Ceria Modified MnOx/TiO2-Pillared Clays Catalysts for the Selective Catalytic Reduction of NO with NH3 at Low Temperature

et al. 2016

Catalysts

Abstract:A series of Fe-Ce-Ti catalysts were prepared via co-precipitation method to investigate the effect of doping Ce into Fe-Ti catalysts for selective catalytic reduction of NO with NH 3 . The NO conversion over Fe-Ce-Ti catalysts was considerably improved after Ce doping compared to that of Fe-Ti catalysts. The Fe(0.2)-Ce(0.4)-Ti catalysts exhibited superior catalytic activity to that of Fe(0.2)-Ti catalysts. The obtained catalysts were characterized by N 2 adsorption (BET), X-ray diffraction (XRD), temperature programmed reduction (H 2 -TPR), temperature programmed desorption (NH 3 -TPD), Fourier transform infrared (FT-IR) spectrophotometry, thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). The data showed that the introduction of Ce results in higher surface area and better dispersion of active components on the catalyst surface and enhances the amount of surface acid sites. The interactions between Fe and Ce species were found to improve the redox ability of the catalyst, which promotes catalytic performance at low temperature. The XPS results revealed that Fe 3+ /Fe 2+ and Ce 4+ /Ce 3+ coexisted on the catalyst surface and that Ti was in 4+ oxidation state on catalyst surface. Ce doping increased the atomic ratio of Fe/Ti and Ce/Ti and enhanced the surface adsorbed oxygen species. In addition, Fe(0.2)-Ce(0.4)-Ti catalyst also showed better tolerance to H 2 O and SO 2 and up to 92% NO conversion at 270˝C with 200 ppm SO 2 added over 25 h, which suggests that it is a promising industrial catalyst for mid-low temperature NH 3 -selective catalytic reduction (SCR) reaction.

Section: Bet Resultssupporting

confidence: 86%

Section: Bet Resultsmentioning

confidence: 99%

Promotional Effect of Ce on Iron-Based Catalysts for Selective Catalytic Reduction of NO with NH3

Wang

et al. 2016

Catalysts

“…Thus, it is crucial to explore the H 2 O resistance to the oxidation of Hg 0 for possible industrial applications. [42] Although the surface area decreased, the efficiency for the oxidation of Hg 0 significantly increased, indicating that TiO 2 -modified Mn-Ce mixed oxide exhibited good performance for the oxidation of Hg 0 , with catalytic oxidation being the main contributor. With the addition of 1% water vapor into simulated flue gas, the efficiency for the oxidation of elemental mercury only reached 78.5% ( Figure 6).…”

Section: Effect Of H 2 Omentioning

confidence: 96%

“…With the further exposure to a higher water vapor concentration to 5%, a lower oxidation efficiency of 69.1% can be obtained. [42] Indeed, the active components did not destroy the catalyst carrier structure. With the loading of Mn-Ce mixed oxide on the TiO 2 surface, the surface area and pore volume decreased because of the deposition of Mn-Ce mixed oxide on the sample surface and blocking of the micropores.…”

Section: Effect Of H 2 Omentioning

confidence: 99%

High efficiency of Mn–Ce‐modified TiO₂ catalysts for the low‐temperature oxidation of Hg⁰ under a reducing atmosphere

Ning

Wang

et al. 2019

Applied Organom Chemis

Manganese-and cerium oxide-modified titania catalysts were prepared by the deposition precipitation for the removal of elemental mercury (Hg 0 ) from simulated yellow phosphorus off-gas at low temperature. In addition, these catalysts were characterized by X-ray diffraction, Brunauer-Emmett-Teller measurements, X-ray photoelectron spectroscopy and field-emission scanning electron microscope to determine the surface morphology of the obtained compounds and explore their formation mechanism. The results revealed that a Mn-Ce loading and reaction temperature of 10% and 150°C, respectively, as well as a Mn/Ce molar ratio of 2:1, led to an optimal efficiency for the oxidation of elemental mercury. Furthermore, the effects of flue gas components were investigated. The presence of O 2 clearly promoted the oxidation of Hg 0 .A CO atmosphere did not affect the Hg 0 oxidation, when compared with N 2 , whereas the presence of H 2 S and water vapor inhibited the oxidation process. Furthermore, the X-ray photoelectron spectroscopy spectra of Hg 4f revealed that the elemental mercury adsorbed by the catalyst is present as HgO. Finally, the Hg 0 catalytic oxidation mechanism was discussed on the basis of the experimental results and characterization analysis.

“…The BET surface area and average pore size of xCo3O4/CNNS dropped to 27-42 m 2 /g and 10-12 nm, respectively. The probable reason for this is that parts of the mesoporous structures of the CNNS were filled or blocked by Co3O4 grains [30]. The nitrogen isotherms of the pure and Co 3 O 4 -modified CNNS are presented in Figure 5.…”

Section: Characterization Analysismentioning

confidence: 99%

Co3O4/g-C3N4 Hybrids for Gas-Phase Hg0 Removal at Low Temperature

Liu

2019

Processes

The Co3O4/g-C3N4 hybrids are constructed via the incipient wetness impregnation method by depositing Co3O4 onto the exterior of g-C3N4, and then employed for Hg0 capture within 60–240 °C. The results show that the Co3O4/g-C3N4 hybrid with a Co3O4 content of 12 wt% performs optimally with the highest Hg0 removal efficiency of ~100% at or above 120 °C. The high performances of the Co3O4/g-C3N4 hybrids are probably attributed to the tight interfacial contact between Co3O4 and g-C3N4, with its improved electron transfer, inferring that cobalt oxide and g-C3N4 display a cooperative effect towards Hg0 removal. NO and SO2 shows a significant suppressive influence on the mercury capture performance, plausibly owing to the competing adsorption and side reactions.