A Data-Driven Approach to Molten Salt Synthesis of N-Rich Carbon Adsorbents for Selective CO2 Capture

Applying a design of experiments methodology to the molten salt synthesis of nanoporous carbons enables inverse design and optimization of nitrogen (N)-rich carbon adsorbents with excellent CO2/N-2 selectivity and appreciable CO2 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 structure-function relationships between the synthesis conditions, physicochemical properties, and achievable selective adsorption performance of N-rich nanoporous carbons derived from molten salt synthesis for CO2 capture. Taking advantage of size-sieving separation of CO2 (3.30 & Aring;) from N-2 (3.64 & Aring;) 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 CO2 capacity (0.73 mmol g(-1) at 30.4 Torr and 30 degrees C) with noteworthy concurrent CO2/N-2 selectivity as predicted by the ideal adsorbed solution theory (S-IAST = 246) with an adsorbed phase purity of 91% from a simulated gas stream containing only 4% CO2. Optimized N-rich porous carbons, with good physicochemical stability, low cost, and moderate regeneration energy, can achieve performance for selective CO2 adsorption that competes with other classes of advanced porous materials such as chemisorbing zeolites and functionalized metal-organic frameworks.