A Molecular Compound for Highly Selective Purification of Ethylene

Abstract

Purification of C2H4 from an C2H4 /C2H6 mixture is one of the most challenging separation processes, which is achieved mainly through energy‐intensive, cryogenic distillation in industry. Sustainable, non‐distillation methods are highly desired as alternatives. We discovered that the fluorinated bis(pyrazolyl)borate ligand supported copper(I) complex {[(CF3)2Bp]Cu}3 has features very desirable in an olefin–paraffin separation material. It binds ethylene exclusively over ethane generating [(CF3)2Bp]Cu(C2H4). This molecular compound exhibits extremely high and record ideal adsorbed solution theory (IAST) C2H4 /C2H6 gas separation selectivity, affording high purity (>99.5 %) ethylene that can be readily desorbed from separation columns. In‐situ PXRD provides a “live” picture of the reversible conversion between [(CF3)2Bp]Cu(C2H4) and the ethylene‐free sorbent in the solid‐state, driven by the presence or removal of C2H4. Molecular structures of trinuclear {[(CF3)2Bp]Cu}3 and mononuclear [(CF3)2Bp]Cu(C2H4) are also presented.

Binding Interactions in Copper, Silver and Gold π‐Complexes

“… [11b] [HB(3,5‐(CF 3 ) 2 Pz) 3 ]Cu(C 2 H 4 ) ( 2 ) has been utilized in ethylene sensing applications, [12] while the bis(pyrazolyl)borate analog [H 2 B(3,5‐(CF 3 ) 2 Pz) 2 ]Cu is a very effective material for the separation of ethylene from ethane. [13] Furthermore, bis‐ and tris‐(pyrazolyl)borate copper complexes [H 2 B(3,5‐(CF 3 ) 2 Pz) 2 ]CuNCMe and [HB(3,5‐(CF 3 ) 2 Pz) 3 ]CuNCMe are excellent catalysts for the cyclopropenation of alkynes, [4a] while [Ph 2 B(3‐(CF 3 ) 2 Pz) 2 ]Cu(C 2 H 4 ) mediates alkene cyclopropanation chemistry. [14] The copper complexes such as [HB(3,5‐(CH 3 ) 2 Pz) 3 ]Cu(C 2 H 4 ) with non‐fluorinated tris(pyrazolyl)borate ligand (Figure 1 ) supports are also proven to be good catalysts for the cyclopropanation of alkenes, cyclopropenation of alkynes, and aziridination of alkenes.…”

Carbonyl and Isocyanide Complexes of Copper and Silver Supported by Fluorinated Poly(pyridyl)borates

“…As a result, metal complexes of fluorinated ligands in comparison to their nonfluorinated, hydrocarbon counterparts usually display different properties such as relatively high thermal and oxidative stability, volatility, and unique reactivity profiles. − They are also ideal for applications in fluorous-biphase media and supercritical CO 2 . − Fluorinated poly­(pyrazolyl)­borates (which belong to a family known as scorpionates) , such as [HB­(3,5-(CF 3 ) 2 Pz) 3 ] − ( 1 , Pz = pyrazolyl, Figure ) and [H 2 B­(3,5-(CF 3 ) 2 Pz) 2 ] − ( 2 ) are a particularly useful group of ligands as they have facilitated the stabilization of rare species such silver­(I)-acetylene, copper­(I) and silver­(I)-organo azide, and silver­(I)-dimethyl diazomalonate complexes and to probe their chemistry under readily accessible conditions. They are also valuable in applications involving catalysis including those in supercritical CO 2 , − ethylene sensing, to olefin-paraffin separations . For example, fluorinated tris­(pyrazolyl)­borates have been useful in supporting catalytically active and fairly reactive copper complexes, without the ligand itself getting destroyed. , The silver complex [HB­(3,5-(CF 3 ) 2 Pz) 3 ]Ag is an effective mediator for the functionalization of inert C–Cl bonds of halocarbons as well as C–H bonds of saturated hydrocarbons via catalytic carbene insertion chemistry. ,,, The bis­(pyrazolyl)­borate [H 2 B­(3,5-(CF 3 ) 2 Pz) 2 ]Cu serves as an excellent nonporous material for the separation of ethylene from an ethylene/ethane mixture …”

“…They are also valuable in applications involving catalysis including those in supercritical CO 2 , − ethylene sensing, to olefin-paraffin separations . For example, fluorinated tris­(pyrazolyl)­borates have been useful in supporting catalytically active and fairly reactive copper complexes, without the ligand itself getting destroyed. , The silver complex [HB­(3,5-(CF 3 ) 2 Pz) 3 ]Ag is an effective mediator for the functionalization of inert C–Cl bonds of halocarbons as well as C–H bonds of saturated hydrocarbons via catalytic carbene insertion chemistry. ,,, The bis­(pyrazolyl)­borate [H 2 B­(3,5-(CF 3 ) 2 Pz) 2 ]Cu serves as an excellent nonporous material for the separation of ethylene from an ethylene/ethane mixture …”

A Microporous Metal‐Organic Framework with Channels Constructed from Nonpolar Aromatic Rings for the Selective Separation of Ethane/Ethylene Mixtures

“…The use of porous materials for adsorption separation is considered to be an energy‐saving method [5–12] . Among various adsorbents, metal‐organic frameworks (MOFs) materials are prominent because of their large specific surface area and highly adjustable pore structure, particularly for the separation of light hydrocarbons [13–21] .…”

“…The use of porous materials for adsorption separation is considered to be an energy-saving method. [5][6][7][8][9][10][11][12] Among various adsorbents, metal-organic frameworks (MOFs) materials are prominent because of their large specific surface area and highly adjustable pore structure, particularly for the separation of light hydrocarbons. [13][14][15][16][17][18][19][20][21] According to the adsorption preference of MOFs for C 2 H 6 /C 2 H 4 , it is divided into C 2 H 4 -selective MOFs and C 2 H 6 -selective MOFs.…”