Chemical Looping Ammonia Decomposition Mediated by Alkali Metal and Amide Pairs for H<sub>2</sub> Production and Thermal Energy Storage
Sheng Feng, Wenbo Gao, Runze Wang, Yeqin Guan, Han Wu, Qianru Wang, Hujun Cao, Lin Liu, Jianping Guo, Ping Chen
Abstract
Abstract Ammonia decomposition to H 2 (ADH) is one of the key reactions in the ammonia‐based energy system. Recent research has been focused on developing more active and affordable catalysts, however, few can operate below 500 °C and typically require the expensive metal ruthenium. Herein, a fundamentally different thermal ADH via a chemical looping process (CLADH) mediated by alkali metal and its amide pairs, which can work under lower temperatures than the catalytic process, is reported. This CLADH consists of two steps: 1) Ammoniation step ̶ NH 3 reacts with Na or K to generate NaNH 2 or KNH 2 , respectively, accompanied by releasing one‐third of H 2 in NH 3 at room temperature; 2) Decomposition step ̶ NaNH 2 or KNH 2 decomposes to N 2 and H 2 with the regeneration of Na or K which can be performed above 275 °C. Additionally, due to the significant enthalpy change in the two‐step reactions of this CLADH, −78.0 kJ mol −1 for the first step and 123.9 kJ mol −1 for the second, using the Na and NaNH 2 pair—suggest potential for thermal energy storage. This work not only reports an alternative route to produce H 2 from NH 3 , but also unravels the potential of chemical looping process for thermal energy storage.