Efficient purification of ethene by an ethane-trapping metal-organic framework

Abstract

Separating ethene (C2H4) from ethane (C2H6) is of paramount importance and difficulty. Here we show that C2H4 can be efficiently purified by trapping the inert C2H6 in a judiciously designed metal-organic framework. Under ambient conditions, passing a typical cracked gas mixture (15:1 C2H4/C2H6) through 1 litre of this C2H6 selective adsorbent directly produces 56 litres of C2H4 with 99.95%+ purity (required by the C2H4 polymerization reactor) at the outlet, with a single breakthrough operation, while other C2H6 selective materials can only produce ca. ⩽ litre, and conventional C2H4 selective adsorbents require at least four adsorption–desorption cycles to achieve the same C2H4 purity. Single-crystal X-ray diffraction and computational simulation studies showed that the exceptional C2H6 selectivity arises from the proper positioning of multiple electronegative and electropositive functional groups on the ultramicroporous pore surface, which form multiple C–H···N hydrogen bonds with C2H6 instead of the more polar competitor C2H4.

A highly stable metal‐organic framework with optimum aperture size for CO2 capture

“…Analyses of breakthrough runs taking pressure drop into consideration have been reported in zeolite and activated carbon materials, [59][60][61][62][63] but not in MOF adsorbents yet. 51,[64][65][66] We thus take the pressure drop (in normal cases, P in > P out ) into consideration and calculate the mean residence time by duly accounting for the changes in exit flow rate (see Eq. 1, exit flow rate is not equal to the inlet flow rate), to precisely determine the CO 2 capture performance of MOFs under working processes.…”

Imparting amphiphobicity on single-crystalline porous materials

“…As an emerging class of porous materials with high single crystallinity, metal-organic frameworks (MOFs)161718, which feature amenability to design, high surface areas, tunable pore sizes and tailorable functionality, have recently been extensively investigated for applications in gas storage1920, separation2122, carbon capture2324, catalysis25262728, sensing2930 and so on (refs 31, 32, 33, 34). However, an issue for their wide applications in practice includes the performance under a variety of environments (for example, stability in humid conditions, interferences by organic vapours in the atmosphere35363738), which necessitate the sophisticated control of the surface wettability of MOFs.…”

Moisture stability of ethane‐selective Ni(II), Fe(III), Zr(IV)‐based metal–organic frameworks

“…Among different temperatures, the adsorption uptakes of ethane always exceed those of ethylene, reflecting ethane‐selective adsorption behavior of Zr‐bptc. At ambient pressure, ethane and ethylene uptakes in Zr‐bptc are 3.72 and 3.50 mmol/g at 288 K, 3.26 and 3.08 mmol/g at 298 K, 2.74 and 2.54 mmol/g at 308 K. The ethane uptake of Zr‐bptc (3.26 mmol/g) at 298 K and 100 kPa is superior to many reported ethane‐selective adsorbents (Table S3), such as activated carbon (2.52 mmol/g), ZIF‐8 (2.50 mmol/g), ZIF‐69 (2.20 mmol/g), ZIF‐4 (2.30 mmol/g), MAF‐49 (1.56 mmol/g), UiO‐66 (2.28 mmol/g) (Figure S11), Cu(ina) 2 (1.99 mmol/g), Cu(Qc) 2 (1.85 mmol/g), and Fe 2 (O 2 )(dobdc) (3.03 mmol/g), but the ethane uptake of Zr‐bptc is inferior to PCN‐245 (3.27 mmol/g) (Figure S12), IRMOF‐8 (4.00 mmol/g), and Ni(bdc)(ted) 0.5 (5.0 mmol/g) (Figure S13). …”