Ce(III) Doped Zr-Based MOFs as Excellent NO₂Adsorbents at Ambient Conditions

Abstract

New hybrid cerium modified zirconium based metal-organic frameworks (MOFs) were synthesized. The as-received materials were evaluated as adsorbents of NO2 in either moist or dry conditions. The surface of the initial and exhausted samples was characterized using XRD, SEM-EDX, nitrogen adsorption, thermal analysis, and FTIR. It was found that the addition of Ce(+3) slightly affects the growth of the framework and introduces new features to Zr-MOF. The shapes of the octahedral crystals are changed, and they are interwoven with rod-flake-like sheets. The extent of the interconnection, and thus the extent of the hybrid MOF formation, depends on the Zr to Ce ratio. The alterations in the surface chemistry and texture are reflected in the amount of NO2 adsorbed. The narrow pore channels present in these new materials enhance adsorption in either moist or dry conditions. The amount of NO2 adsorbed on the Ce-doped MOF increases over 25% in dry conditions in comparison with the unmodified MOF. Exposure of Ce-UiO-66 to NO2 results in a development of porosity. Regardless the conditions, the XRD patterns indicate the stability of this new hybrid MOF upon NO2 adsorption. Interactions of NO2 with MOF result in the formation of nitrate and nitrite species associated either with metals or with organic ligands.

A comparative study of manganese–cerium doped metal–organic frameworks prepared via impregnation and in situ methods in the selective catalytic reduction of NO

“…8,9 However, the in situ doped MnCeMOF showed a very low catalytic ability of below 20% in the SCR of NO (Fig. 2).…”

“…MnCeMOF exhibited a higher BET surface area and larger pore volume than the undoped MOF. Based on the Ebrahim's point, 8 Mn-Ce doping may inhibit the complete growth of the MOF and lead to crystal defects, which result in an increase in the pore volume. Moreover, during the synthesis of MnCeMOF, Mn/Ce may become sites of crystal growth.…”

“…The incorporation of various metals ions, such as Mn 2+ , Li + , Na + , and K + into an MOF structure via an in situ doping method has been reported. 6,7 Ebrahim et al 8 reported a feasible way for the in situ doping of Ce in an MOF using Ce as a co-metal precursor in the synthetic process. Due to the redox properties of the in situ doped Ce, the material exhibited a high affinity for nitrogen oxides.…”

Facile synthesis of morphology and size-controlled zirconium metal–organic framework UiO-66: the role of hydrofluoric acid in crystallization

“…Various modulators have been used to tune the size and morphology of UiO-66 crystals. The modulation mechanism of hydrofluoric acid as well as the changes in structure and 5 properties of UiO-66 crystals caused by the introduction of fluorine was also studied. They also synthesized a Zr-based MOF using fumarate (fum) dianions as linkers and formic acid as a modulator.…”

Preparation and Optical Study of Zn(II) Metal Organic Framework Thin Film for Xylene Gas Sensing Application

“…From the FTIR spectra ( Figure 1a), it can be observed that, for the bdc ligand, the stretching vibrations of C═O and symmetric-asymmetric stretching of O-C-O band in the carboxylic acid appeared at 1674 and 1418 cm À1 , respectively, while the peaks that appeared at 892, 724, and 504 cm À1 were assigned to the C-H plane bending vibration of benzene ring. [34][35][36] For the dpNDI ligand, the weak peaks that appeared at 3383 and 3058 cm À1 were represented to N-H stretching bands; the bands detected at 1674 and 1568 cm À1 were also assigned to the stretching vibrations of C═O in the amide present in dpNDI. [37] For the [Zn 2 (bdc) 2 (dpNDI)] n frame works, the N-H stretching band appeared at 3191 cm À1 and shows redshift for about 133 cm À1 , which was compared with pure dpNDI ligand; this may be caused from the conformation of larger conjugated system between bdc and dpNDI ligand.…”