The structural evolution of the chars frompyrolysis of biomass components (cellulose

hemicellulose and lignin) in a xenon lamp radiation reactor was investigated. The elemental composition analysis showed that the C content increased at the expense of H and O contents during the chars formation. The values of

Δ

H/C

/

Δ

O/C

for the formation of cellulose and hemicellulose chars were close to 2

indicating that dehydrationwas the dominant reaction. Meanwhile

the value was more than 3 for lignin char formation

suggesting that the occurrence of demethoxylation was prevalent. FTIR and XRD analyses further disclosed that the cellulose pyrolysis needed to break down the stable crystal structure prior to the severe depolymerization. As for hemicellulose and lignin pyrolysis

the weak branches and linkages decomposed firstly

followed by the major decomposition. After the devolatilization at the main pyrolysis stage

the three components encountered a slow carbonization process to form condensed aromatic chars. The SEM results showed that the three components underwent different devolatilization behaviors

which induced various surface morpho

logies of the chars.