Preparation of Solid Acid Catalyst from Industrial Waste Kraft Lignin for Methyl Oleate Production by Esterification

A solid acid catalyst KLC-SO3H bearing SO3H, COOH and phenolic OH groups was synthesized by the sulfonation of industrial waste kraft kraft lignin-based activated carbon (KLC) which was prepared from phosphoric acid (PA) activation. The KLC support and the catalyst were characterized by a variety of techniques. The prepared catalyst exhibits good activity to catalyze the esterification of oleic acid with methanol. Yield of methyl oleate as high as 93.2% was obtained under the temperature of 80 °C, methanol to oleic acid molar ratio of 10:1, reaction time of 12 h and catalyst loading of 10% (based on oleic acid). The prepared KLC-SO3H catalyst showed similar catalytic activity with the carbon acid catalyst from cellulose and the commercial catalyst Amberlyst-15 in the esterification reaction. The high catalytic activity of KLC-SO3H was probably due to the large specific surface area, pore volume of KLC support, which provided more acid sites for the reactants.