Articles written in Journal of Chemical Sciences
Volume 126 Issue 2 March 2014 pp 467-472
Vanadium-incorporated molybdophosporic acid catalysts supported on titania were prepared and characterized by FT-IR, X-ray diffraction and laser Raman spectroscopy. Characterization data reveals the incorporation of vanadium into the primary structure of Keggin ion of MPA. Catalysts activities were evaluated for oxidation of 1,2-benzenedimethanol using H2O2 and O2 as oxidants. Vanadium-containing catalysts showed high activity compared to their parent heteropoly acids. Oxidation ability depended on the number of V atoms present in Keggin heteropoly molybdate. Effect of reaction parameters on the oxidation ability was also evaluated.
Volume 126 Issue 2 March 2014 pp 487-498
Influence of the nature of support on the formation of catalytically active species was investigated to clarify the key factor for the synthesis of supported ammonium salt of 12-molybdophosphoric acid (AMPA) catalyst which maintains the activity of ammoxidation during 2-methylpyrazine reaction.With this aim, different loadings of niobia-, silica- and alumina-, supported AMPA catalysts were prepared. The AMPA loading was varied in the range of 5-25 wt%. The synthesized solids were characterized by nitrogen adsorption for BET surface area, XRD and 31P MAS NMR techniques. All the AMPA-supported samples are poorly crystalline even after 25 wt% AMPA loading. Investigations using 31P MAS NMR spectroscopy of samples revealed that Keggin ion existed as at least five different species on the supports. The investigated properties were acidity of the support and amount of AMPA loading on the support. Active sites for the ammoxidation of MP on supported AMPA catalysts seem to be the interacted and/or the lacunary species.Maximum catalytic activity could be obtained at lower loadings with AMPA deposited on acidic supports whereas the less acidic supports require higher loading. It was found that in order to efficiently generate the active interactive species, the support must have an acidity which promotes the formation of support-AMPA interactive species. It is possible to enhance the catalytic activity of the supported AMPA catalyst for ammoxidation of 2-methylpyrazine by controlling the acidity of the support and AMPA loading on the support.
Volume 127 Issue 5 May 2015 pp 897-908 Regular Articles
Catalysts with varying WO3 content on SnO2 were prepared and characterized by X-ray diffraction,
Volume 128 Issue 2 February 2016 pp 227-234 Regular Articles
The objective of this work is to understand the influence of small amount of Mo=O (1, 3 and 5wt.% MoO3) impregnated on FePO4 and its resultant effect on the acidity was studied for the ammoxidation of 2-methyl pyrazine (2-MP) to 2-cyano pyrazine (2-CP) in the temperature range of 380–420°C. The Mo/FeP catalyst characteristics were evaluated by XRD, HAADF-EDS, TPR and NH3-TPD techniques. Primarily, quartz-type XRD phase was observed for the iron phosphate (FeP). The Mo/FeP exhibits MoO3 and quartztype iron phosphate phase. The interface between Mo particles (20 nm) and FeP was clearly established by HR-TEM in 3Mo/FeP. Furthermore, the average atomic composition revealed by HAADF/EDS for 3Mo/FeP as Fe 30.0%, P 40.0% and Mo 1.6% with Fe/Mo surface XPS ratio 6. The greater 2-CP yield of 68.0% on 3Mo/FeP was attributed to enhanced, moderate acid sites coming from MoO3 and cooperation between Mo and FeP at the interface in terms of oxygen and electron transfer to the reactant (2-MP).
Volume 132, 2020
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