Ammonia (NH3) has been reported as promising hydrogen storage media for clean fuel applications and is widely used as a reductant in selective catalytic reduction (SCR) systems. With such a huge potential in various environmental-friendly applications, however, ammonia is facing several challenges in its storage and delivery feasibility. In this study, we have designed three-dimensional (3D) printed zeolite NaX (faujasite)-magnesium chloride (MgCl2) structured units by the pressure-assisted micro-syringe method. The 3D printed unit consists of a NaX scaffold and MgCl2 blocks located inside, where the NaX scaffold provides the space to accommodate the volume swing during ammonia adsorption-desorption cycles, MgCl2 to Mg(NH3)6Cl2 to MgCl2. The 3D printed unit demonstrates a net-zero structural change and offers structural stability during ammonia adsorption-desorption cycles. Moreover, by combining the zeolite and metal ammine complexes, we demonstrate that physisorption and chemisorption of ammonia occur in structured units and offer high sorption capacity and rapid kinetics in ammonia adsorption and desorption.
Keywords ammonia, SCR, 3D printing, zeolite, hydrogen storage