Generating Cationic Nickel Clusters over Oxygen-Functionalized Boron Nitride to Boost Methane Dry Reforming
Fan Jie, Wen‐Cui Li, Lei He, Bowen He, Fan Tang, Zhankai Liu, Dongqi Wang, Xi Liu, Liwei Chen, An‐Hui Lu
Abstract
Ni-based catalysts are the most promising candidates for methane dry reforming (MDR) reaction but still suffer from deactivation caused by coke-deposition. Herein, we reported a coke resistance MDR catalyst consisting of cationic Ni clusters (Ni δ+, 0 < δ < 2) stabilized over oxygen-functionalized boron nitride. A simple method was developed for the fabrication of highly dispersed cationic Ni clusters on boron nitride. The local coordination modes between nickel and boron nitride determine the formation of cationic Ni clusters. We provided detailed spectroscopy and microscopy characterizations to reveal the structure features of these cationic Ni clusters. The average particle size of these clusters is ∼1.7 nm. There are abundant Ni x δ+ –O–B interfaces on the cationic Ni clusters, which serve as catalytically active sites. Compared to conventional metallic Ni nanoparticles, the cationic Ni clusters exhibited comparable apparent catalytic activity and reduced carbon deposition, particularly operated at 600 °C where unavoidable coke formation from CH 4 cracking and the Boudouard reaction usually tends to occur thermodynamically and kinetically. Based on theoretical and experimental evidence, a dynamic synergistic conversion mechanism for CH 4 and CO 2 on the Ni x δ+ –O–B interface has been revealed. The oxygen within the Ni x δ+ –O–B interface could rapidly convert CH x *( x = 1–3) intermediates forming H 2 and CO to avoid carbon deposition. CO 2 is efficiently activated at boron sites of the Ni δ+ –O–B interface to regenerate active oxygen species, thereby boosting the conversion of CH 4 . These insights may shine light on the development of intrinsic coke-free Ni-based catalysts for methane dry reforming in the near future.