Removal of VOCs from gas streams with double perovskite-type catalysts.

Double perovskite-type catalysts including La2 CoMnO6 and La2 CuMnO6 are first evaluated for the effectiveness in removing volatile organic compounds (VOCs), and single perovskites (LaCoO3 , LaMnO3 , and LaCuO3 ) are also tested for comparison. All perovskites are tested with the gas hourly space velocity (GHSV) of 30,000hr-1 , and the temperature range of 100-600°C for C7 H8 removal. Experimental results indicate that double perovskites have better activity if compared with single perovskites. Especially, toluene (C7 H8 ) can be completely oxidized to CO2 at 300°C as La2 CoMnO6 is applied. Characterization of catalysts indicates that double perovskites own unique surface properties and are of higher amounts of lattice oxygen, leading to higher activity. Additionally, apparent activation energy of 68kJ/mol is calculated using Mars-van Krevelen model for C7 H8 oxidation with La2 CoMnO6 as catalyst. For durability test, both La2 CoMnO6 and La2 CuMnO6 maintain high C7 H8 removal efficiencies of 100% and 98%, respectively, at 300°C and 30,000hr-1 , and they also show good resistance to CO2 (5%) and H2 O(g) (5%) of the gas streams tested. For various VOCs including isopropyl alcohol (C3 H8 O), ethanal (C2 H4 O), and ethylene (C2 H4 ) tested, as high as 100% efficiency could be achieved with double perovskite-type catalysts operated at 300-350°C, indicating that double perovskites are promising catalysts for VOCs removal.