Chelating-agent-free incorporation of isolated Ni single-atoms within BEA zeolite for enhanced biomass hydrogenation

Precisely tailoring metal single-atoms within zeolite scattfolds and understanding the origin of the unique behavior of such atomically dispersed catalysts are pivotal and challenge in chemistry and catalysis. Herein, we have successfully fabricated Ni single-atoms within BEA zeolite (Ni₁@Beta) through a facile in situ two-step hydrothermal strategy, notably without using any chelating agent for stabilizing Ni species. With the aid of advanced characterization techniques, such as aberration-corrected high-angle annular dark-field scanning transmission electron microscopy, X-ray absorption spectroscopy, etc., and combined with density functional theory calculations, the nature and micro-environment of isolated Ni species, which are incorporated within 6-membered rings and stabilized by four skeletal oxygens of Beta zeolite, have been identified. The as-obtained Ni₁@Beta exhibits a superior performance in terms of activity (with a turnover frequency value up to 114.1 h^–1) and stability (for 5 consecutive runs) in the selective hydrogenation of furfural, surpassing those of Ni nanoparticle analogues and previously reported Ni-based heterogeneous catalysts. This study provides an efficient strategy for the fabrication of non-noble metal single-atoms within zeolites, which could be of great help for the design of metal-zeolite combinations in the chemoselective reactions involved in biomass conversion and beyond.