Palladium on carbon nanofibers grown on metallic filters as novel structured catalyst

A novel composite material based on carbon nanofibers (CNF) grown on sintered metal fibers (SMFInconel) filter was investigated for its favorable properties as catalytic support. The CNF were formed directly over the SMFInconel by thermal (650 °C) chemical vapor deposition of ethane-hydrogen mixture. The CNF/SMFInconel composite consists of metal fibers entangled by CNF network of microns thickness and strongly anchored to the metal surface. The properties of the CNF/SMFInconel were controlled by the synthesis conditions. The CNF coating reduced the filter porosity and decreased the material permeability, but the pressure drop during the gas passage through the reactor remained low for CNF fraction <10%. Palladium was deposited on CNF previously activated by boiling in hydrogen peroxide. The activity and selectivity of Pd°/CNF/SMFInconel catalysts were tested in the selective hydrogenation of acetylene and compared with Pd supported on activated carbon fibers (Pd°/ACF). The TOF was one order of magnitude higher for Pd°/CNF/SMFInconel as compared to Pd°/ACF. This effect was attributed to a strong metal-support interaction of Pd°-nanoparticles with the graphitized CNF. The reaction was found to be structure sensitive leading to a decrease of TOF for the Pd°-particles <3 nm.