On-Demand Ammonia Capture and Separation with Open Aluminophosphate Frameworks

Area of Science:

• Materials Science
• Chemical Engineering
• Adsorption Science

Background:

• Ammonia capture and separation are critical industrial processes.
• Developing efficient adsorbents is a significant challenge.
• Open aluminophosphate frameworks offer a novel approach.

Purpose of the Study:

• To report, for the first time, open aluminophosphate frameworks for on-demand ammonia adsorption.
• To evaluate the performance of AlPO-18 and AlPO-11 molecular sieves for ammonia capture.
• To elucidate the mechanism of ammonia adsorption in these frameworks.

Main Methods:

• Synthesis and characterization of aluminophosphate molecular sieves (AlPO-18, AlPO-11).
• Dynamic ammonia uptake experiments at various concentrations.
• Regeneration studies and Aspen process simulations.
• Spectroscopic techniques (XPS, in situ FTIR, MAS NMR) and DFT calculations.

Main Results:

• AlPO-18 demonstrated exceptional dynamic ammonia uptake (3.36 mmol/g) at 200 ppm for trace capture.
• AlPO-11 showed high ammonia uptake (5.73 mmol/g) at 50,000 ppm with excellent recyclability.
• Aspen simulations revealed 51% energy savings for AlPO-11 in ammonia recovery compared to compression.
• Coordination of ammonia on framework aluminum sites was elucidated.

Conclusions:

• Open aluminophosphate frameworks are effective for on-demand ammonia adsorption and separation.
• AlPO-18 and AlPO-11 exhibit distinct advantages for trace capture and industrial recovery, respectively.
• These materials offer potential for energy-efficient ammonia capture and separation in diverse applications.