Tunnel structured manganese oxide octahedral molecular sieve (OMS) materials have been recently exploited as potential materials in the field of heterogeneous catalysis and battery technology. In the present study cerium incorporated manganese oxide OMS-2 catalysts have been synthesized by ion-exchange and impregnation methods. Crystal structure, thermal stability, textural property and morphology of as synthesized materials have been characterized using XRD, TGA, BET and TEM techniques. © 2004 Elsevier B.V. All rights reserved.

Balasubramanian Viswanathan

Thirukkallam Kanthadai Varadarajan

CERIUM COMPOUNDS

Crystal Structure

Impregnation

Ion Exchange

Manganese compounds

Molecular sieves

Morphology

Porous materials

Synthesis (chemical)

Thermodynamic stability

Thermogravimetric analysis

X ray diffraction analysis

BIXBYITE

CRYPTOMELANE

Cyclohexanol

Manganese oxide

OCTAHEDRAL MOLECULAR SIEVE (OMS)

TEXTURAL PROPERTY

CATALYSTS

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Catalysis Communications

Potassium-birnessite (K-OL-1) samples of different morphologies (nanowire networks, nanoparticles and mesoporous hierarchical nanowire networks) and textural properties were synthesized from KMnO4 by using oxalate-reduction method under ambient conditions. Cryptomelane (K-OMS-2) samples of similar morphologies were synthesized by the calcination of birnessite samples. The synthesized MnO2 samples were characterized by XRD, TGA, DTA, SEM, TEM, nitrogen adsorption-desorption and ICP-OES analyses. One each of the birnessite and the cryptomelane samples showed mesoporous nature (pore size ∼50 Å and 66 Å respectively). The pH of the reaction medium has been found to have a key role in the properties of the resulting MnO2 samples. Electrochemical studies of MnO 2-carbon black composites were performed in 0.1 M aqueous Na 2SO4 solution using cyclic voltammetry and galvanostatic charge-discharge cycling. One of the birnessite samples with nanowire network morphology and a BET surface area of 202 m2 g-1 exhibited a high capacitance value of 234 F g-1. Electrochemical studies revealed that the specific capacitance values of the studied MnO2 materials have a direct relationship with their BET surface area values. Birnessite samples have exhibited better capacitance behavior and values than their cryptomelane derivatives. The effect of the morphology has also been reflected in the values of the specific capacitance. This journal is © the Partner Organisations 2014.

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RSC Advances

A facile, morphology-controlled synthesis of potassium-containing manganese oxide nanostructures for electrochemical supercapacitor application

Four samples of ceria incorporated manganese oxide (NCMO) were prepared by co-precipitation-calcinations and sol-gel methods, and characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, BET surface area etc. The synthetic samples were nanoparticle agglomerates with irregular surface morphology (Ce:Mn=1:1). The NCMO-1b sample, prepared by the calcination of metal hydroxide at 573K for 3.0h, was a nano-crystalline (70-90nm) and hydrated material having high BET surface area (116.96m2g-1). The arsenic(V)-sorption by the samples at pH 7.0 (±0.2) and 30°C showed that the NCMO-1b is a most efficient material. Optimum pH range for the arsenic(V) sorption is 3.0-7.0 at 303 (±1.0)K. Kinetics and equilibrium data obtained (pH=7.0±0.2, T=303±1.0K and I=0.01M) had described the pseudo-second order kinetics and the Freundlich isotherm models well, respectively. Thermodynamics of the sorption reaction showed that the changes of enthalpy (ΔH°), entropy (ΔS°) and Gibbs free energy (ΔG°), respectively, were +23.901kJmol-1, +0.175kJmol-1K-1 and -25.737 to -32.753kJmol-1 at T=283-323K. Estimation of the sorption energy (E=17.15kJmol-1) indicated that the arsenic(V) was chemisorbed on NCMO-1b. The phosphate only reduced the arsenic(V) removal efficiency of NCMO-1b. © 2011 Elsevier B.V.

Chemical Engineering Journal

Ceria associated manganese oxide nanoparticles: Synthesis, characterization and arsenic(V) sorption behavior

Preparation, characterization and catalytic properties of cerium incorporated porous manganese oxide OMS-2 catalysts

Journal	Catalysis Communications
ISSN	15667367
Open Access	No