Photochemical Oxidation of Dilute Methane Using a Filter-Based System for Air-Treatment Applications
Year: 2026
Type: preprint
Abstract: Atmospheric methane (CH4) removal is challenging because of its low concentration and chemical stability under dilute conditions. Here, we demonstrate a filter-based photochemical system for dilute CH4 oxidation designed for potential integration into ventilation and air-treatment applications. A continuous-flow reactor incorporating UV-C irradiation (190–220 nm), a TiO2coated filter and an activated-carbon filter was tested at 10–50 ppm CH4, 25 °C and 1 bar under dry and humid conditions, at light intensities ranging from 4 to 59 W/m2 and flow rates of 100–300 mL/min. The downstream 4 mm activated-carbon filter reduced UV-C generated ozone (O3) to below the detection limit. CH4 conversion increased with light intensity and humidity and decreased with increasing flow rate and, under dry conditions, with increasing CH4 concentration. At 10 ppm and 100 mL/min, conversion reached 96% under humid conditions at 59 W/m2, compared with 73% under dry conditions. Significant conversion was also observed without the TiO2-coated filter, demonstrating that gas-phase photochemistry is the dominant oxidation pathway, while the TiO2-coated filter provided an additional 4–14% CH4 conversion improvement. Water vapour approximately doubled the effective removal rate. Apparent quantum yields (AQYs) for the overall photochemical system ranged from 9.3 × 10−3% at 10 ppm to 0.2% at 50 ppm, exceeding those previously obtained for TiO2-based photocatalytic oxidation under comparable dilute-CH4 conditions [1]. An advection–diffusion–reaction model reproduced the experimental trends across irradiance, humidity, concentration and flow rate. This work establishes filter-based UV-C photochemistry as a potential route for coupling dilute CH4 mitigation with existing airtreatment infrastructure.
Source: ChemRxiv
Language: English
Field: Energy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7223350220