Understanding carbon dioxide capture on metal–organic frameworks from first-principles theory: The case of MIL-53(X), with X = Fe3+, Al3+, and Cu2+

Abstract

Metal-organic frameworks (MOFs) constitute a class of three-dimensional porous materials that have shown applicability for carbon dioxide capture at low pressures, which is particularly advantageous in dealing with the well-known environmental problem related to the carbon dioxide emissions into the atmosphere. In this work, the effect of changing the metallic center in the inorganic counterpart of MIL-53 (X), where X = Fe 3+ , Al 3+ , and Cu 2+ , has been assessed over the ability of the porous material to adsorb carbon dioxide by means of first-principles theory. In general, the non-spin polarized computational method has led to adsorption energies in fair agreement with the experimental outcomes, where the carbon dioxide stabilizes at the pore center through long-range interactions via oxygen atoms with the axial hydroxyl groups in the inorganic counterpart. However, spin-polarization effects in connection with the Hubbard corrections, on Fe 3d and Cu 3d states, were needed to properly describe the metal orbital occupancy in the open-shell systems (Fe-and Cu-based MOFs). This methodology gave rise to a coherent high-spin configuration, with five unpaired electrons, for Fe atoms leading to a better agreement with the experimental results. Within the GGA+U level of theory, the binding energy for the Cu-based MOF is found to be E b = −35.85 kJ/mol, which is within the desirable values for gas capture applications. Moreover, it has been verified that the adsorption energetics is dominated by the gas-framework and internal weak interactions.

Modelling carbon capture on metal-organic frameworks with quantum computing

“…S4 and S5) suggest differences between these fragmentations in the treatment of correlation for UCCSD compared to CCSD, which may impact the long-range interactions between Al and CO 2 . Comparing to results from the literature, we note that recent works have predicted binding energies of similar order of magnitudes from classical DFT calculations [43].…”

“…In a realistic MIL-53(Al) two Al atoms would be relatively close by, even forming hydrogen bonds via their respective OHgroups. However, since quantum computers are limited in computational space and since studies show that only one of the two neighboring Al atoms participates in CO 2 capture [42,43] we chose the Al-fumarate molecule as a model system. Our choice of an Al-based MOF as a center of the study is also motivated with the fact that the electronic structure of Al-fumarate molecule could be relatively tame.…”

Modelling Carbon Capture on Metal-Organic Frameworks with Quantum Computing

“…S4 and S5) suggest differences between these fragmentations in the treatment of correlation for UCCSD compared to CCSD, which may impact the long-range interactions between Al and CO 2 . Comparing to results from the literature, recent works have predicted binding energies of similar order of magnitudes from classical DFT calculations 45 . Hence, we conclude that ∆E(r=10 Å) lying between 40.9 mHa and 46 mHa, obtained from fragmentations in Fig.…”

Understanding Indium Nitride Thin Film Growth Under ALD Conditions by Atomic Scale Modelling: From the Bulk to the In-Rich Layer

“…In this sense, N atoms exhibit low magnetic moment (~0.40 µ B /atom), an effect that is likely to be originated from the electron delocalization in the crystal structure, as previously discussed. The use of Hubbard corrections could improve the quantitative description of this property [61], but the final model herein utilized for the evaluation of reaction-related processes does not exhibit magnetization, as discussed in section 3.2.2.…”