No abstract

Novel Co@C core–shell nanoparticles were prepared by a straightforward low-temperature carbonization process. The industrially available lignin was used as a low-cost biorenewable carbon source for the first time. The products were characterized by X-ray diffraction, energy-dispersive X-ray spectrometry, transmission electron microscopy, nitrogen adsorption–desorption, and Raman spectrum. The results showed that the synthesized Co@C catalysts had a well-defined core–shell structure with a moderate degree of graphitization, and the metal Co nanoparticles with the sizes of 20–150 nm were wrapped by several layers of graphitic carbon. This unique core–shell structure is useful in a Fischer–Tropsch reaction since it can provide high adsorption space and the graphite carbon layer defects are beneficial for H2 dissociative adsorption. Furthermore, the shell of graphitic carbon layers could restrict the aggregation of the cobalt nanoparticles during the activation and reaction processes. Fischer–Tropsch synthesis results showed that the Co@C core–shell catalysts had a high catalytic performance with the highest C5+ selectivity up to 56.8%, which is much higher compared with the traditional Co/AC catalyst (46.2%).

Zeolite coated fibers with compact and full deposits have been fabricated by electrophoretic deposition of nanozeolites onto carbon fibers, whereafter hollow zeolite fibers have been obtained by calcination to remove the substrates.

Bio-renewable lignin has been used as a carbon source for the preparation of porous carbon materials. Nevertheless, up to now, there are few studies about the influence of molecular weight of lignin on the structure and morphology of the ordered mesoporous carbon. Here, we synthesized the ordered mesoporous carbon derived from different molecular weights of lignin and Pluronic F127. Fortunately, we found that molecular weight is an important factor for obtaining highly ordered channels, high specific surface area, and ordered mesoporous carbon. More importantly, the narrow well-defined mesoporous channel could exert a spatial restriction effect to some extent, which can serve as nanoreactors for efficient reactions and enhance catalytic performance. The highly ordered mesoporous carbon from lignin is a good candidate for Fischer–Tropsch synthesis catalyst supports.

This study reports a novel and flexible technique to synthesize bimodal porous materials with ordered macropores whose walls are composed of microporous zeolites by self-assembly of nanocrystals of silicalite-1 and ZSM-5. The materials prepared by this novel technique are well crystalline and possess uniform macropores interconnected in three dimensions through windows.