Carbon Nanotube Modified Ceramic Foams as Structured Palladium Supports for Polystyrene Hydrogenation

Mechanism of NCNTs Growth on Foamed Nickel and Thus-Prepared PS Hydrogenation High-Performance Carrier NCNTs@FN

Traditional heterogeneous catalysts are affected in the catalytic hydrogenation of PS by the scale effect, viscosity effect, adhesion effect, and conformational effect, resulting in poor activity and stability. Monolithic Pd-CNTs@FN catalysts could eliminate or weaken the impact of these negative effects. We grew nitrogen-doped carbon nanotubes (NCNTs) on monolithic-foamed nickel (FN) and investigate their growth mechanism. Meanwhile, the feasibility of using the NCNTs@FN carrier for PS hydrogenation reaction was also verified. The growth of NCNTs on FN can be divided into 3 stages: initial growth stage, stable growth stage, and supersaturation stage. Finally, a three-layer structure of NCNT layer, dense carbon layer, and FN skeleton is formed. Two types of structures, nickel-doped carbon nanotubes (NiCNTs) and C-Ni alloy, are formed by combining C and Ni, while four nitrogen-doped structures, NPD, NPR, NG, and NO, are formed by C and N. The prepared carrier exhibited an extremely outstanding specific surface area (2.829 × 106 cm2/g) and strength (no NCNTs falling off after 24 h 500 rpm agitation), as well as high catalytic activity for PS hydrogenation after loaded with Pd (2.13 ± 0.95 nm), with a TOF of up to 27.6 gPS/(gPd•h). After 8 repetitions of the catalyst, there was no significant decrease in activity. This proves the excellent performance of Pd-NCNTs@FN in polymer hydrogenation reactions, laying a solid foundation for further research on the mechanism of NCNTs promoting PS hydrogenation and regulating the growth of NCNTs.

Boron nitride-palladium nanostructured catalyst: efficient reduction of nitrobenzene derivatives in water

Boron nitride (BN) supported palladium (Pd) nanostructured catalyst, as an alternative support for heterogeneous reduction of nitrobenzene derivatives, was prepared by a mild reduction of a Pd precursor in water. The structural characteristics and distribution of the synthesized Pd nanoparticles (NPs) on BN support were investigated by transmission electron microscopy, scanning transmission electron microscopy, energy-dispersive x-ray spectroscopy and x-ray photoelectron spectroscopy methods. The potential and efficiency of the BN supported Pd NPs as an active and stable nanostructured catalyst were verified in the reduction of nitroaromatics. Excellent yields of the corresponding aryl amines in water were obtained and due discussion were included about the catalytic activity of the synthesized catalyst. It was also indicated that the nanostructured catalyst can be recycled at least for six consecutive cycles in the reduction of nitrobenzene, without losing significant activity.