Encapsulation of Nonprecious Metal into Ordered Mesoporous N-Doped Carbon for Efficient Quinoline Transfer Hydrogenation with Formic Acid

Abstract

Ordered mesoporous N-doped carbon (OMNC) encapsulating Co nanoparticles (NPs) have been prepared under direct polymerization between [Co­(NH2CH2CH2NH2)2]­Cl2 and carbon tetrachloride through a hard template method. The catalysts (Co@OMNC) are pyrolyzed at various temperatures and characterized by elemental analysis, Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). In the quinoline transfer hydrogenation with formic acid (FA) as the hydrogen source under a base-free condition, the encapsulated Co NPs are physically isolated from the acidic reaction solution, which prevents them from poisoning or leaching. The rich mesopores and N dopants afford enhanced adsorption of quinoline. Co@OMNC-700 (pyrolyzed at 700 °C) gives the best activity (98.8% conversion) as well as >99% 1,2,3,4-tetrahydroquinoline (THQ) selectivity at 140 °C for 4 h, exhibiting significantly improved performance compared to using H2 as the hydrogenation source. Moreover, Co@OMNC-700 is stable for recycling and exhibits high efficiency in FA dehydrogenation. Co@OMNC-700 is also a high-performance catalyst in the transfer hydrogenation of various unsaturated hydrocarbons. On the contrary, without the protection of OMNC, the exposed Co NPs in a control catalyst, Co/OMNC-700, lead to obvious Co leaching and low efficiency for the transfer hydrogenation of quinoline with FA.

Atomically Dispersed Zn‐Nx Sites in N‐Doped Carbon for Reductive N‐formylation of Nitroarenes with Formic Acid

“…[6] Some of these processes could proceeded under mild reaction conditions.To date, however, only fewer non-noble (Fe, Co and Ni) metal catalysts have been used in the reductive Nformylation reaction of nitroarenes by using FA or formate as the hydrogen source and formylation reagents. [7] On the other hand, although the catalytic reductive N-formylation of anilines over transition metal oxide by using CO 2 as a carbonyl source has been well demonstrated, [8] these processes usually require noble metals under harsh reaction conditions. Moreover, the aryl amines used as starting materials are usually prepared by the reduction of nitroarenes over transition metals under a high pressure of hydrogen.…”

Porous Carbon Nitride Frameworks Derived from Covalent Triazine Framework Anchored Ag Nanoparticles for Catalytic CO2 Conversion

“…However, Ag NPs tend to aggregate owing to their high surface energy, thereby resulting in a decrease of catalytic performance. Vast efforts on this problem suggest that rational support can protect Ag NPs against agglomeration and improve their recovery …”

“…Vast efforts on this problem suggest that rational support can protectA gN Ps againsta gglomeration and improve their recovery. [19] Inspired by the aforementioned strategies, porous carbon nitride frameworks (PCNFs) were fabricated through the direct carbonization of CTF and used as as upport to homogeneously immobilize ands tabilizeA gN Ps in CO 2 conversion for the first time ( Figure 1). The resultant Ag NP-supported PCNF catalysts (Ag/PCNFs)s howeds everal important benefits for catalytic CO 2 conversion.1 )The CTF precursors with a2 Dm icrocrystals tructure can endow the catalyst with au nique property.2 )Abundant alkaline nitrogen sites facilitate the coordination properties, which can enhancet he dispersity and stability of Ag NPs in/on the support to contribute to ab etter catalytic performance.…”

Catalytically Active Co−Nx Species Stabilized on Nitrogen‐doped Porous Carbon for Efficient Hydrogenation and Dehydrogenation of N‐heteroarenes

“…The best KCC-1@CoÀ NÀ C-800 catalyst has a high TOF value of 8.24 h À 1 , which is 3-24 times higher than the values reported in the transition-metal-based catalysts towards the base/basefree catalytic transfer hydrogenation or hydrogenation for quinoline (Table S2), such as homogeneous Co(BF 4 ) 2 • 6H 2 O, [40] Mn(CO) 5 Br, [41] and [Co II (L1)(CH 3 CN)](BF 4 ) 2 [42] catalysts and heterogeneous Co@NCNTs-800, [43] Co/Melamine-2@C-700, [8b] ISASÀ Co/ OPNC, [44] Co@OMNC-700, [45] CoOx@CN, [46] Co@NGS-800 [38a] and Co 0 /ZnCl 2 catalysts. [6] A scale-up experiment was performed to ascertain the practicality of the KCC-1@CoÀ NÀ C-800 catalyst.…”