Insights into the structure–property–activity relationship in molybdenum-doped octahedral molecular sieve manganese oxides for catalytic oxidation
Hexavalent molybdenum ions substituted into the mixed-valent framework of octahedral molecular sieve manganese oxides (1–10 mol% Mo–K-OMS-2) were systematically prepared via a single-step refluxing method. Here, the structure, composition, morphology, thermal stability, and textural and redox properties of the Mo–K-OMS-2 materials were characterized by various experimental techniques. Density functional theory (DFT) calculations were performed to study the electronic properties of K-OMS-2 materials, including the influence of molybdenum on such properties. The catalytic activity of K-OMS-2 towards CO oxidation dramatically increased with Mo dopant concentration, until an optimum incorporation of 5 mol% was reached, giving full CO conversion at 120 °C (1 vol% CO, 1 vol% O2). More importantly, the activity of the 5% Mo–K-OMS-2 catalyst was (reversibly) inhibited by water vapour (3%) in the feed only at low temperatures and exhibited better tolerance and stability during long-run experiments (28 h) as compared to undoped K-OMS-2. The superior performance of Mo–K-OMS-2 catalyst for CO oxidation can be attributed to the following factors: (1) morphological evolution from nanofibers to nanospheres, as well as the slightly distorted structure, generated a sharp increase in the specific surface area up to 258 m2 g–1, hence, increased the number of surface active sites; (2) improved mobility of reactive oxygen species at the surface and enhanced redox properties; and (3) tailored electronic properties promoted more active sites for oxidation reactions, which is supported by DFT calculations.
- Research Organization:
- Univ. of Connecticut, Storrs, CT (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
- Grant/Contract Number:
- FG02-86ER13622
- OSTI ID:
- 1598173
- Journal Information:
- Catalysis Science and Technology, Journal Name: Catalysis Science and Technology Journal Issue: 24 Vol. 8; ISSN CSTAGD; ISSN 2044-4753
- Publisher:
- Royal Society of ChemistryCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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