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Oxidative coupling of methane (OCM) over SrO/La2O3 catalyst was studied in a densely perovskite-type Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) mixed-conducting membrane reactor at high temperatures. Oxygen permeation fluxes of the perovskite-type BSCF functional membranes were measured at 973–1123 K, and the membrane surfaces were also studied by SEM for the membranes before and after the catalytic OCM reaction. High selectivity to C2 products was achieved in the oxygen-permeable BSCF mixed-conducting membrane reactor, and the highest C2 yield of 11.6% was obtained in the oxygen-separation membrane reactor at 1123 K. The perovskite-type BSCF mixed-conducting membrane reactor also exhibited good stability for the catalytic OCM membrane reaction during 30-hour preliminary operation. [ABSTRACT FROM AUTHOR]

The number of airborne pollution accidents is second only to that of water-borne pollution accidents, in recorded environmental disasters. Acute casualties and public health costs have prompted many airborne pollution risk analyses. To date, few assessment methods have been carried out at regional-scale to quantify acute airborne pollution risk. Herein, a Hybrid Simulation and Risk Analysis approach, involving a systematic combination of simulation, risk ranking, and standardized analysis, is proposed at regional scale. Gaussian and heavy-gas models are utilized in the simulation process, and acute exposure limits preferentially adopted in the risk analysis. The case study shows that 34 of 243 townships in Zhangjiakou City of north China, one of the twin cities selected to host the 2022 Winter Olympics, are threatened by airborne risk sources. It is found that the accidental air pollution risk is comparatively higher in the Xuanhua and Wanquan conurbations. High-risk chemical enterprises (312-432 risk scores) are mostly located near urban areas with high population density where many people are vulnerable receptors to potential air pollution accidents. The resulting risk map indicates that acute airborne pollution from Zhangjiakou would not be a threat either to the proposed Olympic site at Chongli or to downwind Beijing. [ABSTRACT FROM AUTHOR]