Decomposition of Methane over a Ni−Cu−MgO Catalyst to Produce Hydrogen and Carbon Nanofibers

Abstract

We have found that a Ni−Cu−MgO catalyst maintained its activity for the decomposition of methane at high levels for substantially long periods of time at 665−725 °C, being capable of generating large amounts of CO-free H2 and solid carbon. TEM examinations revealed that the solid carbon consisted exclusively of nanofibers possessing a “platelet” structure, in which the graphite layers are aligned in a direction perpendicular to the axis of the fiber. In sharp contrast, the Ni−MgO−methane system exhibited negligible activity at temperatures ≥650 °C. XRD and H2 chemisorption characterizations indicated that after reduction a Ni−Cu alloy was formed in the Ni−Cu−MgO catalyst and the surface of the particles was enriched in Cu0. A possible explanation for the observed superiority of the Ni−Cu−MgO catalyst over that of the Ni−MgO system is presented.