In-Situ Ligand Formation-Driven Preparation of a Heterometallic Metal–Organic Framework for Highly Selective Separation of Light Hydrocarbons and Efficient Mercury Adsorption

Abstract

By means of the in situ ligand formation strategy and hard-soft acid-base (HSAB) theory, two types of independent In(COO)4 and Cu6S6 clusters were rationally embedded into the heterometallic metal-organic framework (HMOF) {[(CH3)2NH2]InCu4L4·xS}n (BUT-52). BUT-52 exhibits a three-dimensional (3D) anionic framework structure and has sulfur decorating the dumbbell-shaped cages with the external edges of 24 and 14 Å by the internal edges. Remarkably, because of the stronger charge-induced interactions between the charged MOF skeleton and the easily polarized C2 hydrocarbons (C2s), BUT-52 was used for C2s over CH4 and shows both high adsorption heats of C2s and selective separation abilities for C2s/CH4. Furthermore, BUT-52 also displays efficient mercury adsorption resulting from the stronger-binding ability beween the sulfur and the mercury and can remove 92% mercury from methanol solution even with the initial concentration as low as 100 mg/L. The results in this work indicate the feasibility of BUT-52 for the separation of light hydrocarbons and efficient adsorption/removal of mercury.

A “Thermodynamically Stable” 2D Nickel Metal–Organic Framework over a Wide pH Range with Scalable Preparation for Efficient C2s over C1 Hydrocarbon Separations

“…In fact, a diversity of microporous MOFs were explored for their diverse gas separations, such as the separations of CO 2 /CH 4 , C 2 H 2 /C 2 H 4 , C 2 H 4 /C 2 H 6 , and C 3 H 6 /C 3 H 8 . Although many such types of hydrocarbon separation based on MOFs are reported, only a few MOFs thus far have been employed for a systematic C 2 /C 1 separation study . Given that C 1 –C 2 hydrocarbons possess kinetic diameters in the range of 3.3 to 4.4 Å, the design and synthesis of MOFs with narrow pores comparable to and/or slightly bigger than their kinetic diameters will be of distinct importance for the separation of these small hydrocarbons .…”

“…Additionally, Fe‐MOF‐74 showed excellent C 2 /C 1 separations under ambient conditions . Although, thus far, there are a handful MOFs that show such systematic C 2 /C 1 separations, their stability in moisture and/or liquid water or over a pH range has not been explored. Thus, the development of thermodynamically stable MOFs is necessary because such separations ultimately need to be performed in the presence of saturated water vapor and acidic gases, as mentioned before.…”

Leveraging Exchange Kinetics for the Synthesis of Atomically Precise Porous Catalysts

“…Using similar HSAB theory concepts, Li et al described a strategy to control metal ion distribution in the synthesis of BUT-52 (BUT = Beijing University of Technology). [69] BUT-52 consists of In(COO) 4 sites and Cu 6 S 6 clusters and is synthesized by combination of Cu + , a soft Lewis acid, and In 3 + , a hard Lewis acid, with a difunctional ligand, 6,6'-dithiodinicotinic acid (Figure 22). This results in a material in which Cu + preferentially complexes the soft Lewis basic thiol group while In 3 + preferentially complexes the hard Lewis basic carboxylate group.…”

Orthogonal Synthesis of Highly Porous Zr-MOFs Assembled from Simple Building Blocks for Oxygen Storage

“…31,32 Yaghi and coworks reported a 2-D titanium−organic framework with imine ligands in situ condensated. 33 Such strategies have demonstrated cyclisation, 34 dehydrogenative or oxidative coupling, 35,36 hydroxylation, 35,37 hydrolysis, [38][39][40] cleavage of the S−S bonds, 41,42 imine condensation, 33,43 cycloaddition of organic nitriles 44,45 and C-C heterocoupling; in the latter case amorphous hybrid porous materials were produced. 46 More recently, diazo coupling, imidizatio and condensation of boronic acids 47 were also reported to be candidates for one pot strategy during the preparation of this manuscript.…”