Coupling of Methane to Ethane, Ethylene, and Aromatics over Nickel on Ceria-Zirconia at Low Temperatures

Methane is converted over nickel on ceria zirconia (Ni/CZ) into ethane, aromatics, and hydrogen at steady state up to the thermodynamic limit at temperatures of 350 to 500 degrees C. At 450 and 500 degrees C, traces of ethylene are also produced. Ni/NiO particles activate methane and couple the resulting surface species to hydrocarbon products. Large Ni particles are responsible for the formation of carbonaceous deposits. Furthermore, aromatics are formed on these sites. Smaller Ni/NiO particles are responsible for the formation of ethane and ethylene and appear to provide sustained activity. It is suggested that these Ni sites are too small to assemble aromatic deposits, and hence they remain active throughout the reaction.