Nanoglobular carbon and palladium–nanoglobular carbon catalysts for liquid-phase hydrogenation of organic compounds

The results of studies related to the development of synthesis, determination of formation conditions and elucidation of the mechanism of palladium–carbon catalyst action are integrated and critically analyzed. The attention is focused on Pd/NGC compositions (NGC is nanoglobular carbon). Methods for NGC preparation with an emphasis on its most common form, carbon black, are considered. The following issues are addressed: mechanisms of formation of carbon nanoglobules and their aggregates, methods of varying the size of nanoglobules, functionalization of the NGC surface to make it suitable as a support for palladium nanoparticles, views on the formation mechanism of palladium clusters and nanoparticles on the carbon support surface and effect of the structure and surface chemistry of carbon nanoglobules on the state of palladium sites in Pd/NGC compositions. The published data on selective hydrogenation of organic compounds in the presence of Pd/NGC catalytic compositions are integrated and systematized. The catalytic properties of Pd/NGC are analyzed in comparison with the properties of palladium catalysts supported on other carbon materials (activated carbon, carbon nanotubes). The influence of preparation conditions of NGC-based palladium compositions on their catalytic properties in practically important hydrogenation reactions is discussed. Promising trends for further research on the development of molecular design methods, study of the genesis of Pd/NGC compositions and extension of their applications in hydrogenation processes are considered.
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