Syngas production from biomass pyrolysis followed by in-line biochar-catalytic reforming: the effect of space velocity, particle size, and morphology

A continuous pyrolysis combined with an in-line biochar-catalytic reforming of the pyrolysis vapor was investigated in a comprehensive system consisting of an auger reactor and a downstream fixed-bed reactor. The effect of the weight hourly space velocity (WHSV), particle size and morphology of biochar, and the pressure drop of the biochar bed on the catalytic performance were discussed in this study. Results showed that lower WHSV, which allows longer residence time, led to higher syngas yield and increased H 2 +CO proportion. The use of the smallest biochar particles (0.6–1 mm) produced the highest syngas and H 2 yields, correlating with the greatest pressure drops. Spherical and rounded biochar particle shape enhanced syngas and H 2 yields, as well as H 2 +CO proportions, due to improved heat and mass transfer. A maximum of 12 mmol H 2 /g-biomass was achieved, with a dry gas yield of 0.68 Nm 3 /kg, comprising 39 vol % H 2 and 27 vol % CO, at the use of pelletized biochar with a WHSV of 0.51. The used biochar demonstrated stable catalytic performance as a reforming catalyst in a 100-min test period. • An auger pyrolyzer combined with a biochar-fixed-bed for syngas production. • Lower WHSV yield higher syngas and H 2 +CO concentration due to longer residence time. • Smaller particle sizes result in higher syngas yield with higher bed pressure drop. • Spherical and rounded particles favor higher syngas and H 2 yields, H 2 +CO proportion. • Stable biochar catalytic performance for 100-min experimental running.