Kinetics of thermal decomposition of sodium methoxide and ethoxide

Abstract

Sodium methoxide and sodium ethoxide were synthesized. Their thermal decomposition and reaction kinetics were investigated under non-isothermal and isothermal conditions. Non-isothermal experiments were carried out at different linear heating rates. Kinetics of decomposition in each run was evaluated from the dynamic TGA and MS data obtained from thermogravimetric analyzer (TGA) coupled with mass spectrometer based evolved gas analyzer (EGA–MS). The activation energies derived from isothermal experiments by Arrhenius plot were 187.81 ± 11.22 and 150.84 ± 5.32 kJ mol −1 for sodium methoxide and sodium ethoxide, respectively, which agree well with the values from non-isothermal method. The evolved gases were found to be a mixture of saturated and unsaturated hydrocarbons. XRD, IR, AES, CHNS analyzer and volumetric estimation were employed to characterize the decomposition residue and identified as a mixture of sodium carbonate, sodium hydroxide and amorphous carbon. The probable mechanism and kinetics of decomposition of sodium alkoxides described in this paper are reported for the first time.