JASON OWENS

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The specifics of my research:

My present research is focused on aldehyde reactions on the surface of alumina supported palladium catalysts.  Aldehydes are important intermediates in the formation of higher alcohols, as well as important chemicals by themselves.  Some research has been done under ultrahigh vacuum (UHV) conditions for the liquid phase, and several mechanisms for the formation and dissociation of aldehydes on palladium have been proposed.  Following is a proposed mechanism for the dissociation of acetaldehyde (CH₃CHO) on a palladium catalyst:

Proposed mechanism for the dissociation of CH3CHO on a Pd surface. Notice intermediate species that can be identified at various stages (e.g. C2H2O, CO).

My research is focused on testing these reactions under practical conditions and determining if the same species are found – that is, if the aldehyde reactions follow the same mechanisms in normal conditions.  I do this by monitoring the reaction on a thin film of catalyst using FT-IR spectroscopy.

The first step is creating a catalyst.  I do this using the wet impregnation method of catalyst synthesis (see Michelle Casper’s web page).  Once I have made a catalyst, I create  a suspension of the catalyst in a solvent like water.  I then coat a crystal waveguide six times, each time allowing the solvent to evaporate off leaving just the catalyst.  Once the film is prepared, I place the film in the flowcell and set up the experiment. The setup involves a reservoir of solvent, like water, into which I can add reactants or remove them fromthereaction.  I pump the mixture out of the reservoir and across the surface of the catalyst through the flowcell.  The infrared spectrometer takes spectra on the surface of the catalyst at set time increments (I usually have 1 minute between each spectra).  I first create a steady environment on the surface of the catalyst by flowing just water for several hours.  Then I oxidize and reduce the catalyst with oxygen, O₂, and hydrogen, H₂, respectively.  These steps are known as pretreatment and ensure that the conditions are the same for every experiment.  I then inject the aldehyde solution into the system and watch for the formation of surface species as the aldehyde reacts on the surface of the catalyst.  These species show up as peaks on the spectra.  Below is a picture of the setup and an example of the series of spectra taken over the course of an experiment.

Reservoir with gas lines in and out and mixture lines to and from the flowcell. The flowcell is inside the infrared spectrometer

Several spectra taken during an experiment of formaldehyde in water. Notice a peak on the far right side of the screen, corresponding to formaldehyde