Kinetic & thermodynamic studies of green fuel additive solketal from crude glycerol over metakaolin clay catalyst

Abstract

Biodiesel synthesis produces about 10 % glycerol as a byproduct, prompting environmental concerns. The utilization of crude glycerol into valuable products requires an Eco-friendly technique. This study depicts glycerol acetalization using acetone and novel catalyst acid-treated metakaolin clay. Raw kaolin clay was calcined at 600 °C and treated with acid at 102 °C for 3 h. Afterward, acid activated clay was filtrate and dried in oven to remove moisture content. The catalyst prepared with a 5 M solution of sulfuric acid exhibited the highest surface area of 82.33 m2. g−1 and gave the highest yield (80 %) of Solketal with 73 % of glycerol conversion under optimum conditions. The ketalization reaction of Solketal synthesis was studied in terms of thermodynamics and kinetics. A Langmuir-Hinshelwood rate expression based on two-parameter kinetic law was used in this study. From the kinetic studies, activation energies (EA) of forward and backward reactions were found to be K1 = 39.23 kJ. mol−1 and K2 = 35.70 kJ. mol−1 respectively. Furthermore, reaction was exothermic having an enthalpy of ΔHo = −18.86 kJ. mol−1 and the entropy ΔSo = −0.1 kJ. mol−1 calculated from this process. Solketal derived from sustainable sources such as bio-glycerol and biomass-based acetone, has a wide range of uses as fuel additives and medicines industry. This research marks a significant advancement in the development of a continuous synthesis technique for Solketal and its recovery from glycerol-acetone mixtures.