Catalytic decomposition of biogas to produce hydrogen rich fuels for SI engines and valuable nanocarbons

Abstract Catalytic Decomposition of Biogas (CDB), producing simultaneously syngases (SG), with high hydrogen contents, for spark ignition (SI) engines and bio-carbon nanofibers (BCNFs) to be further used as precursor of synthetic graphite, is presented as an alternative to the usual direct combustion. Synthetic biogas mixtures were decomposed in the presence of a Ni catalyst at different temperatures and the SG thus produced were further tested as fuel in a specifically designed SI engine, whereas the BCNFs were subjected to heat treatment to graphitize. The influence of CDB process conditions on product yields and properties, the effect of SG composition/quality in SI engine performance and emissions, as compared with the use of raw biogas and the influence of BCNFs characteristics on the structural and textural properties of the graphitic materials have been studied. The syngases presented better combustion characteristics than biogas resulting in higher engine brake thermal efficiencies and lower exhaust emissions. Furthermore, high added value graphite-like materials, with a crystalline structure similar to that of oil-derived graphite which is currently commercialized to be used as anode in rechargeable lithium-ion batteries, were prepared.