Studies of oxygen species in synthetic Todorokite-like manganese oxide octahedral molecular sieves

Journal Article · Sat Oct 01 04:00:00 EDT 1994 · Chemistry of Materials; (United States)

DOI:https://doi.org/10.1021/cm00046a038· OSTI ID:6564447

Yin, Yuan-Gen; Xu, Wen-Qing; Shen, Yan-Fei; Suib, S L ^[1]; O'Young, C L ^[2]

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1. Univ. of Connecticut, Storrs, CT (United States)
2. Texaco Research Center, New York, NY (United States)

Manganese oxide octahedral molecular sieves of 3 x 3 tunnel structure (OMS-1) doped with various cations possess high thermal stability and were studied by means of temperature-programmed desorption and reduction by H[sub 2] and CO. Different oxygen species can be discerned according to their peak positions in the temperature-programmed desorption and reduction and assigned to chemisorbed dioxygen, oxygen atoms bound to Mn[sup 2+], and those bound to Mn[sup 4+] ions in the framework. Differences in peak positions and availabilities of these species during TPD and TPR can be explained by creation of nascent Mn[sup 2+] ions during TPR. The effects of doping cations on the reactivity and availability of these oxygen species are demonstrated to be more pronounced in TPR in H[sub 2] or CO than in TPD. In some instances, the trends of changes in reactivity and availability of the oxygen species due to doping of Cu[sup 2+], Ni[sup 2+], Zn[sup 2+], and Mg[sup 2+] correlated with the changes in the heat of formation of oxides of these cations. Temperature-programmed reactions with methane show some reactivity of these doped OMS-1 materials. Pulse reactions with CO show higher reactivity of Cu-doped OM-1 than with butane. However, the recovery of Cu-doped OMS-1 by reoxidation with oxygen pulses seems rather incomplete at the same temperature. 27 refs., 9 figs.

• OSTI ID: 6564447
• Journal Information: Chemistry of Materials; (United States), Journal Name: Chemistry of Materials; (United States) Vol. 6:10; ISSN CMATEX; ISSN 0897-4756
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ADSORBENTS
ALKALINE EARTH METALS
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
COPPER
CRYSTAL DOPING
ELEMENTS
HYDROGEN
MAGNESIUM
MANGANESE COMPOUNDS
MANGANESE OXIDES
METALS
MOLECULAR SIEVES
NICKEL
NONMETALS
OXIDES
OXYGEN COMPOUNDS
REDUCTION
SORPTIVE PROPERTIES
SURFACE PROPERTIES
TEMPERATURE DEPENDENCE
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
ZINC