A highly stable metal‐organic framework with optimum aperture size for CO₂ capture

Abstract

We herein report an optimal modulated hydrothermal (MHT) synthesis of a highly stable zirconium metal‐organic framework (MOF) with an optimum aperture size of 3.93 Å that is favorable for CO2 adsorption. It exhibits excellent CO2 uptake capacities of 2.50 and 5.63 mmol g−1 under 0.15 and 1 bar at 298 K, respectively, which are among the highest of all the pristine water‐stable MOFs reported so far. In addition, we have designed a lab‐scale breakthrough set‐up to study its CO2 capture performance under both dry and wet conditions. The velocity at the exit of breakthrough column for mass balance accuracy is carefully measured using argon with a fixed flow rate as the internal reference. Other factors that may affect the breakthrough dynamics, such as pressure drop and its impact on the roll‐up of the weaker component have been studied in details. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4103–4114, 2017

CO2 Capture in Metal–Organic Framework Adsorbents: An Engineering Perspective

“…[55,[63][64][65][66] Hu et al have presented an example of breakthrough setup for gas separation considering those variables (Figure 4). [67] As shown in the scheme, the outlet gas composition is monitored by mass spectrometry. Dry MOF powder is packed into a stainless-steel column.…”

“…Dry MOF powder is packed into a stainless-steel column. [67] The packed column is heated under a constant He flow to fully activate the sample. Before experiments, a binary mixture of CO 2 /N 2 (15/85) with a flow rate of 2.5 ± 0.1 cc min −1 is introduced through the by-pass line with a resistance (controlled by a needle valve) comparable to the pressure drop to calibrate the system dead volume.…”

“…Similarly, using extended DSL model can predict ternary CO 2 isotherm data by assuming a constant 80% RH (0.025% molar ratio) in the wet flue gas by Equation (22) Reproduced with permission. [67] Copyright 2017, Wiley.…”

“…For postcombustion CO 2 capture, Mg-MOF-74 owns the highest binary CO 2 uptake capacity of 5.87 mmol g −1 at 298 K (Figure 8), [64] which is much higher than that of HKUST-1 (1.09 mmol g −1 , ≈1.1 bar) mainly due to the presence of unsaturated Mg sites. [67] By doping with amines, Mg 2 (dobdc)(N 2 H 4 ) 1.8 has a binary CO 2 uptake capacity of 3.52 mmol g −1 at 313 K, [65] so as dmpn-Mg 2 (dobpdc) of 2.7 mmol g −1 at 313 K [155] and mmen-Mg 2 (dobpdc) of 2.52 mmol g −1 at 313 K. [148] By tuning the aperture size, SIFSIX-3-Zn shows a high binary CO 2 uptake capacity of 2.37 mmol g −1 at 313 K (10/90 CO 2 /N 2 mixture). [140] Another example is opt-UiO-66(Zr)-(OH) 2 (2.52 mmol g −1 , Table 3), with a small aperture size of 3.9 Å.…”

“…[140] Another example is opt-UiO-66(Zr)-(OH) 2 (2.52 mmol g −1 , Table 3), with a small aperture size of 3.9 Å. [67] Adsorption selectivity is another Adv. Sustainable Syst.…”