engleski

Experiments and modelling of liquid–liquid equilibria in the mineral oil + N, N-dimethylformamide system

Description of phase behaviour of a highly nonideal system mineral oil + N, N-dimethylformamide system (DMF) is a rather complex task, because hydrocarbon feed, which has to be separated into aromatic and nonaromatic fractions, consists of large number of compounds that differ significantly in molecular weight and chemical structure. Such a complex mixture was substituted by two pseudo-components, aromatic (AR) and nonaromatic (NAR) in order to simplify the procedure. They were represented by adequate model compounds, whose thermodynamic behaviour is similar to the original one. Nonaromatics are represented by n-heptane, while aromatics are represented by benzene and/or toluene and/or dodecyl benzene. DMF was used as the only solvent. Binodal curves were determined by titration technique. Experiments with model compounds are shown in Figure 1. It can be seen that dodecyl benzene represents aromatics quite well. Thermodynamic behaviour of dodecyl benzene + n-heptane + DMF is similar as the behaviour of the real multicomponent system AR + NAR + DMF and it can be used as a model system to describe extraction of complex hydrocarbon mixture to simplify further calculations. Figure 1. Experimental binodal curves at 298.2 K for the AR + NAR + DMF system The chosen model system simulates properly the real one in the sense of the mutual solubility of aromatic and nonaromatic components. However, this simplification of description of strongly nonideal mixtures should be considered as the first approximation.

liquid–liquid equilibria; experiments; modelling; mineral oil; N; N-dimethylformamide system

http://www.chisa.cz/2012/ CD-ROM of Full Texts ; P1.82 ; contr. 1487