Synthesis of Pb(OH)₂/rGO Catalyst for Conversion of Sugar to Lactic Acid in Water

Conversion of sugars from biomass to platform chemicals or fuels is an attracting topic for the utilization of biomass. Pb²⁺ ion is an efficient catalyst for the degradation of sugar to lactic acid, and it will be better to fix lead on a solid catalyst to reduce the risk of exposure of Pb²⁺ to environment. Here, a simple method has been developed to prepare a composite catalyst of Pb(OH)₂/rGO, where the nanoparticles of Pb(OH)₂ in size of 2-5 nm were prepared and fixed over the as-prepared reduced graphene oxide (rGO) nanosheets. The as-obtained catalyst showed an efficient catalytic activity to degrade glucose, fructose, and cellulose in aqueous solution, and the major product is lactic acid. The yield of lactic acid reached 58.7% when fructose was used as the feedstock (433 K and 2.5 MPa N₂), and the catalyst can be recycled with high activity. Cellulose can also be directly converted into lactic acid in aqueous solution over the catalyst without extra acid or alkali, and the maximum yield of lactic acid is 31.7%.