Direct reduction of SO2 to elemental sulfur by the coupling of cold plasma and catalyst (I)

The direct reduction of SO2 to elemental sulfur in flue gas by the coupling of cold plasma and catalyst, being a new approach for SO2 reduction, was studied. In this process, CO2 can be disassembled to form CO, which acts as the reductant under the cold plasma. With the coupling of the cold plasma and the catalyst, sulfur dioxide was selectively reduced by CO to elemental sulfur with a byproduct of metal sulfate, e.g., FeSO4. In the present work, Fe2O3/gamma-Al2O3 was employed as the catalyst. The extent of desulfurization was more than 80%, and the selectivity of elemental sulfur is about 55%. The effects of water vapor, temperature, and the components of simulated flue gas were investigated. At the same time, the coupling of thermogravimetry and infrared method and a chemical analysis method were employed to evaluate the used catalyst. In this paper, we will focus on the discussion of the catalyst. The discussions of the detail of plasma will be introduced in another paper.

A Mossbauer study of In-Fe2O3/HZSM-5 catalysts for the selective catalytic reduction of NO by methane

The selective catalytic reduction of NO by CH4 was compared over In-Fe2O3/HZSM-5 catalysts prepared by impregnation and co-impregnation methods. It was found that the catalyst preparation method greatly affected the catalyst activity. The impregnated catalyst was very active, but the co-impregnated one showed poor activity. The In Fe2O3/HZSM-5 catalysts were investigated by Mossbauer spectroscopy. The results showed that indium cations entered into the iron oxide lattice in the co-impregnated catalyst, while the impregnated catalyst exhibited a more stable structure, when both of the catalysts were treated severely in the reaction atmosphere. Characterization by means of combined in situ temperature programmed reduction (TPR)- Mossbauer spectroscopy further revealed that the performances of the two catalysts were different in the TPR processes.

Green synthesis of 1-2 nm gold nanoparticles stabilized by amine-terminated ionic liquid and their electrocatalytic activity in oxygen reduction

Stable gold nanoparticles with average size 1.7 nm synthesized by an amine-terminated ionic liquid showed enhanced electrocatalytic activity and high stability.

A method for quantitative analysis of nitrogen oxides and N2 by means of mass spectrometry with the assistance of a catalytic technique for the reduction of NO with CO or hydrocarbons

Mass spectrometry is not able to differentiate NOx and N2 from other interferences (e.g. CO and C2H4) in the deNOx reactions. In the present study, a quantitative method for analysis of NOx and N2 simultaneously in these reactions with an assisted converter operated at higher temperature under O2-rich condition, which eliminates the interferences, is developed. The NOx conversion from this method is comparable to the one from an Automotive Emission Analyser equipped with NOx electrochemical sensor. Two types of deNOx reactions are tested in terms of selectivity of N2 production. The application of this method is discussed.

The synthesis of perylene-coated graphene sheets decorated with Au nanoparticles and its electrocatalysis toward oxygen reduction

Chemically converted graphene (CCG)/3,4,9,10-perylene tetracarboxylic acid (PTCA)/Au-ionic liquid (Au-IL) composites (CCG/PTCA/Au-IL) have been prepared by a chemical route that involves functionalization of CCG with PTCA followed by deposition of Au-IL. Transmission electron microscopy revealed well-distributed Au with a high surface coverage. The identity of the hybrid material was confirmed through X-ray diffraction and X-ray photoelectron spectroscopy. The CCG/PTCA/Au-IL composites exhibited good electrocatalytic behavior toward oxygen reduction. The results indicate that modification of CCG with Au-IL could play an important role in increasing the electrocatalytic activity of CCG.

Reduction of Eu3+ to Eu2+ in MAl2Si2O8 (M = Ca, Sr, Ba) in air condition

In general, the reduction of Eu3+ to Eu2+ in solids needs an annealing Process in a reducing atmosphere. in this paper, it is of great interest and importance to find that the reduction of Eu3+ to Eu2+ can be realized in a series of alkaline-earth metal aluminum silicates MAl2Si2O8 (M = Ca, Sr, Ba) just in air condition. The Eu2+-doped MAl2Si2O8 (M = Ca, Sr, Ba) powder samples were prepared in air atmosphere by Pechini-type sol-gel process. It was found that the strong hand emissions of 4f(6)5d(1)-4f(7) from Eu2+ were observed at 417, 404 and 373 nm in air-annealed CaAl2Si2O8, SrAl2Si2O8 and BaAl2Si2O8, respectively, under ultraviolet excitation although the Eu3+ precursors were employed. In addition, under low-voltage electron beam excitation, Eu2+-doped MAl2Si2O8 also shows strong blue or ultraviolet emission corresponding to 4f(6)5d(1)-4f(7) transition.

Gold/platinum hybrid nanoparticles supported on multiwalled carbon nanotube/silica coaxial nanocables: Preparation and application as electrocatalysts for oxygen reduction

A simple approach combining sonication and sol-gel chemistry was employed to synthesize silica coated carbon nanotube (CNTs) coaxial nanocables. It was found that a homogeneous silica layer can be coated on the surface of the CNTs. This method is simple, rapid, and reproducible. Furthermore, gold nanoparticle supported coaxial nanocables were facilely obtained using amino-functionalized silica as the interlinker. Furthermore, to reduce the cost of Pt in fuel cells, designing a Pt shell on the surface of a noble metal such as gold or silver is necessary. High-density gold/platinum hybrid nanoparticles were located on the surface of I-D coaxial nanocables with high surface-to-volume ratios. It was found that this hybrid nanomaterial exhibits a high electrocatalytic activity for enhancing oxygen reduction (low overpotential associated with the oxygen reduction reaction and almost four-electron electroreduction of dioxygen to water).

Raspberry-like Hierarchical Au/Pt Nanoparticle Assembling Hollow Spheres with Nanochannels: An Advanced Nanoelectrocatalyst for the Oxygen Reduction Reaction

In this contribution, we for the first time report the synthesis of raspberry-like hierarchical Au/Pt nanoparticle (NP) assembling hollow spheres (RHAHS) with pore structure and complex morphology through one in situ sacrificial template approach without any post-treatment procedure. This method has some clear advantages including simplicity, quickness, high quality, good reproducibility, and no need of a complex post-treatment process (removing templating). Furthermore, the present method could be extended to other metal-based NP assembling hollow spheres. Most importantly, the as-prepared RHAHS exhibited excellent electrocatalytic activity for oxygen reduction reaction (ORR). For instance, the present RHAHS-modified electrode exhibited more positive potential (the half-wave potential at about 0.6 V), higher specific activity, and higher mass activity for ORR than that of commercial platinum black (CPB). Rotating ring-disk electrode (RRDE) voltarnmetry demonstrated that the RHAHS-modified electrode could almost catalyze a four-electron reduction of O-2 to H2O in a 0.5 M air-saturated H2SO4 solution.

Electrocatalytic reduction of 1,2-diiodoethane by anions of supramolecular complex of (beta-CD)(2)/C-60 in DMF solution

The homogeneous electrocatalytic reduction of 1,2-diiodoethane by anions of the supramolecular complex of (beta-CD)(2)/C-60 in DMF solution is reported. The results show that the trianion of (beta-CD)(2)/C-60 exhibits electrocatalytic behavior towards the reduction of 1,2-diiodoethane, whereas the diani on is unable to reduce the diiodoethane. The second-order catalytic rate constant in DMF solution was determined to be 3.1 x 10(5) M-1 s(-1) by analysis of voltammetric responses under pseudo-first-order conditions with respect to (beta-CD)(2)/C-60. The results suggest that the host beta-cyclodextrin molecules have little effect on the electrocatalytic ability of the encapsulated C-60 toward organic halides.

Electrochemical design of ultrathin platinum-coated gold nanoparticle monolayer films as a novel nanostructured electrocatalyst for oxygen reduction

The deliberate tailoring of nanostructured metallic catalysts at the monolayer-level is an ongoing challenge and could lead to new electronic and catalytic properties, since surface-catalyzed reactions are extremely sensitive to the atomic-level details of the catalytic surface. In this article, we present a novel electrochemical strategy to nanoparticle-based catalyst design using the recently developed underpotential deposition (UPD) redox replacement technique. A single UPD Cu replacement with Pt2+ yielded a uniform Pt layer on colloid gold surfaces. The ultrathin (nominally monolayer-level) Pt coating of the novel nanostructured particles was confirmed by cyclic voltammetry and X-ray photoelectron spectra (XPS). The present results demonstrate that ultrathin Pt coating effects efficiently and behaves as the nanostructured monometallic Pt for electrocatalytic oxygen reduction, and also shows size-dependent, tunable electrocatalytic ability. The as-prepared ultrathin Pt-coated Au nanoparticle monolayer electrodes reduce O-2 predominantly by four electrons to H2O, as confirmed by the rotating ring-disk electrode (RRDE) technique.