Ionic Liquid–Silicotungstic Acid Composites as Efficient and Recyclable Catalysts for the Selective Esterification of Glycerol with Lauric Acid to Monolaurin. Issue 14 (26th September 2016)

• Record Type: Journal Article
• Authors: Han, Xiaoxiang; Zhang, Xiaofang; Zhu, Guangqi; Liang, Juanjuan; Cao, Xianghui; Kan, Renjun; Hung, Chin‐Te; Liu, Li‐Li; Liu, Shang‐Bin
• Is Part Of: ChemCatChem. Volume 9:Issue 14(2017)
• Page Start: 2727
• Page End: 2738
• Publication Date: 2016-09-26
• Subjects: glycerol monolaurate -- kinetic -- process optimization -- propyl sulfonic ionic liquid -- silicotungstic acid; Catalysis -- Periodicals; 541.39505
• DOI: 10.1002/cctc.201600788
• Languages: English
• ISSNs: 1867-3880

Abstract

Abstract: The synthesis of glycerol monolaurate (GML) by the esterification of glycerol (GL) with lauric acid (LA) over a series of propyl sulfonic acid‐functionalized ionic liquids (SAFILs)‐modified silicotungstic acid (STA; H4 SiW12 O40 ) composite catalysts has been investigated. The synthesized organic–inorganic hybrid catalysts were characterized by different physicochemical techniques. In particular, their acidic properties were studied by solid‐state 31 P magic angle spinning (MAS) NMR spectroscopy by using adsorbed trimethylphosphine oxide (TMPO) as a probe. The effects of key reaction parameters, such as glycerol/lauric acid molar ratio, amount of catalyst, reaction time, and reaction temperature on LA conversion and GML product yield were elucidated and optimized with response surface methodology (RSM). The N, N ‐dimethyl(benzyl)ammonium propyl sulfobetaine (DMBPS)‐modified STA [DMBPSH]H3 SiW12 O40 exhibited the optimal catalytic activity and was exploited for process optimization. A highest GML yield of 79.1 % was achieved with the optimized reaction conditions. The high catalytic activity of these hybrid catalysts were attributed to strong acidity, low transport resistance, and their "pseudoliquid" characteristics. A kinetic study was made based on a second‐order irreversible model of the esterification reaction, which resulted in an activation energy of 39.49 kJ mol −1 for [DMBPSH]H3 SiW12 O40 under optimized reaction conditions. Abstract : Ionic liquid/silicotungstic acid composites : Eco‐friendly [DMBPSH]H3 SiW12 O40 (DMBPS= N, N ‐dimethyl(benzyl)ammonium propyl sulfobetaine) catalyst shows superior activity and a unique self‐separation property for facile recovery and recycling in the synthesis of glycerol monolaurate.