Measurement and correlation of the solid–liquid–gas equilibria for carbon dioxide + normal chain saturated aliphatic hydrocarbon systems

Abstract

The pressure p–temperature T projections of solid–liquid–gas (S–L–G) three-phase coexistence lines for the carbon dioxide + tetradecanoic acid (C 14H 28O 2) system, the carbon dioxide + hexadecanoic acid (C 16H 32O 2) system, and the carbon dioxide + 1-hexadecanol (C 16H 34O) were measured by the first melting point method in which the initial appearance of the liquid phase was observed. The profiles of the p– T projections of the S–L–G lines for the carbon dioxide + acid systems are similar to each other, the S–L–G equilibria for the carbon dioxide + acid systems are, however, different from that for the carbon dioxide + 1-hexadecanol systems. The experimental p– T projections of the S–L–G lines were also correlated by the Peng–Robinson equation of state and the van der Waals type mixing rules with two binary interaction parameters introduced into attraction term and size terms, respectively. The present model gave good correlation results for all of the experimental S–L–G lines with maximum average absolute relative deviations of 0.075% for the carbon dioxide + tetradecanoic acid system, 0.14% for the carbon dioxide + hexadecanoic acid system and 0.28% for the carbon dioxide + 1-hexadecanol system, respectively.