(172b) CATALYTIC Conversion of BIOMASS Pyrolysis Oil to Syngas and Chemicals
Pyrolysis is a technique to convert solid biomass into a more energy-dense liquid form known as pyrolysis oil or bio-oil. Bio-oil is chemically complex and unstable, but can be upgraded to produce commodity chemicals and/or a mixture of carbon monoxide and hydrogen gas called synthesis gas (or syngas). Selectivity to desired products depends on the catalyst system, the relative abundance of homogeneous and heterogeneous chemistry, and the presence of molecular oxygen. This work investigates autothermal refining of bio-oil and bio-oil model compounds to syngas and non-equilibrium products such as ethylene and acetaldehyde over ceramic-supported Pt and Rh catalysts. The presence of sufficient oxygen yields high conversion to C_1 compounds, H_2 and H_2O, while limited oxygen produces high selectivity to nonequilibrium products. Furthermore, the presence of nonequilibrium products facilitates elucidation of homogeneous/heterogeneous reaction pathways. Results are compared between experiments in the presence and absence of catalyst, support, and oxygen to determine which species are produced homogeneously, which are produced heterogeneously, and which require combinations of metal catalyst, ceramic support and oxygen. Ethylene and methane formation appears to be inhibited by the metal catalyst, while acetaldehyde can be produced homogeneously or heterogeneously, but is rapidly consumed in the presence of oxygen.