Thermal catalytic oxidation performance study of SWTCO system for the degradation of indoor formaldehyde: Kinetics and feasibility analysis

- A novel application combining TCO with solar-collected wall (SWTCO) was proposed.
- Performance of MnOx-CeO2 under various temperatures and low concentrations was investigated.
- Reaction rate considering concentrations and temperature based on modified L-H model fit the experimental data well.
- A simple model predicted the formaldehyde degradation curves in SWTCO system.
- SWTCO had great potential for indoor formaldehyde control.

This article proposes a novel application combining the thermal catalytic oxidation with solar-collected wall (SWTCO) in buildings without auxiliary energy. Thermal catalyst MnOx-CeO2 was prepared by the method of modified coprecipitation. The performance and kinetics of MnOx-CeO2 for catalytic oxidation of indoor formaldehyde were investigated. Once-through experiments at different concentrations of 300-4300 ppb and temperatures 20-100 °C were conducted. Moreover, formaldehyde conversion experiments in SWTCO system at several typical indoor concentrations (289 ppb, 587 ppb and 1374 ppb) were performed. Furthermore, a simple system model predicting the degradation of indoor formaldehyde versus the time in SWTCO system was built. Results were as follows: (1) The reaction rate expression considering two parameters i.e. concentration and temperature based on modified L-H model fit the experimental data well; (2) System model calculation results showed initial formaldehyde concentration was an important factor to the formaldehyde degradation capability; (3) SWTCO system could realize high pollutant-removal efficiency and low energy costs simultaneously under higher temperature compared with the system using electrical heating; (4) The purification time constant increased with the horizontal solar radiation and the influence of concentration in typical indoor formaldehyde concentration on it could be neglected.