A Data-Driven Approach to Molten Salt Synthesis of N-rich Carbon Adsorbents for Selective CO 2 Capture.

Applying a design of experiments methodology to molten salt synthesis of nanoporous carbons enables inverse design and optimization of N-rich carbon adsorbents with excellent CO 2 /N 2 selectivity and appreciable CO 2 capacity for carbon capture via swing adsorption from dilute gas mixtures, such as natural gas combined cycle flue gas. This data-driven study reveals fundamental relationships between the synthesis conditions, physicochemical properties, and achievable selective adsorption performance of N-rich nanoporous carbons derived from molten salt synthesis for CO 2 capture. Taking advantage of size-sieving separation of CO 2 (3.30 Å) from N 2 (3.64 Å) within the turbostratic nanostructure of these N-rich carbons, while limiting deleterious N 2 adsorption in a weaker adsorption site that harms selectivity, enables a large low-pressure CO 2 capacity (0.73 mmol/g at 30.4 Torr and 30°C) with noteworthy concurrent CO 2 /N 2 selectivity (S IAST = 246, adsorbed phase purity = 91%) from a simulated gas stream with only 4% CO 2 . This study reveals general structure-function relationships of selective CO 2 adsorption by nanoporous carbon adsorbents. Optimized N-rich porous carbons, with good physicochemical stability, low cost, and moderate regeneration energy, can achieve performance for selective CO 2 adsorption that competes with other classes of advanced porous materials, such as chemisorbing zeolites and functionalized metal-organic frameworks. This article is protected by copyright. All rights reserved.