Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A. This journal is The Royal Society of Chemistry 2015 Electronic Supplementary Information Adsorption of CO 2 on a micro-/mesoporous polyimine modified with tris(2-aminoethyl)amine Chao Xu, Zoltán Bacsik and Niklas Hedin* Department of Materials and Environmental Chemistry, Berzelii Center EXSELENT on Porous Materials, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden. E-mail: niklas.hedin@mmk.su.se; Fax: +46-8-152187; Tel: +46-8-162417
N-H C-H Transmittance C=N C=N 4000 3500 3000 2500 2000 1500 1000 500 Wavenumber (cm -1 ) Figure S1.Infrared spectra of PP1-2 (blue line) and PP1-2-tren (red line). 1 [ν(n-h) + δ(n-h 2 ) 4930 Absorbance 0.5 2ν a (N-H) 6512 tris(2-aminoethyl)amine 0 2v(C-H) PP1-2-tren 6500 6000 5500 5000 4500 Wavenumber (cm -1 ) Figure S2. Near infrared spectra of tris(2-aminoethyl)amine (tren)and PP1-2-tren.
100 Residual weight (%) 80 60 100 200 300 400 500 600 700 800 Temperature ( o C) Figure S3. Thermal gravimetric analysis (TGA) curves of PP1-2 (solid line) and PP1-2-tren (dashed line).
Regression analyses of CO 2 adsorption isotherms The CO 2 adsorption isotherms of PP1-2 and PP1-2-tren recorded at 273 K and 293 K adhered well with a dual-site Langmuir model q = q A + q B = q sat,a b A p 1 + b A p + q sat,b b B p 1 + b B p (1) where A and B are two distinct adsorption sites, q sat is saturation loading in mol kg -1, b is temperature dependent Langmuir constant (Pa -1 ) expressed as b = b 0 exp ( E RT ) (2) Calculation of isosteric heat of adsorption (Q st ) The Q st was determined by using the Clausius-Clapeyron equation Q st = RT 2 ( lnp T )q (3) The details for the calculation of Q st in the dual-site Langmuir model are given by Mason et al. 1 The regression analysis results are presented in Table S1-2, Figure S4-5. The heat of adsorption of CO 2 for PP1-2-tren determined by this method is shown in Figure S6. The Qst for PP1-2 and PP1-2-tren were also calculated directly from the experimental isotherms recorded at 273 K and 293 K by using equation (3). The value of Q st was directly obtained from a plot of lnp against the reciprocal of the temperature, as presented in Figure S7-8. [1] J. A. Mason, K. Sumida, Z. R. Herm, R. Krishna and J. R. Long, Energy Environ. Sci., 2011, 4, 3030-3040.
Table S1. Parameters for the dual-site Langmuir model for adsorption of CO 2 in PP1-2. The parameters were determined by regression analyzes using the adsorption isotherms recorded at temperatures of 273 K and 293 K. (Figure S4) q sat,a = 0.70 mol kg 1 q sat,b = 2.57 mol kg 1 b A = b A0 exp ( E A RT ) b A0 = 3.85 10 10 Pa 1 E A = 29.5 kj mol 1 b B = b B0 exp ( E B RT ) b B0 = 5.67 10 10 Pa 1 E B = 22.2 kj mol 1
Table S2. Parameters for the dual-site Langmuir model for adsorption of CO 2 in PP1-2-tren. The parameters were determined by regression analyzes using the adsorption isotherms recorded at temperatures of 273 K and 293 K. (Figure S5) q sat,a = 0.85 mol kg 1 q sat,b = 1.84 mol kg 1 b A = b A0 exp ( E A RT ) b A0 = 4.28 10 18 Pa 1 E A = 80.6 kj mol 1 b B = b B0 exp ( E B RT ) b B0 = 4.76 10 13 Pa 1 E B = 40.8 kj mol 1
2.5 Quantity adsorbed (mmol/g) 2.0 1.5 1.0 0.5 273 K 293 K 0.0 0 20 40 60 80 100 Pressure (kpa) Figure S4. CO 2 adsorption isotherms of the substrate PP1-2 recorded at temperatures of 273 K (circle) and 293 K (triangle) and the corresponding isotherms (solid line) in a dual-site Langmuir model.
2.5 273 K Quantity adsorbed (mmol/g) 2.0 1.5 1.0 0.5 293 K 0.0 0 200 400 600 800 1000 Pressure (kpa) Figure S5. CO 2 adsorption isotherms of PP1-2-tren recorded at 273 K (circle) and 293 K (triangle) and the corresponding isotherms (solid lines) in a dual-site Langmuir model.
80 Heat of adsorption (kj/mol) 70 60 50 40 273K 293K 0.0 0.5 1.0 1.5 2.0 CO 2 loading (mmol/g) Figure S6. The isosteric heat of adsorption of CO 2 (Q st ) for PP1-2-tren at different temperatures determined within a dual-site Langmuir model. The temperature dependence of Q st for CO 2 /PP1-2-tren is very weak.
2.5 2.5 273 K Quantity adsorbed (mmol/g) 2.0 1.5 1.0 0.5 273 K 283 K 293 K Quantity adsorbed (mmol/g) 2.0 1.5 1.0 0.5 283 K 293 K 303 K 0.0 0.0 0.2 0.4 0.6 0.8 1.0 Pressure (bar) (a) 0.0 0.0 0.2 0.4 0.6 0.8 1.0 Pressure (bar) (b) 6 1.3 mmol/g 6 1.30 mmol/g 4 4 lnp lnp 2 303 K 2 0 293 K 283 K 0.025 mmol/g 273 K 0-2 293 K 283 K 0.35 mmol/g 273 K 0.0034 0.0035 0.0036 0.0037 0.0033 0.0034 0.0035 0.0036 1/T 1/T (c) (d) Figure S7. CO 2 adsorption isotherms of (a) PP1-2 (273, 283 and 293 K) (b) PP1-2-tren (273, 283, 293 and 303 K); CO 2 adsorption isosters for (c) PP1-2 and (d) PP1-2-tren. The linearity of the isosters confirmed the accuracy of the Q st calculated from the temperature dependent CO 2 adsorption isotherms.
90 80 Heat of adsorption (kj/mol) 70 60 50 40 30 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 CO 2 loading (mmol/g) Figure S8. Loading dependent isosteric heat of adsorption of CO 2 for PP1-2 (blue triangles) and PP1-2-tren (red circles). The curves were directly calculated from the experimental CO 2 adsorption isotherms recorded at 273, 283 and 293 K (and also 303 K for PP1-2-tren) using Clausius-Clapeyron equation.
Table S3. Estimated CO 2 -over-n 2 selectivities of PP1-2 and PP1-2-tren for two CO 2 /N 2 mixtures. CO 2 /N 2 mixture (15v%/85v%) CO 2 /N 2 mixture (5v%/95v%) Materials CO 2 loading at 0.15 bar (mmol/g) N 2 loading at 0.85 bar (mmol/g) Selectivity S=(q 1 /q 2 )/(p 1 /p 2 ) CO 2 loading at 0.05 bar (mmol/g) N 2 loading at 0.95 bar (mmol/g) Selectivity S=(q 1 /q 2 )/(p 1 /p 2 ) PP1-2 0.901 0.1636 31 0.463 0.1815 48 PP1-2- tren 1.446 0.01795 456 1.132 0.02079 1035