Angew. Chem. Int. Ed. 55, 8850–8855 (2016)

Reducing the oxygen content of biomass-derived feedstocks is key to producing quality liquid biofuels with high energy density and stability. However, harsh conditions are often required to perform the catalytic hydrodeoxygenation (HDO) process and more effective catalysts are sought that can operate in milder conditions. Now, Ferdi Schüth and colleagues in Germany and the UK demonstrate how small, bimetallic PtCo nanoparticles supported on nitrogen-doped mesoporous carbon are highly active and selective catalysts for the HDO of compounds derived from biomass, generating product streams suitable for use as drop-in fuels.

Credit: WILEY

To prepare the catalysts, the researchers used a soft-templating method to yield nitrogen-doped carbon with well-defined pores in either a cubic or hexagonal arrangement, depending on the polymerization temperature. They then introduced uniformly dispersed 1.5 nm PtCo nanoparticles by ion-exchanging appropriate metal salts into the polymerized precursor before pyrolysis in a stream of dilute hydrogen at 500 °C. The resulting catalysts produce alkanes from phenolic compounds with high selectivity (>99%) at high conversion, while, by comparison, monometallic catalysts based on Co or Pt are less active and selective. The catalysts also perform well in the conversion of bio-oil — a complex mixture of phenols derived from lignin — producing a product stream composed of 99% carbon and hydrogen, mainly in the form of cycloalkanes.