Catalytic propane dehydrogenation by anatase supported Ni single-atom catalysts

With the increasing production of propane from shale gas and the growing demand for propylene, propane dehydrogenation (PDH) has gained significant attention as a promising route for the on-purpose production of propylene. As a cheap yet efficient catalyst, Ni-based catalysts have attracted interest because of its ability to activate alkane. Single-atom catalysts (SACs) can maximize the metal atom utilization. Here, we demonstrate that anatase TiO2 supported Ni SAC (Ni1/A-TiO2) exhibits not only superior intrinsic activity and propylene selectivity but also much better stability than the corresponding Ni nanoparticle (NP) catalyst (NiNP/A-TiO2) in PDH reaction at 580 °C. The rate of propylene production on Ni1/A-TiO2 is about 1.96 molC3H6 gNi−1 h−1, about 65 times higher than that of NiNP/A-TiO2 sample (0.03 molC3H6 gNi−1 h−1). In combination of high-angle annular dark-field scanning transmission electron microscopy, in-situ diffuse reflectance infrared Fourier transform spectra, in-situ X-ray photoelectron spectroscopy and X-ray absorption spectroscopy characterizations, we confirm that the Ni SAC mainly contains individual Ni atom singly dispersed on the support in positive Ni (II) valence state. In addition, as a result of strong metal-support interaction (SMSI) between Ni NP and TiO2 carrier under reduced conditions, the Ni NPs sites are encapsulated by TiOx overlayer (~2 nm thick) thus display poor reaction performance.