EQUILIBRIUM-CONSTANTS FOR METHYL TERT-BUTYL ETHER LIQUID-PHASE SYNTHESIS

Equilibrium constants for the liquid-phase synthesis of methyl tert-butyl ether (MTBE) were determined experimentally In the temperature range 40-80-degrees-C. Equilibrium was established in the methanol addition to isobutylene for obtaining MTBE over the sulfonic acid resin Lewatit SPC 118 as the catalyst in a batch reactor maintained at 1.6 MPa. The experimental equilibrium constant is given as a function of temperature, and enthalpy, free energy, and entropy changes have been determined as well. At 298 K, DELTA-H-degrees = -38.0 +/- 0.8 kJ mol-1, DELTA-G-degrees = -13.6 +/- 0.8 kJ mol-1, and DELTA-S-degrees = -81.7 +/-0.5 J mol-1 K-1. The UNIFAC estimates of activity coefficients have been used to describe the liquid-phase nonideality. A comparison of experimental, thermodynamic, and literature data has been carried out.