To determine whether or not furfural is the key intermediate to
produce lactic acid, we examined furfural as the reactant under the
same conditions that xylose reacted. No lactic acid was produced
with furfural as feedstock (Table S1), suggesting that a dehydration step is unnecessary for lactic acid production over the ZrO2.It is widely accepted that Brønsted acids catalyze the dehydration
of xylose to produce furfural [29], while bases catalyze retro-aldol
condensation leading to the formation of lactic acid from glucose
or xylos