Decomposition of biomass gasification tar model compounds over waste tire pyrolysis char

Gasification of biomass produces a syngas containing trace amounts of viscous hydrocarbon tar, which causes serious problems in downstream pipelines, valves and processing equipment. This study focuses on the use of tire-derived pyrolysis char for tar conversion using biomass tar model compounds representative of tar. The catalytic decomposition of tar model compounds, including methylnaphthalene, furfural, phenol, and toluene, over tire char was investigated using a fixed bed reactor at a bed temperature of 700 °C and 60 min time on stream. The influence of temperature, reaction time, porous texture, and acidity of the tire char was investigated with the use of methylnaphthalene as the tar model compound. Oxygenated tar model compounds were found to have higher conversion than those containing a single or multi-aromatic ring. The reactivity of tar compounds followed the order of furfural > phenol > toluene > methylnaphthalene. The conversion of the model compounds in the presence of the tire char was much higher than tar thermal cracking. Gas production increased dramatically with the introduction of tire char. The H₂ potential for the studied tar model compounds was found to be in the range of 40%–50%. The activity of tire char for naphthalene removal was compared with two commercial activated carbons possessing a very well-developed porous texture. The results suggest that the influence of Brunauer-Emmett-Teller surface area of the carbon on tar cracking is negligible compared with the mineral content in the carbon samples.

Graphical abstract