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)2Ni(III)(OH)(PDDA)3·5.5DMF·2H2O and JLU-MOF192 Co3(OH)(PDDA)3·(CH3)2NH2·4DMA·3H2O were successfully synthesized. JLU-MOF192-Li was obtained through Li+ exchange, which involved replacing (CH3)2NH2+ 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 H2PDDA 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 Qst for C3H8, C3H6, and C2H6, 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 C3H8, C3H6, and C2H6 compared to C2H4 and CH4. The column penetration experiment demonstrated that JLU-MOF192-Li could respectively obtain methane (purity: 99.9%) and C2H4 (purity: 99.9%) from the two mixtures of C3H8/C2H6/CH4 and C3H6/C2H4. The excellent adsorption and separation performances of JLU-MOF192-Li for natural gas and MTO products make it a potential material for industrial applications.
Zhang et al. (Fri,) studied this question.