Waste of biodiesel production: conversion of glycerol into biofuel additives

Abstract

The condensation of glycerol with acetone was performed using silicotungstic acid (SiW) immobilized in SBA-15, at 70ºC. The main product of glycerol acetalization was solketal. Different techniques were used to characterize the catalysts. A series of catalysts with dif-ferent heteropolyacid loading were prepared. It was observed that the catalytic activity in-creases with the amount of SiW immobilized in SBA-15, being the SiW2@SBA-15 (with 7.8 wt. %) the most active sample. All catalyst exhibited good values of selectivity to sol-ketal (about 99% near complete conversion). To optimize the reaction conditions, the ef-fect of different reaction parameters (catalyst loading, molar ratio of glycerol to acetone and temperature), on the glycerol acetalization over the SiW2@SBA-15 catalyst, was stud-ied. Catalytic stability of the SiW2@SBA-15 was evaluated by performing consecutive batch runs with the same catalyst sample. It was observed that, after the third use, the cata-lytic activity stabilized.