Role of Structural Defects in the Adsorption and Separation of C3 Hydrocarbons in Zr-Fumarate-MOF (MOF-801)

Abstract

An effective separation of propylene/propane mixtures is one of the most important processes in the petrochemical industry. Incidentally this separation is challenging due to the extensive similarities between both gases in terms of physicochemical properties such as, but not only limited to, boiling point, kinetic diameter and molecular weight. A drive to switch to less energy consuming processes, like adsorption or membrane separation, has highlighted several microporous metal organic frameworks as promising materials. In this work, we present a combined numerical and experimental investigation on propane and propylene adsorption in Zr-fumarate-MOF (also known as MOF-801), a small pore isoreticular analogue of UiO-66. Here, we demonstrate how the presence of structural defects can completely change the sorptive properties and separation performance of the Zr-fumarate-MOF, with enhanced capacity and gas diffusion rates for C3-sized hydrocarbons at the cost of kinetic selectivity. Extensive GCMC simulations performed on mixed defective supercells show that a percentage of missing cluster defects of around 1/8 th can best account for the experimental results. Furthermore, analysis of low-frequency phonon spectra is used to explain gaseous diffusion in the original pristine material. A slight preference for propane over propylene is highlighted in the defective sample, and confirmed through column breakthrough experiments, suggesting the potential applicability of the Zr-fumarate-MOF in this challenging separation. File list (3) download file view on ChemRxiv manuscript.pdf (3.98 MiB) download file view on ChemRxiv manuscript-SI.pdf (3.63 MiB) download file view on ChemRxiv structures.zip (60.21 KiB)

Metal‐Organic Framework Materials for Light Hydrocarbon Separation

“…Paul et al reported that MOF-801 containing defects could selectively adsorb C 3 H 8 when separating C 3 H 6 /C 3 H 8 mixtures, and at the same time increase the adsorption capacity and diffusion rate. [38] This work proves that the selectivity of MOF materials for C 3 H 6 /C 3 H 8 separation can be controlled by MOF defect chemistry, and opens up a new path for the separation of C 3 H 6 / C 3 H 8 mixtures by MOF materials.…”

One‐Step Room‐Temperature Synthesis of Metal(IV) Carboxylate Metal—Organic Frameworks

“…N 2 adsorption‐desorption isotherms at 77 K (Figure 2 d and Table 1) evidenced that these materials are highly porous, with Brunauer‐Emmett‐Teller (BET) surface area of 1035(±5) m 2 g −1 (MOF‐801(Zr)), 735(±6) m 2 g −1 (MOF‐801(Hf)) and 780(±5) m 2 g −1 (MOF‐801(Ce)). These values are slightly larger than those for the pristine MOF‐801(Zr) (680 m 2 g −1 ), which suggests that these MOFs present a significant amount of defects, as reported previously using other synthesis conditions [18] . In order to determine the defect nature (missing nodes or linkers), FT‐IR analysis was carried out (see Figure S1 in the Supporting Information).…”

The Role of Defects in Metal–Organic Frameworks for Nitrogen Reduction Reaction: When Defects Switch to Features

“…The resulting structure showed defects in the structure which have been confirmed by single‐crystal XRD. [ 88 ] Afterward, many research works have reported the synthesis of defects in MOFs by using the typical technique but with different monocarboxylic modulators such as acetic acid (AA), [ 93–95 ] formic acid (FA), [ 96,97 ] difluoro acetic acid (DFA), [ 98 ] trifluoroacetic acid (TFA), [ 99 ] and others. [ 100,101 ]…”