SiO2-template synthesis of mesoporous MgF2 highly effective for Cl/F exchange reaction

An efficient and cost-effective route has been developed for the controllable synthesis of high-surface-area MgF2 materials with variable surface acidity and improved catalytic performance for Cl/F exchange reaction. This route is based on a facile non-surfactant template method, in which MgO–SiO2 precursors were obtained at varied Si/Mg ratios via ammonia coprecipitation in aqueous media, followed by depletion of the SiO2 template in 40% aqueous HF solution. The thus-derived MgF2 is featured with superior surface area, uniform mesopores, and significantly improved Lewis acidity relative to conventional MgF2. Among samples synthesized, that with Si/Mg molar ratio at 1/6 achieved the highest surface area amounted to 92 m2/g after calcination at 573 K. Probe reaction by CHClF2 dismutation has demonstrated far superior Cl/F exchange activities for SiO2-templated MgF2 samples relative to their non-templated analog, as may be accounted for by the combined effect of promoted surface properties and significantly enhanced surface acidity.