Search results for "COBALT OXIDE"

Deep oxidation of volatile organic compounds using ordered cobalt oxides prepared by a nanocasting route

2010

Ordered Co3O4 with high surface area (until 173 m2/g) has been successfully obtained through a nanocasting route using mesoporous KIT-6 silica as a hard template and tested in the deep oxidation of a series of representative volatile organic compounds (VOCs): propane as a model of short chain alkane and toluene as a model of monoaromatic hydrocarbon. It has been demonstrated that the catalytic activity for VOC deep oxidation is very elevated and its catalytic stability at moderate temperatures very good. However, the role of the ordered structure in the catalytic performance does not seem to be beneficial. The enhanced catalytic activity has been explained in terms of both the high surface …

CoOx catalysts supported on alumina and alumina-baria: influence of the support on the cobalt species and their activity in NO reduction by C3H6 in l…

2003

Abstract CoO x catalysts (Co 1 and 3 wt.%) were prepared by incipient-wetness impregnation of the supports, Al 2 O 3 and Al 2 O 3 (80 wt.%)-BaO (20 wt.%), and calcined at 500 and 800 °C. The samples were characterized by X-ray diffraction (XRD) and BET techniques. H 2 -temperature programmed reduction (TPR) and UV-Vis diffuse reflectance spectroscopy (DRS) spectra were recorded with the aim to identify the different Co species formed. The presence of Co 2+ species tetrahedrally and octahedrally coordinated appears strongly influenced by the nature of the support and the cobalt content. Co 3 O 4 particles were detected after calcination at 500 °C, a successive treatment at 800 °C promotes th…

Electrosynthesis of Ce–Co Mixed Oxide Nanotubes with High Aspect Ratio and Tunable Composition

2008

Cerium oxide and cobalt oxides have attracted the interest of several researchers due to their potential application in several technological fields electrochromism, lithium batteries, catalysis, etc.. Ceria has been used as a promoter in the so-called “three-way catalyst” for the control of toxic emission from automobile exhaust. The promotion consists of the enhancement of the noble metal dispersion, as well as stabilization of the supporting medium toward thermal sintering. 1,2 A direct catalytic effect of CeO2 in chemical processes such as water–gas shift reaction or NOx decomposition has been also evidenced. 3,4

Fabrication of cobalt and cobalt oxide/graphene composites: towards high-performance anode materials for lithium ion batteries.

2010

Deep oxidation of pollutants using gold deposited on a high surface area cobalt oxide prepared by a nanocasting route.

2011

Gold deposited on a cobalt oxide with high surface area (138 m2 g−1), obtained through a nanocasting route using a siliceous KIT-6 mesoporous material as a hard template, has demonstrated high activity for the total oxidation of propane and toluene, and ambient temperature CO oxidation. The addition of gold promotes the activity when compared to a gold-free Co3O4 catalyst prepared using the same nanocasting technique. The enhanced catalytic activity when gold is present has been explained for the deep oxidation of propane and toluene in terms of the improved reducibility of cobalt oxide when gold is added, rather than to the intrinsic activity of metallic gold particles. The improved behavi…

Synthesis and host properties of tetragonal Li2Mn2O4 and Li2Co0.4Mn1.6O4

2000

Abstract This paper presents synthesis and electrochemical properties of tetragonal lithium manganese dioxide, Li2Mn2O4 and its cobalt doped analogue Li2Co0.4Mn1.6O4. The materials are compared as host materials for lithium insertion and the behavior during the initial lithium extraction as well as on repeated cycling is presented. These materials show an initial lithium extraction capacity between 200 and 270 mAh/g. On repeated cycling, they are converted into spinel-like lattices with reversible capacities in the range 82–90 mAh/g. As they are chemically compatible with the manganese spinel, they will be well suited as additives compensating for the capacity loss during the initial formin…

Topography and morphology of multicomponent catalytic materials based on Co, Ce and Pd oxides deposited on metallic structured carriers studied by AF…

2013

A system of interfaced AFM and Raman microscopes was used to study heterogeneity of complex cat- alytic materials providing information on both the topography and the chemical composition of the surface in one measurement. The catalysts surface was examined at various stages of their preparation: precalcination of steel, washcoating, impregnation and doping. It has been shown that the surface of the precalcined steel sheets is covered mostly by -Al 2 O 3 although there are places where -Fe 2 O 3 and Fe 3 O 4 are also present. Washcoating of the precalcined sheets gives only partly uniform grain distribution of CeO 2 . Impregnation with cobalt leads to formation of uniform coverage of Co 3 O…

Enhanced kinetics of hole transfer and electrocatalysis during photocatalytic oxygen evolution by cocatalyst tuning

2016

Understanding photophysical and electrocatalytic processes during photocatalysis in a powder suspension system is crucial for developing efficient solar energy conversion systems. We report a substantial enhancement by a factor of 3 in photocatalytic efficiency for the oxygen evolution reaction (OER) by adding trace amounts (∼0.05 wt %) of noble metals (Rh and Ru) to a 2 wt % cobalt oxide modified Ta3N5 photocatalyst particulate. The optimized system exhibited high quantum efficiencies (QEs) of up to 28 and 8.4% at 500 and 600 nm in 0.1 M Na2S2O8 at pH 14. By isolation of the electrochemical components to generate doped cobalt oxide electrodes, the electrocatalytic activity of cobalt oxide …

Co3O4 particles grown over nanocrystalline CeO2: influence of precipitation agents and calcination temperature on the catalytic activity for methane …

2015

Crystalline cobalt oxides were prepared by a precipitation method using three different precipitation agents, (NH4)(2)CO3, Na2CO3 and CO(NH2)(2). Cobalt oxide nanoparticles corresponding to a Co3O4 loading of 30 wt% were also deposited over high-surface area nanocrystalline ceria by the same precipitation agents. The effect of calcination temperature, 350 or 650 degrees C, on the morphological and structural properties was evaluated. Characterization by BET, XRD, SEM, TEM, Raman spectroscopy, H-2-TPR, XPS and NH3-TPD was performed and the catalytic properties were explored in the methane oxidation reaction. The nature of the precipitation agent strongly influenced the textural properties of…

Catalytic performances of Co3O4/CeO2 and Co3O4/CeO2-ZrO2Composite oxides for methane combustion: influence of catalyst pretreatment temperature and o…

2007

Abstract The influence of catalyst pre-treatment temperature (650 and 750 °C) and oxygen concentration ( λ  = 8 and 1) on the light-off temperature of methane combustion has been investigated over two composite oxides, Co 3 O 4 /CeO 2 and Co 3 O 4 /CeO 2 –ZrO 2 containing 30 wt.% of Co 3 O 4 . The catalytic materials prepared by the co-precipitation method were calcined at 650 °C for 5 h (fresh samples); a portion of them was further treated at 750 °C for 7 h, in a furnace in static air (aged samples). Tests of methane combustion were carried out on fresh and aged catalysts at two different WHSV values (12 000 and 60 000 mL g −1  h −1 ). The catalytic performance of Co 3 O 4 /CeO 2 and Co 3…