2.1 Materials
Aluminum nitrate nonahydrate (Al(NO3)3·9H2O, 99%) and 1,2,4,5-benzenetetracarboxylic acid (BTEC, 98%) were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. Sodium hydroxide (NaOH, 99%) and methanol (CH3OH, 99%) were provided by Sinopharm Chemical Reagent Co., Ltd. The above reagents were used directly without further purification. The distilled water used in our experiments was prepared in our laboratory.
The synthesis and purification of MIL-120Al were performed according to a previously reported method with some modifications.40 The synthesis process was as follows: Al(NO3)3·9H2O (3.2 g, 8.5 mmol) and BTEC (0.5 g, 2.0 mmol) were added to a 100 mL polytetrafluoroethylene reaction kettle and 20 mL of water added using a pipette. The above mixture was stirred at 298 K for 20 min. NaOH (0.54 g, 13.6 mmol) was added to the resulting mixture and stirring continued at 298 K for 20 min. The resulting mixture was sealed in a stainless-steel shell and placed in an oven. The oven temperature was increased from room temperature to 473 K within 2 h and kept at 473 K for 24 h. The reaction kettle was removed from the oven and allowed to cool naturally to the room temperature. The white powder was collected upon repeated centrifugation and thorough washing with 353 K distilled water and 423 K CH3OH, and the product dried at room temperature.
A large-scale synthesis of MIL-120Al was carried out as follows: Al(NO3)3·9H2O (0.13 kg, 0.34 mol), BTEC (0.02 kg, 0.08 mol), and NaOH (0.02 kg, 0.56 mol) were dissolved in 0.8 L of deionized water. The solution was stirred for 30 min and then placed in a 2 L stainless steel reactor for synthesis at 473 K for 24 h. After cooling down to room temperature, the sample was filtered, washed with H2O/CH3OH (1/1, v/v) solution at 423 K three times, and dried at room temperature. The product was obtained with a yield of ~40–45 g.