Two Trinuclear-Cluster-Based MOFs with High-Density N Sites for One-Step Natural Gas Purification and MTO Product Separation

Metal–organic frameworks exhibit high adsorption and separation capabilities in the one-step separation of natural gas mixtures and purifying MTO products. In this work, JLU-MOF191 [Ni(II) 2 Ni(III)(OH)(PDDA) 3 ]·5.5DMF·2H 2 O and JLU-MOF192 [Co 3 (OH)(PDDA) 3 ]·[(CH 3 ) 2 NH 2 ]·4DMA·3H 2 O were successfully synthesized. JLU-MOF192-Li was obtained through Li + exchange, which involved replacing (CH 3 ) 2 NH 2 + inside the anion framework of JLU-MOF192 by Li + . Both MOFs possess permanent pores, excellent thermal stability, and notable high BET surface areas. The nitrogen-containing heterocyclic carboxylic acid ligand H 2 PDDA provides a large number of N-binding sites inside the channels, which increases the C–H···N interactions between the frameworks and the gases. JLU-MOF191 and JLU-MOF192-Li exhibit high adsorption capacities and Q st for C 3 H 8, C 3 H 6, and C 2 H 6, which endow them with the ability to purify natural gas and MTO products. By changing the metal nodes, JLU-MOF192-Li exhibits higher adsorption and separation capabilities than JLU-MOF191 . The DFT theoretical calculation confirmed that JLU-MOF192-Li exhibits a higher adsorption for C 3 H 8, C 3 H 6, and C 2 H 6 compared to C 2 H 4 and CH 4 . The column penetration experiment demonstrated that JLU-MOF192-Li could respectively obtain methane (purity: 99.9%) and C 2 H 4 (purity: 99.9%) from the two mixtures of C 3 H 8 /C 2 H 6 /CH 4 and C 3 H 6 /C 2 H 4 . The excellent adsorption and separation performances of JLU-MOF192-Li for natural gas and MTO products make it a potential material for industrial applications.