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Graphical abstract Highlights • A HNO 3 assisted MIL-101(Cr) was successfully synthesized. • Higher surface area (3841 m2/g) and pore volume (1.72 cm3/g) were obtained. • MIL-101-HNO 3 exhibited higher H 2 S and CO 2 uptake than MIL-101-HF. • The CO 2 /CH 4 , H 2 S/CH 4 and CO 2 /N 2 selectivies of MIL-101-HNO 3 were higher than those of MIL-101-HF. Abstract Despite worldwide attention toward MIL-101(Cr) as a superior adsorbent during past decade, it is still failed to be commercialized. The main barrier can be addressed to the poisonous and expensive synthesis procedure of MIL-101(Cr). In this study, nitric acid (HNO 3) was introduced as a premier, inexpensive and non-poisonous substitute for typical hydrofluoric acid (HF) in the hydrothermal synthesis of MIL-101(Cr). A series of MIL-101-HNO 3 nanoadsorbents, with different amounts of HNO 3 , were synthesized and characterized by different techniques. For the first time, the H 2 S, CO 2 , CH 4 , and N 2 isotherms on the MIL-101-HNO 3 samples were measured in a wide pressure region (1–35 bar) and different temperatures (273, 283, and 293 K) using an in-house made volumetric setup. The results indicated that the MIL-101-HNO 3 -1 possessed the maximum surface area (3841 m2/g), pore volume (1.72 cm3/g), and as a consequence, the highest H 2 S (8.80 mmol/g at 1 bar and 27.16 mmol/g at 35 bar) and CO 2 uptake (5.86 mmol/g at 1 bar and 21.98 mmol/g at 35 bar) among all synthesized samples. More importantly, ideal adsorbed solution theory (IAST) indicated that H 2 S/CH 4 , CO 2 /CH 4, and CO 2 /N 2 adsorption selectivity elevated up to 166.9%, 21.8%, and 13.6% at 1 bar compared to the conventional MIL-101-HF-1. These advantageous were all ascribed to the additional open Cr3+ metal sites and more electrostatic adsorptive behavior of MIL-101-HNO 3 -1. The impressive preferential gas adsorption, along with excellent cyclic performance, thermal and water stability, made the MIL-101-HNO 3 -1 a promising replacement for hazardous MIL-101-HF-1 and other commercial adsorbents. [ABSTRACT FROM AUTHOR] |
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