Schlatzer Thomas, Goult Christopher A, Hayward Michael A, Gouverneur Véronique
Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Oxford OX1 3TA, United Kingdom.
Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, Oxford OX1 3QR, United Kingdom.
J Am Chem Soc. 2025 Feb 26;147(8):6338-6342. doi: 10.1021/jacs.4c16608. Epub 2025 Feb 17.
Alkali metal fluorides (MF) are commodity chemicals currently synthesized from naturally occurring fluorite (fluorspar, CaF) 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) under mechanical energy for MF formation and sequestration of calcium (hydr)oxide byproducts as calcium titanate (CaTiO). Ca sequestration prevents reversible CaF formation upon aqueous extraction, thus enabling the isolation of alkali metal fluorides. We also demonstrate that alkali metal titanates (MTiO) are suitable reagents for both CaF activation and Ca sequestration, with KTiO being optimal for KF synthesis.
碱金属氟化物（MF）是目前通过两步法从天然萤石（氟石，CaF）合成的商品化学品：首先将酸级萤石（AGF）转化为高危险性的氟化氢（HF），然后用碱金属氢氧化物/碳酸盐进行中和。在此，我们报道了一种一步机械化学反应，该反应在碱性条件下将AGF转化为碱金属氟化物，绕过了HF。该方法包括在机械能作用下使AGF与碱金属（氢）氧化物和二氧化钛（TiO₂）反应以形成MF，并将氢氧化钙副产物螯合为钛酸钙（CaTiO₃）。钙的螯合可防止水萃取时可逆形成CaF₂，从而能够分离出碱金属氟化物。我们还证明碱金属钛酸盐（MTiO₃）是用于CaF₂活化和钙螯合的合适试剂，其中K₂TiO₃对于KF合成最为理想。
