CO₂capture and conversion using Mg-MOF-74 prepared by a sonochemical method

Abstract

Mg-MOF-74 crystals were successfully prepared in 1 h by a sonochemical method (Mg-MOF-74(S)) after triethylamine (TEA) was added as a deprotonating agent. Mg-MOF-74(S) (1640 m 2 g À1 BET surface area) displayed similar textural properties to those of a high-quality MOF sample synthesized in 24 h by the solvothermal method (Mg-MOF-74(C), 1525 m 2 g À1 ). However, mesopores were formed, probably due to the competitive binding of TEA to Mg 2+ ions, and the average particle size of the former (ca. 0.6 mm) was significantly smaller than that of the latter (ca. 14 mm). The H 2 O adsorption capacity was 593 mL g À1 at 298 K for Mg-MOF-74(S), displaying higher hydrophilicity than Zeolite 13X. The adsorption isotherms of Mg-MOF-74(S) for CO 2 showed high adsorption capacity (350 mg g À1 at 298 K) and high isosteric heats of adsorption for CO 2 (42 to 22 kJ mol À1 ). The breakthrough experiment confirmed excellent selectivity to CO 2 over N 2 at ambient conditions (saturation capacity of ca. 179 mg g À1 ). Ten consecutive adsorption-desorption cycles at 298 K established no deterioration of the adsorption capacity, which showed reversible adsorbent regeneration at 323 K under helium flow for a total duration of 1400 min. Mg-MOF-74(S) also demonstrated excellent catalytic performance in cycloaddition of CO 2 to styrene oxide under relatively mild reaction conditions (2.0 MPa, 373 K) with close to 100% selectivity to carbonate, which was confirmed by GC-MS, 1 H-NMR, and FT-IR. Mg-MOF-74(S) could be reused 3 times without losing catalytic activity and with no structural deterioration.

The Potential Applications of Nanoporous Materials for the Adsorption, Separation, and Catalytic Conversion of Carbon Dioxide

“…This research group has also compared the activity of selected MOF systems for the cycloaddition of CO 2 onto styrene oxide and among them, UIO-66-NH 2 MOF was found to be the most active, with 70% conversion in 1 h. [ 138 ] However, the reaction conditions remained at high pressure and temperature with the use of a toxic solvent. There are other examples showing the catalytic activity of MOFs (Ni(salphen)-MOF, [ 139 ] Mg-MOF-74, [ 140 ] ZIF-8 [ 141 ] and MIXMOF-5 [ 142 ] as catalysts for cycloaddition of CO 2 onto an epoxide. Compared with zeolite catalysts, the larger pores of MOF catalysts did promote cycloaddition of CO 2 on larger epoxides, but most of these systems were operated at high pressure (>5 atm) and temperature (100-140 °C), with quarternary ammonium ions as co-catalysts in some cases.…”

Force-Field Development from Electronic Structure Calculations with Periodic Boundary Conditions: Applications to Gaseous Adsorption and Transport in Metal–Organic Frameworks

“…The symbols are the isotherms from the GCMC simulations as predicted by the different models. 35 compared to the UFF isotherm at the lowpressure region. At the higher-pressure region (i.e., P = 0.1−1 kPa); however, both the model B and UFF predict a much higher loading than the experimental measurement.…”

Facile Synthesis of M-MOF-74 (M=Co, Ni, Zn) and its Application as an ElectroCatalyst for Electrochemical CO2 Conversion and H2 Production

“…Among the current MOF materials, MOF-74 is known to exhibit an exceptionally large surface area and higher CO 2 adsorption capacity under atmospheric conditions compared to the other MOFs [31,32]. [33].…”