Reaction Condition-Modulated Selectivity Enhancement in Glucose Photorefining under Visible Light-Driven Photocatalysis

Abstract

Awareness of the effects of modernization have endowed environmentally friendly alternatives for existing technologies with a newfound priority. In particular, the chemicals production industry is an example of a field with great opportunity for green innovation and the incorporation of renewable feedstocks and energy sources. The potential of the novel photo-biorefinery concept outshines traditional biomass utilization strategies due to its use of solar energy to produce valuable chemicals from biomass feedstocks. In light of this, it is important to anticipate questions that will dictate the industrial feasibility of the photo-biorefinery. The present study examines the effects of various critical process parameters on the photocatalytic conversion of the primary building block of biomass – glucose. Two visible light photocatalysts are chosen for study – nickel titanate (NTO) and functionalized carbon nitride (NCN). In the photocatalytic conversion of glucose by NTO, a pure aqueous solvent under an air headspace proved optimal and resulted in 9% glucose conversion with 75% selectivity for arabinose. The optimal reaction conditions for photocatalytic conversion of glucose by NCN were determined to be 1M NaOH and an ambient headspace. At these conditions, 100% glucose conversion to lactic acid and 78% H2 yield was attained. This study identifies the active radical species in glucose conversion by nickel titanate and proposes mechanisms for the conversion of glucose by both nickel titanate and a functionalized carbon nitride. The study also provides new insights into how various reaction conditions affect the photocatalytic conversion of glucose by nickel titanate and functionalized carbon nitride.