Low temperature catalytic oxidation of hydrogen sulfide in sour produced wastewater using activated carbon catalysts

A process is proposed for the removal of H2S from sour produced wastewater at lower temperatures (<25 degrees C) using an activated carbon as a catalyst and oxygen in air as an oxidizing agent. Hydrodarco-activated carbon catalyst was successfully used in this process in a continuous-flow stirred-tank reactor (CFSTR) in an aqueous solution with a pH of 3-10, and temperature and residence time of the feed in the reactor ranging from 8 to 24 degrees C and 5.2 to 18.6 min, respectively. This catalyst has higher activity than that of Calgon catalyst in this process. The H2S conversion was increased with temperature, the conversion approaching 100% at 24 degrees C after 90 min of operation at a pH of 4.5 and a residence time of 11.4 min. The Hydrodarco-activated carbon was capable of sorbing 0.66 g of sulfur/g of carbon before its activity decreased significantly giving conversions below 90%. In a CFSTR, for the sour water with a pH value of 4.5, the rate of H2S oxidation in the temperature range 8-24 degrees C was -r(H2S) = (5.072 x 10(10) (mu mol/L)(0.76)(1/min)) exp(-21.3 kJ/mol/RT)[H2S](0.24), [mu mol/(L min)].