One-Step HF-Free Synthesis of Alkali Metal Fluorides from Fluorspar
Alkali metal fluorides (MF) are commodity chemicals currently synthesized from naturally occurring fluorite (fluorspar, CaF<sub>2</sub>) in two steps: conversion of acid grade fluorspar (AGF) into highly hazardous hydrogen fluoride (HF) followed by neutralization with alkali metal hydroxides/carbonates. Herein, we report a one-step mechanochemical reaction that converts AGF into alkali metal fluorides under basic conditions, bypassing HF. The method consists of reacting AGF with alkali metal (hydr)oxides and titanium dioxide (TiO<sub>2</sub>) under mechanical energy for MF formation and <i>in situ</i> sequestration of calcium (hydr)oxide byproducts as calcium titanate (CaTiO<sub>3</sub>). Ca<sup>2+</sup> sequestration prevents reversible CaF<sub>2</sub> formation upon aqueous extraction, thus enabling the isolation of alkali metal fluorides. We also demonstrate that alkali metal titanates (M<sub>2</sub>TiO<sub>3</sub>) are suitable reagents for both CaF<sub>2</sub> activation and Ca<sup>2+</sup> sequestration, with K<sub>2</sub>TiO<sub>3</sub> being optimal for KF synthesis.
Authors
- Michael A. Hayward (ORCID: https://orcid.org/0000-0002-6248-2063)
- Christopher A. Goult (ORCID: https://orcid.org/0000-0002-5834-8371)
- Véronique Gouverneur (ORCID: https://orcid.org/0000-0001-8638-5308)
- Thomas Schlatzer (ORCID: https://orcid.org/0000-0001-5034-0968)
Institutions
- University of Oxford (GB)
- Laboratoire de Chimie (FR)
Publication Details
- Journal
- Journal of the American Chemical Society
- Published
- 2025-02-18
- DOI
- https://doi.org/10.1021/jacs.4c16608
- Citations
- 9
- Primary Topic
- Inorganic Fluorides and Related Compounds
- Type
- article
- Field-Weighted Citation Impact
- 4.84
Funders
- Austrian Science Fund
- H2020 European Research Council