Adsorptive separation of methanol-acetone on isostructural series of. metal-organic frameworks M-BTC (M = Ti, Fe, Cu, Co, Ru, Mo): A

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1 Supporting information Adsorptive separation of methanol-acetone on isostructural series of metal-organic frameworks M-BTC (M = Ti, Fe, Cu, Co, Ru, Mo): A computational study of adsorption mechanisms and metal-substitution impacts Ying Wu a, Huiyong Chen b, Jing Xiao a, Defei Liu a, Zewei Liu a, Yu Qian a, Hongxia Xi a, * a- The School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, Guangdong, People s Republic of China b- School of Chemical Engineering, Northwest University, Xi an, Shanxi, People s Republic of China * Corresponding author: Hongxia Xi *, Tel.: / Fax: cehxxi@scut.edu.cn (H. Xi). S-1

2 Fig. S1 Schematic of cluster model of M-BTCs (M= Ti, Fe, Cu, Co, Ru, Mo) used for atomic partial charge calculations. Color code: M= orange, C= gray, H= white, O= red. Table S1 LJ parameters and the atomic partial charges of M-BTCs (M= Ti, Fe, Cu, Co, Ru, Mo, the atomic types of frameworks are denoted in Fig. S1) C1 C2/C3 H1 O1 Ti Fe Cu Co Mo Ru σ (Å) ε/k B (K) q (ev) C1 C2 C3 H1 O1 M Ti-BTC Fe-BTC Cu-BTC Co-BTC Mo-BTC Ru-BTC Table S2 LJ parameters and the atomic partial charges of methanol and acetone σ (Å) ε/k B (K) q (ev) methanol_ch methanol_o methanol_h acetone_ch acetone_c acetone_o S-2

3 Table S3 Fitting parameters of DSLF model for adsorption isotherms of methanol and acetone on M-BTCs N 1 MOFs Ads (mmol/g) b 1 (kpa -1 ) n 1 N 2 (mmol/g) b 2 (kpa -1 ) n 2 R 2 Ti-BTC Methanol Acetone Fe-BTC Methanol Acetone E Cu-BTC Methanol Acetone E Co-BTC Methanol Acetone E Mo-BTC Methanol Acetone Ru-BTC Methanol E Acetone E Experimental Synthesis of Cu-BTC Cu-BTC was prepared through solvothermal reactions according to the literature procedures 1-2, in which Cu(NO 3 ) 2 3H 2 O ( g, 3mmol) and 1,3,5-benzene tricarboxylic acid ( g, 2 mmol) were stirred for 1 hour and mixed with 36 ml of solvent containing equal components of N, N-dimethylformanide (DMF), ethanol and deionized water. After the reaction process, the as-synthesized sample was dried in a hot (373 K) nitrogen flow, and subsequently went through 453 K under vacuum to activate the coordinatively unsaturated sites (CUS) by removing the residual solvent. Finally, the blue dehydrated Cu-BTC sample was obtained and sealed in a desiccator before use. Gas adsorption measurements A HIDEN IGA-003 gravimetric uptake device was employed to measure the vapor phase methanol and acetone adsorption isotherms. The pure adsorbate flows (methanol or acetone) were transferred to the sample tube containing adsorbent at S-3

4 certain pressures, in which the temperature was held at 298 K until the weight of the adsorption system was stable. After that, the evacuated sample tube was weighted again and the adsorption uptakes could be estimated by subtracting the mass of guest-free adsorbent and the tared tubes. Characterizations The powder X-ray diffraction (PXRD) patterns of Cu-BTC was obtained by a Bruker Advance D8 diffractometer under the Nickel-filtered Cu-Kα radiation (40 kv within 30 ma at 5 and 25 ), where the sample was flattened as a thin layer on a glass slide inside a polyurethane domed sample holder. To make a comparison, the simulated XRD patterns of the six M-BTC (M= Ti, Fe, Cu, Co, Ru, Mo) analogues were lied out. In addition, the particle size and the crystalline structure of Cu-BTC sample were observed through a Philips FEI XL-30 scanning electron microscope (SEM) using 20 kv accelerating voltage. A Micromeritics ASAP 2020 Surface Area and Porosity Analyzer was used to measure N 2 adsorption isotherm, so as to collect the textural properties of Cu-BTC sample, involving the pore volume, BET and Langmuir surface area. Fig. S2 Simulated XRD patterns of M-BTCs (M= Ti, Fe, Cu, Co, Ru, Mo), and the experimental data of Cu-BTC sample. S-4

5 The XRD patterns of M-BTCs were shown in Fig. S2. We found that the diffraction peaks of Cu-BTC sample was in a good agreement with the corresponding simulated data, which also consistent with the experimental results in literatures 3-4, implying that the synthesized sample was in good crystallinity. Additionally, the M-BTC analogues showed similar XRD patterns, despite some slight discrepancies were observed in small angles, suggesting that these metal-substituted variants possess identical framework topology, although the lattice length and pore size may vary with each other. Fig. S3 SEM photograph of Cu-BTC sample Fig. S3 illustrated the SEM image of the synthesized Cu-BTC sample. Similar as previous literature 3, the particle of Cu-BTC sample exhibited a well-ordered octahedral morphology, with the largest size approximately equaled to 4~6 µm, which was slightly smaller than that reported in the literature 3. S-5

6 Fig. S4 Nitrogen adsorption isotherms of the activated Cu-BTC sample at 77 K, with pink and cyan data representing the adsorption and separation branches, respectively. Fig. S4 denoted N 2 adsorption isotherm on Cu-BTC, which reflected a type-ii isotherm category according to the International Union of Pure and Applied Chemistry (IUPAC) classification 5. The rapid rise of isotherm at low pressures resulted from the presence of micropores in the framework that provided favorable adsorption environment for N 2. The second increase of the uptakes should be ascribed to the formation of textural meso/macroporosity resulted from the multilayer adsorption and molecular-clustering. In addition, there was only small to negligible hysteresis could be noticed between adsorption and desorption branches, indicating that the sample held good crystallinity. The measured microporous volume was around 0.71 cm 3 g -1, offering the BET and Langmuir surface area of 1540 and 2173 m 2 g -1, respectively. S-6

7 Fig. S5 The cluster models of (a) Fe-BTC(Cl) and (b) Ru-BTC(Cl) with partial atomic charge. We used the same simulation procedure mentioned in the manuscript to describe the electrostatic and vdw interactions on Fe- and Ru-BTC containing counterions (Cl - ions). The calculated partial charge was denoted in Fig. S5, while the LJ parameters of the additional Cl ions were taken from UFF. Fig. S6 GCMC-simulated adsorption isotherms of methanol and acetone on (a) Fe-BTC and (b) Ru-BTC with and without counterions of Cl -. S-7

8 Fig. S7 Simulated single-component adsorption isotherms of (a) methanol and (b) acetone on different M-BTCs (M= Ti, Fe, Cu, Co, Ru, Mo) from 0 to 100 kpa at 298K. Fig. S8 DFT-optimized interaction configurations of methanol on different M-BTCs (M= Ti, Fe, Cu, Co, Ru, Mo) S-8

9 Fig. S9 DFT-optimized interaction configurations of acetone on different M-BTCs (M= Ti, Fe, Cu, Co, Ru, Mo) Fig. S10 IAST-predicted adsorptive selectivities for equimolar mixtures of methanol/acetone on M-BTCs (M= Ti, Fe, Cu, Co, Ru, Mo) at 298 K. S-9

10 Fig. S11 DFT-optimized interaction configurations of methanol+methanol, acetone+acetone, and acetone+methanol on Ti-BTC References (1) Rose, M.; Böhringer, B.; Jolly, M.; Fischer, R.; Kaskel, S. MOF Processing by Electrospinning for Functional Textiles. Adv. Eng. Mater. 2011, 13, (2) Schlichte, K.; Kratzke, T.; Kaskel, S. Improved Synthesis, Thermal Stability and Catalytic Properties of the Metal-Organic Framework Compound Cu 3 (BTC) 2. Microporous Mesoporous Mater. 2004, 73, (3) Karra, J. R.; Walton, K. S. Molecular Simulations and Experimental Studies of CO 2, CO, and N 2 Adsorption in Metal Organic Frameworks. J. Phys. Chem. C 2010, 114, (4) Karra, J. R.; Walton, K. S. Effect of Open Metal Sites on Adsorption of Polar and Nonpolar Molecules in Metal Organic Framework Cu-BTC. Langmuir 2008, 24, (5) Sing, K.; Everett, D.; Haul, R.; Moscou, L.; Pierotti, R.; Rouquerol, J.; Siemieniewska, T. Reporting Physisorption Data for Gas/Solid Systems, with Special Reference to the Determination of Surface Area and Porosity (Recommendations 1984). Pure Appl. Chem. 1985, 57, S-10