Continuous Synthesis of Fuel Additives Alkyl Levulinates via Alcoholysis of Furfuryl Alcohol over Silica Supported Metal Oxides

Aiming at synthesizing alkyl levulinates via alcoholysis of furfuryl alcohol in continuous mode for the first time an attempt is made using cheapest and eco-friendly solid acid catalysts. Different silica supported solid acid catalysts containing the oxides of aluminium, tungsten, zirconium and titanium have been prepared. The nature, number and strength of surface acidic sites were evaluated by DRIFT spectroscopy with pyridine adsorption and NH 3 -TPD and also structural and textural features of the catalysts have been investigated by XRD and BET surface area techniques. Al 2 O 3 /SiO 2 catalyst exhibited better activity with 100% conversion of furfuryl alcohol and 92.8% selectivity of methyl levulinate, which may be due to more number of surface acidic sites with large number of weak Lewis acidic sites. The catalytic activity of these solid acid catalysts is as follows: Al 2 O 3 /SiO 2 > ZrO 2 /SiO 2 > WO 3 /SiO 2 > TiO 2 /SiO 2 . This is well correlated with the number of surface acidic sites. The stable catalytic activity during the 10 h time-on-stream study confirmed the sturdiness of Al 2 O 3 /SiO 2 catalyst and also it is active for the selective formation of ethyl, n -propyl, n -butyl levulinates. Graphical Abstract