relate the presence of acetyl groups in xylan to the lower lactic acid
yields with xylan as the feedstock compared to those using xylose
as the feed. A doping study was performed to verify the acetyl
group effect on xylan. Acetic acid and ethyl acetate, as probes, were
deliberately added into the xylose conversion reaction system,
respectively. Table 3 shows thatthe yields of lactic acid from xylose
slightly decreased from ∼35% to ∼34% or ∼30% with adding ethyl
acetate or acetic acid, respectively, implying that the acetyl group
may only slightly affect the catalyst activity. On the other hand,
under the same reaction condition, the yield of lactic acid from
xylan was only ∼15%. Therefore, the extent of depolymerization
of xylan and the corresponding mass transfer limitations cannot be
excluded thatlead to a much lower lactic acid yield from xylan than
that from xylose if other reaction conditions are kept identical.