A mixture of ethylbenzene (EB) and the three isomers (ortho, meta, and para) of xylene is widely available in petroleum refineries.

(a) Based on differences in normal boiling points, verify that the separation between meta-xylene (MX) and para-xylene (PX) by distillation is far more difficult than the separations between EB and PX, and MX and ortho-xylene (OX).

(b) Prepare a list of properties for MX and PX similar to Table 1.11. From that list, which property differences might be the best ones to exploit to separate a mixture of these two xylenes?

(c) Explain why melt crystallizalion and adsorption are used commercially to separate MX andPX.

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Property Propylene Propane Molecular weight van der Waals volume, m'/kmol van der Waals area, m/kmol x 10-8 42.081 44.096 0.03408 0.03757 5.060 5.590 Acentric factor 0.142 0.152 Dipole moment, debyes 0.4 0.0 Radius of gyration, m x 1010 2.254 2.431 Normal melting point, K Normal boiling point, K Critical temperature, K Critical pressure, MPa 87.9 85.5 225.4 231.1 364.8 369.8 4.61 4.25