TAILIEUCHUNG - Mg-Al-MoO4 layered double hydroxides used as catalysts for the oxidation of styrene

The catalytic activity and product selectivity depend on the reaction conditions and oxidant nature. The styrene conversion is moderate about 10-15 % and the total selectivity to benzaldehyde and styrene oxide reached 99 % as air and t-butyl hydrogen peroxide used as milder oxidants. | Vietnam Journal of Chemistry, International Edition, 55(4): 489-493, 2017 DOI: Mg-Al-MoO4 layered double hydroxides used as catalysts for the oxidation of styrene Nguyen Tien Thao*, Nguyen Duc Trung, Dang Van Long, Vu Dong Thuc Faculty of Chemistry, Vietnam National University, Hanoi Received 19 September 2016; Accepted for publication 28 August 2017 Abstract Mg-Al layered double hydroxides have been prepared by the precipitation method and characterized by the physical methods such as XRD, EDS, SEM. The synthesized solids showed the layered hydroxide structure with molybdate and carbonate anions as interlayer compensating anions in the uniform particles. While Mg-Al-CO3 is inactive for the liquid oxidation of styrene, Mg-Al-MoO4–LDH catalyst exhibits a good activity in the conversion of styrene into benzaldehyde and phenyl oxirane. The catalytic activity and product selectivity depend on the reaction conditions and oxidant nature. The styrene conversion is moderate about 10-15 % and the total selectivity to benzaldehyde and styrene oxide reached 99 % as air and t-butyl hydrogen peroxide used as milder oxidants. Keywords. Benzaldehyde, styrene, molybdate, hydrotalcite, oxidation. 1. INTRODUCTION Layered double hydroxides (LDHs) are composed of an unusual class of layered materials with positively charged hydroxide layers and charge balancing, mobile anions stayed in the interlayer regions. In details, LDHs have a similar structure to brucite-like Mg(OH)2 sheet where an isomorphous substitution of Mg2+ by a trivalent element M3+ occurs. In brucite, each magnesium cation is octahedrally surrounded by hydroxyl groups [1]. The resulting octahedron shares edges to form infinite sheets. When Mg2+ ions are isoamorphously replaced by a trivalent ion, a positive charge is created in the brucite layer. The positive charge is then compensated by foreign anions in the interlayer sheets [1, 2]. The layered hydroxide compounds are generally .

• Hoá học
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• Mg Al MoO4 layered double hydroxides
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• The synthesized solids showed the layered hydroxide structure
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