Macroscopically shaped monolith of nanodiamonds @nitrogen-enriched mesoporous carbon decorated SiC as a superiormetal-free catalyst for the styrene production

Nanodiamonds (NDs) are recognized as a class of robust metal-free catalysts for the steam-free, directdehydrogenation (DDH) of ethylbenzene (EB) to styrene (ST). In spite of that, some main drawbacks,such as their powdery form along with their tendency to form aggregates, limit their full exploitationat the industrial level. In this work, we describe the preparation of macroscopically shaped monolithsconsisting of silicon carbide-based foams coated with a nitrogen-rich mesoporous carbon matrix (NMC)as a non-innocent glue for highly dispersed ND fillers. The NMC phase is prepared from cheap and non-toxic food-grade components and it prevents the undesired NDs agglomeration thus maximizing thereagents exposure throughout the catalytic DDH tests. Moreover, the NMC phase represents a key sourceof surface basicity capable of inhibiting the occurrence of EB cracking side reactions during the catalyticruns. As a result, the ND@NMC/SiC composite shows excellent dehydrogenation performance already atlow ND loading if compared with the powdery NDs and/or the SiC-supported NDs of the state-of-the-art.Noteworthy, the ND@NMC/SiC composite presents its best catalytic performance under DDH conditionsclose to those used in industrial plants (reaction temperture up to 600oC and EB concentrations up to 10vol.%) with high ST rates (catal.of 9.9 mmolSTgcat-1h-1), ST selectivity over 96% and long term stabilityon stream.