New nickel catalysts for the formation of filamentous carbon in the reaction of methane decomposition

A method for intentional synthesis of metal catalysts, specifically nickel catalysts for methane decomposition, was developed. The method was based on impregnation of a porous metal oxide with the precursor of a textural promoter followed by reduction of the latter. The desired texture of NiO was provided by precalcining it at a certain temperature within the range 300 to 900 degrees C, A family of nickel-based catalytic systems with various concentrations of the active component, metal particle sizes, and stability to deactivation in the course of synthesis of filamentous carbon was prepared. The yield of carbon and mechanical strength of carbon particles growing on the catalyst during methane decomposition were found to increase with the concentration of nickel in the catalyst, to reach their maxima at 90-96% nickel. The highest yield of carbon (375-384 g carbon per g nickel) was observed for the catalyst with particles of 10-40 nm average diameter. The effect of textural promoters (SiO2, Al2O3, MgO, TiO2, and ZrO2) on the catalyst performance was studied; the highest carbon yield was obtained with SiO2. (C) 1999 Academic Press.