The researchers studied how char from Fallopia Japonica stem affects the conversion of tar during biomass gasification. They made different chars at varying temperatures and times, then used them as catalysts for tar reforming. They found that chars with lower pyrolysis temperatures had higher reactivity but lower tar reforming ability. Chars with higher surface areas had decreased reactivity initially, but then increased. The promoting effect of char on tar reforming first increased and then decreased due to changes in chemical components and pore structure.