Because of these limitations, there has been great interest in
developing processes where oxygen is released from the carbon framework
of the biomass during the pyrolysis step. The goal is to produce
thermally stable pyrolysis oils which require only a lesser degree of
upgrading to be considered as fungible fuels or refinery blendstocks.
Two processes that produce stabilized deoxygenated pyrolysis oil are
1) catalytic fast pyrolysis (CFP) over zeolites such as HZSM-5
and 2) tail gas reactive pyrolysis (TGRP). In both of these
processes, a large fraction of the remaining oxygen in the pyrolysis oil
mixtures is in the form of alkyl phenols. Phenols are weakly acidic and not readily subject to direct deoxygenation due to the relatively strong
aromatic C–O bond. We therefore chose to investigate means of
upgrading alkyl phenols to their corresponding, more chemically
benign, alcohols or deoxygenated products using p-cresol as a model
compound.