Paper

Optimizing Absorptive Separation for Intensification of Ammonia Production

High pressure requirements of Haber-Bosch process imposes substantial operating (e.g., compression) and capital (compressor cost, advanced costly alloys, thick reactor casing, etc.) expenses in the ammonia production. Cost considerations force ammonia producers to take advantage of the economy of scale to drive down the manufacture cost, while small and energy-efficient processes that can be powered with off-grid renewable energy are required for ammonia-mediated hydrogen economy. Small-scale reaction-absorption process is proposed to be a viable technology to reduce the operating pressure requirements of Haber-Bosch process.1–4 Here, we present an overview of our efforts to further intensify ammonia production via reaction-absorption process.…

Paper

Ammonia Absorption and Desorption in Ammines

While adsorption onto solids is a common separation process, absorption into solids is much less often used. The reason is that absorption is usually assumed ineffective because it includes very slow solute diffusion into the solid. An exception may be the separation of ammonia from nitrogen and hydrogen using ammines, especially at temperatures close to those used in ammonia synthesis. There, ammonia can be selectively absorbed by calcium chloride; nitrogen and hydrogen are not absorbed. The kinetics of ammonia release seem to be diffusion controlled. The kinetics of absorption are consistent with a first order reaction and diffusion in series,…

Paper

Lower Pressure Ammonia Synthesis

Ammonia is a very important chemical, mainly produced through the Haber-Bosch process. This process requires high temperature (>400 °C) and pressure (>150 bar) in order to ensure fast kinetics and high conversions, respectively.1 As a result, ammonia synthesis is known to be very complex and energy-intensive.2 To alleviate the complexity and energy requirements of ammonia synthesis, and to reduce the CO2 emissions, we are proposing an innovative reaction-absorption process to synthesize carbon-free ammonia in small plants.3 This green ammonia can be synthesized in wind-powered plants, with hydrogen from electrolysis of water and nitrogen from pressure swing adsorption of air.4 In…

Paper

Small Scale Low-Pressure Ammonia Synthesis

Ammonia is one of the most important chemical commodities in the US and will be a key component in helping the world meet the rising demand for food and energy. Ammonia is needed in distributed locations for agriculture (as fertilizer for small grain and corn production), for indirect hydrogen storage1 (transported as a liquid at moderate pressure to hydrogen stations), or as a liquid fuel2 (for internal combustion engines or solid oxide fuel cells). Recently, there has been significant effort to develop scalable technologies for conversion of intermittent energies (e.g., solar, wind) into energy dense carbon-neutral liquid fuels, and ammonia…