Sulfate Surfactant Assisted Approach to Fabricate Sulphur‐Doped Supported Nanodiamond Catalyst on Carbon Nanotube with Unprecedented Catalysis for Ethylbenzene Dehydrogenation

Abstract

Direct dehydrogenation (DDH) of ethylbenzene is an efficient chemical process for styrene production. Nanocarbon materials, as clean and low‐cost catalysts, have drawn more and more attention in this field. In this work, inspired by the promoting effect of support modulation on the catalytic performance of the general supported‐type catalyst, we present a facile sulfate surfactant assisted dispersion with subsequent annealing (SADA) approach for preparing sulphur‐doped supported nanodiamond catalyst on carbon nanotube (ND/CNT‐SDS) with abundant active sites by using sodium dodecyl sulfate (SDS) as both the dispersing agent for promoting the dispersion of catalytically active ND motif and the CNT support and the sulphur source for sulphur doping, yielding an outstanding supported ND catalyst for DDH of ethylbenzene to styrene with 7.7 mmol g−1cat. h−1 of styrene rate and 98.2 % of styrene selectivity. ND/CNT‐SDS catalyst demonstrates 3.0 times higher styrene rate of the pristine ND. Moreover, ND/CNT‐SDS catalyst shows 1.5 times higher styrene rate of the previously reported defect‐enriched N,O‐codoped ND/CNT (N,O‐ND/CNT‐d) with up to 98 % of similar styrene selectivity, ascribed to its more exposed C=O active sites and higher specific surface area originating from the promoted dispersion of both ND and CNT by SDS, as well as the sulphur‐doping. Moreover, this work also presents a novel and efficient method for the designing the other supported nanocarbon catalysts from dispersion‐required catalytically active nanocarbon motif and the nanocarbon carrier.

Poly(imidazolium-methylene)-Assisted Grinding Strategy to Prepare Nanocarbon-Embedded Network Monoliths for Carbocatalysis

“…The characteristic peaks at ca. 23.2, 25.6, 27.8, 31.9, 34.0, 43.8, 75.4, and 91.3° on pristine ND are well resolved. − In comparison with the only one diffraction on conventional N-doped carbon, two well-resolved peaks appear on the as-synthesized NC from PImM. One appearing at ca.…”

“…As a consequence, ND@NC shows a remarkably enlarged surface area (371 m 2 g –1 ) compared to ND (211 m 2 g –1 ) and NC (70 m 2 g –1 ), improving the accessibility of active sites and benefitting catalysis. Moreover, both ND and ND@NC show typical IV isotherms, suggesting the existence of mesopores from ND accumulation. − Compared to ND, ND@NC shows decreasing accumulated mesopores (Figure b), owing to the improved ND dispersion (Figure ) by the filling and isolating effect of PImM in the process of grinding the mixture of ND and PImM. TG profile can be interesting to represent the evolution of the material during the pyrolysis treatment, as well as the temperature resistance.…”

“…The former two peaks are the characteristic peaks of NC, while the latter two peaks correspond to ND. Interestingly, in contrast to ND, the ND@NC shows wider and weaker characteristic peaks, suggesting the improved ND dispersion by the isolating effect of PImM in the preparation process. − Furthermore, compared to NC (0.341 nm), the broadened interlayer d spacing (0.400 nm) of the (002) plane of the graphite phase can be ascribed to the effect of NDs on the formation of NC from PImM. As a result, the ND@NC network monolith shows a unique crystal structure.…”

“…As a result, the ND@NC network monolith shows a unique crystal structure. Raman spectroscopy was employed to study the surface structure and N-doping state (Figure b). − The 785 nm wavelength laser was used on NC to avoid the strong fluorescent interference at the visible region, while 532 nm was used for the other two samples. For clear comparison, the Raman spectrum of NDs is multiplied by 10.…”

“…Although the ultrasonic treatment can effectively deagglomerate the nanocarbon aggregates, reagglomeration takes place while they leave from the dispersant. In our previous works, we found that reagglomeration could be overcome by designing nanocarbon-based hybrids, and also, the hybrid exhibited synergistically enhanced catalysis between nanocarbons and the introduced “nanoobjects”, such as NC, CNTs, and GRN, acting as an inter-isolating unit. − Recently, we prepared a new and efficient ND/NC hybrid catalyst for EDH reaction with an intensified ND–NC interaction by using PImM salt, a polymeric multiple cations compound (Figure a) as NC precursor through strong cation−π interactions, − π–π interactions, and van der Waals force especially electrostatic interactions since many nanocarbons have negative charge. − It is amazing that the mixture of ND and PImM features plasticine, and a hard lump can be obtained by pyrolysis of the plasticine. Inspired by the accidental discovery, herein, we report a general poly­(imidazolium-methylene)-assisted strategy for scalably synthesizing a mechanically robust nanocarbon-embedded network monolith, featuring nanocarbons well dispersed within the NC network.…”