Solvent-based fatty alcohol synthesis using supercritical butane. Thermodynamic analysis

Conventional liquid‐phase fatty ester hydrogenolysis processes are necessarily operated at high pressures owing to the limited solubility of hydrogen in the reaction medium. In a solvent‐based process this problem can be overcome, but recycling and product‐solvent separation may turn out to be difficult. An alternative is the use of supercritical solvents, for which the solubility of fatty esters and fatty alcohols is high. Dropping the pressure into the subcritical domain allows for easy product separation and reactant recycle. In the present work we have analyzed the hydrogenolysis of methyl palmitate in supercritical butane. A reliable estimation of properties of the supercritical mixture can be obtained by fitting experimental vapor‐liquid equilibrium data with Schwatzentruber‐Renon cubic equation of state. The reaction mixture remains supercritical for a maximum pressure of 9 MPa and temperature of 470 K for mole fractions of hydrogen and methyl palmitate of 0.1 and 0.025, respectively. In these conditions an equilibrium conversion of more than 99% can be reached. An industrial process is feasible.