EAGER: Photocatalytic extension of short-chain molecules for biomass conversion

Boston College, Chestnut Hill MA

Investigators

Abstract

The project investigates a sustainable process that uses catalytic reactions driven by solar energy to convert biomass to hydrocarbon chemicals. The process uses a new catalytic material that generates small reactive molecules that combine to form larger molecules with 10-20 carbon atoms, like those found in diesel and jet fuels. By using biorenewable feedstocks in combination with solar-driven chemical processing, the project could lay the groundwork for a near-zero greenhouse gas technology for producing fuels and high-value chemicals from biomass. The project includes a novel outreach program that educates high-school students in current science issues and provides opportunities for them to be spokespersons for conveying those issues to the broader public. Photocatalysis has recently been reported to enable room-temperature dehydrogenative C-C coupling of 2,5-dimethyl furan (2-5 DMF) and 2-methy furan (2-MF) while producing hydrogen simultaneously. However, the process suffers from low conversion and poor selectivity, as well as sensitivity to oxygen. The underpinning mechanism (i.e. the radical species generated from C-H activation of the methyl group would resonate to furan rings and lead to a variety of isomer products) is understood as a key reason for this important deficiency. Recently, one of the investigators has discovered that under photoelectrochemical conditions, Ta3N5 can enable an alternative radical-based pathway that is not only highly efficient but also insensitive to impurities such as H2O or O2 in ambient air. The project will extend those studies to photocatalytic biomass conversion. To that end, detailed understanding of the reaction mechanism is needed. The mechanistic studies will include light-dark experiments, detailed product characterization, and experimentation with various radical generator and acceptor species. Moreover, comparisons will be made between the Ta3N5 utilized as a photoelectrode and as a heterogeneous photocatalyst, with co-catalysts such as platinum included in some cases. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.