Single Co atoms anchored on nitrogen-doped hierarchically ordered porous carbon for selective hydrogenation of quinolines and efficient oxygen reduction

Emerging Ultrahigh‐Density Single‐Atom Catalysts for Versatile Heterogeneous Catalysis Applications: Redefinition, Recent Progress, and Challenges

“…[27,87] Herein, we present the high selectivity and high conversion of AFCs in two typical selective hydrogenation reactions: selective hydrogenation [9,37] (or hydrochlorination [84] ) of acetylene and selective hydrogenation of quinoline (and its derivatives) (see Table 2 for details). [53,88,89] Utilizing selective hydrogenation to remove trace acetylene from ethylene is an important reaction process in ethylenerelated industry to avoid poisoning and deactivation of downstream polymerization catalyst. At present, it is still a big challenge to realize supported atomically dispersed catalysts (SADCs) with high loading (or high atom density), high activity, and high stability for semihydrogenation reaction of acetylene to ethylene, because atomic dispersed metal species usually show a higher tendency of metal atom agglomeration in the "thermochemical reduction" environment.…”

“…[105] Lately, Guo et al reported high-density single Co atoms anchored on N-doped hierarchically ordered porous carbon (Co-SAs/NHOPC) support for the selective hydrogenation of quinolines with high catalytic activity and excellent stability (see Figure 11A-F). [88] In this study, the ordered macro-microporous bimetallic single-crystalline and J-M) Ir 1 /α-MoC. A-F) Reproduced with permission.…”

“…The excellent performances of these Co AFCs are credited to the exquisite integration of the interconnected macroporous network construction (fast gas diffusion and mass transfer), abundant micropores within N-doped carbon skeletons, well-defined tetrakaidecahedron morphology, and atomically dispersed single Co atoms with relatively high atomic density (better than most low-density transition metal atomic catalysts). [88] Previously, Wang et al [53] also reported the pyrolysis preparation of high-density single Ru sites (%4 atoms nm À2 ) dispersed on the nitrogen-doped carbon (Ru SAs/NC) support via a free amine group-assisted coordination strategy from UiO-66-NH 2 , where the Ru sites are of single-mind N coordination (with Ru-N 1 C 2 moiety) that served as the high-efficiency QHR catalyst (see Figure 11G-I). Importantly, these Ru-based AFCs can effectively catalyze selective hydrogenation of quinolone to the target product of 1,2,3,4-tetrahydroquinoline (py-THQ, 1a) with almost exclusive selectivity (%100%) and very high conversion (>99%) under five recycles (see Figure 11G).…”

“…In the process of single-atom-site catalytic reaction, the micropore or small mesoporous structure (1-5 nm) [9,50] around active sites can dynamically accelerate the movement state of reactants and product molecules and then improve the catalytic reaction activity. [253] Therefore, designing porous structure of the support materials (including regular mesopores in 2-50 nm and macropores in 50-300 nm [88,102] ) to promote the molecules to approach the catalytic active site is very helpful to improve the actual utilization of the sites and promote the catalytic efficiency. [29] However, most of the current high-density or high-loading SACs have ignored the design of nanoporous support materials, such as using the easily stacked pristine 2D graphene (or rGO) nanosheets, [59,125] large-volume polymer (e.g., g-C 3 N 4 , C 2 N, or GDY), [46,48,56] and dense metallic compounds [70,116,140] as support materials.…”

“…Selective hydrogenation of quinolines based on various AFCs: A-F) Co 1 /NC G-I) Ru 1 /NC, and J-M) Ir 1 /α-MoC. A-F) Reproduced with permission [88]. Copyright 2022, Elsevier.…”