CREATION OF BASIC CARBON SURFACES WITH UNIQUE ADSORPTION PROPERTIES
Dr. Jonathan Phillips
Penn State University
Departments of Chemical Engineering and Materials Science
Wednesday, May 22nd, 3:30 pm
Ben Bandy Conference Room
Center for Applied Energy Research
A method was developed to create highly basic carbon surfaces, which are stable in ambient laboratory conditions (do not adsorb oxygen or water), yet able toadsorb considerable amounts of gas at slightly elevated temperatures ( >325 K). Microcalorimetric, point of zero charge and chemical analysis studies showed that carbons treated in hydrogen at high temperatures (>1175 K) were oxygen free, highly basic (PZC >8.5), and stable in ambient conditions for periods of months. Calorimetric and TPD studies also showed that these carbons had significant oxygen adsorption capacity at temperatures in excess of 325 K. In contrast, the same techniques showed that carbons treated in nitrogen at high temperature were initially 'basic', but rapidly adsorbed oxygen (with unusually high heats of adsorption), and gained acidity, upon exposure to air. The following hypothesis was found consistent with all data and explains the difference between high temperature hydrogen and nitrogen treatments: Both treatments thermally decompose oxygen groups, but only the hydrogen treatments removes (hydrogasifies) the 'dangling' carbons which are produced during the removal of oxygen as CO or CO2.