This study examines the feasibility of steam reforming the aqueous fraction of the bio-oil.  Fast pyrolysis bio-oils can be separated into aqueous and organic fractions by the addition of water or solvent or by hydrotreating to less than 20 wt. % O.  Other liquefaction technologies, such as hydrothermal liquefaction and some permutations of catalytic pyrolysis, directly yield biphasic bio-oils.  The loss of organic species in the aqueous phase that would need to be treated in order to reclaim the water is a potentially negative economic impact.  The higher value predominantly organic fraction can be used to make chemicals or upgraded to provide gasoline, diesel, or jet fuels.  The lower value predominantly aqueous fraction can be converted into syngas by steam reforming, producing hydrogen which can be recycled in-plant for hydrogenation purposes (e.g. hydrodeoxygenation upgrading).  Process hydrogen would otherwise be supplied from either natural gas, or steam reforming of the entire bio-oil, which includes the higher value organic fraction.  Reformation of the bio-oil aqueous fraction would increase overall biomass carbon utilization, decrease hydrogen requirement for the overall liquefaction process, and reduce aqueous stream waste processing costs.  Initial reforming tests have been performed with typical model compounds found in the aqueous stream.  Model compounds and their concentrations for the various processes were chosen based on literature reports and internally generated experimental information.  The steam reforming of model biomass compounds, including acetic acid, propylene glycol, sorbitol, tetrahydrofurfuryl alcohol, and phenol have been carried out with Ni and noble metal based catalysts. Temperature, steam-to-carbon ratios, and space velocity were process variables explored.  The conversion levels of the oxygenated compounds, product selectivity and the effect on the catalyst life time will are discussed with particular attention to the effect on the expected steam-to-carbon ratios of the various feedstreams on catalyst coking rates.

Steam reforming the aqueous phase components produced in direct liquefaction processes

246th National Meeting (2013)

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