Hydrogen production by sequential cracking of biomass-derived pyrolysis oil over noble metal catalysts supported on ceria-zirconia

Conversion of crude pyrolysis bio-oil for H2 production is investigated using a sequential process which alternates (i) cracking reaction steps, during which the bio-oil is converted to syngas and carbon stored on the catalyst and (ii) regeneration steps allowing to combust coke under an air flow. The performances of Pt and Rh catalysts supported on ceria-zirconia in powder form or deposited on cordierite monoliths are comparatively studied. From these data and calculated thermodynamic equilibrium, the co-existence of thermal and catalytic processes is demonstrated. A stable hydrogen productivity up to ca. 18 mmol of H2 g−1 of bio-oil (∼50% H2 in the gas stream) with a minimized methane formation (ca. 6%) is obtained with the monolith configuration. Both Pt and Rh-based catalysts allow a good control of carbon formation, the coke being fully combusted during the regeneration step. Slow deactivation phenomena and selectivity changes along time on stream, mostly observed for platinum powder samples, are related to changes in catalyst structure and to the peculiar role of oxygen stored in the zirconia-ceria support. The heat balance evaluation of the sequential cracking/regeneration cycle shows that the process could be auto-thermal, i.e., minimizing the energy input, being competitive with conventional steam-reforming process under the same operating temperature.

Hydrogen production from biomass-derived pyrolysis oil is performed using a cracking/regeneration sequential process. Pt/and Rh/Ce0.5Zr0.5O2 catalysts are comparatively studied, both leading to efficient H2 production and ensuring a good control of carbon deposition and combustion. The use of supported monolith instead of powder catalyst enhances H2 productivity and stability by decreasing side-products formation and improving soots gasification.Figure optionsDownload as PowerPoint slide