Received for review June 21, 2007

Revised manuscript received August 30, 2007

Accepted August 30, 2007

Abstract:

Temperature swing adsorption (TSA) of polycyclic aromatic hydrocarbons (PAH) has been studied. Naphthalene (Np)-two aromatic rings-and phenanthrene (Phe)-three aromatic rings-have been selected as model compounds for the PAH hot gas cleaning process. Five activated carbons (AC) were produced from pyrolytic carbon black obtained in waste tire recycling. Carbon dioxide was used as a gasifying agent during five different reaction times, bringing about adsorbents with different textural properties. The influence of these properties has been assessed in the loss of adsorption capacity with the number of cycles of both model compounds. The adsorption process was performed at 150 C in helium atmosphere with a gas hourly space velocity of 25 000 h^-1. Under these conditions, the breakthrough curve of each model compound was obtained with an inlet concentration of ca. 250 ppbv. AC regeneration was carried out in air by thermal desorption under fixed conditions (300 C, 25 000 h^-1, and 100 min) during five cycles. It was observed that the AC performance depends mainly on the model compound nature, total micropore volume, and micropore size distribution. In this work, it is shown that although the Np adsorption capacity is fairly constant with the number of cycles, Phe removal drastically decreases after the first regeneration cycle, but it is maintained in the successive adsorption/desorption cycles. This fact is likely due to a pore-blocking effect by Phe molecules retained in the molecular size pores.

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