(350c) Catalytic Activity of Graphite Nanofibers

Graphite nanofibers are a high surface area material produced from dissociation of a carbon containing gas over a catalyst. Their large surface area makes them an ideal candidate to be used as a heterogeneous catalyst for various reactions. Catalytic activity of three different types of graphite nanofibers with different orientations of the graphene sheets; herringbone, platelet, and ribbon; are being analyzed. Dehydrogenation of ethanol to acetaldehyde and ethyl acetate is the main reaction being examined. Significant differences in percent conversion and product selectivity have already been found with respect to fiber type, temperature, residence time of reactant through the packed bed reactor, and gas flow ratio of oxygen to nitrogen. Trials were run at 30 degree Celsius intervals from 200 degrees C to 320 degrees C. Below 200 degrees C, minimal conversions were found, while fiber oxidation and degradation become concerns at temperatures above 320 degrees Celsius. Nitrogen is used as a carrier gas to promote flow through the reactor, while oxygen gas was found to regenerate the catalyst and promote increased conversions. Also, dimineralized fibers (fibers that have had the fiber growth catalyst removed), are being analyzed to show that the graphite fibers themselves are responsible for catalytic activity and not the fiber growth catalyst.