TPO-TPD study of an activated carbon-supported copper catalyst-sorbent used for catalytic dry oxidation of phenol

Adsorption of organic pollutants in wastewater by carbon-based catalyst-sorbents followed by in situ catalytic dry oxidation of the adsorbed pollutants to regenerate the catalyst-sorbents at low temperatures is promising for the treatment of toxic and/or biorefractory wastewater streams. This paper investigates an activated carbon-supported copper catalyst-sorbent (CuO/AC) for catalytic dry oxidation of phenol at low temperatures in a TG/MS system through temperature-programmed oxidation (TPO) and temperature-programmed desorption (TPD). Phenol oxidation activities and ignition characteristics of the catalyst-sorbent were mainly discussed. The results indicate that the CuO/AC catalyst-sorbent has high catalytic activities for phenol oxidation and for AC ignition compared to the AC support itself; the initial oxidation temperature for phenol is about 190 degreesC, which is 130 degreesC lower than that for the AC. Consecutive adsorption-oxidation experiments show that the phenol adsorption capacity of the CuO/AC catalyst-sorbent decreases from an initial value of about 140 mg/g to a stable value of about 70 mg/g in 9 cycles, which is much better than the performance of activated carbon reported in the literature. TPD results indicate that phenol molecules adsorb on different types of active sites on AC and CuO/AC catalyst-sorbent. CuO plays an important role both in enhancing the affinity between phenol and CuO/AC catalyst-sorbent during phenol adsorption and in promoting catalytic activity for phenol oxidation. (C) 2004 Elsevier Inc. All rights reserved.