Direct synthesis of nitrogen-containing filamentous carbon on a high-percentage Ni-Cu catalyst

Nitrogen-containing catalytic filamentous carbon (N-CFC) of chemical composition NC₁₈-NC₁₀₄ has been synthesized by the decomposition of pyridine (Py) from gaseous mixtures with argon or H₂ at 550–800°C on Ni/Al₂O₃ (Ni) and Ni-Cu/Al₂O₃ (Ni-Cu) high-percentage catalysts. The activity of the Ni-Cu catalyst in Py decomposition in mixtures with H₂ is about one order of magnitude higher than its activity in Py/Ar mixtures (more than 70 g N-CFC per metal gram in 4.5 h at 750°C), which is interpreted as arising from the nickel-catalyzed hydrogenation of Py. The formation and growth of carbon fibers occurs through the decomposition of Py (from Ar/Py mixtures) and/or Py hydrodenitrification products (from H₂/Py mixtures). The carbon material has been characterized by elemental analysis, low-temperature nitrogen adsorption, high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS). The effect of the noncatalytic reactions of Py and its transformation products on the composition and texture of N-CFC is discussed.