(653f) Hydrodeoxygenation of Biomass Pyrolysis Vapors Using Metal Supported USY Zeolite

Hydrodeoxygenation of biomass pyrolysis vapors using metal supported USY
Zeolite

David
P. Gamliel andJulia A. Valla

Department of Chemical
& Biomolecular Engineering, University of Connecticut, 191 Auditorium Road,
Unit 3222, Storrs, CT 06269-3222, USA,

Phone: +1-860-486 4602, e-mail: ioulia.valla@.uconn.edu

The
objective of this work was to understand the role of metals on the hydrodeoxygenation (HDO) reaction pathways of three bio-oil
model compounds. Ni, Ru and Pd were impregnated on
USY zeolite, and the catalysts were characterized using Temperature Program
Reduction (TPR), X-ray Diffraction (XRD), X-ray photoelectron spectroscopy
(XPS) and Transmission Electron Microscopy (TEM) to determine metal reduction
profile, surface concentration and nanoparticle size. Ru-USY and Pd-USY were completely reduced at a temperature below 450
°C, but Ni-USY still contained surface metal oxides after reduction. There was
no indication of strong interactions between the metals and USY support. The
dispersion of metal on Ni-USY and Pd-USY were
similar, while the metal dispersion of Ru-USY was slightly lower, as determined
by H2 chemisorption.

Anisole,
4-ethylphenol and benzofuran were used as bio-oil
model compounds, in order to determine the effects of each metal on
deoxygenation of methoxy-, phenol and furan
functional groups, respectively. Pd-USY was the most
effective HDO catalyst, exhibiting the highest turnover frequency for HDO of
all three model compounds, and high selectivity to deoxygenated products.
Initial TOF increased in the order Ni-USY<Ru-USY<Pd-USY.
A mechanism was proposed for the HDO of each model compound, and kinetic
parameters were fit for each catalyst using a least-squares algorithm. This
analysis showed that the higher Pd-USY initial TOF
was a result of better hydrogenation capability. Pd-USY
and Ru-USY also significantly promoted C-C coupling reactions. Direct
deoxygenation was not favored over ring hydrogenation/dehydration for any of
the catalysts tested. Pd-USY was the only material
capable of ring-opening during benzofuran HDO. Pd-USY was concluded to be the most effective HDO catalyst
for all three model compounds. A mechanism was proposed for each model
compound, and the kinetics of hydrogenation, dehydration, C-C coupling and
ring-opening reactions were determined.