MnO2 nanorods with exposed (110), (100), or (310) facets were prepared and investigated for catalytic oxidation of chlorobenzene, then the (110)-exposed MnO2 nanorod was screened as the candidate parent and further modified by Pt and/or Mo with different contents. The loading of Pt enhanced activity and versatility of the pristine MnO2, but the polychlorinated byproducts and Cl2 were promoted, conversely, as the decoration of Mo inhibited the polychlorinated byproducts and improved durability. Determination of structure and properties suggested that Pt facilitated the formation of more oxygen vacancies/Mn3+ and surface adsorbed oxygen weakened the bonds of surface lattice oxygen, while Mo stabilized surface lattice oxygen and increased acid sites, especially Brønsted acid sites. Expectedly, Pt and Mo bifunctionally modified MnO2 presented a preferable activity, selectivity, and durability along with the super resistance to H2O, high-temperature, and HCl, and no prominent deactivation was observed within 30 h at 300 °C under dry and humid conditions, even at high-temperature aging at 600 °C and HCl-pretreatment (7 h). In this work, the optimized Mo and Pt codecorated MnO2 was considered a promising catalyst toward practical applications for catalytic oxidation of actual Cl-VOCs emissions.

No abstract

While inoculating pre-acclimatized floccular sludge, nitrite-denitrifying granular sludge was obtained after approximately 40 days of cultivation in a 10 L upflow sludge blanket (USB) reactor. The nitrite removal efficiency was approximately 95% when the nitrite concentration was 50 mg L(-1)at an influent flow rate of 20 L h(-1). The nitrite granular sludge had several notable features including good settleability (110 m h(-1)), high ash content (79%), and high density (1.248 g cm(-3)). The mixed liquor suspended solids (MLSS) of the sludge bed remained at 130.04 g L(-1), at a hydraulic upflow velocity of 2 m h(-1). These interesting characteristics were attributed to a high effluent pH (9.7) caused by the release of alkalinity during the nitrite denitrification process. The surfaces of the granules were dominated by cocci bacteria with a diameter of approximately 3 μm, which could be classified as Nitrosomonas-like species based on our analysis of 16 S rDNA sequences.

No abstract

Ru-based catalysts are the most promising and concerned candidates for catalytic combustion of propane as one of light hydrocarbons (LHs). In this work, different supports such as SiO2, Al2O3, CeO2, and Co3O4 were investigated to unravel the nature of high activity for catalytic combustion of LHs, and effects of Ru content, high-temperature aging, high weight hourly space velocity, and H2O were focused on. The pristine CeO2 was lowly active for catalytic combustion of methane, ethane, and propane (T 90C3 > 400 °C), while the pristine Co3O4 and doped Co3O4 presented high activity (T 90C3 < 200 °C), the loading of Ru sharply improved the activity of CeO2 especially for ethane and propane (T 90C3 < 150 °C) and observably depended on the Ru content, and the promotion of RuO x to Co3O4-based supports was inconspicuous. However, Ru/CeO2 catalysts were inferior to catalytic combustion of methane and lowly resistant to the high-temperature aging compared with Ru/Co3O4 catalysts. Based on characterization results and comparison with SiO2 supports with different surface areas, the Ru–O–M interface or highly dispersed RuO x species were determined as the main active sites for catalytic combustion of LHs and as follows: Ru–O–Ce interface > Ru–O–Co interface ≈ Co3O4 > highly dispersed RuO x ≫ CeO2. Ru-supported Co3O4 and doped Co3O4 especially Ce-doped Co3O4 demonstrated superior versatile activity, stability, and resistance to high temperature and H2O under harsh conditions close to the real full-scale applications, which showed the potential to eliminate the industrial VOC emissions. By contrast, Ru/CeO2 was considered to be promisingly practiced in the portable NMHC detection/monitoring system due to the huge difference in catalytic combustion of ethane/propane and methane. This work was considered to be attributed to the further understanding of the activation of C–H bonds, the optimization of Ru-based catalysts for catalytic combustion of LHs, and the rational screening of potential catalysts for different practical application scenarios.