Determination and correlation of heat of mixing of the carbon dioxide + tert-butyl methyl ether system at 298.15 and 303.15 K and 5.0–7.0 MPa

• The heat of mixing (ΔHM) of the CO2 + tert-butyl methyl ether system have been measured at 298.15 and 303.15 K and 5.0–7.0 MPa.
• The experimental ΔHM data indicated exothermic behavior for all compositions at all studied temperatures and pressures.
• Two-phase region, where ΔHM varied linearly with composition, was found in the CO2-rich region except at 298.15 K and 7.0 MPa.
• Experimental ΔHM data within the one-phase region were correlated with the modified Redlich–Kister equation and Peng-Robinson equation of state coupled with the van der Waals one fluid mixing rule.
• The correlated results from the modified Redlich–Kister equation are better than those from the Peng-Robinson equation of state.

The heat of mixing (ΔHM) of the carbon dioxide + tert-butyl methyl ether system was measured near the critical point of carbon dioxide using a flow-type isothermal microcalorimeter at 298.15 and 303.15 K and 5.0–7.0 MPa. The mixtures showed strong exothermic behavior in these regions. The maximum absolute value of ΔHM (maximum exothermic value) was about 7.9 kJ mol−1 at 298.15 K and 5.0 MPa. A two-phase region, where ΔHM varied linearly with composition, was found in the CO2 rich region at all temperatures and pressures except at 298.15 K and 7.0 MPa.