Optimization of the Graphitization Process at AGE-1

Abstract

The reaction conditions for the graphitization of CO2 with hydrogen were optimized for a fast production of high-quality carbon samples for accelerator mass spectrometry (AMS) measurement. The iron catalyst in use is first oxidized by heating with air to remove possible carbon and other impurities and then after evacuation reduced back to iron with hydrogen in several flushing steps to remove any iron oxide. The optimum conditions for a fast graphitization reaction were experimentally determined by changing the reaction temperatures and the H2/CO2 ratio. The resulting graphite samples were measured by AMS to find the smallest isotopic changes (13C) at a minimum of molecular fragment formation (13CH current). The improvements are based on thermodynamic data and are explained with Baur-Glaessner diagrams.