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J Am Chem Soc

Title:		"Adsorptive and acidic properties, reversible lattice oxygen evolution, and catalytic mechanism of cryptomelane-type manganese oxides as oxidation catalysts"
Author(s):		Luo J; Zhang Q; Garcia-Martinez J; Suib SL;
Address:		"U-60, Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, USA. Jian.luo@klchemtech.com"
Journal Title:		J Am Chem Soc
Year:		2008
Volume:		20080214
Issue:		10
Page Number:		3198 - 3207
DOI:		10.1021/ja077706e
ISSN/ISBN:		1520-5126 (Electronic) 0002-7863 (Linking)
Abstract:		"Cryptomelane-type manganese oxides have been synthesized, characterized, and tested in the total oxidation of volatile organic compounds and CO oxidation. The structural, compositional, morphological, acid-base, physisorptive-chemisorptive, and thermal stability properties (especially the reversible evolution of lattice oxygen) have been studied in detail using ICP-AES (inductively coupled plasma-atomic emission spectroscopy), HRSEM (high-resolution scanning electronic microscope), XRD (X-ray diffraction), IR (infrared) and adsorbate-IR, N2 and CO2 physisorption at 77 and 273 K, respectively, TPD-MS (temperature-programmed decomposition-mass spectroscopy), and TGA-DSC (thermogravimetric analysis-differential scanning calorimetry) techniques. Kinetic and mechanistic studies for the catalytic function have been conducted and related to the characterization results. Cryptomelane has shown to be highly microporous, by using CO2 physisorption, and highly hydrophobic, possessing both Bronsted and Lewis acid sites. A part of the lattice oxygen atoms can be reversibly removed from the framework and recovered at elevated temperature without changing the framework structure. These lattice oxygen atoms can react with CO even at room temperature and are active sites for the oxidation of benzene. The consumed lattice oxygen atoms are replenished by gaseous oxygen to complete a catalytic cycle. The ease of reversible evolution of lattice oxygen, together with the high porosity, hydrophobicity, and acidity, leads to the excellent oxidation properties of OMS-2"
Keywords:
Notes:		"PubMed-not-MEDLINELuo, Jian Zhang, Qiuhua Garcia-Martinez, Javier Suib, Steven L eng 2008/02/15 J Am Chem Soc. 2008 Mar 12; 130(10):3198-207. doi: 10.1021/ja077706e. Epub 2008 Feb 14"