V2O5 fuses with transition metals to create dozens of different metal vanadates, whose acidic/redox traits can be diverse yet optimized for selective catalytic NOX reduction (SCR) by changing the metals used or their metal:vanadium stoichiometry. However, no metal vanadate has been compared with its metal oxide composite analogue as an active phase for SCR, albeit a vanadate occasionally outperforms an oxide composite simulating a commercial catalyst (V2O5–WO3). Herein, Cu3V2O8 and CuO–VO2/V2O5 were rationally selected as model phases of metal vanadates and oxide composites and isolated using pH regulation of their synthetic mixture to ≤∼5 (pH1/pH5) and ∼11 (pH11), respectively. The pH1/pH5/pH11 samples were comparable with regard to morphological, textural, and compositional traits but not for crystallographic features. This thus provided the impetus to simulate the pH1/pH5/pH11 surfaces under a SO2-containing feed-gas stream, by which SOA 2–/HSOA – functionalities (A = 3–4) were anchored on their (defective) Lewis acidic metals and/or labile oxygens (Oα). This could result in the formation of pH1-S/pH5-S/pH11-S, whose major surface species were Brönsted acidic bonds (SOA 2–/HSOA –) and redox sites (Oα; mobile oxygen (OM); oxygen vacancy (OV)). pH1-S/pH5-S/pH11-S were similar in terms of NH3 binding energies and energy barriers in SCR yet escalated collision frequencies among the surface species involved in the sequence of pH11-S < pH5-S < pH1-S (via kinetic assessments), as was the case with the numbers of SOA 2–/HSOA – functionalities of the catalysts (via temperature-resolved Raman spectroscopy). These were coupled to elevate the efficiency of acidic cycling on the order of pH11-S < pH5-S < pH1-S. Meanwhile, the amounts of Oα and OV (or OM) innate to pH1-S/pH5-S were smaller than and comparable to those of pH11-S, respectively. Nonetheless, pH1-S/pH5-S provided greater OM mobility than pH11-S, thereby proceeding better with redox cycling than pH11-S (via 18O-labeling O2-on/off runs). Furthermore, pH1-S/pH5-S outperformed pH11-S in SCR under diffusion-limited domains, while enhancing the resistance to H2O, ammonium (bi)­sulfate poisons, or hydro-thermal aging over pH11-S by diversifying the selective N2 production pathway other than SCR.

Mn oxide is a particular class of metal phase highly active in reducing NO X or oxidizing NH3 at low temperatures yet needs amendment in terms of surface acidic/redox sites to improve selectivities to desired N2 (S N2) along with the promotion of SO2 tolerance. This study reports the use of supercritical CO2 extraction (SC-CO2) as a means to adjust the quantities/strengths of surface sites present in the resulting Mn oxides on TiO2 (Mn-CO2) and validates the advantages of SC-CO2 with regard to mechanistic viewpoints via kinetic evaluation and control reactions. SC-CO2 was demonstrated to promote the activity or diversity of Langmuir–Hinshelwood-type or Eley–Rideal-type NO X reduction pathways to produce N2 only. This was enabled by increasing the area of surface sites accessible to NH3/NO X /O2 at ≤200 °C, as evidenced by a large NO X consumption rate and pre-factor of Mn-CO2 in addition to in situ DRIFT experiments. In addition, SC-CO2 could tailor redox sites in such a way as to circumvent an Eley–Rideal-type NO X reduction pathway to produce undesired NO2/N2O at 220–280 °C while detouring Langmuir–Hinshelwood-typed NO X reduction to yield undesired products. Furthermore, SC-CO2 could attenuate the Lewis acidic strength of surface sites and therefore deterred NH3 oxidation at up to ∼280 °C. Meanwhile, Mn-CO2 regulated the formation of intermediates vital to direct NH3 consumption rates (−r NH3) and N2 selectivities in a desired manner at 280–400 °C. Hence, Mn-CO2 provided higher S N2 values despite exhibiting smaller −r NH3 values in comparison with those of the analogue unsubjected to SC-CO2 (Mn). The benefits provided by SC-CO2 were coupled to enhance NO X reduction performance of Mn-CO2 over Mn at 150–400 °C. Importantly, Mn-CO2 enhanced long-term stability in reducing NO X over Mn in the presence of SO2 at ≤200 °C by encouraging the formation of Brönsted acidic sites and hampering the transition of Lewis acidic Mn species to MnSO3/MnSO4.

Anthropogenic flue gases consist of NOX/SO2/H2O, among which H2O resistance is often underrated in activating acidic/redox cycles of NH3-assisted catalytic NOX reduction (SCR), SO2/H2O-induced evolution of ammonium (bi)sulfate (AS/ABS) poisons,...

No abstract

No abstract

No abstract

No abstract

Oryctes rhinoceros nudivirus (OrNV) has been known to cause severe disease in coconut palm rhinoceros beetle, Oryctes rhinoceros, in Southeastern Asia and is used as a biological control to reduce the pest population. Here, we report for the first time that the OrNV may have landed on Korea and may be the major pathogen for diseased larvae of Korean horn beetle, Allomyrina dichotoma. After peroral inoculation, over 60% of infected larvae perished in 6 wk. This viral disease spreads very fast in several locations throughout Korea. This threat not only makes economic loss of local farms rearing A. dichotoma larvae but also may disturb the ecosystem by transmitting to wild A. dichotoma.