Ionic liquid hybrid metal–organic frameworks for efficient adsorption and selective separation of ammonia at high temperature

Abstract

Efficient adsorption and selective separation of ammonia at high temperature is a crucial and challenging issue. In this work, a series of stable ionic liquid hybrid materials have been developed by simple impregnation of ionic liquids into stable metal–organic framework Al-fum with 1D pores. The hybrid material [C2N][Zn3Cl7]@Al-fum-60% exhibited an exceptionally high uptake (9.9 mmol/g at 80 °C, 8.8 mmol/g at 100 °C) at high temperature, excellent uptake (9.8 mmol/g at 25.0 °C) at low ammonia concentration (100,000 ppm), and remarkable selective separation performance (selectivity factor is 25.1) of NH3 from NH3/CO2 mixture at high temperature. The NH3 uptake of [C2N][Zn3Cl7]@Al-fum-60% at 100 °C was higher than the capacity of most of typical porous NH3 adsorbents at room temperature. It is revealed that such superior NH3 capacity and selective separation performance are mainly attributed to coordination interactions of NH3 to Zn centre of the ionic liquids and the hydrogen bonding interactions of NH3 with Cl of the ionic liquids and NH3 with μ-OH of Al-fum.