Efficient recovery of C2+ alkanes from natural gas using porous ZIF-8/iso-hexadecane slurry on laboratory and pilot-scale

Abstract

The efficient recovery of C2+ alkanes from natural gas is of great significance since the C2+ alkanes are the essential petrochemical raw material. This paper presents the novel absorption-adsorption hybrid method to recover the C2+ alkanes components from natural gas using a flowable zeolitic imidazolate framework-8 (ZIF-8)/iso-hexadecane slurry. The ZIF-8 particles have an excellent dispersion in the iso-hexadecane solvent. The sorption capacity for C2H6 and C3H8 in the slurry is significantly higher than that for CH4. Moreover, in competitive adsorption, the slurry showed a significant advantage for C2H6 and C3H8 over CH4. In the experiments of recovering C2+ alkanes from natural gas, the recovery ratio can reach a staggering 91.59%. Besides, in the regeneration tests, 97.79% of the sorption capacity for C2H6 can be recovered by vacuuming without temperature swings, and the characteristic structure of the recycled ZIF-8 remains intact. More encouragingly, a continuous pilot separation plant was established, and the test results show that the recovery ratio for C2+ alkanes can reach 86.75%. The excellent selective recovery performance is comparable to the mature cryogenic separation process. To our knowledge, this is the first time to apply metal–organic frameworks (MOFs) to separate natural gas on pilot-scale. This work has thus furthered the industrial application of MOFs in gas separation.