Efficient Separation of Acetylene and Carbon Dioxide in a Decorated Zeolite

Abstract

The almost identical molecular sizes and volatilities of acetylene and carbon dioxide make their separation extremely challenging in industry. Reported here is the efficient separation of acetylene and carbon dioxide (v/v=2/1, which is relevant to that in the industrial cracking stream) in faujasite zeolites decorated with atomically‐dispersed copper(II) sites under ambient conditions. In situ neutron powder diffraction and inelastic neutron scattering confirm that the confined copper(II) site displays chemoselective yet reversible binding to acetylene, whereas adsorbed carbon dioxide molecules are stabilized by weak host–guest supramolecular interactions with the framework oxygen centers, thus resulting in the efficient separation of these two gases under flow conditions. A designed adsorption‐purging‐desorption system based upon Cu@FAU is established for the recovery of high purity acetylene (98–99 %) from the mixture of acetylene and carbon dioxide, offering an unprecedented separation factor of 22.2 with an effective dynamic uptake of acetylene of 1.51 mmol g−1 at 298 K.

Efficient C2H2/CO2 Separation in Ultramicroporous Metal–Organic Frameworks with Record C2H2 Storage Density

“…Compared with the C 2 H 2 /C 2 H 4 and C 2 H 2 /CH 4 separation, − C 2 H 2 /CO 2 separation is much more difficult because of their very close molecular size/shape (kinetic diameter of 3.3 Å for both C 2 H 2 and CO 2 ) and physical properties . Over the past few decades, a variety of porous physisorbents, such as zeolites, silicas, and activated carbons, have been exploited to realize this challenging separation but are yet unprosperous. − …”

Preparation of an interpenetrating bimetal metal–organic framework via metal metathesis used for promoting gas adsorption

“…10 The C 2 H 2 uptake value at 298 K and 1 bar was 81.57 cm 3 mmol −1 (88.09 cm 3 g −1 ) for MIL-126(Cr/Sc), which was higher than that of MIL-126(Sc) and comparable to those of most of the top-performing materials reported to date (Table S4 †), such as UTSA-74a (108 cm 3 g −1 ), 47 FeNi-M′MOF (96 cm 3 g −1 ) 48 and Cu@FAU (79.5 cm 3 g −1 ). 49 To explore the affinity between the MOF framework and gas molecules, the isosteric heat of adsorption (Q st ) was calculated using the Clausius-Clapeyron equation (ESI †). Obviously, MIL-126(Cr/Sc) exhibited a higher gas binding energy (40.1, 31.4 and 36.9 kJ mol −1 for CO 2 , N 2 O and C 2 H 2 , respectively) than MIL-126(Sc) (18.4, 15.5 and 26.3 kJ mol −1 for CO 2 , N 2 O and C 2 H 2 , respectively), indicating that MIL-126(Cr/Sc) had a stronger affinity than MIL-126(Sc) (Fig.…”

One-step ethylene production from a four-component gas mixture by a single physisorbent

“…Since the quadrupole moment of C 2 H 4 (1.5 × 10 −26 esu cm 2 ) also lies between CO 2 (4.3 × 10 −26 cm 2 ), C 2 H 2 (7.2 × 10 −26 esu cm 2 ) and C 2 H 6 (0.65 × 10 −26 esu cm 2 ) 8 , one-step purification of C 2 H 4 by thermodynamics (selective binding) has thus far proven to be elusive. Metal organic materials (MOMs) 9 , also called metal-organic frameworks (MOFs) 10 , 11 or porous coordination polymers (PCPs) 12 , have promising applications as C2 and CO 2 selective physisorbents for several binary mixtures, including C 2 H 2 /C 2 H 4 , C 2 H 4 /C 2 H 6 , C 2 H 6 /C 2 H 4 , C 2 H 2 /CO 2 and CO 2 /C 2 H 2 13 – 34 There are also examples of physisorbents that are effective against ternary C2 and C2-CO 2 mixtures such as C 2 H 2 /C 2 H 4 /C 2 H 6 and C 2 H 2 /C 2 H 4 /CO 2 35 – 41 . Certain classes of physisorbents are amenable to systematic fine-tuning of pore chemistry and pore size 42 , 43 and have resulted in “second generation” sorbents with > one order of magnitude improvement in performance 18 , 24 , 44 , 45 , 47 .…”