Phase behavior measurement of the binary carbon dioxide-N, N-dimethylacetamide and carbon dioxide-N, N-diethylacetamide systems at high pressure

Pressure-composition isotherms are obtained for the carbon dioxide-N, N-dimethylacetamide (N, N-DMA) and for the carbon dioxide-hi N-diethylacetamide (N, N-DEA) systems at 40, 60, 80, and 100 degrees C. These two carbon dioxide-polar solute systems have continuous critical mixture curves that exhibit maximums in pressure at temperatures between the critical temperatures of carbon dioxide and N,N-DMA or N,N-DEA. The experimental data are modeled using the multi-fluid-nonrandom lattice fluid (MF-NLF) equation of state. The coefficient of energy and volume parameters for each pure N,N-DMA or N,N-DEA is determined from a fit of the vapor pressure curve and saturated liquid densities. A good fit of the data is obtained with the MF-NLF equation using one adjustable mixture parameter that is temperature-independent, for the carbon dioxide-N,NDMA and carbon dioxide-N, N-DEA systems. (C) 2000 Elsevier Science B.V. All rights reserved.