Synthesis of Zinc-Organic Frameworks Nano Adsorbent and their Application for Methane Adsorption

Abstract

In the present work, MOF-5 consisting of Zn 4 O inorganic vertices was hydrothermally synthesized. Three-step activation treatment including preservation in initial solvent, solvent exchange and drying under evacuated condition was performed and it was found that activation is efficient by increasing the methane adsorption capacity of samples. The final product was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM) and pore size distribution (PSD). The corresponding pore size of MOF-5/DEF (sample A) and MOF-5/DMF (sample B) which was determined by nitrogen adsorption at 77 K, were equal to 31.27 Å and 42.65 Ǻ and also BET surface area of samples were 2157 and 1532 m 2 /g, respectively. Methane adsorption equilibrium for both samples was measured in a volumetric adsorption unit and it was found that the adsorbent (A) and (B) in this work have methane adsorption capacity of 18.15 and 11.36 mmol/g at temperature of 298 K and pressure of 36 bar, respectively. Four different models (Langmuir, Unilan, Toth and Sips) were used to correlate the experimental equilibrium data. The root mean square error values demonstrated that the Toth and Sips equation provide better models for correlating adsorption isotherms.