Investigation of ALD-synthesized Mixed Metal Oxide Catalysts

Improvements in the selective oxidation of hydrocarbons have the potential to transform the chemical industry.   The most active and well-studied catalyst is supported vanadia.  Evidence has shown that modifying the supporting material can have profound consequences on the catalytic ability of the active phase by changing the redox character of vanadium.  The goal of the present work is to better understand the effect that V-O-Support bonds have on catalyst performance by introducing molybdenum oxide to the surface.  By comparing the Mo/V mixed metal oxide catalysts to the corresponding single component catalysts, we hope to learn how molybdenum, which is more reducible than vanadium, influences the behavior of supported vanadia.

Currently, we have developed an atomic layer deposition (ALD) process using bisethylbenzene molybdenum and water that is capable of depositing small quantities of molybdenum oxide per cycle atop powder supports.  This process and the resulting material have been characterized by quartz crystal microbalance studies, Raman spectroscopy, and ultraviolet-visible diffuse reflectance spectroscopy.  We have investigated how the loading and structure changes depending on the number of deposition cycles, reactor temperature, and the underlying support.  Preliminary data has also been collected on the corresponding mixed metal oxide catalysts.  For future work, structural characterization will continue on the mixed metal oxide catalysts concurrent with catalytic studies to determine the presence and effect of V-O-Mo linkages. 

Figure 1: Synthetic strategy for forming V-O-Mo linkages on the surface of a support

Tasha Drake

Grant: ICEP