Effects of bimetallic Ce/Fe nanoparticles on the desulfurization of thiophenes using activated carbon

CeO2 nanoparticles (NPs) have shown promising approaches as therapeutic agents in biology and medical sciences. The physicochemical properties of CeO2-NPs, such as size, agglomeration status in liquid, and surface charge, play important roles in the ultimate interactions of the NP with target cells. Recently, CeO2-NPs have been synthesized through several bio-directed methods applying natural and organic matrices as stabilizing agents in order to prepare biocompatible CeO2-NPs, thereby solving the challenges regarding safety, and providing the appropriate situation for their effective use in biomedicine. This review discusses the different green strategies for CeO2-NPs synthesis, their advantages and challenges that are to be overcome. In addition, this review focuses on recent progress in the potential application of CeO2-NPs in biological and medical fields. Exploiting biocompatible CeO2-NPs may improve outcomes profoundly with the promise of effective neurodegenerative therapy and multiple applications in nanobiotechnology. © 2017 Charbgoo et al.

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Cerium oxide nanoparticles: green synthesis and biological applications.

In this study, different amounts of Fe and Co species were loaded on activated semi-coke (ASC) using a hydrothermal method for the reduction of NO by CO. The series of prepared catalysts were characterized by SEM, N2 physisorption, ICP, XRD, XPS, H2-TPR, and in situ DRIFTS, as well as ESR and Raman spectroscopy. In addition, the denitration (deNOx) performance and water/SO2 resistance were investigated. The precursor solution with a molar ratio of 0.8:0.2 for Fe:Co (Fe0.8Co0.2/ASC) produced spherical clusters that were uniformly dispersed on the surface. Moreover, Fe0.8Co0.2/ASC exhibited the most effective deNOx activity. The highest deNOx activity for Fe0.8Co0.2/ASC (determined from the characterization) was attributed to the high fraction of Bronsted acid sites, high possibility for the formation of oxygen vacancies, and a strong redox performance. The DRIFTS results suggested a possible mechanism involving the adsorption of NO on the Fe0.8Co0.2/ASC surface, followed by its transformation to nitrates or nitrite/nitro species. At low temperatures ( 200 °C), the coordinated nitrates and CO species on the surface reacted with the produced CO2 and N2. The effects of water and SO2 on the deNOx performance were examined. In the presence of only water, the deNOx performance decreased because of the competitive adsorption with NO, and in the presence of only SO2, reversible deactivation was observed; however, if both water and SO2 were present, irreversible catalyst deactivation was observed.

Investigation on Fe-Co binary metal oxides supported on activated semi-coke for NO reduction by CO

Iron doped effects on active sites formation over activated carbon supported Mn-Ce oxide catalysts for low-temperature SCR of NO

Supported V2O5/Ce1–xTixO2 (3, 5, and 7 wt % V; x = 0, 0.1, 0.3, 0.5, 1) and bare supports have been tested in the selective catalytic reduction (SCR) of NO by NH3 at different gas hourly space velocities (GHSVs) and were comprehensively characterized using XRD, pseudo in situ XPS, and UV–vis DRS as well as EPR and DRIFTS in in situ and operando mode. The best V/Ce1–xTixO2 (x = 0.3, 0.5) catalysts showed almost 100% NO conversion and N2 selectivity already at 190 °C with a GHSV value of 70000 h–1, which belongs to the best performances observed so far in low-temperature NH3-SCR of NO. The corresponding bare supports still converted around 80% to N2 under the same conditions. On bare supports, SCR proceeds via a Langmuir–Hinshelwood mechanism comprising the reaction of adsorbed surface nitrates with adsorbed NH3. On V/Ce1–xTixO2, nitrate formation is not possible, and an Eley–Rideal mechanism is working in which gaseous NO reacts with adsorbed NH3 and NH4+. Lewis and Bronsted acid sites, though adsorption o...

Efficient VOx/Ce1–xTixO2 Catalysts for Low-Temperature NH3-SCR: Reaction Mechanism and Active Sites Assessed by in Situ/Operando Spectroscopy

In situ DRIFTS investigation on the SCR of NO with NH3 over V2O5 catalyst supported by activated semi-coke

Promoting effect of Nd on the reduction of NO with NH3 over CeO2 supported by activated semi-coke: an in situ DRIFTS study

Activated semi-coke, an economical carbonaceous material, is employed in the removal of SO2 from simulated flue gas of an industrial power plant. Activation by four commonly used agents, including CO2, KOH, ZnCl2, and H3PO4, is studied in detail, which demonstrates that the sample treated with KOH at high temperature presents the best performance on removal of SO2. Further investigation on the physical and chemical properties reveals that both optimized pore structure and increased amount of active sites of activated semi-coke could contribute to the high desulfurization capacity. The semi-coke activated with KOH is selected to discuss possible mechanisms of the adsorption and desorption processes. Performances with variation of desulfurization temperatures evidence that physically adsorbed SO2 can transform into chemically adsorbed SO2, which is significantly affected by temperature. Desulfurization behaviors under different flue gas compositions show that oxidation of SO2 to SO3 plays a key role in SO2 ...

Activated Semi-coke in SO2 Removal from Flue Gas: Selection of Activation Methodology and Desulfurization Mechanism Study

Low-temperature SCR of NO with NH3 over activated semi-coke composite-supported rare earth oxides

Nanosized CeO2 particles with a diameter of ∼200 nm were successfully loaded on activated carbon (AC) via a single-step hydrothermal process. The synthetic parameters, including hydrothermal temperature, precursor concentration, and reaction time, were regulated to control the size of the as-prepared CeO2 nanoparticles. The catalytic activity of CeO2 nanoparticles/AC was investigated by dynamic adsorption of SO2 from simulated flue gas, and the results exhibited remarkably enhanced SO2 adsorption capacity. The reaction mechanism of adsorbing and trapping SO2 by CeO2 nanoparticles/AC was discussed by laser Raman spectroscopy, X-ray powder diffraction, and thermodynamic calculations, which demonstrated that, in the presence of SO2 and O2, the generation of sulfate, accompanied by partial reduction of Ce4+ to Ce3+, was the key process during SO2 removal in our desulfurization experiments.

Zheng Yan

Papers

In situ DRIFTS investigation on the SCR of NO with NH3 over V2O5 catalyst supported by activated semi-coke

Promoting effect of Nd on the reduction of NO with NH3 over CeO2 supported by activated semi-coke: an in situ DRIFTS study

Activated Semi-coke in SO2 Removal from Flue Gas: Selection of Activation Methodology and Desulfurization Mechanism Study

Low-temperature SCR of NO with NH3 over activated semi-coke composite-supported rare earth oxides

Hydrothermal Synthesis of CeO2 Nanoparticles on Activated Carbon with Enhanced Desulfurization Activity