Efficient catalytic oxidation of biomass to formic acid coupled with low-energy formaldehyde production from methanol

Formic acid (FA) is a bulk chemical and a promising hydrogen energy carrier. The development of FA production from renewable biomass instead of multiple-step production from diminishing fossil resources is attractive. Formaldehyde (FAld) is another bulk chemical but industrial production requires high temperatures (250–600 °C). Herein, efficient oxidation of biomass to FA coupled with low-energy FAld production was developed using heteropoly acids as catalysts. Biomass and derivatives were oxidized to FA in yields of up to 88.6% while methanol was selectively oxidized to FAld at 90–190 °C with a markedly enhanced reaction rate. The synergistic mechanism has been unveiled that biomass activates methanol oxidation by boosting the catalytic redox cycle to form hydroxyl radicals and methanol scavenges the hydroxyl radicals to inhibit the overoxidation of biomass. This work opens up a promising direction for efficient FA production from biomass coupled with low-energy oxidation of alcohols to aldehydes.