We report here a thermal reduction method for preparing Ru catalysts supported on a carbon substrate. Mesoporous SBA-15 silica, surface-carbon-coated SBA-15, templated mesoporous carbon, activated carbon, and carbon black with different pore structures and compositions were employed as catalyst supports to explore the versatility of the thermal reduction method. Nitrogen adsorption, X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, scanning transmission electron microscopy, thermogravimetric analysis, and X-ray absorption near-edge structure techniques were used to characterize the samples. It was observed that carbon species that could thermally reduce Ru species at high temperatures played a vital role in the reduction process. Ru nanoparticles supported on various carbon-based substrates exhibited good dispersion with an appropriate particle size, high crystallinity, strong resistance against oxidative atmosphere, less leaching, lack of aggregation, and avoidance of pore blocking. As such, these catalysts display a remarkably high catalytic activity and stability in the hydrogenation of benzene and toluene (up to 3-24-fold compared with Ru catalysts prepared by traditional methods). It is believed that the excellent catalytic performance of the thermally reduced Ru nanoparticles is related to the intimate interfacial contact between the Ru nanoparticles and the carbon support.

The immobilization of metal nanoparticles in the framework of porous carbon for heterogeneous catalysis may avoid particle aggregation, movement, and leaching, thus leading to a high catalyst efficiency. In this Full Paper, an approach to prepare Ru nanoparticles incorporated into the pore walls of porous carbon to form a sandwiched Ru/C nanostructure for heterogeneous hydrogenation is demonstrated. Physical adsorption of nitrogen, X‐ray diffraction, thermogravimetric analysis, field‐emission transmission electron microscopy, field‐emission scanning electron microscopy, and energy dispersive X‐ray spectroscopy techniques are employed to study the structure and morphology of the catalysts. Catalytic results show that the Ru nanoparticles sandwiched in the pore walls of porous carbon display a remarkably high activity and stability in the hydrogenation of benzene. An enhanced hydrogen spillover effect is believed to play a significant role in the hydrogenation reaction because of the intimate interfacial contact between Ru nanoparticles and the carbon support. The catalyst system described in this work may offer a new concept for optimizing catalyst nanostructures.

No abstract

Mesoporous aluminas with a uniform fibrous morphology were synthesized using a copolymer-controlled homogeneous precipitation method under hydrothermal conditions. Scanning electron microscopy, X-ray diffraction, solid-state magic-angle spinning nuclear magnetic resonance, transmission electron microscopy, thermogravimetric analysis, nitrogen adsorption, Fourier transform infrared spectrometry, and elemental analysis techniques were used to characterize the samples. The effect of various synthesis conditions on the morphology and mesoporous structure of the alumina fibers was investigated. Such porous alumina microfibers may find applications in nanotechnology and catalysis. They can also be used as advanced high-temperature composite materials and templates for fabrication of fibrous materials of various compositions, such as carbon, transition-metal oxides, and polymers.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

No abstract

No abstract