A high yielding catalytic system for the reduction of the pyrolysis
oil model compounds p-cresol and furfural using transfer hydrogenation
from isopropanol is reported. Bimetallic, non-noble metal
catalysts Ni–Cu on Al2O3 and C supports were effective catalysts for
both model compounds. Greater than 95% yield of a mixture of ring
hydrogenation and deoxygenation products with high selectivity for
4-methylcyclohexanol was achieved at 300 °C in neat isopropanol.
Furfural was reduced to furfuryl alcohol in similarly high yield, but
required the use of lower temperatures. TGRP bio-oils were upgraded
over Ni–Cu/C catalyst, and the results indicated that the upgraded biooils
contained a higher level of hydrogen and were partially deoxygenated.
The acidity of bio-oils mostly decreased through esterification of
acids with isopropanol, and reduction of the alkyl phenols was not
observed. Transfer hydrogenation of bio-oil could aid in the stabilization
of bio-oils prior to further processing via the reduction of reactive
unsaturated carbon–carbon and carbon–oxygen bonds, but further
development is still required to achieve these goals.