The study of the formation, characterization, and functionality of isolated surface hydrides on solid materials is a formidable task because of the complexity of solid surfaces and the difficulty of analyzing structures in solids. Herein, we found the formation of indium (In) hydride species supported by CHA zeolites. The In hydrides were formed by treatment of an In-exchanged CHA zeolite (In-CHA) with H 2 at high temperatures (>773 K). In situ Fourier transform infrared (FTIR) spectroscopy and density functional theory (DFT) calculations revealed that an [InH 2 ] + ion on a framework anionic site is a plausible structure. In-CHA exhibited high selectivity and durable catalytic activity for the nonoxidative dehydrogenation of ethane for at least 90 h. Kinetic and in situ spectroscopic studies as well as transition state (TS) calculations suggested that [InH 2 ] + ions serve as catalytically active sites for selective dehydrogenation using In-CHA.

The oxidative dehydrogenation of propane using CO2 (CO2-ODP) is a promising technique for high-yield propylene production and CO2 utilization. Developing a highly efficient catalyst for CO2-ODP is of great interest and benefit to the chemical industry and for carbon recycling. However, the efficiency of the existing catalysts is limited. Here, we report a Pt-Co-In ternary nanoalloy on CeO2 having a (Pt1−xCox)2In3 pseudo-binary alloy structure, which exhibits a considerably high catalytic activity, C3H6 selectivity, stability, and CO2 utilization efficiency at 550 °C. Alloying Pt with In and Co significantly improves the C3H6 selectivity and CO2 reduction ability, respectively. The Co species provide a high density of states near the Fermi level, which lowers the energy barrier of CO2 reduction.The catalyst stability is drastically enhanced by combining the strong CO2 activation ability of the alloy and the CeO2 support capable of oxygen release, which facilitate Mars-van Krevelen-type coke combustion.

The oxidation of NO to NO2 and the subsequent reduction by NH3 via a NO + intermediate over a proton-type chabazite zeolite (H-CHA) were investigated by the combination of in situ infrared (IR) spectroscopy and density functional theory (DFT) calculations. The in situ IR spectral results indicate that the NO + species formed under a flow of NO + O2 at 27-250 °C are more stable at lower temperatures over both H-CHA and copper-cation-exchanged CHA zeolite (Cu-CHA). The Arrhenius plot (T = 27-120 °C) shows a negative apparent activation barrier energy (−11.5 kJ mol⁻ 1 ) for the formation of NO + species under the NO + O2 flow over H-CHA. The time course of the IR spectra at 27 °C shows that NO is oxidized by O2 to NO2 and then further converted via N2O4 to NO + and NO3⁻. The subsequent exposure to NH3 at 27 °C reduces the NO + species to N2. DFT calculations revealed that Brønsted acid sites in zeolite pores promote the dissociation of N2O4 intermediates into NO + and NO3⁻ species with a low activation barrier (15 kJ mol⁻ 1 ). Moreover, the computed activation barrier for the reduction of NO + species by NH3 was considerably low (6 kJ mol⁻ 1 ). The experimental and theoretical results of this study demonstrate the high potential of Cu-free H-CHA zeolites for promoting the lean NOx capture to form NO + species and the subsequent reduction by NH3 at room temperature.

Propane dehydrogenation has been a promising propylene production process that can compensate for the increasing global demand for propylene. However, Pt-based catalysts with high stability at ≥600 °C have barely been reported because the catalysts typically result in short catalyst life owing to side reactions and coke formation. Herein, we report a new class of heterogeneous catalysts using high-entropy intermetallics (HEIs). Pt−Pt ensembles, which cause side reactions, are entirely diluted by the component inert metals in PtGe-type HEIs. The resultant HEI (PtCoCu) (GeGaSn)/Ca−SiO 2 exhibited an outstandingly high catalytic stability, even at 600 °C (k d −1 = τ = 4146 h = 173 d), and almost no deactivation of the catalyst was observed for 2 months for the first time. Detailed experimental studies and theoretical calculations demonstrated that the combination of the site-isolation and entropy effects upon multimetallization of PtGe drastically enhanced the desorption of propylene and the thermal stability, eventually suppressing the side reactions even at high reaction temperatures.

Atomic dispersion of metal species has attracted attention as a unique phenomenon that affects adsorption properties and catalytic activities and that can be used to design so-called single atom materials. In this work, we describe atomic dispersion of bulk Pd into small pores of CHA zeolites. Under 4% NO flow at 600°C, bulk Pd metal on the outside of CHA zeolites effectively disperses, affording Pd 2+ cations on Al sites with concomitant formation of N 2 O, as revealed by microscopic and spectroscopic characterizations combined with mass spectroscopy. In the present method, even commercially available submicrosized Pd black can be used as a Pd source, and importantly, 4.1 wt % of atomic Pd 2+ cations, which is the highest loading amount reported so far, can be introduced into CHA zeolites. The structural evolution of bulk Pd metal is also investigated by in situ X-ray absorption spectroscopy (XAS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), as well as ab initio thermodynamic analysis using density functional theory (DFT) calculations.