Abstract: A process for recovering hydrogen from a cracking effluent wherein a cracking effluent is compressed, and then at least a portion of the hydrogen is separated from the cracking effluent prior to cooling of the cracking effluent to remove lower-boiling components. The separation of hydrogen is preferably accomplished by passing the cracking effluent through at least one semi-permeable membrane.

Abstract: Isophthalonitrile (IPN) is recovered from an isophthalonitrile production reaction effluent, which contains water vapor, by direct contact quenching of the effluent with an organic quench liquid to cool the effluent to a temperature at which essentially all of the isophthalonitrile is condensed as a solution in the organic quench liquid, without condensation of water vapor. In this manner, isophthalonitrile is recovered from the effluent and separated from water vapor, thereby preventing the liquid phase hydrolysis of IPN which occurred in prior art procedures.

Abstract: Terephthalonitrile is separated from p-xylene containing solution by fractional distillation in the presence of p-tolunitrile, with the p-tolunitrile being present in the fractional distillation tower in an amount sufficient to solubilize the terephthalonitrile in all portions of the column at which the temperature in the column is below the melting point of tetephthalontrile, whereby terephthalonitrile can be recovered as a liquid. The solution generally includes p-xylene, benzonitrile, p-tolunitrile and terephthalonitrile and is separated from a terephthalonitrile production reaction effluent by direct contact quenching with an organic liquid containing p-tolunitrile.