Photocatalytic Conversion of Biomass and Nitrate into Glycine

Biomass is a renewable carbon source that comes from plants, containing chemical energy from the sun. Nitrate, which is a N-containing feedstock with a lower dissociation energy, has a rich distribution in wastewater. Renewable biomass and nitrate waste can be converted into valuable C–N products through photocatalytic processes, which is becoming promising but challenging in the production of different kinds of chemicals and fuels. Herein, we report the photoconversion of biomass and nitrate into glycine with a 765 μmol gcat–1 h–1 production rate and 15.3% yield over a Ba2+-modified TiO2 catalyst. The process cascades multiple reactions containing the photoreforming of biomass to glycol, nitrate reduction to NH3, and finally, C–N coupling to glycine, among which nitrate ions play a dominant role in the selective cleavage and oxidation of biomass. Surprisingly, after hydrolysis pretreatment, biopolyols or sugars and even raw wood sawdust could react with nitrate to generate glycine. This study provides an effective catalytic system to produce glycine from renewable biomass and nitrate waste under mild conditions.