Application of Zr-Cluster-Based MOFs for the Adsorptive Removal of Aliphatic Aldehydes (C₁ to C₅) from an Industrial Solvent

Abstract

Metal-organic frameworks (MOFs) are recognized as advanced sorbents for the effective removal and recovery of various hazardous pollutants in liquid and gaseous environments. In this research, the potential applicability of two Zr-based MOFs (UiO-66 (U6) and its amine counterpart UiO-66-NH2 (U6N)) was investigated relative to activated carbon (AC, tested as a reference adsorbent) for the purification of industrial organic solvents (e.g., methanol) from six different carbonyl impurities (CCs (C1 to C5): formaldehyde (FA, CH2O), acetaldehyde (AA, CH3CHO), propionaldehyde (PA, C3H6O), butyraldehyde (BA, C4H8O), isovaleraldehyde (IA, C5H10O), and valeraldehyde (VA, C5H10O)). In the sorptive removal of these CCs (both individually and in binary mixtures with FA), U6N showed higher efficacy in capturing all of the target CCs than U6 and AC. The adsorption selectivity of U6N toward single CC compounds was in the order of PA (165.1 mg g–1) > BA (158.9 mg g–1) > IA (154 mg g–1) > AA (136 mg g–1) > VA (131.5 mg g–1) > FA (120 mg g–1). In all binary mixtures, U6N selectively captured FA over the heavier CCs (C2–C5) by 1.5–3.3 times due to the steric hindrance of the C2–C5 aliphatic tails in the pore diffusion mechanism. The preferential adsorption of FA onto U6N can also be accounted for by the contribution of chemical bonding (Schiff base interaction) between the −NH2 groups in U6N and the CO functionalities (aldehyde molecules) and physisorption, as confirmed by density functional theory (DFT) calculations. Theoretical DFT simulations also revealed that the competition between aldehyde molecules for Brønsted acidic sites (μ3-OH of Zr-clusters) created minor distortions in the U6/U6N frameworks.

Analysis of Sequential Adsorption–Oxidation of VOCs on Atomic Layer-Deposited PtNi/ZrO2–SiO2 Dual-Function Materials

“…The blank run was included therein to show the hydrodynamics of benzene in the empty column. At first glance, the trends observed herein could be linked to the textural and surface qualities of the materials as well as to the bed porosity andweight, and inlet conditions . However, as the dynamic experiments were investigated at the same inlet conditions and bed weight with similar bed porosity, it was conclusive that material properties are the dominant factors of the characteristic times.…”

“…At first glance, the trends observed herein could be linked to the textural and surface qualities of the materials as well as to the bed porosity andweight, and inlet conditions. 27 However, as the dynamic experiments were investigated at the same inlet conditions and bed weight with similar bed porosity, it was conclusive that material properties are the dominant factors of the characteristic times. Moreover, it is conclusive that the equilibrium adsorption uptakes and the dynamic adsorption uptakes and characteristic times are all explainable based on the same rationale.…”

Benzene Oxidation in Air by an Amine-Functionalized Metal–Organic Framework-Derived Carbon- and Nitrogen-Loaded Zirconium Dioxide-Supported Platinum Catalyst

“…The TGA profiles of both the MOFs and Pt/UiO-66-NH 2 catalysts displayed three prominent weight loss events: (i) physisorbed moisture removal in the RT-119 °C range, (ii) vaporization of the solvent molecules from the MOF structure along with dehydroxylation of the Zr oxo-clusters in the 119–572 °C range, and (iii) structural decomposition beyond 572 °C (Figure c). The superior UiO-66-NH 2 thermal stability over UiO-66 aligns with previous reports , (Figure c). Also, superior thermal stabilities were observed for the Pt/UiO-66-NH 2 catalysts in comparison to the parent MOF (Figure c).…”

Highly Efficient Electrocatalytic Upgrade of n‐Valeraldehyde to Octane over Au SACs–NiMn2O4 Spinel Synergetic Composites

“…[ 1–4 ] Depending on the level of exposure, aldehydes can cause severe headaches, fatigue, nausea, dizziness, and vomiting. [ 5–8 ] In addition, aldehydes involve in photochemical reactions in the atmosphere, which contribute to haze pollution, photochemical smog, and ozone layer destruction. [ 9–11 ] As an important aldehyde, n ‐valeraldehyde is a significant intermediate in organic synthesis and raw materials of spices, which is widely applied in organic synthesis fields.…”