Active Carbon from Date Stones for Phenol Oxidation in Trickle Bed Reactor, Experimental and Kinetic Study

Abstract

The catalytic wet air oxidation (CWAO) of phenol has been studied in a trickle bed reactor

using  active  carbon  prepared  from  date  stones  as  catalyst  by  ferric  and  zinc  chloride activation (FAC and ZAC). The activated carbons were characterized by measuring their surface area and adsorption capacity besides conventional properties, and then checked for CWAO using a trickle bed reactor operating at different conditions (i.e. pH, gas flow rate, LHSV, temperature and oxygen partial pressure). The results showed that the active carbon (FAC and ZAC), without any active metal supported, gives the highest phenol conversion. The reaction network proposed accounts for all detected intermediate products of phenol oxidation that composed by several consecutive and parallel reactions. The parameters of the model estimated using experimental data obtained from a continuous trickle bed reactor at different temperatures (120-160 C) and oxygen partial pressures (8-12 bar). Simple power law  as  well  as  Langmuir-Hinshelwood  (L-H)  expressions  accounting  for  the  adsorption effects were checked in the modeling of the reaction network. A non-linear multi-parameter estimation  approach  was  used  to  simultaneously  evaluate  the  high  number  of  model parameters. Approach by simple power law only succeeds in fitting phenol disappearance. Instead, when L-H expressions are incorporated for the intermediate reaction steps, the model accurately  describes  all  the  experimental  concentration  profiles,  giving  mean  deviations below 10%.