Highly Dispersed Ionic Liquids in Mesoporous Molecular Sieves Enable a Record NH₃ Absorption

Abstract

Ammonia (NH3) has high hydrogen energy density and is a promising sustainable energy in the future. However, developing simple, stable, and efficient materials for NH3 uptake and storage remains a challenge. Here, a family of stable ionic liquid hybrid materials has been developed by a simple impregnation of Zn-based ionic liquids (ZnILs) into a stable mesoporous molecular sieve FDU-12 for high-efficient NH3 capture. The ZnIL hybrid adsorbents exhibit a record NH3 adsorption capacity (25.2 mmol/g at 25.0 °C and 1.0 bar), along with an exceptionally high uptake at high temperature (15.2 mmol/g at 80.0 °C and 1.0 bar) and low NH3 concentration (5.0 mmol/g at 25.0 °C and 10,000 ppm). Notably, [C1NH3]­[Zn3Cl7]@FDU-12-40% shows an almost unchanged breakthrough performance after five cycles, indicating excellent cycling stability of these hybrid adsorbents. It is revealed that such superior NH3 capacity is mainly attributed to the highly dispersed ZnILs in FDU-12, which facilitate the coordination and hydrogen-bonding interactions of NH3 with the ILs.

Sulfonated and ordered mesoporous polymers for reversible adsorption of ammonia: Elucidation of sequential pore-space diffusion

“…This result is particularly important, because the contents of NH 3 in industrial gas are normally low, and the performance of solid adsorbents for adsorption of NH 3 at low pressures is more concerned. 45,46 For the separation of NH 3 , the most important task is to selectively adsorb NH 3 from N 2 and H 2 mixture.…”

Regulating the Pore Microenvironment of Microporous Metal–Organic Frameworks for Efficient Adsorption of Low-Concentration Ammonia

“…NH 3 static adsorption and breakthrough experiments were performed by the similar procedures reported in our previous works. , Briefly, a 3H-2000PM specific surface pore size analyzer (BeiShiDe) was used to determine NH 3 adsorption–desorption isotherms on MOFs at 25.0 °C. Before each adsorption experiment, about 60 mg of sample was weighed and degassed at 150 °C for 24 h under vacuum.…”

“…To reduce the impact of ammonia on the environment, membrane, catalytic degradation, biological conversion, and adsorption technologies have been used to mitigate the emissions of ammonia into the atmosphere. − Due to the advantages of simple operation, low-energy consumption recovery, and high separation efficiency, adsorption separation is a promising technique for the capture of low-concentration ammonia. ,− In this regard, solid porous materials, such as activated carbon, zeolites, covalent organic frameworks, hydrogen organic frameworks, and metal–organic frameworks (MOFs), have been used for ammonia capture. ,,− Among these adsorbents, MOFs have attracted great attention in the adsorption of low-concentration ammonia due to their unique adjustable functions, varied pore structures, high pore volumes, and large specific surface areas. ,,, More importantly, MOFs have shown high affinity for ammonia because of the metal sites in their pore structures …”

A Mini-Review on NH3 Separation Technologies: Recent Advances and Future Directions

“…137 Combining ILs with porous materials provides more viability when designing solid adsorbents for NH 3 separation, and the viscous issue of pure ILs was also avoided. For examples, Yu et al supported protonated ILs on ACs for efficient NH 3 adsorption; 138 Zeng et al supported metal-based ILs on silica gels for efficient NH 3 adsorption; 139 141 The porous materials used for the physical impregnation of ILs should better have large pore size and high pore volume. The large pore size is beneficial for the dispersion of ILs in nanopores, and the high pore volume is beneficial for the accommodation of more active sites enabling strong interaction with NH 3 .…”

“…Combining ILs with porous materials provides more viability when designing solid adsorbents for NH 3 separation, and the viscous issue of pure ILs was also avoided. For examples, Yu et al supported protonated ILs on ACs for efficient NH 3 adsorption; Zeng et al supported metal-based ILs on silica gels for efficient NH 3 adsorption; Han et al impregnated Zn-based ILs in Cr-based MOFs for efficient NH 3 adsorption; Cao et al dispersed Zn-based ILs in mesoporous zeolites for efficient NH 3 adsorption . The porous materials used for the physical impregnation of ILs should better have large pore size and high pore volume.…”