Total catalytic oxidation of chlorinated aromatics over bimetallic Pt-Ru supported on hierarchical HZSM-5 zeolite

Combination of great redox-acidity and strong chlorine-resistant, are critical to constructing efficient catalyst for the total oxidation of chlorinated aromatics. Herein, bimetallic Pt-Ru supported on hierarchical HZSM-5 zeolites were prepared by an improved co-impregnation. The distinct catalytic properties of the well-characterized Pt-O-Ru structures were demonstrated for chlorobenzene (CB) oxidation. For CB streams containing 1000 ppm CB/dry air, GHSV = 40,000 mL/g h, T-50 of Pt0.5Ru0.5/m-HZ (234 degrees C) is significantly better than monometallic Pt-1/m-HZ (294 degrees C) and Ru-1/m-HZ (298 degrees C). Additionally, Pt0.5Ru0.5/m-HZ is stable during 50-h test with high selectivity for less toxic products (CO2 and HCl) and scarce formation of chlorinated byproduct. In situ DRIFTS reveals that CB reacted with Bronsted acid sites to produce phenolates, which is sequentially converted into maleic anhydride, aldehyde and carboxylates under the synergetic effects of redox-acidity properties prompted by Pt-O-Ru structures. The partial oxidation products are finally oxidized into CO2, HCl and H2O by surface oxygen.