Synthesis optimization of metal-organic frameworks MIL-125 and its adsorption separation on C8 aromatics measured by pulse test and simulation calculation.

The metal-organic frameworks (MIL-125) were synthesized by the solvothermal method and the experimental parameters of preparation, purification and activation were optimized and the physicochemical properties were characterized. The adsorption capacity of MIL-125 on C 8 aromatics was tested by the intelligent gravimetric analyzer (IGA) and the toluene vapor static adsorption device. The adsorption selectivity was studied by liquid static adsorption equilibrium experiment and large-scale pulse test. The C 8 aromatics adsorption conformation and adsorption heat in MIL-125 was simulated by Materials Studio software. The characterization results show that the synthesized sample has excellent crystallinity, regular morphology with a grain size of about 1 ​μm, surface area of 1315 ​m2/g, micropore volume of 0.601 ​mL/g and a bulk density of 0.45 ​g/mL. Moreover, the vapor static adsorption results show that the synthesized sample has almost three times of adsorption capacity as large as BaX zeolite and the liquid dynamic adsorption results indicate the synthesized sample is preferentially selective to pare-xylene with the alkane desorbent. The simulation results show that the adsorption heat of pare-xylene in the synthesized sample and the binding energy of pare-xylene in the tetrahedral cage are the largest among these four isomers. The optimized synthesis of MIL-125 with tetrahedral and octahedral cages was completed and the relation between experimental parameters and surface properties was illustrated. The adsorption capacity for C8 aromatics is 500 mg/g and the adsorption heat for PX is highest calculated by MS. PX is preferentially adsorbed in tablet MIL-125 with the alkane as the desorbent measured by large-scale pulse test. Image 1 • PX preferential adsorbent with large micropore volume was synthesized • The relationship between synthesis parameters and surface properties is provided • The tablet adsorbent is utilized in a large scale by dynamic liquid pulse device • Adsorption heat and binding energy are calculated to study adsorption selectivity • Liquid and vapor static adsorption are carried out to prove the capacity. [ABSTRACT FROM AUTHOR]