Pomegranate-like Core–Shell Ni-NSs@MSNSs as a High Activity, Good Stability, Rapid Magnetic Separation, and Multiple Recyclability Nanocatalyst for DCPD Hydrogenation

Abstract

A novel pomegranate-like Ni-NSs@MSNSs nanocatalyst was successfully synthesized via a modified Stöber method, and its application in the hydrogenation of dicyclopentadiene (DCPD) was firstly reported. The Ni-NSs@MSNSs possessed a high specific area (658 m 2 /g) and mesoporous structure (1.7–3.3 nm). The reaction of hydrogenation of DCPD to endo -tetrahydrodicyclopentadiene ( endo -THDCPD) was used to evaluate the catalytic performance of the prepared materials. The distinctive pomegranate-like Ni-NSs@MSNSs core–shell nanocomposite exhibited superior catalytic activity (TOF = 106.0 h –1 and STY = 112.7 g·L –1 ·h –1 ) and selectivity (98.9%) than conventional Ni-based catalysts (experimental conditions: Ni/DCPD/cyclohexane = 1/100/1000 (w/w), 150 °C, and 2.5 MPa). Moreover, the Ni-NSs@MSNSs nanocatalyst could be rapidly and conveniently recycled by magnetic separation without appreciable loss. The Ni-NSs@MSNSs also exhibited excellent thermal stability (≥750 °C) and good recycling performance (without an activity and selectivity decrease in four runs). The superior application performance of the Ni-NSs@MSNSs nanocatalyst was mainly owing to its unique pomegranate-like structure and core–shell synergistic confinement effect.

Double-Confined Ultrafine Cobalt Clusters for Efficient Peroxide Activation

“…As seen in Figure b,c, all samples showed an initial mass loss in the DTG curve at 30–110 °C due to the loss of physically adsorbed water . The CTAB@mSiO 2 displayed a weight loss of 28.7% at 150–500 °C, corresponding to the CTAB decomposition . As the temperature further increased, a slow decrease in weight (4.3%) at 500–650 °C derived from the decomposition of NC dots in mSiO 2 .…”

“…Recent studies found that CTAB can be used as promising precursors to prepare NC dots via the carbonization process. , The repulsive force between the metal particles is greater than the van der Waals force due to the increased CTAB molecules near the metal particles. In this case, the NPs would gradually change from agglomeration to monodispersion . This further inspires us to directly obtain NC dots by utilizing CTAB carbonization to further enhance metal dispersion via the double confinement during the synthesis of mSiO 2 .…”

“…26 The CTAB@mSiO 2 displayed a weight loss of 28.7% at 150− 500 °C, corresponding to the CTAB decomposition. 25 As the temperature further increased, a slow decrease in weight (4.3%) at 500−650 °C derived from the decomposition of NC dots in mSiO 2 . 23 As for the presynthesized Co/NC@mSiO 2 , about 4.8% of weight loss was observed from 100 to 200 °C with a DTG peak at 180 °C corresponding to the decomposition of Co(NO 3 ) 2 •6H 2 O.…”

“…In this case, the NPs would gradually change from agglomeration to monodispersion. 25 This further inspires us to directly obtain NC dots by utilizing CTAB carbonization to further enhance metal dispersion via the double confinement during the synthesis of mSiO 2 . Herein, we originally developed the ultrafine Co clusters confined in mSiO 2 nanospheres containing NC dots (termed as Co/NC@mSiO 2 ) by a facile solvent-free method.…”

“…In this case, the NPs would gradually change from agglomeration to monodispersion. 25 This further inspires us to directly obtain NC dots by utilizing CTAB carbonization to further enhance metal dispersion via the double confinement during the synthesis of mSiO 2 .…”