(117a) Aqueous-Phase Reforming of Bio-Oil Model Compounds Over Pt-Re/C

While fast pyrolysis bio-oil
is an inexpensive liquid fuel derived from lignocellulosic biomass, the quality
of bio-oil is poor partially due to its high content of oxygenated species,
which included various acids, alcohols, aldehydes, ketones, sugars, guaiacols, syringols
furans, and furfurals.  These
species can be divided into water soluble and insoluble compounds, with the
water soluble species coming primarily for the carbohydrate portion of the
biomass.  Aqueous-phase reforming
(APR) is a potential approach to convert these highly oxygenated compounds to H₂
and mono-functional species that can be subsequently upgraded to hydrocarbons.
 However, a myriad of reactions will
occur when APR is applied to the soluble portion of bio-oil, so there is a need
to perform model compound studies to better understand the reaction
system.  As a starting point, we conducted APR of ethanol over Pt-Re/C at
250 °C. 
H₂, CO₂, CH₄, C₂H₆,
acetaldehyde, ethyl ether, ethyl acetate, acetic acid were main products.  Additionally, acetaldehyde, acetic acid
and formic acid were employed as reactants for APR, to provide information on the
reaction pathways over Pt-Re/C.  Flux
analysis on the ethanol reaction system was made to determine the reaction pathway
and relative rates (v₁-v₈) for each step, which is shown
in Figure 1.

Figure
1.  The reaction pathway
for aqueous phase reforming of ethanol over Pt-Re/C.