as fast pyrolysis or hydrothermal liquefaction, followed by a catalytic upgrading pathway is one of the most promising ways to produce fuels and chemicals. The resultant oil is a complex liquid mixture of paraffins, aromatics, oxygenates and other components. Main differences between bio-derived oils and petroleum based oils include the high water, acid, and oxygen content of the former. Using current technologies we are able to characterize and account for the majority of the carbon containing species, but still striving to account for 35% unknowns. We also believe that oxygenates present in these oils results in instability and cause complications in down-stream processing. A better knowledge of oxygenates present in bio-oil is needed to properly evaluate bio-oil quality and may provide the key to solving processing issues encountered in the upgrading and refining.

Producing an infrastructure-ready fuel from biomass also requires a better understanding of the chemical constituents of the gasoline, diesel and jet fuel fractions of the biofuel product. Determining the distribution of heteroatoms, especially O and S, impacts the acceptability of a distillate fraction within specific fuel specifications. These reactive and corrosive components can cause complication during downstream processing of bio-oils. We have developed a suite of standardized methods to analyze and describe bio-oils. We refined the analysis of distillates from pyrolysis oil by controlling the source and processing of hydroprocessed bio-oils with two oxygen contents. The upgraded bio-oils were subsequently distilled into five fractions. Analytical techniques such as elemental analysis, density, viscosity, simulated distillation (ASTM D2887), ¹³C NMR, PIANO and HPLC measurement were used and results will be presented. Specific fractions were found to satisfy boiling point requirements but functional group characterization will likely preclude their direct use as fuel. The methods developed, lessons learnt, and application of these methods to different oils will be discussed.