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

• Published in: Journal of fluorine chemistry Vol. 150; pp. 46 - 52
• Main Authors: Chen, Miao, Jin, Jia-Min, Lin, Sheng-Da, Li, Ying, Liu, Wu-Can, Guo, Li, Li, Ling, Li, Xiao-Nian
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.2013
• Subjects: Chlorodifluoromethane dismutation; High surface area; Lewis acidity; Magnesium fluoride; Silica-template; Silica-template; Chlorodifluoromethane dismutation; Lewis acidity; Magnesium fluoride; High surface area
• ISSN: 0022-1139; 1873-3328
• DOI: 10.1016/j.jfluchem.2013.03.003

Silica-template synthesis was adopted in the synthesis of mesoporous MgF2. In contrast to conventional MgF2, higher Lewis acidity, modified surface and textual properties and far superior catalytic performance in dismutation of CHClF2 were achieved for the silica-templated samples. •Preparation of mesoporous MgF2 via SiO2-template method.•Sample MgF2-1/6 achieved surface area of 92m2/g after calcination at 573K.•Increased Lewis acidity, especially for strong acid site, was achieved.•SiO2-templated MgF2 showed far superior activity for CHClF2 dismutation.•Improved activities were attributed to beneficial surface and acidic properties. 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 92m2/g after calcination at 573K. 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.