Catalytic formic acid dehydrogenation via hexagonal-boron nitride supported palladium

Abstract

Formic acid dehydrogenation is an effective pathway for hydrogen storage, transportation, and in situ supply; however, the problems of catalyst sintering and agglomeration remain challenging. In this regard, this study aims at modulating hexagonal boron nitride-supported Pd catalyst with strong metal support interactions, thereby promoting its long-term stability. Effects of particle sizes of h-BN (500 nm, 1–2 μm, 5–10 μm) and dehydrogenation temperatures on formic acid conversion, hydrogen yield, CO concentration, and product distribution are investigated. The nano-scaled h-BN supported Pd nanoparticles show the best performance of 24.25 mmol H2 mL-1 HCOOH with a H2 concentration of 44.7 vol%. Characterizations such as N2 adsorption and desorption, XRD, TEM-EDX mapping, and XPS are used to study the physicochemical properties of the as-synthesized and reacted catalysts. Specifically, the diffraction peaks of Pd cannot be detected from XRD, possibly attributing to the homogeneous dispersion of its nanoparticles, as confirmed by the TEM-EDX mapping results. The durability tests indicate that the Pd/h-BN (500 nm) catalyst remains long-term stability under a temperature as high as 160 °C. Moreover, results from XPS reveal that there is a strong interaction between the Pd nanoparticles and the hexagonal BN support, as proved by the electronic transformation from Pd to N by XPS, thereby enhancing the stability of the Pd/h-BN catalyst.