Quasi‐Tree Shaped Carbon Nanotubes‐Based Monolithic Carbocatalysts for Direct Dehydrogenation of Ethylbenzene to Styrene

Abstract The nanodiamond (ND) has long been recognized as a highly efficient carbocatalyst for synthesizing styrene via direct dehydrogenation (DDH) of ethylbenzene, but the high cost and complex preparation of ND depressed its potential for industrial‐scale use. In our previous work, it was found that the carbon nanotubes could be alternative to ND for DDH, but the induced sharp pressure drop of its powder form limits its industrial application in heterogeneous catalysis. In this work, we present a modified quasi‐tree shaped carbon nanotubes‐based (CNTs‐based) monolithic carbocatalyst (HN‐CNT″‐CNT′/SiC) prepared by a facile two‐step CNTs growing strategy with subsequent hexamethylenetetramine nitrate (HN) pyrolysis, featuring thick CNTs as tree truck and thin CNTs as branches growing on macroporous SiC foam. Thanks to increased amount of surface ketonic C═O, abundant structural defects, and improved nucleophilicity by N ‐doping, the HN‐CNT″‐CNT′/SiC monolithic carbocatalyst shows outstanding catalytic performance with 8.4 mmol g −1 h −1 of high styrene rate and 98.2% of styrene selectivity, which is comparable or even higher than those of the previously reported ND‐based monolithic carbocatalysts for clean production of styrene via DDH of ethylbenzene. This work not only presents an efficient and practical catalyst for clean production of styrene, but also paves a new avenue to design highly efficient monolithic carbocatalysts for diverse transformations.