Biomass to Hydrogen via Fast Pyrolysis and Catalytic Steam Reforming of the Pyrolysis Oil or Its Fractions

Abstract

Pyrolysis of lignocellulosic biomass and reforming of the pyroligneous oils are being studied as a strategy for producing hydrogen. A process of this nature has the potential to be cost competitive with conventional means of producing hydrogen. We propose a regionalized system of hydrogen production, where small- and medium-sized pyrolysis units (<500 Mg/day) provide bio-oil to a central reforming unit to be catalytically converted to H 2 and CO 2 . Thermodynamic modeling of the major constituents of the bio-oil has shown that reforming is possible within a wide range of temperatures and steam-to-carbon ratios. In addition, screening tests aimed at catalytic reforming of model compounds to hydrogen using Ni-based catalysts have achieved essentially complete conversion to H 2 . Existing data on the catalytic reforming of oxygenates have been studied to guide catalyst selection. A process diagram for the pyrolysis and reforming operations is discussed, as are initial production cost estimates. A window of opportunity clearly exists if the bio-oil is first refined to yield valuable oxygenates so that only a residual fraction is used for hydrogen production.