首页|A rapid synthesis of Hf-Beta zeolite as highly active catalyst for Meerwein-Ponndorf-Verley reduction by controlling water content of precursor gel
A rapid synthesis of Hf-Beta zeolite as highly active catalyst for Meerwein-Ponndorf-Verley reduction by controlling water content of precursor gel
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NSTL
Elsevier
Hf-Beta is a promisingly active Lewis acid catalyst for Meerwein-Ponndorf-Verley (MPV) reduction and other important organic reactions. However, the conventional hydrothermal synthesis of Hf-Beta inevitably requires the troublesome procedure for hydrolysis of tetraethoxysilane and the long period to complete crystallization. In the present study, we applied a synthetic approach of reducing water content of precursor gel and succeeded in considerably shortening the period for crystallization of Hf-Beta using fumed silica as silicon source. By using precursor gel with H2O/SiO2 = 1.4-7.6, effect of water content of precursor gel on the crystallization of Hf-Beta, the incorporation of Hf into the zeolite framework, and the catalytic performance were thoroughly investigated. Low water content was favorable for accelerating the crystallization, but unfavorable for the incorporation of Hf into the zeolite framework, resulting in poor catalytic activity. With the assistance of seed crystal, Hf-Beta with a relatively large amount of framework Hf was obtained from the precursor gel with H2O/SiO2 = 6.4 in 24 h. HfBeta synthesized in this way showed higher catalytic activity for MPV reduction than Hf-Beta as well as Zr-, and Sn-Beta synthesized by the conventional hydrothermal method.
NSTL
Elsevier
