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Manganese-based catalysts have shown excellent low-temperature selective catalytic reduction (SCR) activity for NO x removal. However, they would always produce a high amount of more toxic byproduct, N 2 O. Ca modification has been reported to be able to promote N 2 selectivity for SCR catalysts, but the mechanism is still not clear. In this study, a series of Ca-modified Ce 0.02 Mn 0.4 /TiO 2 SCR catalysts were utilized for mechanism study. In terms of DRIFT analysis, the addition of Ca had significantly reduced the formation of NH on catalyst surface, which limited its reaction with NO to form N 2 O. Furthermore, Ca addition had also caused a deceased formation of NO 2 , reducing its reaction with NH 3 to form N 2 O, further increasing the N 2 selectivity of the catalysts. The results present herein could be beneficial to the development of efficient low-temperature SCR catalysts, particularly for Mn-based SCR catalysts.

Copper(I) sulfide (Cu(2)S) nanodisks with controllable size and aspect ratio have been synthesized by using a one-pot colloidal process, in which no pre-prepared organometallic precursors are required. The reaction involves the injection of dodecanethiol into a hot solution containing copper salt, surfactants, and a high boiling-point organic solvent. Copper thiolate forms at the beginning of the reaction which effectively acts as a precursor whose decomposition leads to further nucleation and growth of Cu(2)S nanocrystals. The nanocrystals begin as small nanodots in the early stages of the reaction, gradually turning into nanodisks with aspect ratios (average disk diameter divided by thickness) up to 2.0, while the band gap of the nanocrystals decreases accordingly. As the growth of nanocrystals follows the monomer addition mechanism, the diameter, thickness, aspect ratio, and optical property of the Cu(2)S nanodisks can be tuned systematically by changing the reaction time, the amount of surfactants, and the concentration of the precursors. This synthesis provides a simple and highly reproducible method for the preparation of Cu(2)S nanocrystals that may find potential applications in the fabrication of photovoltaic devices.

A novel process on simultaneous removal of NO and SO2 using aqueous peroxymonosulfate (PMS) with synergic activation of Cu2+/Fe3+ and high temperature in an impinging stream reactor is developed for the first time. Effects of PMS concentration, Cu2+/Fe3+ concentration, reaction temperature, solution pH, flue gas flow, liquid–gas ratio, gas components, and inorganic ions on NO/SO2 removals were investigated. Active species and products were determined by electron spin resonance spectroscopy and ion chromatography. Removal pathways of NO/SO2 were revealed, and mass transfer‐reaction kinetics of NO removal was studied. The optimal experimental conditions are obtained. H2SO4 and HNO3 are the main products. It is found that there is a clear synergy between Cu2+/Fe3+ and high temperature for activating PMS. and ·OH are found to be the main oxidants for NO removal. NO removals belong to pseudo‐first fast reactions in the two investigated oxidation systems. Besides, the kinetic parameters are also measured. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1287–1302, 2017

Titanium dioxide (TiO 2 ) codoped with bismuth (Bi) and sulfur (S) elements was prepared by a simple solgel method using tetrabutyl titanate, bismuth nitrate pentahydrate, and thiourea as precursors. The codoped TiO 2 calcined at 400 °C exhibits an intense absorption in the range of 500-800 nm. The absorption edge corresponds to a band gap of 2.0 eV. An indigo carmine solution of 20 mg/L was completely photodegraded in 40 min in the presence of such photocatalyst under visible light (λ > 410 nm). This highly active photocatalytic performance is associated with the existence of numerous oxygen vacancies, the acidic sites on the surface of TiO 2 , and the high specific surface area.

Materials for high‐efficiency photocatalytic CO2 reduction are desirable for solar‐to‐carbon fuel conversion. Herein, highly dispersed nickel cobalt oxyphosphide nanoparticles (NiCoOP NPs) were confined in multichannel hollow carbon fibers (MHCFs) to construct the NiCoOP‐NPs@MHCFs catalysts for efficient CO2 photoreduction. The synthesis involves electrospinning, phosphidation, and carbonization steps and permits facile tuning of chemical composition. In the catalyst, the mixed metal oxyphosphide NPs with ultrasmall size and high dispersion offer abundant catalytically active sites for redox reactions. At the same time, the multichannel hollow carbon matrix with high conductivity and open ends will effectively promote mass/charge transfer, improve CO2 adsorption, and prevent the metal oxyphosphide NPs from aggregation. The optimized hetero‐metal oxyphosphide catalyst exhibits considerable activity for photosensitized CO2 reduction, affording a high CO evolution rate of 16.6 μmol h−1 (per 0.1 mg of catalyst).

N-doped TiO 2 (anatase) with high visible light photoactivity was obtained by the thermal treatment of nanotube titanic acid (denoted as NTA) in an NH 3 flow and investigated by means of X-ray diffraction (XRD), transmission electronic microscopy (TEM), diffuse reflectance spectra (DRS), X-ray photoelectron spectroscopy (XPS), electron spin resonance (ESR), and photoluminescence (PL). With increasing NH 3 treatment temperature at T = 400 to 600 1C, the anatase crystallinity of the N-NTA(400-600) samples was gradually enhanced, while at 700 1C a new phase, TiN, appeared in the N-NTA(700) sample. XPS results show that the doped N atoms incorporated into anatase TiO 2 exist in the form of NO. A revised explanation for the triplet ESR signals obtained from the N-NTA(500-700) samples was put forward, i.e. the g = 2.004 main peak is contributed by single-electron-trapped oxygen vacancies (denoted as V o ), while two weak peaks (g = 2.023, 1.987) are contributed by chemisorbed NO in well-crystallized anatase TiO 2 .The visible light photoactivity is proportional to the height of the g = 2.004 main peak, which suggests that the photoactive centers are V o -NO-Ti. The adsorbed NO molecule can effectively suppress the photoluminescence of V o defects, which facilitates photogenerated charge transfer to the surface reactive centers to conduct redox reactions. The higher the V o -NO-Ti concentration, the better the visible light photoactivity. The highest photoactivity was obtained for the catalyst, NH 3 -treated at 600 1C. But the formation of TiN at T = 700 1C can readily destruct V o -NO-Ti photoactive centers, and thus readily decreases photoactivity efficiency.

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