An Efficient Co-Based Metal–Organic Framework Nanocrystal (Co-ZIF-67) for Adsorptive Desulfurization of Dibenzothiophene: Impact of the Preparation Approach on Structure Tuning
Mitra Jafarinasab, Azam Akbari, Mohammadreza Omidkhah, Mozaffar Shakeri
Abstract
Metal–organic frameworks (MOFs) have attracted considerable attention for selective deep removal of refractory sulfur compounds from fuels. In this work, cobalt-based MOFs (nanocrystals of Co-ZIF-67) were successfully prepared to find a capable adsorbent for removal of dibenzothiophene (DBT) from fuel. This paper revealed the main importance of preparation conditions in adjusting the surface area and pore structure of Co-ZIF-67 crystals for DBT adsorption purposes. Several methods including XRD, SEM, TEM, FTIR, TGA, BET, BJH, and N2 adsorption–desorption were used for characterization of the prepared adsorbents. Screening the adsorbents demonstrated the proper structure and performance of Co-ZIF-67/M nanocrystals synthesized by methanol at room temperature. A considerable promotion in DBT adsorption ability was further reached through exposing more active centers by surface activation. By employing activated Co-ZIF-67/M-A1 (SBET = 2478.8 m2/g), a maximum adsorption capacity of 550 mg/g was attained at T = 65 °C and Madsorbent/Vfuel = 0.8 mg/mL, with an excellent reusability of the adsorbent in four repeated uses. The endothermic nature of DBT adsorption was verified by the positive influence of temperature. A good fitting of experimental data with Langmuir–Freundlich isotherm expressed a possible combination of monolayer and multilayer adsorption of DBT. The kinetic and mechanism studies were also conducted, and possible adsorption pathways were suggested.