Synthetic Control Method for Crystallite Size of MOF-5

• Published in: Chemical research in Chinese universities Vol. 30; no. 3; pp. 356 - 361
• Main Authors: Han, Pengfei, Yuan, Changfu, Xu, Junyi, Liu, Jin
• Format: Journal Article
• Language: English
• Published: Heidelberg Jilin University and The Editorial Department of Chemical Research in Chinese Universities 01.06.2014; School of Metallurgy and Environment, Central South University, Changsha 410083, P.R.China
• Subjects: Analytical Chemistry; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Inorganic Chemistry; Langmuir; Organic Chemistry; Physical Chemistry; 二甲基甲酰胺; 合成控制; 晶粒尺寸; 溶剂热法; 粉末X射线衍射; 粒度分布; 质量损失; Metal-organic framework-5(MOF-5); Size distribution; Dripping solvothermal method
• ISSN: 1005-9040; 2210-3171
• DOI: 10.1007/s40242-014-3349-y

We reported a dripping solvothermal method for synthesizing metal-organic framework-5（MOF-5）. It started from separately dissolving Zn（NO3）2 and terephthalic acid（H2BDC） in dimethyl formamide（DMF）, and then dripping one solution into the other. Results of SEM, XRD and laser particle size distribution show that regular cubic-shaped and micro-crystallite powder of MOF-5 can be obtained. The d0.5（volume-median-diameter） values are 4.32 μm for particles prepared by dripping Zn（NO3）2 into H2BDC（ZH） and 9.32 μm for those prepared by dripping H2BDC into Zn（NO3）2（HZ）, much smaller than 22,7 μm that of particles prepared by the traditional adding water solvothermal method（L）. The standard deviations of the particle size distributions fitted by the GaussAmp model are 2.49, 4.38 and 15.4 respectively for ZH, HZ and L, further revealing narrower size distributions of particles prepared by the dripping method. In addition, the Langmuir specific surface areas are 923 m^2/g for ZH and 868 m^2/g for HZ. The TGA results present mass losses of 4.18% and 3.62% at 105 ℃, 17.19% and 14.78% at 245 ℃, 39.04% and 34.85% at 600℃ separately for ZH and HZ, which correspond to the removal of H20, DMF and the decomposition of MOF-5. This indicates that MOF-5 has a strong adsorption ability for small molecules. Besides, the mass loss of 48.39%（ZH） and 41.02%（HZ）between 400 ℃ and 600 ℃ are less than the theoretical value of 57.81% for MOF-5 decomposition to ZnO, suggesting that an impure phase with an extra amount of ZnO may exist in the cavities of MOF-5.