Oxygenated gasoline additives: Saturated heat capacities between (277 and 355) K

The saturated heat capacities of oxygenated gasoline additives methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), diisopropyl ether (DIPE), and tert-amyl methyl ether (TAME) in the temperature range of 277.15 K to some degrees below their normal boiling temperatures have been measured. A Micro DSC II from Setaram (France) with batch cells designed in our laboratory and the “scanning method” were used to perform the measurements. The estimated uncertainty of the saturated heat capacities was better than 0.3%. In the literature, there exist csat(T) data for some of the liquids studied. Agreement with our measurements is within the range of the experimental uncertainties. At each temperature, the saturated heat capacity of liquid MTBE is smaller than those of ETBE, DIPE, and TAME, and the corresponding csat values of these three liquids are similar. This behavior can be related with the surface fraction of the ether group in each molecule.