No abstract

Isothermal vapor−liquid equilibria (VLE) were obtained for ethyl tert-butyl ether + n-alcohol (C1−C4) at 333.15 K by headspace gas chromatography, and excess molar volumes were determined from density measurements using a vibrating tube densimeter at 298.15 K. The binary mixtures showed positive deviation from the Raoult's law, and those containing methanol and ethanol have minimum boiling azeotropes. The excess molar volumes of all the binary mixtures were negative. The measured VLE data are well described using a modified UNIFAC equation (Dortmund), and excess molar volumes are correlated with the Redlich−Kister polynomial.

The separation of propylene carbonate (PC) and γ-butyrolactone (GBL) from their primary impurities, which include water, propylene glycol (PG), and diethyl succinate (DES) and lower the potential of PC as a solvent in lithium batteries, was investigated. Consequently, the isobaric vapor−liquid equilibria (VLEs) for the PG + PC, GBL + DES, and water + GBL binary systems, as well as the solid−liquid equilibria (SLEs) for the GBL + DES and water + GBL binary systems, were characterized. The Wilson, nonrandom two-liquid (NRTL), and universal quasi-chemical (UNIQUAC) equations are used to describe the aforementioned VLEs and SLEs. Furthermore, we report the vapor pressures of PG, GBL, DES, and PC with a dynamic glass still from T = (376.99 to 485.91) K, as well as excess molar volume mixture properties (V E), deviations in the molar refraction (ΔR), and deviations in viscosity (Δη) at 298.15 K for the same compositions.

Alkyl amines, which have multiple amino groups, are used as activators to improve the CO2 absorption performances of aqueous methyldiethanolamine (MDEA) solutions. The aqueous MDEA blends consisted of 20% (w/w) of MDEA and 10% (w/w) of activators, which are 3-methylamino propylamine (MAPA), diethylenetriamine (DETA), triethylene tetramine (TETA), and tetraethylenepentamine (TEPA). Aqueous solutions of monoethanolamine (MEA; 30% (w/w)) and MDEA (30% (w/w)) are used as reference absorbents for comparison. The CO2 absorption performances of aqueous MDEA blends were investigated by measurements of absorption capacities, absorption rates, and heats of absorption. The MDEA blends have higher CO2 absorption capacities than MEA and MDEA. MDEA/TEPA shows the highest CO2 loading amount of 0.753 mol-CO2·mol-absorbent–1 at 313 K. In addition, the MDEA blends show high cyclic capacities (0.241–0.330 mol-CO2·mol-absorbent–1), the values of which are about 3 times higher than that of MEA. All MDEA blends show higher absorption fluxes than MDEA. The MDEA/MAPA showed the highest overall mass transfer coefficient of 3.351 × 103 mol·m–2·s–1·kPa–1, 8 times higher than that of MDEA (0.451 × 103 mol·m–2·s–1·kPa–1) and even higher than that of MEA (3.014 × 103 mol·m–2·s–1·kPa–1). The heats of absorption of the MDEA blends (57.21–59.53 kJ·mol-CO2 –1) are about 30% higher than that of MDEA and about 30% lower than that of MEA.

Ether mixtures containing oxygen in their body such as 2-methoxy-2-methylbutane (tert-amyl methyl ether; TAME) and 2-methoxy-2-methylpropane (methyl tert-butyl ether; MTBE) are used as octane boosters for lead-free or low-leaded gasoline because of their octane-enhancing and pollution-reducing capabilities. In this work, isothermal vapor-liquid equilibrium was measured by headspace gas chromatography, one of the static methods, for TAME + n-alcohol (C 1 -C 4 ) binary mixtures at 323.15 and 333.15 K. The binaries showed positive deviations from Raoult's law and have minimum boiling azeotropes, except for TAME + 1-butanol. Results were correlated with G E model equations and also compared with the values predicted by modified UNIFAC (Dortmund).