Catalytic Material with Enhanced Contacting Efficiency for Volatile Organic Compound Removal at Ultrashort Contact Time

Abstract

A unique catalyst structure, microfibrous entrapped catalyst (MFEC), was prepared by entrapping support particles (γ-Al2O3, 150–250 μm diam) into metal (Ni-200) microfibers and forming thin flexible sheets. Pleated structures of MFECs containing Pd/γ-Al2O3, Pd–Mn/γ-Al2O3, and Pd–Ce/γ-Al2O3 were investigated systematically for volatile organic compound (VOC) removal at various face velocities (ca. 3–30 m/s) and at low temperatures (<473 K). The optimized structure of MFEC (e.g., W-structure with 8 μm Ni fiber) resulted intralayer residence times from 750 to 65 μs with pressure drops from 0.35 to 10.22 kPa. The study exhibited that low intralayer residence times had a significant effect on the catalytic reaction which followed the Mars–Van Krevelen mechanism in this velocity controlled region. The overall reaction rate for VOC removal was limited by the surface reaction. Furthermore, mixed metal oxide based MFECs showed better performance in VOC removal due to the high oxygen storage capacity of reducible o...