Due to the advantages of high surface areas, large pore volumes and pore sizes, abundant nitrogen content that favored the metal-support interactions, N-doped ordered mesoporous carbons are regarded as a kind ...Due to the advantages of high surface areas, large pore volumes and pore sizes, abundant nitrogen content that favored the metal-support interactions, N-doped ordered mesoporous carbons are regarded as a kind of fascinating and potential support for the synthesis of effective supported cat-alysts. Here, a N-doped ordered mesoporous carbon with a high N content （9.58 wt%）, high surface area （417 m^2/g）, and three-dimensional cubic structure was synthesized successfully and used as an effective support for immobilizing Pt nanoparticles （NPs）. The positive effects of nitrogen on the metal particle size enabled ultrasmall Pt NPs （about 1.0 ± 0.5 nm） to be obtained. Moreover, most of the Pt NPs are homogeneously dispersed in the mesoporous channels. However, using the ordered mesoporous carbon without nitrogen as support, the particles were larger （4.4 ± 1.7 nm） and many Pt NPs were distributed on the external surface, demonstrating the important role of the nitrogen species. The obtained N-doped ordered mesoporous material supported catalyst showed excellent catalytic activity （conversion 100%） and selectivity （〉99%） in the hydrogenation of halogenated nitrobenzenes under mild conditions. These values are much higher than those achieved using a commercial Pt/C catalyst （conversion 89% and selectivity 90%）. This outstanding catalytic perfor-mance can be attributed to the synergetic effects of the mesoporous structure, N-functionalized support, and stabilized ultrasmall Pt NPs. Moreover, such supported catalyst also showed excellent catalytic performance in the hydrogenation of other halogenated nitrobenzenes and nitroarenes. In addition, the stability of the multifunctional catalyst was excellent and it could be reused more than 10 times without significant losses of activity and selectivity. Our results conclusively show that a N-doped carbon support enable the formation of ultrafine metal NPs and improve the reaction ac-tivity and selectivity.展开更多
A convenient,expeditious,and high-efficiency protocol for the transformation of alcohols into esters using a Co-modified N-doped mesoporous carbon material（Co-N/m-C）as the catalyst is proposed.The catalyst was prepa...A convenient,expeditious,and high-efficiency protocol for the transformation of alcohols into esters using a Co-modified N-doped mesoporous carbon material（Co-N/m-C）as the catalyst is proposed.The catalyst was prepared through direct pyrolysis of a macromolecular precursor.The catalyst prepared using a pyrolysis temperature of 900°C（labeled Co-N/m-C-900） exhibited the best per-formance.The strong coordination between the ultra-dispersed cobalt species and the pyridine nitrogen as well as the large area of the mesoporous surface resulted in a high turnover frequencymethyl benzoate.This value is much higher than those of state-of-the-art transition-metal-based nanocatalysts reported in the literature.Moreover,the catalyst exhibited general applicability to various structurally diverse alcohols,including benzylic,allylic,and heterocyclic alcohols,achieving the target esters in high yields.In addition,a preliminary evaluation revealed that Co-N/m-C-900 can be used six times without significant activity loss.In general,the process was rapid,simple,and cost-effective.展开更多
基金supported by the National Natural Science Foundation of China(201573136,U1510105)the Scientific Research Start-up Funds of Shanxi University(RSC723)~~
文摘Due to the advantages of high surface areas, large pore volumes and pore sizes, abundant nitrogen content that favored the metal-support interactions, N-doped ordered mesoporous carbons are regarded as a kind of fascinating and potential support for the synthesis of effective supported cat-alysts. Here, a N-doped ordered mesoporous carbon with a high N content （9.58 wt%）, high surface area （417 m^2/g）, and three-dimensional cubic structure was synthesized successfully and used as an effective support for immobilizing Pt nanoparticles （NPs）. The positive effects of nitrogen on the metal particle size enabled ultrasmall Pt NPs （about 1.0 ± 0.5 nm） to be obtained. Moreover, most of the Pt NPs are homogeneously dispersed in the mesoporous channels. However, using the ordered mesoporous carbon without nitrogen as support, the particles were larger （4.4 ± 1.7 nm） and many Pt NPs were distributed on the external surface, demonstrating the important role of the nitrogen species. The obtained N-doped ordered mesoporous material supported catalyst showed excellent catalytic activity （conversion 100%） and selectivity （〉99%） in the hydrogenation of halogenated nitrobenzenes under mild conditions. These values are much higher than those achieved using a commercial Pt/C catalyst （conversion 89% and selectivity 90%）. This outstanding catalytic perfor-mance can be attributed to the synergetic effects of the mesoporous structure, N-functionalized support, and stabilized ultrasmall Pt NPs. Moreover, such supported catalyst also showed excellent catalytic performance in the hydrogenation of other halogenated nitrobenzenes and nitroarenes. In addition, the stability of the multifunctional catalyst was excellent and it could be reused more than 10 times without significant losses of activity and selectivity. Our results conclusively show that a N-doped carbon support enable the formation of ultrafine metal NPs and improve the reaction ac-tivity and selectivity.
基金supported by the National Natural Science Foundation of China (21773232, 21403219, 21773227)~~
文摘A convenient,expeditious,and high-efficiency protocol for the transformation of alcohols into esters using a Co-modified N-doped mesoporous carbon material（Co-N/m-C）as the catalyst is proposed.The catalyst was prepared through direct pyrolysis of a macromolecular precursor.The catalyst prepared using a pyrolysis temperature of 900°C（labeled Co-N/m-C-900） exhibited the best per-formance.The strong coordination between the ultra-dispersed cobalt species and the pyridine nitrogen as well as the large area of the mesoporous surface resulted in a high turnover frequencymethyl benzoate.This value is much higher than those of state-of-the-art transition-metal-based nanocatalysts reported in the literature.Moreover,the catalyst exhibited general applicability to various structurally diverse alcohols,including benzylic,allylic,and heterocyclic alcohols,achieving the target esters in high yields.In addition,a preliminary evaluation revealed that Co-N/m-C-900 can be used six times without significant activity loss.In general,the process was rapid,simple,and cost-effective.
