Synthesis of catalytic filamentous carbon by the pyrolysis of alkanes on alumina-silica foam supporting nickel nanoparticles

Nickel compounds were deposited on alumina-silica ceramic foam by different methods, in particular a homogeneous precipitation and a heterogeneous sol-gel processing to prepare catalyst for pyrolysis of alkanes (methane, propane-butane). Carbon deposits, in particular catalytic filamentous carbon (CFC) were synthesized on the Al/Si surface during the catalytic pyrolysis. Comparative analysis of the textural parameters of the initial support and composite carbon-mineral adsorbents was carried out. The effect of the method of catalyst preparation upon the morphology of supported nickel compounds and synthesized carbon deposits was examined in scanning electron microscope. The carbon yield for catalysts prepared by homogeneous precipitation was shown to be an order of magnitude higher than for the catalysts prepared by other methods. A uniform distribution of nickel nanoparticles deposited on the Al/Si foam by homogeneous precipitation led to the formation of a mesoporous CFC-layer with thickness of 0.5-2.0 μm and specific surface area ca. 500 m2/g due to chaotic interlacing of carbon nanofibers with a diameter of 50-100 nm and length exceeding 1 μm.