The structure of dispersed vanadyl species plays a crucial role in the selective catalytic reduction (SCR) of NO with NH3 over vanadia-based catalysts. Here, we demonstrate that the polymeric vanadyl species have a markedly higher NH3-SCR activity than the monomeric vanadyl species. The coupling effect of the polymeric structure not only shortens the reaction pathway for the regeneration of redox sites but also substantially reduces the overall reaction barrier of the catalytic cycle. Therefore, it is the polymeric vanadyl species, rather than the monomeric vanadyl species, that determine the NH3-SCR activity of vanadia-based catalysts, especially under low-temperature conditions. The polymeric vanadia-based SCR mechanism reported here advances the understanding of the working principle of vanadia-based catalysts and paves the way toward the development of low vanadium-loading SCR catalysts with excellent low-temperature activity.
In this study, Ir−Fe/SiO2 catalyst was prepared by coimpregnation and investigated for preferential oxidation of CO under the presence of H2. It was found that the presence of H2, even in a slight excess, led to a large increase in the reaction rate for CO oxidation over the Ir−Fe/SiO2 catalyst, which was quite different from the case of Ir/SiO2. To reveal the promotional role of Fe associated with the presence of H2, quasi in situ Mössbauer spectroscopy, in combination with in situ DRIFTS and microcalorimetry, was employed. The results showed that the relative amount of Fe2+ increased with increasing H2 concentration in the reaction stream, well consistent with the trend of reaction rate for CO conversion, strongly suggesting that Fe2+ is the active site for oxygen activation. H2 promoted CO oxidation mainly via maintaining a substantial amount of Fe existing as Fe2+.
【目的】以Journal of Environmental Sciences（JES）获得中国科技期刊国际影响力提升计划A类资助为契机,探索提升JES国际影响力的方法。【方法】分析JCR数据和JES发表数据,学习优秀国际期刊办刊经验,结合办刊实践,探索一条提升期刊国际影响力的道路。【结果】JES在编委会组建、期刊质量、国际化的投审稿系统及品牌形象等方面,进行全方位的设计与改革,取得了一定成效。【结论】以品牌建设为核心,加强期刊宣传,吸收优秀稿源,提升期刊国际影响力。
White birch (Betula platyphylla Suk.) is a typical pioneer tree species that is important in forest restoration in northern China, Japan, and Korea. In the present study, 37 isolates were obtained from B. platyphylla rhizosphere soils in Heilongjiang Province; they were identified as T. pleuroticola (3 isolates), T. virens (2 isolates), T. hamatum (8 isolates), T. atroviride (21 isolates, dominant species) and T. asperelloides (3 isolates). Stress tolerance tests (salt, alkali, and nutritional stress that simulated saline alkali or barren soil) and confrontation assays (with four pathogens) were performed to determine which isolates had good biocontrol ability in barren soil; the results show that T. atroviride was outstanding. Then, in order to determine the effect of T. atroviride on plants and soil, Gynura cusimbua seeds were sown and treated with a T. atroviride spore suspension, as was unsown soil. The seedlings treated using T. atroviride had significantly greater height, stem diameter, soluble protein content, soluble sugar content, and malonaldehyde (MDA) content and their catalase (CAT) activity was also significantly increased. In addition, when the plants were inoculated with Alternaria alternata, the plants treated using T. atroviride had stronger CAT activity, significantly higher soluble protein content and soluble sugar content, and significantly lower MDA content, which indicates stronger resistance and less injury caused by the pathogen. In addition, T. atroviride not only increased the content of available nitrogen and available phosphorus in the soil, but also promoted G. cusimbua seedlings' absorption of available nitrogen and available phosphorus. Thus, the characteristics of T. atroviride may make it the main factor that helps B. platyphylla colonise cut-over lands. T. atroviride, a promising biocontrol candidate, can be used in agriculture and forestry.
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