Substituent-Induced Electron-Transfer Strategy for Selective Adsorption of N2 in MIL-101(Cr)-X Metal-Organic Frameworks.

N2 removal is of great significance in high-purity O2 production and natural gas purification. Here, we present a substituent-induced electron-transfer strategy for improving N2 capture performance by controlling the Lewis acidity of Cr(III) metal unsaturated sites in Cr-based metal-organic frameworks. With the enhancement of the electron-withdrawing ability of the modified group on terephthalic acid (-NO2 > -CH3), the N2 adsorption ability of MIL-101(Cr)-X was improved significantly. For MIL-101(Cr)-NO2, the adsorption enthalpy of N2 at zero coverage was 30.01 kJ/mol, which was much larger than that of MIL-101(Cr)-CH3 (14.31 kJ/mol). In situ infrared spectroscopy studies, Bader charges, and density functional theory calculations showed that the presence of -NO2 could enhance the Lewis acidity of Cr(III) metal unsaturated sites, which resulted in a strong interaction affinity for N2. The adsorption isotherms indicated that MIL-101(Cr)-NO2 had an excellent N2/O2 (79/21, v/v) selectivity of up to 10.8 and a good N2/CH4 separation performance (SN2/CH4 = 2.8, 298 K, 1 bar). Breakthrough curves showed that MIL-101(Cr)-NO2 had great potential for the efficient separation of N2/O2 and N2/CH4.

[1]  Hongtao Yu,et al.  Electronic modulation of iron-bearing heterogeneous catalysts to accelerate Fe(III)/Fe(II) redox cycle for highly efficient Fenton-like catalysis , 2020 .

[2]  Alexander C. Forse,et al.  Selective nitrogen adsorption via backbonding in a metal–organic framework with exposed vanadium sites , 2020, Nature Materials.

[3]  S. Deng,et al.  Evaluation and optimization of VPSA processes with nanostructured zeolite NaX for post-combustion CO2 capture , 2019, Chemical Engineering Journal.

[4]  C. Cramer,et al.  Metal–Organic Frameworks with Metal–Catecholates for O2/N2 Separation , 2019, The Journal of Physical Chemistry C.

[5]  R. Krishna,et al.  Ethane/ethylene separation in a metal-organic framework with iron-peroxo sites , 2018, Science.

[6]  Donghui Zhang,et al.  Experiment and simulation study of a dual-reflux pressure swing adsorption process for separating N2/O2 , 2017 .

[7]  Y. Hwang,et al.  N2 Capture Performances of the Hybrid Porous MIL-101(Cr): From Prediction toward Experimental Testing , 2017 .

[8]  Xiao-Ming Chen,et al.  Controlling guest conformation for efficient purification of butadiene , 2017, Science.

[9]  Diego A. Gómez-Gualdrón,et al.  Bottom-up construction of a superstructure in a porous uranium-organic crystal , 2017, Science.

[10]  J. Lee,et al.  Selective nitrogen capture by porous hybrid materials containing accessible transition metal ion sites. , 2017, Nature materials.

[11]  P. Voort,et al.  Synthesis, characterization and sorption properties of functionalized Cr-MIL-101-X (X=–F, –Cl, –Br, –CH3, –C6H4, –F2, –(CH3)2) materials , 2016 .

[12]  Rajamani Krishna,et al.  Pore chemistry and size control in hybrid porous materials for acetylene capture from ethylene , 2016, Science.

[13]  Shengqian Ma,et al.  Applications of metal-organic frameworks featuring multi-functional sites , 2016 .

[14]  R. D. Whitley,et al.  Two-Stage Vacuum Pressure Swing Adsorption Using AgLiLSX Zeolite for Producing 99.5+% Oxygen from Air , 2016 .

[15]  Craig M. Brown,et al.  Design of a metal-organic framework with enhanced back bonding for separation of N₂ and CH₄. , 2014, Journal of the American Chemical Society.

[16]  S. Sakaki,et al.  Self-Accelerating CO Sorption in a Soft Nanoporous Crystal , 2014, Science.

[17]  Michael O’Keeffe,et al.  The Chemistry and Applications of Metal-Organic Frameworks , 2013, Science.

[18]  J. Marrot,et al.  First keto-functionalized microporous Al-based metal-organic framework: [Al(OH)(O2C-C6H4-CO-C6H4-CO2)]. , 2013, Inorganic chemistry.

[19]  S. Kitagawa,et al.  Effect of functional groups in MIL-101 on water sorption behavior , 2012 .

[20]  Rajamani Krishna,et al.  Hydrocarbon Separations in a Metal-Organic Framework with Open Iron(II) Coordination Sites , 2012, Science.

[21]  Hong-Cai Zhou,et al.  Metal-organic frameworks for separations. , 2012, Chemical reviews.

[22]  Randall Q Snurr,et al.  Development and evaluation of porous materials for carbon dioxide separation and capture. , 2011, Angewandte Chemie.

[23]  Shyam Biswas,et al.  New functionalized flexible Al-MIL-53-X (X = -Cl, -Br, -CH3, -NO2, -(OH)2) solids: syntheses, characterization, sorption, and breathing behavior. , 2011, Inorganic chemistry.

[24]  C. Serre,et al.  Direct covalent post-synthetic chemical modification of Cr-MIL-101 using nitrating acid. , 2011, Chemical communications.

[25]  Chongli Zhong,et al.  Characterization of Lewis Acid Sites in Metal−Organic Frameworks Using Density Functional Theory , 2010 .

[26]  C. Serre,et al.  Porous Chromium Terephthalate MIL‐101 with Coordinatively Unsaturated Sites: Surface Functionalization, Encapsulation, Sorption and Catalysis , 2009 .

[27]  Hong-Cai Zhou,et al.  Selective gas adsorption and separation in metal-organic frameworks. , 2009, Chemical Society reviews.

[28]  Hong‐Cai Zhou,et al.  A mesh-adjustable molecular sieve for general use in gas separation. , 2007, Angewandte Chemie.

[29]  Alírio E. Rodrigues,et al.  Separation of CH4/CO2/N2 mixtures by layered pressure swing adsorption for upgrade of natural gas , 2006 .

[30]  J. I. Siepmann,et al.  Direct calculation of Henry’s law constants from Gibbs ensemble Monte Carlo simulations: nitrogen, oxygen, carbon dioxide and methane in ethanol , 2006 .

[31]  Min-Bae Kim,et al.  Three‐bed PVSA process for high‐purity O2 generation from ambient air , 2005 .

[32]  Min-Bae Kim,et al.  Parametric study of pressure swing adsorption process to purify oxygen using carbon molecular sieve , 2005 .

[33]  R. T. Yang,et al.  Tailored Clinoptilolites for Nitrogen/Methane Separation , 2005 .

[34]  Michael O'Keeffe,et al.  A route to high surface area, porosity and inclusion of large molecules in crystals , 2004, Nature.

[35]  Michael Tsapatsis,et al.  A titanosilicate molecular sieve with adjustable pores for size-selective adsorption of molecules , 2001, Nature.

[36]  R. T. Yang,et al.  Clinoptilolite: Untapped potential for kinetics gas separations , 1992 .

[37]  R. T. Yang,et al.  Diffusion in ion‐exchanged clinoptilolites , 1991 .

[38]  Fernão D. Magalhães,et al.  High-Purity Oxygen Production by Pressure Swing Adsorption , 2007 .