Ammonia made with hydrogen from sustainable wind energy can be separated from unreacted hydrogen and nitrogen by absorption in magnesium chloride. The absorption is rapid, but desorption can be slower. This work shows that the mechanism of desorption involves two steps: (i) decomposition of ammines to make ammonia and (ii) solid-state diffusion of the produced NH3. With current absorbents, the diffusion step is usually controlling. These experiments suggest the best operating conditions for a pilot scale, wind-powered ammonia separation and provide a strategy for improving the metal-chloride absorbent.
Bibliographical noteFunding Information:
The authors thank J. Schott, S. Biswas, M. Reese, Z. Pursell, C. Smith, M. Malmali, and M. Palys (all UMN) for helpful discussions. This work was funded largely by the Advanced Research Projects Agency-Energy (ARPA-E), United States Department of Energy, under Award No. DE-AR0000804. Other funding came from the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources, and from the MnDRIVE initiative of the University of Minnesota. The views and opinions of the authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.
- Mass transfer
- Pilot testing
- Process design
- Renewable ammonia