Fine-Tuning Pore Dimension in Hybrid Ultramicroporous Materials Boosting Simultaneous Trapping of Trace Alkynes from Alkenes

摘要

Removing trace amounts of alkynes from alkenes is one of the most critical and challenging steps to produce high-purity alkenes, the fundamental raw materials in petrochemical industry. Selective hydrogenation using noble metal catalysts under harsh conditions can convert trace alkynes to alkenes, but suffers from limited selectivity, over-hydrogenation, and energy-intensive consumption. Herein, the simultaneously adsorptive removal of trace propyne (C_3H_4) and acetylene (C_2H_2) from quaternary C_2H_2/C_2H_4/C_3H_4/ C_3H_6 mixture is reported for the first time using an anion-pillared hybrid ultramicroporous material ZU-16-Co (or TIFSIX-3-Co) by finely tuning the pore dimensions and introducing different binding sites to match the shape of alkynes. ZU-16-Co with contracted aperture size and judiciously extended cell dimension simultaneously exhibits superior trapping capacity for propyne under low concentration (2.45 mmol g~(-1) at 5000 ppm) and surprisingly high C_2H_2 uptake (4.18 and 1.4 mmol g~(-1) at 1.0 and 0.01 bar, respectively) through synergistic host-guest and guest-guest interactions. Importantly, the ability of ZU-16-Co to capture trace alkynes (C_2H_2 and C_3H_4) in one step is confirmed by breakthrough experiments for quaternary C_3H_4/C_2H_2/C_3H_6/C_2H_4 mixtures, presenting ZU-16-Co as a promising material for alkyne trapping.