Brute force determination of the optimum pore sizes for CO2 uptake in turbostratic carbons

Abstract

Porosity, and in particular pore size is one of the most important considerations in the development of porous carbons for CO₂ capture. Current methods for determining the optimum pore size for adsorption of gases either make very broad assumptions (in computational studies), or are not sufficiently exhaustive (in experimental studies). Herein we present a piece of software known as the python Porosity Uptake Correlator (pyPUC) which employs a brute force, first principles method for determining the range of pore sizes, Ω, best suited to adsorption of a given sorptive at a range of pressures. As an initial test, pyPUC is used to determine Ω for CO₂ in a broad pressure range according to N₂ porosimetry. The analysis is then extended to other porosimetric sorptives and combinations thereof to assess their efficacy in determining Ω for CO₂, and we find that traditional N₂ porosimetry is insufficient for determining the relationship between pore size and CO₂ uptake in ultramicroporous turbostratic carbons. While pyPUC is not meant as a predictive tool, it facilitates a more robust and thorough investigation of the relationship between porosity and adsorbate uptake capacity than current methods, and provides a method for understanding such relationships more generally.