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

该项目研究了一个可持续的过程，利用太阳能驱动的催化反应将生物质转化为碳氢化合物化学物质。这个过程使用了一种新的催化材料，可以产生小的反应分子，这些分子结合形成含有10-20个碳原子的大分子，就像柴油和喷气燃料中发现的那样。通过将生物可再生原料与太阳能驱动的化学加工相结合，该项目可以为从生物质中生产燃料和高价值化学品的近零温室气体技术奠定基础。该项目包括一个新颖的外展项目，教育高中生了解当前的科学问题，并为他们提供机会成为向更广泛的公众传达这些问题的代言人。最近有报道称，光催化可以实现2,5-二甲基呋喃（2-5 DMF）和2-甲基呋喃（2- mf）的室温脱氢C-C偶联，同时产生氢。然而，该工艺的缺点是转化率低，选择性差，对氧敏感。基础机制（即甲基C-H活化产生的自由基会与呋喃环共振并导致各种异构体产物）被认为是这一重要缺陷的关键原因。最近，一位研究人员发现，在光电化学条件下，Ta3N5可以实现一种替代的基于自由基的途径，这种途径不仅效率高，而且对环境空气中的H2O或O2等杂质不敏感。该项目将把这些研究扩展到光催化生物质转化。为此，需要详细了解反应机理。机理研究将包括光-暗实验、详细的产物表征以及不同自由基产生和受体种类的实验。此外，还将比较Ta3N5作为光电极和作为非均相光催化剂，在某些情况下还包括铂等共催化剂。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.