Cu containing octahedral molecular sieves and octahedral layered materials

Journal Article · Sat Jun 01 04:00:00 EDT 1996 · Journal of Catalysis

DOI:https://doi.org/10.1006/jcat.1996.0168· OSTI ID:476034

Shen, Yan-Fei; Suib, S L ^[1]; O`Young, Chi-Lin ^[2]

---

1. Univ. of Connecticut, Storrs, CT (United States)
2. Texaco Inc., Beacon, NY (United States)

Manganese oxide octahedral molecular sieves (OMS) with Cu{sup 2+} in the tunnel(Cu-OMS-1) and octahedral layer (OL) manganese oxides with Cu{sup 2+} in the interlayer of buserite-like materials (Cu-OL-1) were prepared and characterized by X-ray diffraction, scanning electron microscopy/energy dispersive X-ray analysis, temperature programmed reduction, thiosulfate titrations, and volumetric adsorption of carbon monoxide (CO). The materials were tested as CO oxidation catalysts. Results show that autoclave treatment of Cu-OL-1 suspensions induces complete removal of chlorine as well as a change of the Cu/Mn ratio and average manganese oxidation state. Such changes depend on the initial MnO{sub 4}{sup -}/Mn{sup 2+} ratio. At a ratio of 0.34-0.40., autoclave treatment increases the manganese oxidation state and the Cu/Mn ratio. At a ratio of 0.44, however, treatment decreases manganese oxidation state and the Cu/Mn ratio. A possible mechanism is proposed for the hydrothermal transformation of Cu-OL-1 to Cu-OMS-1. CO oxidation data show that Cu-OMS-1 has a CO conversion of 89-99% at 60-100{degrees}C, while Cu-OL-1 has almost activity in the same temperature region. This dramatic difference is due to the fact that Cu-OMS-1 has more surface oxygen and a larger CO adsorption capacity, as compared to Cu-OL-1. Different structural properties may also contribute to the difference in catalytic activity, since the todorokite tunnel structure of OMS-1 is correlated with CO conversion. Blockage of the tunnels by water and tunnel collapse cause a significant decrease in CO oxidation. Kinetic studies of CO oxidation show that water vapor in the feed stream induces a small and reversible inhibition and that a positive reaction order is found with respect to CO partial pressure under these experimental conditions. 44 refs., 6 figs., 6 tabs.

• OSTI ID: 476034
• Journal Information: Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 1 Vol. 161; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

20 FOSSIL-FUELED POWER PLANTS
33 ADVANCED PROPULSION SYSTEMS
40 CHEMISTRY
ADSORPTION
CARBON MONOXIDE
CATALYST SUPPORTS
CATALYTIC EFFECTS
CHEMICAL REACTION KINETICS
COPPER
HETEROGENEOUS CATALYSIS
HYDROTHERMAL SYNTHESIS
MANGANESE OXIDES
MOLECULAR SIEVES
OXIDATION
REDUCTION
SCANNING ELECTRON MICROSCOPY
SORPTIVE PROPERTIES
STRUCTURAL CHEMICAL ANALYSIS
X-RAY DIFFRACTION