A pilot plant study for catalytic decomposition of PCDDs/PCDFs over supported chromium oxide catalysts

Abstract

Chromium oxide catalysts supported on TiO2 and A1(2)O(3) were examined in a fixed-bed flow reactor system for the removal of PCE (perchloroethylene), a simulant of 2,3,7,8-TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin), and in a pilot plant employing actual flue gas from a sintering plant for the removal of PCDDs/PCDFs (poly-chlorinated dibenzo-dioxin/poly-chlorinated dibenzo-furan). The 12.5 wt.% chromium oxides supported on TiO2 and Al2O3 revealed excellent stability and performance of PCE removal in the feed gas stream containing water vapor. In a pilot plant study, the catalysts washcoated on the honeycomb reactor revealed 93-95% of PCDDs/PCDFs removal activity over CrOx/Al2O3-HC20 (CrOX/Al2O3 catalyst washcoated on 20 cell-honeycomb), and more than 99% of the decomposition activity over CrOx/Tio(2)-HC20 (CrOx/TiO2 catalyst washcoated on 20 cell-honeycomb) at 325 C and 5000 h(-1) of reactor space velocity without the de novo synthesis of PCDDs/PCDFs. In particular, CrOx/TiO2-HC20 showed 94% of PCDDs/PCDFs decomposition activity even at 280degreesC reaction temperature. The catalyst also exhibited significant NO removal activity. The chromium oxide seems to be a promising catalyst for the removal of PCDDs/PCDFs and NOx contained in the flue gas. (C) 2002 Elsevier Science B.V. All rights reserved.