in Wiley Online Library (wileyonlinelibrary.com) Sulfur oxides (SO 2 ) and nitrogen oxides (NO x ) are principal pollutants in the atmosphere due to their harmful impact on human health and environment. We use molecular simulations to study different adsorbents to remove SO 2 and NO x from flue gases. Twelve representative porous materials were selected as possible candidates, including metal-organic frameworks, zeolitic imidazolate frameworks, and all-silica zeolites. Grand canonical Monte Carlo simulations were performed to predict the (mixture) adsorption isotherms to evaluate these selected materials. Both Cu-BTC and MIL-47 were identified to perform best for the removal of SO 2 from the flue gases mixture. For the removal of NO x , Cu-BTC was shown to be the best adsorbent. Additionally, concerning the simultaneous removal of SO 2 , NO x , and CO 2 , Mg-MOF-74 gave the best performance. The results and insights obtained may be helpful to the adsorbents selection in the separation of SO 2 and NO x and carbon capture.

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Effectively separating CO2 from the natural gas, which is one of alternative “friendly” fuels, is a very important issue. A hybrid material CNT@Cu3(BTC)2 has been prepared to separate CO2 from the CO2/CH4 mixture. For comparison of separation efficiency, a series of representative metal–organic frameworks (MOF-177, UMCM-1, ZIF-8, MIL-53 (Al), and Cu3(BTC)2) have also been synthesized by the solvothermal method. Adsorption isotherms of CO2 and CH4 pure gases are measured by Hiden Isochema Intelligent Gravimetric Analyzer (IGA-003). The dual-site Langmuir–Freundlich (DSLF)-based ideal adsorption solution theory (IAST) is used to predict adsorption of each component in the CO2/CH4 mixture. The IAST-predicted results show that the hybrid material CNT@Cu3(BTC)2 exhibits the greatest selectivity among the six materials, and its selectivity keeps in the range of 5.5 to 7.0 for equimolar CO2/CH4 mixture at 1 < p < 20 bar, which is higher than activated carbons. Moreover, the selectivity of CNT@Cu3(BTC)2 for the CO2/CH4 mixture keeps almost no change with the composition of CH4, which is one of the excellent properties as a promising separation material. In short, this hybrid material CNT@Cu3(BTC)2 shows great potential in separation and purification of CO2 from various CO2/CH4 mixtures by adsorptive processes in important industrial systems.

The adsorption of pure N 2 /H 2 /CH 4 /CO 2 along with the adsorption and separation of mixtures thereof in two metal organic frameworks (MOFs) of UMCM-1 and UMCM-2 have been extensively studied using a hybrid method of computer simulation and adsorption theory. It is found that the excess adsorption isotherms from grand canonical Monte Carlo (GCMC) simulations basically agree with the available experimental data of pure gases, except for H 2 adsorption in UMCM-1 at 298 K. Moreover, the GCMC results show that both MOF materials exhibit an excellent storage capacity for pure CH 4 and CO 2 at room temperature. The excess uptakes of CH 4 by UMCM-1 and UMCM-2 for at 5000 kPa are 12.53 and 15.06 mmol g À1 , while those of CO 2 at 4500 kPa are 30.13 and 36.04 mmol g À1 , respectively, which approaches and even exceeds the 30.82 mmol g À1 of MOF-177. In addition, dual-site Langmuir-Freundlich (DSLF)-based ideal adsorption solution theory (IAST) is also used to correlate the simulated adsorption isotherms of pure gases and further predict the separation of equimolar mixtures. IAST shows a good agreement with the GCMC results in most cases studied here. The selectivities of both MOF materials in CH 4 /H 2 and CH 4 /N 2 are insensitive to the pressure. The selectivities of both MOF materials for CH 4 /H 2 are almost the same having a value of 4, while they are 2 for CH 4 /N 2 . By contrast, the selectivities for CO 2 /H 2 , CO 2 /N 2 and CO 2 /CH 4 apparently rely on the pressure, showing 16.4 and 26.9, 5.4 and 7.8, and 2.9 and 4.7 at 4000 kPa for UMCM-1 and UMCM-2, respectively. Compared with other MOFs materials, their separation ability is not prominent, but they are suitable for gas storage.