Vacancy Healing as a Desorption Tool: Oxygen Triggered Removal of Stored Ammonia from NiO1-x/MOR Validated by Experiments and Simulations

Gas storage via adsorption in microporous crystals, such as zeolites, has the potential to transform both the energy and transportation sectors. This potential results from the highly tunable pore chemistry and geometry of zeolites, which allows for precise control of the chemical environment of the adsorbed gas. However, while strong gas-solid interactions are desirable to maximize gas storage capacity, they hinder the effective release of the stored gas species. In the current work, the partial reduction of a nickel-oxide/zeolite nanocomposite led to a remarkable heat release upon exposure to air, which was attributed to the exothermic healing of oxygen vacancies in the NiO(1-x )lattice. This heating effect was reproducible over at least 10 treatments and was compared to different types of porous supports, providing evidence that uniform micropores and an optimal pore size are required to obtain the observed heating properties. We demonstrate that this heating phenomenon can be applied to the desorption of hysteretic ammonia, leading to 38% desorption of the chemisorbed gas without the need for external heating or pressure swing.