High pressure investigations on fluid mixtures with a diamond anvil cell: Liquid-liquid phase equilibria and ''high pressure immiscibility'' of the system 1-butanol plus 2-methyl-2-propanol plus water up to 2.9 GPa

The phase equilibria of the ternary system 1-butanol + 2-methyl-2-propanol + water are investigated in the temperature range from 320 K to 470 K and at pressures up to 2.9 GPa using the diamond anvil cell (DAC) technique. T(p) isopleths that have been determined experimentally for selected constant compositions are presented. Liquid-liquid phase separation exhibiting lower solution pressures is found; here a pressure increase results in an expansion of the miscibility gap. In the lower temperature range crystallization occurs. The results are discussed especially with respect to the appearance of so-called ''high pressure immiscibility'' phenoma.