Start
Aug 21, 2014 - 17:00
End
Aug 21, 2014 - 18:00
Venue
Creativity Hall Room 118 Chemical Engineering
Event Type
Speaker
Dr. Kamalakanta Routray PhD Reliance Industries Bombay
Title
Catalysis Science of Bulk Mixed Metal Oxides
Abstract : Bulk mixed metal oxide catalysts are used in industry for a number of oxidation processes. Some examples are iron-molybdate for methanol oxidation to formaldehyde and bismuth-molybdate for propylene ammoxidation to acrylonitrile. However the reason behind their activity and selectivity is still not well-understood. To address these fundamental questions spectroscopic and kinetic studies were undertaken to provide quantitative bulk and surface information. Raman IR and CH3OH-temperature programmed surface reaction (TPSR) low energy ion scattering (LEISS) spectroscopy along with steady state methanol oxidation were employed to investigate the fundamentals responsible for the activity of bulk mixed molybdate catalyst. To examine the literature hypothesis that M=O bonds are responsible for the activity of bulk mixed metal oxides a series of bulk mixed vanadates and molybdates were synthesized. Their methanol oxidation activity was compared with the corresponding M=O Raman vibrations and crystallographic bond lengths. No particular relationship however was found between the bulk M=O bond length and its catalytic activity (TOF). Low energy ion scattering spectroscopy (LEISS) has been employed to probe the surface of bulk mixed vanadium and molybdenum oxides. The results reveal the enrichment of the surface with vanadium and molybdenum oxide species which is responsible for the activity and selectivity of mixed oxides towards formaldehyde product. The result encouraged towards investigating bulk iron-molybdate (Fe2(MoO4)3) catalyst for their catalytic activity towards the methanol oxidation reaction. The stoichiometric iron-molybdate (Mo/Fe=1.5) has mostly exposed molybdate species along with a small amount of exposed FeOx sites on the surface. With increasing Mo/Fe ratio (> 1.5) the excess MoO3 covers the exposed FeOx sites and increases the selectivity towards the desired HCHO product from surface MoOx sites and reduces the selectivity of undesired dimethyl ether from surface FeOx sites. Similar information was also obtained from the CH3OH-IR spectroscopy measurements. The bulk Fe2(MoO4)3 catalyst follow the Mars-van Krevelen reaction mechanism employing bulk lattice oxygen. These studies demonstrate that the bulk mixed metal molybdate catalysts are surface enriched with surface molybdena species which are the catalytic active sites for redox selective oxidation reactions. It is noteworthy that similar results have also been observed with bulk mixed metal vanadates.Short Bio of speaker Kamalakanta obtained his Ph.D. from Lehigh University Bethlehem PA in the area of heterogeneous catalysis. During this time he focused on understanding bulk mixed metal oxide catalysts for the oxidation of methanol through various characterization techniques. He worked on conversion of biomass to biofuels during his Postdoc at Univ. of Massachusetts Amherst. He has 5 years of industrial experience having worked for Evonik Degussa and currently at Reliance Industries Limited. He has 7 scientific publications and 1 patent in the area of heterogeneous catalysis.