A novel composite material based on carbon nanofibers (CNF) grown on sintered metal fibers (SMF Inconel ) filter was investigated for its favorable properties as catalytic support. The CNF were formed directly over the SMF Inconel by thermal (650 8C) chemical vapor deposition of ethane-hydrogen mixture. The CNF/SMF Inconel composite consists of metal fibers entangled by CNF network of microns thickness and strongly anchored to the metal surface. The properties of the CNF/SMF Inconel 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 Pd8/CNF/SMF Inconel catalysts were tested in the selective hydrogenation of acetylene and compared with Pd supported on activated carbon fibers (Pd8/ACF). The TOF was one order of magnitude higher for Pd8/CNF/SMF Inconel as compared to Pd8/ACF. This effect was attributed to a strong metal-support interaction of Pd8-nanoparticles with the graphitized CNF. The reaction was found to be structure sensitive leading to a decrease of TOF for the Pd8-particles <3 nm. #
Carbon nanofibers (CNF) were synthesized on sintered metal fibers (SMF) filters of nickel and Ni-containing alloys (Inconel, stainless steel (SS)) by thermal chemical vapor deposition of ethane in the presence of hydrogen at $660 8C. The CNFs were formed directly over the SMF filters without deposition of metal particles. The catalytic active sites leading to the CNF formation were attained by oxidation-reduction of the SMF filter. The CNFs present platelet morphology as determined by X-ray diffraction and transmission electron microscopy. The CNF/ SMF composites have thin carbon layer in the microns range strongly anchored to the metal surface. The initial open structure of SMF filters is preserved. Scanning electron microscopy together with temperature programmed oxidation suggests the formation of uniform CNFs deposits on SMF Inconel with fiber's diameters in the range of 70 nm. Carbon deposits with a different nature were observed over SMF Ni and SMF ss .The CNF/SMF Inconel composites have high specific surface area due to mesopores of CNFs, high thermo-conductivity and open 3D macrostructure. This is advantageous for catalytic applications, especially during the catalysis of highly exo/endothermic reactions in reactors with structured catalytic bed. #
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