Herein, Pd supported on UiO-66 as well as its NH₂- and NO₂-functional materials with ultra-low Pd loadings (0.05 ​wt%) were synthesized for toluene oxidation. Pd–U, using UiO-66 as the support, exhibited superb catalytic performance, water resistance, and resistance to SO₂. A series of experiments and characterizations revealed that a high dispersion of small Pd clusters, high Pd⁰/Pd_total proportion, better adsorption for toluene, and the best adsorption and activation capacities of gaseous oxygen species enhanced toluene degradation over Pd–U. Additionally, the catalytic mechanism over the Pd-based catalysts was revealed and discussed. Furthermore, the water-resistance and the SO₂ concentration influence were tested and analyzed. Introducing H₂O suppressed the adsorption and activation of toluene as well as gaseous oxygen species, and decreased catalytic performance over the three catalysts. The mechanism of the different impacts of SO₂ on the three catalysts was investigated and elucidated. This study provides guidance for rationally designing catalysts for removing toluene under in-field operating conditions.

This study conducted the numerical models validated by wind-tunnel experiments to investigate the issues of Re-independence of indoor airflow and pollutant dispersion within an isolated building. The window Reynolds number (Re_w) was specified to characterize the indoor flow and dispersion. The indicators of RRC (ratio of relative change) or DR (K_DR) (difference ratio of dimensionless concentration) ≤ 5% were applied to quantitatively determine the critical Re_w for indoor flow and turbulent diffusion. The results show that the critical Re (Re_crit) value is position-dependent, and Re_crit at the most unfavorable position should be suggested as the optimal value within the whole areas of interest. Thus Re_{H, crit} = 27, 000 is recommended for the outdoor flows; while Re_{w, crit} = 15, 000 is determined for the indoor flows due to the lower part below the window showing the most unfavorable. The suggested Re_{w, crit} (=15, 000) for indoor airflow and cross ventilation is independence of the window size. Moreover, taking K_DR ≤ 5% as the indicator, the suggested Re_{w, crit} for ensuring indoor pollutant diffusion enter the Re-independence regime should also be 15, 000, indicating that indoor passive diffusion is completely determined by the flow structures. The contours of dimensionless velocity (U/U₀) and concentration (K) against the increasing Re_w further confirmed this critical value. This study further reveals the Re-independence issues for indoor flow and dispersion to ensure the reliability of the data obtained by reduced-scale numerical or wind-tunnel models.

In the recent paper, entitled "Outdoor ventilation performance of various configurations of a layout of two adjacent buildings under isothermal conditions" by Ayo et al. (2015) (Building Simulation, 8: 81–98), an expression is presented for evaluating the temporal average of positive air exchange rate (AER+) in a three-dimensional canyon. This comments show that this expression for the temporal average of AER+ is incorrect. Also, this discussion gives a corrected expression for the temporal average of AER+.