Novel catalysts for methane activation. Final progress report, September 30, 1992--April 30, 1996

Abstract

DXSCLAIMERPortions of this document may be illegible in electronic image products. Images are produced from the best available original document. EXECUTIVE SUMMARYThis fmal report summarizes the results of our research under Contract No. DE-AC22-92PC92112, Novel Catalysts for Methane Activation. In this research we prepared and tested fullerene soots for converting methane into higher hydrocarbons. We conducted the methane conversions using dehydrwoupling conditions, primarily in the temperature regimes of 6OOO-1000°C and atmospheric pressures. The research was divided into three sections. The first section focused on comparing fullerene soots with other forms of carbon such as acetylene black and Norit-A. We found that the fullerene soot was indeed more reactive than the other forms of carbon. However, due to its high reactivity, it was not selective. The second section focused on the effect of metals on the reactivity of the soots, including both transition metals and alkali metals. We found that potassium could enhance the selectivities of fullerene soot to higher hydrocarbons, but the effect was unique to fullerene soot and did not improve the performance of other forms of carbon. The third part focused on the use of co-feeds for methane activation to enhance the selectivities and lower the temperature threshold of methane activation. The principal fmdings of this project are summarized below and in the Appendix.Fullerene soot can promote methane conversion at temperatures more than 200°C lower than other carbons.Addition of certain transition metals to the fullerene soot increased both the activities and selectivities for methane conversion to C2 hydrocarbons.Alkali metals, particularly potassium, increased the C2-C4 hydrocarbon formation and increased the ability of the soot to promote dehydrogenation reactions.Co-feeds of ethylene decreased the temperature threshold for methane activation when fullerene soot was doped with certain combinations of alkali and transition metals.These fullerene-based catalysts allow us to significantly lower the temperature threshold for methane activation. However, the conversions are limited by secondary reactions. Proper reactor configuration will be essential for practical use of these fullerene-based catalysts.