Synthesis of UiO-66 Using Solvothermal Method at High Temperature

UiO-66 solids have been synthesized using solvothermal method in which reaction mixtures of zirconium tetrachloride (ZrCl4) and 1,4-benzenedicarboxylic acid (BDC) in N-N'-dimethylformamide (DMF) were heated at 140 °C for 6, 12, 24, 36, 48, 72 and 144 hours, respectively. The weight of reaction products, in the form white powder, increased with the increase in heating time up to 72 hours, then decreased. Characterization results using XRD showed that the diffractogram of the solid obtained at heating time of 6 h had the same pattern to that of reported UiO-66, characterized by a main peak with a high intensity at 2θ of 7.3°, as well as other characteristic peaks with lower intensity at 2θ of 8.4°; 25.6° and 30.6°. The longer the heating time (12 and 24 h), the lower the intensity of the main peak. When the reaction mixtures were heated for 36 h or longer, the obtained solid diffractograms showed that the main peak intensity at 2θ of 7.3° was lower than the second peak, and new peaks appeared at 2θ of 13.8°; 15.8° and 17.5°. SEM micrographs showed that the solid synthesized for 6 h was in the form of clusters of square morphology, whereas solids synthesized for 72 h showed needle-like surface morphology