The
development of bifunctional and bimetallic catalysts is of
crucial importance for the bio-oils upgrading applications. To improve
the quality of bio-oils as fuels, hydrodeoxygenation (HDO) is one
of the most promising reactions for the upgrading of lignin-derived
bio-oils. However, this process has been typically operated under
high H2 pressures (40–50 atm). Therefore, the development
of catalysts for the HDO of lignin-derived compounds operated under
mild conditions is still a great challenge. In this context, the mild
HDO of 4-propylphenol as a model bio-oil compound operated at atmospheric
pressure using hierarchical bimetallic Pt–Ru/HZSM-5, prepared
by co-impregnation of metals on zeolite nanoparticles obtained by
a one-pot hydrothermal synthesis with the aid of tetrabutylphosphonium
hydroxide as a dual structure-directing agent, is reported. The combination
of Pt and Ru together with hierarchical structures of zeolites eventually
results in the unexpectedly excellent catalytic performance toward
the alkylcycloalkane production. Not only the presence of hierarchical
structure provides the beneficial effect for promoting the high dispersibility
of bimetallic active sites, eventually leading to a significant decrease
in the nanometallic particle size (20.0 ± 8.0 to 2.7 ± 0.6
nm over conventional zeolite and hierarchical one, respectively),
but also the synergistic effect of bimetallic Pt and Ru active sites
can greatly enhance a very high yield of propylcyclohexane (100%).
The synergistic bifunctional and bimetallic catalytic platform illustrates
scientific opportunities toward bio-oil upgrading applications.
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