Catalytic hydrodeoxygenation of simulated phenolic bio-oil to cycloalkanes and aromatic hydrocarbons over bifunctional metal/acid catalysts of Ni/HBeta, Fe/HBeta and NiFe/HBeta

Abstract

Bifunctional metal/acid catalysts of 5wt% Ni/HBeta, 5wt% Fe/HBeta, 2.5wt% Ni-2.5wt% Fe/HBeta (NiFe-5/HBeta) and 5wt% Ni-5wt% Fe/HBeta (NiFe-10/HBeta) were used for hydrodeoxygenation (HDO) of a simulated phenolic bio-oil consisting of phenol (50wt%), o-cresol (25wt%) and guaiacol (25wt%). Nickel and iron metals were supported on hydrogen form Beta zeolite (HBeta) under similar ion-exchange conditions. BET surface area and acid sites density of Ni/HBeta, Fe/HBeta, NiFe-5/HBeta and NiFe-10/HBeta were 463, 445, 455, 417m2/g and 0.53, 0.48, 0.50, 0.38mmol/g, respectively. Cycloalkanes (21.39wt%) and aromatic hydrocarbons (20.21wt%) were the dominant hydrocarbons obtained over monometallic catalysts of Ni/HBeta and Fe/HBeta through reactions of hydrogenation and hydrogenolysis, respectively. It was revealed that both hydrogenation and hydrogenolysis mechanisms were effectively proceeded over the bimetallic catalyst of NiFe/HBeta which showed enhanced HDO efficiency compared to monometallic catalysts of Ni/HBeta and Fe/HBeta due to the synergistic effect between the two metals. The effect of reaction temperature on HDO efficiency of NiFe-10/HBeta catalyst was investigated at 220, 260, 300 and 340°C. Maximum catalytic activity and hydrocarbons selectivity was observed at 300°C. Replacement of water with methanol as solvent in HDO of the simulated phenolic bio-oil over NiFe-10/HBeta remarkably reduced the selectivity towards hydrocarbons.