No abstract

N-doped carbon black (NCB) supported Ni NPs exhibited higher activity than most Ni-based catalysts for selective HDO of vanillin at mild conditions, ascribing to higher reducibility, lower oxidation state of Ni NPs and enhanced spillover hydrogen of Ni to NCB.

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.

The strong Pd–N interaction on biomass-derived N-doped highly mesoporous carbons (NMCs) generates co-existence of electron-deficient Pd (Pdδ+) and metallic Pd (Pd0), leading to Pd/NMC as novel bifunctional catalyst for both FA dehydrogenation and vanillin hydrogenation.

CN is prepared via polymerization between EDA and CF, which renders coordinated Pd with high activity for selective HDO of vanillin at low H2 pressure and temperature. This Pd/CN is reusable and the best TOF reaches 295.4 h−1.