(544fs) Nanostructured Metal Nitrides and Carbides for Industrial & Environmental Catalysis

Interstitial transition-metals, such as transition metal nitrides and carbides, have been investigated to better understand their unique mechanical hardness, thermal resistance, optical, electronic, electrocatalytic and catalytic properties. Nanostructured metal nitrides & carbides prepared using topotactic, temperature programmed reduction (TPR) synthesis methods have been more recently studied specifically as industrial & environmental catalysts for reaction systems including NH₃ decomposition, CO hydrogenation, n-C₂H₆ hydrolysis, steam reforming, CH₄ dry reforming, partial oxidation of methane, hydrodenitrogenation (HDN) and hydrodesulfurization (HDS) reactions. In this work, the synthesis, characterization, solid-state diffusion analysis, and kinetic investigation of several interstitial nitride and carbide nanomaterials, g-Mo₂N, b-Mo₂C, h-MoC and WC, have been conducted using various synthesis routes including TPR synthesis, sonolytic irradiation and sol-gel synthesis of parent metal oxides. Catalysts have been characterized using XRD, BET surface area analysis, DSC, TGA, SEM, TEM, and STM. Metal nitride and carbide nanostructured materials have been reported to demonstrate similar catalytic properties to Noble metals. Adjustments in the product nanostructure of these unsupported, interstitial transition-metal compounds has been reported to demonstrate significant effects on catalytic activity and selectivity. Ongoing work seeks to gain improvements in the oxidation resistance of these catalytic nanomaterials in oxygen-rich systems, to acquire a more complete understanding of the solid-state TPR synthesis mechanism, and to elucidate a comprehensive description of the effects of nanomaterial composition, particle size and structure on performance in various engineering technologies.