Novel Na 2 Mo 4 O 13 /α-MoO 3 hybrid material as highly efficient CWAO catalyst for dye degradation at ambient conditions

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A method for producing a metal powder product involves: Providing a supply of a precursor metal powder; combining the precursor metal powder with a liquid to form a slurry; feeding the slurry into a pulsating stream of hot gas; and recovering the metal powder product.

Metal Powders and Methods for Producing the Same

Preparation of Hydrated Potassium Molybdenum Bronzes and Their Thermal Decomposition

To develop new catalysts which can be used in catalytic wet air oxidation (CWAO) with ambient temperature and atmospheric pressure, a series of M 2 Mo 4 O 13 /α-MoO 3 (M = Li, Na or K) hybrid catalysts for cationic red GTL removal were synthesized by a facile hydrothermal method. The growth of crystals under different synthesis pH and the phase evolution during thermal treatment were carefully monitored using various analytical tools. The influence of synthesis pH, calcination temperature, reaction temperature, degradation time, and bubbling with air or N 2 on the decolorization efficiency, and the removal rates of total organic carbon (TOC) and chemical oxygen demand (COD) were systematically investigated. For all three catalysts, approximately 100% of color and over 93% of TOC could be removed within 30 min. Compared to many catalysts reported in literature, these novel catalysts showed higher catalytic activity in dye wastewater degradation. The catalytic activity tests in the presence of 2,2,6,6-tetramethyl-1-piperidinyloxy- N -oxyl (TEMPO) and the electron spin resonance (ESR) analysis suggested that the existence of M 2 Mo 4 O 13 (M = Li, Na or K) promotes the formation of OH radicals and is critical for their superior catalytic activity. Considering the ambient operating condition and the excellent catalytic activity, these novel CWAO catalysts are very promising for practical applications.

Synthesis, characterization, and catalytic activity of alkali metal molybdate/α-MoO3 hybrids as highly efficient catalytic wet air oxidation catalysts

Hydrated molybdenum bronzes have been prepared by reduction reaction of MoO3 with NaBH4 in ethanol and DMSO. The reduction reactions in both solvents occur smoothly; thus, the layered structure of MoO3 is maintained in the product. Divalent cation Ca2+ has been intercalated between the MoO3 layers, which leads to highly reduced molybdenum bronze (Mo5.26+). Solvated molybdenum bronze catalyzes the reduction reaction of DMSO by NaBH4, producing CH3SCH3. The structure model of hydrated sodium molybdenum bronze has also been reinvestigated by using the Rietveld analysis. The hydrated molybdenum bronze crystallizes in an orthorhombic structure, in which the structure of Mo octahedron layers is closely related to that in MoO3. However, the structure refinement reveals that the Mo octahedron in the MoO3 layers is axially distorted, which is different from that in MoO3 but similar to an isoelectron compound H0.33MoO3.

Manabu Yanagi-ishi

Papers

Preparation of Hydrated Potassium Molybdenum Bronzes and Their Thermal Decomposition

Low temperature preparation of the blue potassium bronze from a hydrated potassium molybdenum bronze by heat treatment in a nitrogen atmosphere