Regulating isomerization of gasoline-alkanes in aqueous-phase hydrodeoxygenation of sorbitol using regenerable Ni@MoOx catalysts

Abstract

Aqueous-phase hydrodeoxygenation (HDO) has been regarded as an efficient biorefinery strategy for sustainable production of gasoline-alkanes from bio-polyols. However, current research focuses mainly on exploiting noble-metal HDO catalysts to acquire straight-chain C5-C6 alkanes. Herein, the aqueous-phase HDO route was firstly proposed to regulate isomerization of gasoline-alkanes in the sorbitol hydrogenolysis utilizing non-noble Mo-based catalysts in a continuous-flow fixed-bed reactor. The selective reduction removal of hydroxyl groups and isomerization of carbon chains were strongly coupled together for boosting the octane value of gasoline-alkanes over the regenerable Ni@MoOx binary catalysts derived from NiMoO4 spinel. Further characterization studies revealed that the synergism of Ni0 and MoOx played a crucial role in regulating selective dissociation of CO bonds and rearrangement of CC bonds, and suppressing excessive cleavage of CC bonds toward C1-C4 alkanes and CO/CO2. The effects of reaction parameters including reaction temperature, H2-pressure and reduction temperature were also evaluated for manipulating the product distribution between n-alkanes and isoalkanes. After optimization, a high C5-C6 yield of 87.5% with 51.7% of C5-C6 isoalkanes mainly including cycloalkanes was achieved at 280 °C under H2-pressure of 1.0 MPa over the Ni@MoOx catalyst reduced at 500 °C. This catalytic strategy could create new opportunities for producing high-quality biofuels from biomass-derived oxygenated compounds.