A Metal-Organic Framework with Suitable Pore Size and Specific Functional Sites for the Removal of Trace Propyne from Propylene.

Abstract

Separation of propyne/propylene (C3 H4 /C3 H6 ) is more difficult and challenging than that of acetylene/ethylene (C2 H2 /C2 H4 ) because of their closer molecular sizes. A comprehensive screening of a series of metal-organic frameworks with broad types of structures, pore sizes, and functionalities was carried out. UTSA-200 was identified as the best separating material for the removal of trace C3 H4 from C3 H4 /C3 H6 mixtures. Gas sorption isotherms reveal that UTSA-200 exhibits by far the highest C3 H4 adsorption capacity (95 cm3 cm-3 at 0.01 bar and 298 K) and record C3 H4 /C3 H6 selectivity, which was mainly attributed to the suitable dynamic pore size to efficiently block the larger C3 H6 molecule whilst the strong binding sites and pore flexibility capture smaller C3 H4 . This material thus provides record purification capacity for the removal of C3 H4 from a 1:99 (or 0.1:99.9, v/v) C3 H4 /C3 H6 mixture to produce 99.9999 % pure C3 H6 with a productivity of 62.0 (or 142.8) mmol g-1 .