Nickel and oxygen-containing functional groups co-decorated graphene-like shells as catalytic sites with excellent selective hydrogenation activity and robust stability

Iron-Based Catalysts with Oxygen Vacancies Obtained by Facile Pyrolysis for Selective Hydrogenation of Nitrobenzene

“…Clearly, the presence of sulfides, such as potassium thiocyanate (KSCN), sodium sulfide (Na 2 S), and thiourea (CH 4 N 2 S), had a significant impact on the catalytic hydrogenation of p -CNB to p -CAN, directly resulting in the conversion of the substrate, which was less than 5% in all cases, which indicated that the catalyst Fe@C-2 was susceptible to poisoning by sulfides. In our previous work, sulfides were weakly adsorbed on the carbon layer of the prepared encapsulated nonprecious metal catalyst, making it difficult to form chemical adsorption and not affecting the catalytic performance of the catalyst. , However, in similar experiments with the catalyst Fe@C-2, sulfides caused serious deactivation of the catalyst, further indicating that the carbon layer on the catalyst surface might be discontinuous and the strong adsorption of sulfides and metal oxides might be the main reason for its deactivation. Therefore, it can be inferred that metal oxides might be the active sites of catalysts.…”

“…In our previous work, sulfides were weakly adsorbed on the carbon layer of the prepared encapsulated nonprecious metal catalyst, making it difficult to form chemical adsorption and not affecting the catalytic performance of the catalyst. 63,64 However, in similar experiments with the catalyst Fe@C-2, sulfides caused serious deactivation of the catalyst, further indicating that the carbon layer on the catalyst surface might be discontinuous and the strong adsorption of sulfides and metal oxides might be the main reason for its deactivation. Therefore, it can be inferred that metal oxides might be the active sites of catalysts.…”

Shield Effect in Palladium@Graphene with Stability in Strong Acid and Sluggish H-Dissociation for Robust Coupling Hydrogenation–Bamberger Rearrangement of Nitrobenzene

“…Moreover, the high temperature (550−800 °C) reduction peaks were observed for two of the three samples due to the decomposition of carbon layers. Subsequently, to confirm that the H 2 consumption peaks were related to the decomposition of carbon layers, the possible products were analyzed by H 2 -TPR-MS, and the results are shown in Figure S8b−d, which demonstrated that the consumption of hydrogen was related to the oxygen-containing functional groups on the surface of catalyst, 29 coupled with FT-IR results (Figure S6).…”

“…The acid-resistance properties of the catalysts are critical to defend the active center from loss during the strong acidic reaction system. , The as-prepared supported Pd/C catalyst manifested extremely disadvantaged acid resistance in sulfuric acid solution (Figure S1), leading to metal loss in the reaction system. In order to maintain the activity and reduce metal loss, the S,N-doped graphene shell served as a shield to encapsulate metal.…”

“…The development of Pd-based catalysts for hydrogenation of NB to PAP has been intensively probed due to their excellent intrinsic activities for the reduction of nitro groups. − However, the poor stability and low abundance of noble metals suppress the extensive application of Pd-based catalysts. Herein, a large number of works have indicated that the graphite-shell encapsulated Pd nanoparticles (NPs) structure could hinder the inner metal poisoning and simultaneously activate the catalytic performance of inert graphite carbon due to the electronic transmission from the metal NP core. − The catalytic hydrogenation could be significantly influenced by the surface electronic architecture of graphite carbon, which could potentially depend on the type and ratio of encapsulated metal NPs. ,, Additionally, catalysts with an amorphous structure could usually offer more unsaturated atoms as effective active sites, which would be beneficial for increasing the catalytic activity . Analogously, it was widely demonstrated that the heteroatom (e.g., B, N, P, and S)-doped-graphite materials obtained enormous defect sites over the surface, which often reconstituted the electron, physical and chemical characteristics, facilitating the increase in catalytic performance .…”