Urban hydrological responses to climate change and urbanization in cold climates.

This study explores hydrological response of urban catchment in Southern Finland to climate change and urbanization. Process-based urban hydrological modelling and statistical analysis are applied to various urbanization and climate scenarios. Future changes in precipitation and temperature under Representative Concentration Pathways 4.5 and 8.5 (RCP4.5 and RCP8.5, respectively) clearly influence urban streamflow all year-round. We found snowpack shrinks during 2061 to 2090, snowmelt becomes earlier and the amount of melted runoff is reduced under both climate scenarios. The most significant runoff increase occurs in winter with the growth rates of 79% and 127%, respectively. It is also found that the dominant portion of urban streamflow shifts from summer to autumn in the future under both RCP4.5 and RCP8.5. Results indicate that urbanization has direct impact on hydrological response due to the change of imperviousness, but climate change will have more significant impact on seasonal distribution of urban streamflow. Additionally, urbanization impacts shrink monthly streamflow differences along with climate change.

Poisoning-Resistant NOx Reduction in the Presence of Alkaline and Heavy Metals over H-SAPO-34-Supported Ce-Promoted Cu-Based Catalysts.

Selective catalytic reduction (SCR) of NOx using NH3 in the presence of alkaline and heavy metals is still an issue in the application of a stationary source. Reported here is the rational design of a novel H-SAPO-34-supported ceria-promoted copper-based catalyst (CuCe/H-SAPO-34) that demonstrates exceptional resistance against alkali (K), alkaline earth (Ca), and heavy metal (Pb) poisoning during SCR of NOx. The H-SAPO-34 support contained numerous acid sites that allowed Cu-based catalysts to maintain their catalytic activity while also resisting poisoning by K and Ca. Decorating the catalyst with CeO2 promoted the low-temperature deNOx activity by accelerating the redox cycle with Cu species and assisted the H-SAPO-34 in capturing Ca and Pb. H-SAPO-34-supported ceria-promoted copper oxide catalysts prevented the irreversible combination of K, Ca, or Pb with the active centers, providing the catalyst with excellent poisoning resistance. This work provides a strategy for the development of high-performance, poisoning-resistant catalysts for NH3-SCR of NOx in the presence of alkaline and heavy metals.

Dual Promotional Effects of TiO2-Decorated Acid-Treated MnO x Octahedral Molecular Sieve Catalysts for Alkali-Resistant Reduction of NO x.

Alkali metals generated during waste incineration in power stations are not conducive to the control of nitrogen oxide (NO x) emission. Hence, improved selective catalytic reduction of NO x with ammonia (NH3-SCR) in the presence of alkali metals is a major issue for practical NO x removal. In this work, we developed a novel TiO2-decorated acid-treated MnO x octahedral molecular sieve (OMS-5(H)@TiO2) catalyst with improved alkali-resistant NO x reduction at low temperature, and the dual promotional effects of OMS-5(H)@TiO2 catalysts were clarified. It was found that the special structure of the acid-treated MnO x octahedral molecular sieve (OMS-5(H)) was responsible for the trapping of alkali metals and high deNO x activity at low temperature. Subsequently, the decoration by TiO2 further improved the redox properties by accelerating the high ratio of Mn4+ and Oα on the surface of the highly active (OMS-5(H)@TiO2) catalyst. Moreover, a thorough mechanism study via in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTs) demonstrated that the acid treatment led to remarkable increment of acid sites, which enabled the catalyst to resist alkali metals in the form of ion exchange. Meanwhile, the decoration of TiO2 further increased the strength of the Lewis acid sites, assisting more active intermediate species to effectively take part in the deNO x reaction. Besides, a "fast SCR" process was observed to certify that the decoration of TiO2 promoted the improvement of low-temperature activity in the presence of alkali metals. The dual effects combining OMS-5(H) with TiO2 decoration in terms of alkali metal resistance and high catalytic activity at low temperature proved that the high-performance deNO x catalyst was successfully developed in this work. The work paves a way for the development of superior low-temperature SCR catalysts with improved NO x reduction efficiency in the presence of alkali metals.