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

Double perovskite-type catalysts including La₂CoMnO₆ and La₂CuMnO₆ 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 30,000 hr^{− 1}, and the temperature range of 100–600°C for C₇H₈ removal. Experimental results indicate that double perovskites have better activity if compared with single perovskites. Especially, toluene (C₇H₈) can be completely oxidized to CO₂ at 300°C as La₂CoMnO₆ 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 68 kJ/mol is calculated using Mars-van Krevelen model for C₇H₈ oxidation with La₂CoMnO₆ as catalyst. For durability test, both La₂CoMnO₆ and La₂CuMnO₆ maintain high C₇H₈ removal efficiencies of 100% and 98%, respectively, at 300°C and 30,000 hr^{− 1}, and they also show good resistance to CO₂ (5%) and H₂O_(g) (5%) of the gas streams tested. For various VOCs including isopropyl alcohol (C₃H₈O), ethanal (C₂H₄O), and ethylene (C₂H₄) 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.