NH3 Uptake and NH3/CO2 Separation by a [MEA][SCN]-Based Deep Eutectic Solvent: Experimental Investigation and Process Simulation

NH3 has attracted increasing attention as a fundamental material and promising hydrogen carrier. The uptake of NH3 from NH3-containing exhausted gas presents economic and environmental issues. In this study, [MEA][SCN] was paired with glycerol, acetamide, formamide, phenol (PhOH), ethylene glycol, urea, glycerolformal, or 1,3-dimethyl-2-imidazolidinone to construct deep eutectic solvents (DESs) for effective NH3 absorption and NH3/CO2 separation investigation. All of the [MEA][SCN]-based DESs exhibited good NH3 absorption and separation performance. Notably, [MEA][SCN]-PhOH (1:1) realized an atmospheric capacity of 0.2459 g of NH3·g–1 DES and NH3/CO2 selectivity of 194.53 at 303.15 K. Based on the experimental data, a new process for NH3 recovery from melamine tail gas using [MEA][SCN]-PhOH (1:1) (DES-M) was developed and simulated from operational parameters optimization, heat exchange network design, and economic evaluation. DES-M can recycle NH3 with purity of 99.6% and save 82.01% utility costs compared to the water scrubbing method. The heat integration network design in DES-M reduces 66.94% low-pressure steam and 9.00% separation costs. Specially, the optimized DES-M can exceed 59% after-tax rate of return using renewable energy.