(108c) Decomposition of Isopropanol As a Probe for Acidic and Basic Sites On Graphite Nanofibers

Three types of as-produced and treated graphite nanofibers (GNFs) were used as catalysts in the decomposition of isopropanol to propene and acetone in the presence of oxygen to evaluate the surface chemistry of the fibers.  As-produced herringbone fibers were found to produce higher selectivity for propene compared to the as-produced platelet and ribbon fibers at all temperatures explored.  Herringbone fibers that had undergone oxidative treatment with nitric acid, phosphoric acid, ruthenium tetroxide or potassium permanganate were also evaluated at a single temperature of 290 °C.  BET surface analysis and SEM/EDS were used to assess the effects of oxidation on fiber structure.  Selectivity for acetone dehydrogenation product or propene dehydration product could be achieved by the appropriate surface treatment.  Nitric acid was the mildest treatment and the treated fibers showed minimal changes.  Phosphoric acid treated fibers were found to produce very high conversions and almost pure selectivity for propene.  Ruthenium tetroxide did not appear to have a large affect on fiber morphology; however, selectivity for acetone was much higher when GNFs treated with RuO₄ were used as the catalyst.  Potassium permanganate was a very harsh treatment that almost completely degraded fiber structure, creating amorphous carbon.