Regenerable cerium oxide based odor adsorber for indoor air purification from acidic volatile organic compounds

Abstract Indoor odor management currently relies on energy-intensive high air exchange rates, or, more sustainable, on single use volatile organic compounds (VOC) adsorbers or ozonisation. This study investigates a more sustainable, multi-cycle use of an odor adsorber system that combines concepts from catalytic oxidation and air cleaning. Both pure and sodium doped, nanostructured CeO 2 were tested as adsorber material for high volume removal of odorous compounds from air. As a representative compound for unpleasant odors, hexanoic acid (HA) was used. After air cleaning on fixed beds of CeO 2 or Na/CeO 2 , both hexanoic acid loaded adsorber materials were heated under air and displayed considerable oxidation activity at 191 °C and 263 °C, respectively. Mass spectroscopy was used to confirm that no hexanoic acid desorbed during combustion. Cerium oxide showed an adsorber efficiency of ≥96.5% over a period of 60 h (C in  = 0.044 mg/L, gas hourly space velocity, GHSV = 440 h −1 ) and sodium doped cerium oxide adsorbed ≥97% for over 90 h (C in  = 0.056 mg/L, GHSV = 1100 h −1 ). CeO 2 was regenerated at 220 °C in air and could be successfully re-used as adsorber without noticeable loss in performance. The study demonstrates that CeO 2 has most promising properties for application as re-usable air cleaner due to its very good ability for adsorption even at highly dilute conditions (ppm-level) using a representative acidic test compound with rancid and sweaty odor. Sodium as a basic dopant further improved the adsorption of hexanoic acid but requires a higher regeneration temperature.