Gasification char as a functional reactor material for tar reforming and hydrogen-enriched syngas production

Biomass gasification produces raw syngas containing tar and light hydrocarbons, which reduce carbon-conversion efficiency and increase the complexity of downstream cleaning and utilization. This study investigates gasification char as an in situ reforming medium for primary syngas upgrading under realistic high-temperature conditions (800–1000°C), with a comparison among an empty reformer, a fixed bed containing alumina and char, and dilute transported-char injection. Gravimetrically measured tar reduction increased by approximately 30–40% relative to thermal reforming alone under the tested conditions, with the strongest tar removal observed in the upper part of the investigated temperature range. First-order kinetic analysis gave apparent activation energies of 113 and 98 kJ mol⁻¹ from laminar-flow and plug-flow interpretations, respectively, confirming the strong temperature dependence of tar reforming. In the fixed-bed configuration, methane conversion approached about 30% near 925°C, whereas dilute transported-char injection did not produce a comparable hydrocarbon-conversion effect. In addition, transported-char experiments showed increased CO₂ formation and a rise in outlet H₂/CO ratio from about 1.48 to 2.08 across the investigated char-concentration range, indicating a stronger water–gas shift-related response. These results show that gasification char can function as a useful reactor material for tar reforming and syngas upgrading rather than merely as a residual solid.