Efficient separation of C4 olefins using tantalum pentafluor oxide anion-pillared hybrid microporous material

With the increasing demand for synthetic rubber, the purification of 1,3-butadiene (C4H6) is of great industrial significance. Herein, the successful removal of n-butene (n-C4H8) and iso-butene (iso-C4H8) from 1,3-butadiene (C4H6) was realized by synthesizing a novel TaOF52− anion-pillared ultramicroporous material TaOFFIVE-3-Ni (also referred to as ZU-96, TaOFFIVE = TaOF52−, 3 = pyrazine). Single-component adsorption isotherms show that TaOFFIVE-3-Ni can achieve the exclusion of n-C4H8 and iso-C4H8 in the low pressure region (0–30 kPa), and uptake C4H6 with a high capacity of 92.78 cm3·cm−3 (298 K and 100 kPa). The uptake ratio of C4H6/iso-C4H8 on TaOFFIVE-3-Ni was 20.83 (298 K and 100 kPa), which was the highest among the state-of-the-art adsorbents reported so far. With the rotation of anion and pyrazine ring, the pore size changes continuously, which makes smaller-size C4H6 enter the channel while larger-size n-C4H8 and iso-C4H8 are completely blocked. The excellent breakthrough performance of TaOFFIVE-3-Ni shows great potential in industrial separation of C4 olefins. The specific adsorption binding sites within ZU-96 was further revealed through the modeling calculation.