Carbon-free H2 production from ammonia triggered at room temperature with an acidic RuO2/γ-Al2O3 catalyst

Katsutoshi Nagaoka; Takaaki Eboshi; Yuma Takeishi; Ryo Tasaki; Kyoko Honda; Kazuya Imamura; Katsutoshi Sato

doi:10.1126/sciadv.1602747

Carbon-free H₂ production from ammonia triggered at room temperature with an acidic RuO₂/γ-Al₂O₃ catalyst

Sci Adv. 2017 Apr 28;3(4):e1602747. doi: 10.1126/sciadv.1602747. eCollection 2017 Apr.

Authors

Katsutoshi Nagaoka¹, Takaaki Eboshi¹, Yuma Takeishi¹, Ryo Tasaki¹, Kyoko Honda¹, Kazuya Imamura¹, Katsutoshi Sato^{1

2}

Affiliations

¹ Department of Applied Chemistry, Faculty of Engineering, Oita University, 700 Dannoharu, Oita 870-1154, Japan.
² Elements Strategy Initiative for Catalysts and Batteries, Kyoto University, 1-30 Goryo-Ohara, Nishikyo-ku, Kyoto 615-8245, Japan.

Abstract

Ammonia has been suggested as a carbon-free hydrogen source, but a convenient method for producing hydrogen from ammonia with rapid initiation has not been developed. Ideally, this method would require no external energy input. We demonstrate hydrogen production by exposing ammonia and O₂ at room temperature to an acidic RuO₂/γ-Al₂O₃ catalyst. Because adsorption of ammonia onto the catalyst is exothermic, the catalyst bed is rapidly heated to the catalytic ammonia autoignition temperature, and subsequent oxidative decomposition of ammonia produces hydrogen. A differential calorimeter combined with a volumetric gas adsorption analyzer revealed a large quantity of heat evolved both with chemisorption of ammonia onto RuO₂ and acidic sites on the γ-Al₂O₃ and with physisorption of multiple ammonia molecules.

Keywords: Renewable Energy; adsorption heat; energy carrier; fuel cell; heterogeneous catalyst; hydrogen carrier; hydrogen engine; internal heat generation; oxidative decomposition of ammonia.