Isolated Indium Hydrides in CHA Zeolites: Speciation and Catalysis for Nonoxidative Dehydrogenation of Ethane

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 structure 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 H2 at high temperatures (> 773 K). In situ Fourier transform infrared (FTIR) spectroscopy and density functional theory (DFT) calculations revealed that [InH2]+ ion on a framework anionic site is a plausible structure. In-CHA exhibited high selectivity and durable catalytic activity for the non-oxidative dehydrogenation of ethane for at least 90 h. Kinetic and in situ spectroscopic studies as well as transition state (TS) calculations suggested that [InH2]+ ions serve as catalytic active sites for the selective dehydrogenation using In-CHA.