Metal–Acid Synergy: Hydrodeoxygenation of Anisole over Pt/Al‐SBA‐15
Atal Shivhare, James A. Hunns, Lee J. Durndell, Christopher M. A. Parlett, Mark A. Isaacs, Adam F. Lee, Karen Wilson
Abstract
Abstract Hydrodeoxygenation (HDO) is a promising technology to upgrade fast pyrolysis bio‐oils but it requires active and selective catalysts. Here we explore the synergy between the metal and acid sites in the HDO of anisole, a model pyrolysis bio‐oil compound, over mono‐ and bi‐functional Pt/(Al)‐SBA‐15 catalysts. Ring hydrogenation of anisole to methoxycyclohexane occurs over metal sites and is structure sensitive; it is favored over small (4 nm) Pt nanoparticles, which confer a turnover frequency (TOF) of approximately 2000 h −1 and a methoxycyclohexane selectivity of approximately 90 % at 200 °C and 20 bar H 2 ; in contrast, the formation of benzene and the desired cyclohexane product appears to be structure insensitive. The introduction of acidity to the SBA‐15 support promotes the demethyoxylation of the methoxycyclohexane intermediate, which increases the selectivity to cyclohexane from 15 to 92 % and the cyclohexane productivity by two orders of magnitude (from 15 to 6500 mmol g Pt −1 h −1 ). Optimization of the metal–acid synergy confers an 865‐fold increase in the cyclohexane production per gram of Pt and a 28‐fold reduction in precious metal loading. These findings demonstrate that tuning the metal–acid synergy provides a strategy to direct complex catalytic reaction networks and minimize precious metal use in the production of bio‐fuels.