Development of HF-Shuttling Catalysts for Fluorocarbon Recycling

• Applicant: Dr. Raphael Bühler
• Subject Area: Inorganic Molecular Chemistry - Synthesis and Characterisation
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 575637459

Fluorocarbons have come under increasing scrutiny due to their environmental persistence, potential health risks, and contribution to global warming. At the same time, fluorine-containing compounds remain essential across a range of high-value sectors, including pharmaceuticals, agrochemicals, and advanced materials. Their synthesis, however, continues to depend on raw materials such as fluorspar (CaF2), a non-renewable and sensitive resource. This unsustainable reliance highlights the urgent need for circular chemical strategies that can enable fluorine recovery, reduce dependency on primary sources, and minimize environmental impact. The objective is to address this challenge by developing molecular HF-shuttling catalysts based on main-group Lewis acid and base pairs. These systems will mediate the selective transfer of hydrogen fluoride equivalents between donor and acceptor molecules, thereby enabling the catalytic defluorination and upcycling of fluorocarbon waste streams and by-products. This approach represents a new conceptual framework for achieving circular fluorine economy through main group Lewis acid and base catalysis, with the potential to unlock sustainable pathways for fluorine recycling. The project integrates recent breakthroughs in main-group chemistry with cutting-edge automation and mechanistic insight. A tailored library of borane-phosphine catalysts will be constructed and systematically screened using robotic high-throughput experimentation (HTE) under air- and moisture-free conditions. The use of Design of Experiment (DOE) principles will ensure rational and efficient exploration of chemical space. Mechanistic understanding will be developed through multinuclear NMR spectroscopy, in situ infrared spectroscopy, and advanced mass spectrometry optimized for reactive intermediates. These data will feed directly into quantum chemical based mechanistic modeling, enabling a fully integrated experimental-theoretical approach to catalyst design and optimization. In the final stage, promising catalytic systems will be translated from batch to continuous flow conditions, leveraging available Vapourtec and Uniqsis reactors for the safe and scalable handling of demanding substrates, including fluorinated gases such as HFC-134a. This transition will demonstrate the platform’s practical viability, robustness, and potential for industrial adaptation. By establishing a new molecular platform for selective C-F bond activation, this project will contribute to the foundations of sustainable fluorine chemistry and offer a catalytic blueprint for circular resource utilization.

• DFG Programme: WBP Fellowship
• International Connection: United Kingdom
• Host: Professor Dr. Mark R. Crimmin