Electron microscopy of some molybdenum oxide phases after use as catalysts in oxidative ammonolysis and ammoxidation of toluene

Journal Article · Mon Aug 01 04:00:00 EDT 1988 · J. Solid State Chem.; (United States)

DOI:https://doi.org/10.1016/0022-4596(88)90162-4· OSTI ID:5999675

Hansen, S; Andersson, A

Five molybdenum oxide samples, subjected to conditions of oxidative ammonolysis and ammoxidation of toluene at 450 and 460/degrees/C, respectively, have been characterized using X-ray diffraction, scanning and transmission electron microscopy, and specific surface area measurements. In oxidative ammonolysis, the relatively large, freshly prepared MoO/sub 3/ crystals are reduced to smaller MoO/sub 2/ crystals with a crystallite size of 5-30 nm. This process gives a perfectly pseudomorphous product with pores less than 5 nm. The specific surface area increases from < 0.1 m/sup 2//g to almost 40 m/sup 2//g. In subsequent ammoxidation, MoO/sub 2/ transforms first into orthorhombic MoO/sub 4/O/sub 11/ and finally into MoO/sub 3/. The crystals of Mo/sub 4/O/sub 11/ are about 1 ..mu..m in diameter, and their formation leads to a decrease of specific surface area. The original MoO/sub 3/ morphology is retained even after the sequence of transformation as follows: MoO/sub 3/ ..-->.. MoO/sub 2/ ..-->.. Mo/sub 4/O/sub 11/ (..-->..MoO/sub 3/). In some cases, the new generation of MoO/sub 3/ crystals grows parallel to the original MoO/sub 3/ crystals.

• Research Organization: Lund Institute of Technology (Sweden)
• OSTI ID: 5999675
• Journal Information: J. Solid State Chem.; (United States), Journal Name: J. Solid State Chem.; (United States) Vol. 75:2; ISSN JSSCB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
&amp; Refractories-- Structure &amp; Phase Studies
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical &amp; Physicochemical Properties
ALKYLATED AROMATICS
AMMONOLYSIS
AROMATICS
CATALYSIS
CATALYSTS
CHALCOGENIDES
CHEMICAL REACTIONS
COHERENT SCATTERING
CRYSTAL-PHASE TRANSFORMATIONS
DATA
DECOMPOSITION
DIFFRACTION
ELECTRON MICROSCOPY
EXPERIMENTAL DATA
HIGH TEMPERATURE
HYDROCARBONS
INFORMATION
MICROSCOPY
MOLYBDENUM COMPOUNDS
MOLYBDENUM OXIDES
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHASE STUDIES
PHASE TRANSFORMATIONS
REFRACTORY METAL COMPOUNDS
SCANNING ELECTRON MICROSCOPY
SCATTERING
SOLVOLYSIS
TOLUENE
TRANSITION ELEMENT COMPOUNDS
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION