Photochemical Oxidation of Dilute Methane Using a Filter-Based System for Air-Treatment Applications
7 affiliations
- 1Department of Engineering
- 2University of Cambridge
- 3Centre for Climate Repair
- 4School of Computing and Mathematical Sciences
- 5University of Greenwich
- 6Department of Mechanical Engineering
- 7Stanford University
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.
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BibTeX
@misc{tsopelakou2026photochemical,
title = {{Photochemical Oxidation of Dilute Methane Using a Filter-Based System for Air-Treatment Applications}},
author = {Aliki Marina Tsopelakou and Samuel D. Tomlinson and Tzia Ming Onn and Adam M. Boies and Shaun Fitzgerald},
howpublished = {ChemRxiv},
year = {2026},
month = oct,
doi = {10.26434/chemrxiv.15010952/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010952/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Photochemical Oxidation of Dilute Methane Using a Filter-Based System for Air-Treatment Applications
AU - Aliki Marina Tsopelakou
AU - Samuel D. Tomlinson
AU - Tzia Ming Onn
AU - Adam M. Boies
AU - Shaun Fitzgerald
PY - 2026
DA - 2026/10/23
PB - ChemRxiv
DO - 10.26434/chemrxiv.15010952/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010952/v1
AB - 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.
ER -