Direct Observation and Quantification of CO ₂ Binding Within an Amine-Functionalized Nanoporous Solid

Abstract

Understanding the molecular details of CO(2)-sorbent interactions is critical for the design of better carbon-capture systems. Here we report crystallographic resolution of CO(2) molecules and their binding domains in a metal-organic framework functionalized with amine groups. Accompanying computational studies that modeled the gas sorption isotherms, high heat of adsorption, and CO(2) lattice positions showed high agreement on all three fronts. The modeling apportioned specific binding interactions for each CO(2) molecule, including substantial cooperative binding effects among the guest molecules. The validation of the capacity of such simulations to accurately model molecular-scale binding bodes well for the theory-aided development of amine-based CO(2) sorbents. The analysis shows that the combination of appropriate pore size, strongly interacting amine functional groups, and the cooperative binding of CO(2) guest molecules is responsible for the low-pressure binding and large uptake of CO(2) in this sorbent material.

Structurally simple complexes of CO2

“…Interactions such as these have been observed in other CO2 complexes of nitrogen-containing porous materials, [56][57][58][59] and some have been studied computationally. 60 The stabilizing effect of nitrogen is not surprising considering the known reactivity of CO2 towards basic nitrogen atoms, primary and secondary amines in particular, which will be discussed in the next section.…”

Structurally Designed Synthesis of Mechanically Stable Poly(benzoxazine-co-resol)-Based Porous Carbon Monoliths and Their Application as High-Performance CO2 Capture Sorbents

“…The higher Q st in the initial stage leads to a preferential adsorption of CO 2 over N 2 , which can be interpretated as the strong quadrupolar interactions of CO 2 molecules with the heterogeneous micropore walls (e.g., nitrogen groups) at low pressures. 26,28 Figure 7eÀf show the N 2 adsorption isotherms of HCM-DAH-1, HCM-DAH-1-900-1, and HCM-DAH-1-900-3 under a low relative pressure range of 1.0 Â 10 À7 À1.0 Â 10 À3 and the corresponding micropore size distributions. Clearly, activation causes a remarkable uptake of isotherms ( Figure 7e).…”

Microporous metal-organic framework with potential for carbon dioxide capture at ambient conditions

“…The emerging porous metal-organic frameworks (MOFs) are promising as the cost-effective and efficient materials for CO 2 capture and separation [5][6][7][8][9][10] . The regeneration energy cost to utilize these porous materials for CO 2 capture by the implementation of temperature swing adsorption, pressure swing adsorption (PSA) and vacuum swing adsorption is significantly lower than the abovementioned alkanolamine technology.…”