RECYCLED THERMAL SWING ADSORPTION - APPLIED TO SEPARATION OF BINARY AND TERNARY MIXTURES

Research has been conducted on a process that is an offshoot of the liquid-phase parametric pumping and cycling zone adsorption processes. The shortcomings of those processes were the former could achieved high overall separation factors (alpha-0 = cBARh/cBARl) only when operated in the batch mode and the latter never achieved high separation factors. The present recycled thermal swing adsorption process appears to overcome those problems. Experimental and theoretical results are presented for a multisolute system. The separation of aromatic solutes from aliphatic solvents, specifically toluene and xylene from n-heptane, was studied. The theory was based on local equilibrium and traveling-wave thermal cycling and was solved via hodograph transformation. Experiment showed that the purified product concentration depends strongly on the feed concentration. For a feed of 1300 ppm toluene, the product was less than 0.5 ppm. For a feed of 10 000 ppm the product concentration was 810 ppm. The enriched product concentrations were typically 3-5 times that of the feed, regardless of the feed concentration. Thus, overall separation factors ranged from alpha-0 = 37 to over 10 000.