Catalytic decomposition of tar using iron supported biochar

• Iron supported biochar catalysts lowered the activation energy for toluene reforming by 47% (91 to 48 kJ/mole).
• Toluene decomposition activity was comparable to, or higher than olivine, or nickel supported catalysts.
• Benzene selectivity declined with increasing reaction temperature and never increased above 0.2 for the iron biochar.
• Long term catalytic activity (~4 days) resulted in a high toluene conversion (>90%) and lower benzene selectivity (<0.05).

Iron supported biochar catalysts were used to decompose toluene, a model tar compound, over a temperature range of 600–900 °C. Toluene conversion and decomposition rates increased linearly with increasing temperature and catalyst loading from 600 to 700 °C. Relative to biochar alone, the iron supported catalysts lowered the activation energy by 47% and decreased the formation of benzene, an intermediate in toluene decomposition. At 800 °C for the 13 and 18.7 wt.% iron loaded catalyst, toluene conversion approached 100% and benzene selectivity (SB) was zero, compared to an SB of 0.025% and 0.35% for 10% iron and the biochar, respectively. Time on stream studies with the 13 wt.% iron biochar catalyst, over the course of four days, resulted in a mean toluene conversion of 91% and benzene selectivity of 0.02%. These results indicate that inexpensive iron impregnated biochar catalysts could potentially be used to catalytically decompose tar molecules in syngas generated via biomass gasification.