In-situ glycerol aqueous phase reforming and phenol hydrogenation over Raney Ni®

Abstract

In-situ glycerol aqueous phase reforming and phenol hydrogenation (IGAPH) was conducted with Raney Ni® at 180–240 °C for phenol to glycerol ratios from 0 to 4.88. Thermodynamic analysis of the complex IGAPH reaction system revealed the need to balance endothermic glycerol aqueous phase reforming (APR) and exothermic phenol hydrogenation reactions. It was found that maximum glycerol carbon selectivity for APR and maximum hydrogen selectivity for phenol hydrogenation occurred at 220 °C. Addition of phenol to glycerol APR increased glycerol conversion and glycerol carbon selectivity for APR. These observations can be attributed to an equilibrium shift to the forward APR reaction due to hydrogen consumption and suppression of competing parallel reactions by phenol hydrogenation. An initial rate model of the system suggests that IGAPH proceeds via the Langmuir-Hinshelwood mechanism and is rate-limited by phenol hydrogenation. Perspectives for future process development in terms of reaction heat and catalyst stability are provided.