The Effects of Catalyst Properties on the Conversion of Biomass via Catalytic Fast Hydropyrolysis

Catalytic fast hydropyrolysis (CFHP) is an attractive and alternative method for thermochemical conversion of biomass to fuels. The objective of the present work is to determine the effects of support porosity, acidity, and impregnated metal species on the CFHP product distribution. CFHP of Miscanthus x giganteus in the presence of SiO2 and Al2O3 results in high solid and low volatile product yields, :due to the lack of Broristed acidity, whereas CFHP with the acidic and shape-selective ZSM-5 returns high volatile products yield and aromatic selectivity. Increasing ZSM-5 acidity reduces monoaromatic hydrocarbon (MAH) and solid-yield, but increases yields to naphthalenes, polyaromatic hydrocarbons; and carbon oxides. Ni supported on inesoporous ZSM-5 slightly increases aromatic yields and decreases solid yield. Impregnation of Ni on all supports significantly shifts CFHP selectivity from solids to CH4. Ni, Ru, and Pd impregnated on ZSM-5 all have different effects on the CFHP product distribution. Improved MAH yields can be obtained with a Pd-ZSM-5 catalyst; which promotes decarbonylation over inethanation. Ru and Ni catalysts promote methanation and C-C bond scission. Alkane yields were low for all catalysts tested. The effects of catalyst properties on CFHP reaction pathways are also compared to the effects on traditional catalytic fast pyrolysis.