Thiadiazole‐Linked Covalent Organic Frameworks for Efficient Separation of Propylene

Comprehensive Summary The construction of functional and robust covalent organic frameworks (COFs) for gas separation, particularly for the efficient removal of CO 2 from propylene (C 3 H 6 ), is both significant and challenging. Herein, thiadiazole‐linked COFs were reported by postsynthetic modification (PSM) of hydrazone‐linked COFs with Lawesson's reagent (LR). The as‐prepared thiadiazole‐linked COFs not only retain porosity and crystallinity but also enhance their chemical stability. Furthermore, both thiadiazole‐linked COFs demonstrate excellent C 3 H 6 adsorption capacity. Notably, TDA‐Ta‐ODH‐COF exhibits higher C 3 H 6 adsorption capacity, which can separate C 3 H 6 from the C 3 H 6 /CO 2 mixture. Dynamic separation results at 298 K and 1 bar indicate that CO 2 first breaks through the bed at 80 min/g due to the higher adsorption affinity of C 3 H 6 . C 3 H 6 is not detected until 100 min/g. Consequently, this process yields a polymer‐grade C 3 H 6 output of 2.01 mmol/g. In addition, TDA‐Ta‐ODH‐COF also has the potential to separate polymer‐grade C 3 H 6 from a ternary mixture of C 3 H 6 /CH 4 /CO 2 (1/1/1). The observed adsorption disparity originates from the abundant heteroatomic sites (N, O, S) in the thiadiazole‐linked COFs, which exhibit distinct adsorption affinities for C 3 H 6 , CH 4 , and CO 2 . A suitable isosteric heat of adsorption ( Q st ) provides sufficient driving force for selective capture while facilitating low‐cost and efficient regeneration. This work presents a facile protocol for fabricating stable and functional COFs, providing references for gas adsorption and separation applications.