Single Co Sites in Ordered SiO₂ Channels for Boosting Nonoxidative Propane Dehydrogenation

Abstract

Searching for low-cost, environmentally friendly, and highly active catalysts for C−H bond activation in propane dehydrogenation (PDH) reaction remains a great challenge. Herein, SiO 2 nanomeshes (NMs) with ultrashort three-dimensional (3D) channels were constructed to effectively confine the Co single atoms (Co SAs/ SiO 2 NMs). The ultrashort 3D channels were formed by gasifying carbon in the self-assembled SiO 2 @polymer composites under the air atmosphere. The carbon removal process resulted in abundant oxygen (O*) defects in the channel windowsill that immobilized the dissociative Co 1 species to afford the sintering-resistant Co SAs/SiO 2 NMs catalyst. The as-obtained Co SAs/SiO 2 NMs with unsaturated Co−O 3 sites exhibited an outstanding PDH catalytic behavior (95% selectivity and 196 h −1 turnover frequency), superior to Co SAs/SiO 2 commerce (83%, 49 h −1 ), Co NPs/SiO 2 NMs (87%, 13 h −1 ), and most non-noble metal-based catalysts. Furthermore, Co SAs/SiO 2 NMs showed high long-term stability with no significant deactivation during 24 h of reaction. Theoretical and experimental analysis indicated that these unsaturated Co−O 3 sites could selectively activate the first and second C−H bonds and limit the further splitting of C−H (C) bonds during PDH. This work paves a way for designing high-efficiency single-atom catalysts for PDH.

Exposing Single Ni Atoms in Hollow S/N‐Doped Carbon Macroporous Fibers for Highly Efficient Electrochemical Oxygen Evolution

“…Electron paramagnetic resonance is an efficient technique for detecting unpaired electrons in materials. [ 27,28 ] The intensity at the g value of 2.003 for Ni SAs@S/N‐CMF is higher than that of Ni NPs@S/N‐CMF, suggesting that abundant C and N defects emerge on the skeleton of Ni SAs@S/N‐CMF during the atomization process (Figure S18, Supporting Information). [ 29–31 ] Besides, the N K‐edge X‐ray absorption near edge structure spectrum (Figure S19, Supporting Information) reveals that three peaks can be attributed to the π*‐transition of pyridinic‐N (peak a) and graphitic‐N (peak b), and the σ*‐transition of CN bonds (peak c).…”

Introducing Co–O Moiety to Co–N–C Single-Atom Catalyst for Ethylbenzene Dehydrogenation

“…17 On the basis of the above characterizations, a proposed reaction mechanism for EB dehydrogenation over the CoN 3 O 1 structure can then be suggested according to the propane dehydrogenation mechanism occurring on the silica supported Co(II) sites reported in the literature. 50,83,84 As illustrated in Scheme 1, the EB molecule is first adsorbed on the N-doped carbon surface via the weak π−π interaction with its ethyl group approaching to the Co−O moiety. The activation of α-H bonds in the ethyl group of EB then probably goes through a heterolytic cleavage across the Co−O bond, leading to an adsorbed Co-ethyl intermediate and a surface hydroxyl.…”

Efficient CO2catalytic hydrogenation over CuOx–ZnO/silicalite-1 with stable Cu+species

“…Silicalite-1(S-1) has plenty of micropores and is rich in silanol groups, which can stabilize metallic nanoparticles and even form M–O x , such as Zn–O x , 36 Co–O x (ref. 37) and Ni–O x . 38 Therefore, in this study, S-1 was chosen as the support for CuO to study the activity/stability and the real active site of CuO/S-1 for the hydrogenation of CO 2 .…”