Quantifying hydrogen uptake by porous materials Nuno Bimbo Postdoctoral Research Officer Department of Chemical Engineering University of Bath N.M.M.Bimbo@bath.ac.uk http://www.bath.ac.uk/chem-eng/people/bimbo MH 2014 Summer School Salford, 17 th July 2014
Outline Hydrogen storage in porous materials Experimental measurements Absolute and excess adsorption Critical points in supercritical adsorption Quantifying hydrogen in porous systems A model for supercritical gas adsorption Fitting experimental data to the model Parameters adsorbed density, pore volume Hydrogen densities Constant density of adsorbate Adsorptive hydrogen storage Compression vs adsorption Optimal conditions for adsorptive storage Adsorbed hydrogen as an energy store Thermodynamics of adsorption The isosteric enthalpies of adsorption Clapeyron and Clausius-Clapeyron The virial equation
Motivation Food 60 % increase by 2050 (in comparison with 2005/7) The energy, food and water nexus Water 55 % increase 2050 Sustainability of elements Energy 40 % increase by 2035 UN FAO - World Agriculture towards 2030/2050 (2012) UN Water - World Water Development Report (2014) IEA - World Energy Outlook 2011 tce, October 2011 issue, IChemE
Hydrogen storage Alternative ways of storage include: Metal hydrides Cryogenic adsorption Chemical hydrides Liquefaction (at 20 K and 1 bar) Compression (at 298 K and 350 or 700 bar) Sodium alanate AX-21 Ammonia borane David, WIF. Faraday Discuss (2011) 151, 399-414 (adapted from DOE 2011 Annual Merit Review Storage)
Hydrogen storage Eberle et al. Angewandte Chemie International Edition (2009) 48, 6608-6630
Hydrogen storage in porous materials Storage in porous materials can increase its volumetric density at higher temperatures than liquefaction and lower pressures than compression Synthetic chemistry of highly porous materials has known tremendous developments and new materials include metal-organic frameworks and porous polymers 16000 14000 Topic: metal-organic frameworks 12000 10000 8000 6000 4000 NU-100 (6,100 m 2 g -1 ) 2000 0 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 Furukawa, Yaghi et al. Science (2010), 329, 5990 Farha, Hupp et al. Nat Chem (2010), 2, 944 Yuan, Zhou et al. Adv Mat (2011), 23, 3723 ISI Web of Knowledge PPN-4 (6,400 m 2 g -1 ) MOF-210 (6,240 m 2 g -1 )
H 2 excess gravimetric uptake / wt.% Hydrogen storage in porous materials Experimental measurements High-pressure adsorption in a porous material Micromeritics ASAP 2020 0.1 MPa range (volumetric) Hiden IGA 2 MPa range (gravimetric) 2.5 2.0 1.5 1.0 0.5 0.0 86.53 K 100.78 K 120.16 K 150.14 K 200.16 K Hiden HTP-1 20 MPa range (volumetric) 0 2 4 6 8 10 12 14 absolute pressure P / MPa MAST TE7 Carbon beads H 2 isotherms in the 86 to 200 K range, up to 14 MPa
Hydrogen storage in porous materials Absolute and excess adsorption In a supercritical fluid, this difference is negligible at low pressures but becomes very significant with increasing pressures Experimental sorption techniques (volumetric and gravimetric) can only account for excess adsorption Because adsorptive storage of hydrogen will most likely occur above the critical temperature and at high pressures, understanding and quantifying absolute adsorption is critical
Hydrogen storage in porous materials Critical points in supercritical adsorption Critical points in high-pressure, supercritical adsorption n max max max 0 a, ne, Pe, Pe Absolute quantity is the excess quantity plus the bulk quantity in the potential field of the adsorbent n n a a n n e e n Excess reaches a maximum and then starts to decrease with increasing density in the bulk, until eventually reaching zero b V b 0 b a P When the excess reaches a maximum, the gradient of the absolute adsorbed quantity is equal to the gradient of the bulk quantity P e a na nb when max P T P T P P e Bimbo et al. Faraday Discussions (2011) 151, 59
Hydrogen storage in porous materials Ideal vs real gas Data for real gas equation taken from NIST database Based on Leachman s Equation of state for normal hydrogen Leachman et al. J Phys Chem Ref Data (2009) 38
Hydrogen storage in porous materials Ideal vs real gas H P, T 2 1 Z P RT 1 A1 P A2 P Z( P) 1 A P A P 3 4 2 2 Leachman s EOS is a complex equation A rational fit at different temperatures is done to obtain the densities at different pressures
Quantifying hydrogen in porous materials A model for supercritical gas adsorption Absolute ne Amount in bulk n a na nb n b max n a b Vp Density b 1 Z P RT 1 1 1 A1 P A P 3 A2 P A P 4 2 2 P RT ne n max a b V max 1 P p n e n V a p Z RT
Quantifying hydrogen in porous materials A model for supercritical adsorption na Determined from fitting max n a IUPAC Type I equations (θ) Each has different parameters Langmuir (1) Tóth (2) Jovanović-Freundlich (3) Sips (4) UNILAN (5) Dubinin-Astakhov (6) Dubinin-Radushkevich (7) (1) bp 1 bp 1 (2) bp 1 c bp c (3) ( bp) c 1 e 1 (4) (6) (7) c bp bp c 1 2c ln (5) 1 bp exp( c) 1 bp exp( c) e E RT T E m ln P 0 P m e E RT T E 2 ln P 0 P 2 Myers and Monson. Langmuir (2002) 18, 10261; Leachman et al. J. Phys. Chem. Ref. Data (2009) 38, 721; Langmuir. J Am Chem Soc (1918) 40, 1361; Sips. J Chem Phys (1948) 16, 490; Tóth, Acta Chim Acad Sci Hung (1962) 32, 39; Honig and Reyerson, J Phys Chem (1952) 56, 140; Quiñones and Guiochon, J Colloid Interface Sci (1996) 183, 57; Dubinin and Astakhov, Izv Akad Nauk SSSR, Ser Khim (1971), 5, 11; Dubinin and Astakhov, Russ Chem Bull (1971) 20, 8; Bimbo et al. Faraday Discuss (2011) 151, 59
H 2 excess gravimetric uptake / wt.% H 2 excess gravimetric uptake / wt.% Quantifying hydrogen in porous materials A model for supercritical adsorption Non-linear fitting n n max e V a a 1 Z P RT max n a n a 3.5 3.5 3.0 3.0 2.5 2.5 2.0 2.0 1.5 1.5 1.0 1.0 0.5 0.5 0.0 0.0 0 2 4 6 8 10 12 14 absolute pressure P / MPa Hydrogen Isotherm for MAST TE-7 carbon beads at 86 K Excess fitted with the Tóth equation 0 2 4 6 8 10 12 14 absolute pressure P / MPa Hydrogen Isotherms for MAST TE-7 carbon beads at 86 K Excess and absolute using the Tóth equation n n, P e max a, V a Experimental points (dependent and independent variable, respectively) Variable parameters (determined from the fitting)
Quantifying hydrogen in porous materials Fitting experimental data to the model Activated carbon TE7 Materials MAST TE7 carbon beads BET Surface area (m 2 g -1 ) Skeletal density (g cm -3 ) Micropore volume (cm 3 g -1 ) 810 1.94 0.43 AX-21 2258 2.23 1.03* MIL-101 2886 1.69 1.51** Metal-organic framework MIL-101 Activated carbon AX-21 *Quirke and Tennison, Carbon (1996), 34, 1281-1286 **Streppel and Hirscher. Phys Chem Chem Phys (2011) 13, 3220-3222
Quantifying hydrogen in porous materials Fitting experimental data to the model TE7 fitted with the Sips equation TE7 fitted with the UNILAN equation TE7 fitted with the Dubinin-Astakhov equation TE7 fitted with the Dubinin-Radushkevich equation TE7 fitted with the Jovanović-Freundlich equation TE7 fitted with the Tóth equation
Quantifying hydrogen in porous materials Parameters TE7
Quantifying hydrogen in porous materials Parameters AX-21
Quantifying hydrogen in porous materials Parameters MIL-101
H 2 excess gravimetric uptake / wt.% Quantifying hydrogen in porous materials Fitting experimental data to the model 4.0 3.5 3.0 2.5 2.0 Tóth Sips Langmuir Jovanovic-Freundlich UNILAN Dubinin-Radushkevich Dubinin-Astakhov 0 10 20 30 40 absolute pressure P / MPa MAST TE7 carbon beads extrapolation to higher pressures using the parameters from the multi-fit of different Type I isotherms at 100 K
gravimetric uptake / wt.% Quantifying hydrogen in porous materials Verifying the model - NMR PEEK Carbons at 100 K 6 5 4 3 2 CO 2-9-1-542 m 2 g -1 CO 2-9-26-1027 m 2 g -1 CO 2-9-59-1986 m 2 g -1 CO 2-9-80-3103 m 2 g -1 Steam-9-20 - 1294 m 2 g -1 Steam-9-35 - 981 m 2 g -1 Steam-9-70 - 1956 m 2 g -1 1 0 0 2 4 6 8 10 absolute pressure P / MPa Anderson et al. J Am Chem Soc (2010) 132, 8618
H 2 uptake / wt.% H 2 uptake / wt.% Quantifying hydrogen in porous materials Verifying the model - NMR 4.5 4.0 Excess data Fitted excess with the Tóth Absolute estimation with the Tóth Absolute uptake with NMR 4.5 4.0 3.5 3.5 3.0 3.0 2.5 2.0 1.5 2.5 2.0 1.5 1.0 0.5 0.0 1.0 0.5 0.0 Excess data Fitted excess with the Tóth Absolute estimation with the Tóth Absolute uptake with the NMR 0 2 4 6 8 10 12 14 16 18 20 absolute pressure P / MPa 0 2 4 6 8 10 12 14 16 18 20 absolute pressure P / MPa PEEK Carbon Steam-9-35 HTP volumetric excess, NMR absolute estimation and absolute uptake from modelling PEEK Carbon Steam-9-20 HTP volumetric excess, NMR absolute estimation and absolute uptake from modelling
Quantifying hydrogen in porous materials Parameters densities and maximum capacities Using the Tóth equation LIM * na From fitting A * max A A LIM n max a A From experiment
Quantifying hydrogen in porous materials Density of hydrogen T, P ρ (kg m -3 ) Liquid V-L Critical point 33.145 K 1.296 MPa Triple point 13.957 K 0.007 MPa 31.26 77.01 Leachman et al. J Phys Chem Ref Data (2009) 38
Quantifying hydrogen in porous materials Density of hydrogen 20.38 K A compressible liquid And a compressible solid Para-hydrogen at 4 K Johnston et al. J Am Chem Soc (1954) 76, 1482 Silvera, Rev Mod Phys (1980), 52, 393
Quantifying hydrogen in porous materials Density of adsorbed hydrogen Solid density at 4 K and 0 MPa Liquid density at the triple point Liquid density at the V-L critical point
Quantifying hydrogen in porous materials Constant density of adsorbate Excess adsorption + Absolute adsorption + Total adsorption P A B A E V m Sharpe et al. Adsorption (2013), 19, 643 Bimbo et al. Adsorption (2014), 20, 373 Excess adsorption P A b E A P A A A V m m V m Absolute adsorption P B E T A P B P A A T V m m V V m 1 Total adsorption
Quantifying hydrogen in porous materials Constant density of adsorbate AX-21 fitted at 90 K TE7 fitted with the Tóth Bimbo et al. Adsorption (2014), 20, 373 Ting et al. Submitted
H 2 uptake / wt.% Quantifying hydrogen in porous materials Constant density of adsorbate 2.5 Modelled absolute INS integrated elastic line 2.0 1.5 1.0 0.5 0.0 2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 1E-3 0.01 0.1 1 10 0 2 4 6 8 10 Absolute pressure, P / MPa INS on TE7 TE7 fitted with the Tóth Ting et al. Submitted
g H 2 L -1 Adsorptive hydrogen storage Compression vs Adsorption Comparing quantity adsorbed with the quantity at the same P and T without an adsorbent n a mh, wt.%, 2 100 m Solid Calculate mass of solid in 1 L using density of solid ρ s (from He pycnometry) 50 40 50 TE7 g H 2 L -1 30 20 40 30 20 77 K 100 K 120 K 150 K 180 K 200 K Compression at the same temperature 10 10 0 0 0 2 4 6 8 10 12 14 16 18 20 22 24 absolute pressure P / MPa 0 2 4 6 8 10 12 14 16 18 20 22 24 absolute pressure P / MPa Bimbo et al. Colloids and Surfaces A (2013), 437, 113
Absolute pressure, P / MPa g H 2 L -1 g H 2 L -1 50 40 50 Adsorptive hydrogen storage MIL-101 Compression 40 vs Adsorption 30 20 77 K 100 K 120 K 150 K 180 K 200 K Compression at the same temperature 30 10 AX-21 20 10 0 0 2 4 6 8 10 12 14 16 18 20 22 24 absolute pressure P / MPa 50 40 0 0 2 4 6 8 10 12 14 16 18 20 22 24 30 absolute pressure P / MPa g H 2 L -1 20 20 18 16 10 14 12 10 0 8 0 2 4 6 8 10 12 14 16 18 20 22 24 6 4 2 AX-21 MIL-101 MAST TE7 carbon beads absolute pressure P / MPa 0 60 80 100 120 140 160 180 200 Temperature, T / K Bimbo et al. Colloids and Surfaces A (2013), 437, 113
g H 2 L -1 g H 2 L -1 g H 2 L -1 45 40 35 30 Adsorptive hydrogen storage Compression vs Adsorption MAST TE7 Carbon beads at 100 K Comparison with compression 45 40 35 30 AX-21 at 100 K Comparison with compression 25 25 20 15 10 5 Full of adsorbent (1056 g) Filling ratio 0.75 Filling ratio 0.50 Filling ratio 0.25 No adsorbent 20 15 10 5 Full of adsorbent (676 g) Filling ratio 0.75 Filling ratio 0.5 Filling ratio 0.25 No adsorbent 0 0 0 2 4 6 8 10 12 14 16 18 20 22 24 0 2 4 6 8 10 12 14 16 18 20 22 24 absolute pressure P / MPa absolute pressure P / MPa 45 MIL-101 at 100 K 40 35 30 Comparison with compression n n a mass b V t V c 25 20 15 10 5 0 Full of adsorbent (475 g) Filling ratio 0.75 Filling ratio 0.5 Filling ratio 0.25 No adsorbent Filling ratio V V c t V V V t c a V c V sk a mass 0 2 4 6 8 10 12 14 16 18 20 22 24 absolute pressure P / MPa Bimbo et al. Colloids and Surfaces A (2013), 437, 113
g H 2 L -1 g H 2 L -1 g H 2 L -1 Adsorptive hydrogen storage Optimal conditions of storage 25 MAST TE7 Carbon beads at 100 K 25 AX-21 at 100 K 20 15 10 Full of adsorbent (1056 g) Filling ratio 0.75 Filling ratio 0.5 Filling ratio 0.25 20 15 10 Full of adsorbent (676 g) Filling ratio 0.75 Filling ratio 0.5 Filling ratio 0.25 5 5 0 0 0 2 4 6 8 10 12 14 16 18 20 22 24 0 2 4 6 8 10 12 14 16 18 20 22 24 absolute pressure P / MPa absolute pressure P / MPa 25 20 Full of adsorbent (475 g) Filling ratio 0.75 Filling ratio 0.5 Filling ratio 0.25 15 10 MIL-101 at 100 K 5 0 0 2 4 6 8 10 12 14 16 18 20 22 24 absolute pressure P / MPa Bimbo et al. Colloids and Surfaces A (2013), 437, 113
Adsorptive hydrogen storage Comparison energy stored V C Container volume V B Bulk hydrogen volume V D Displaced volume V T Total adsorbate volume V F Volume of tank containing adsorbent V BI Volume of bulk hydrogen in the interstitial sites V BC Volume of bulk hydrogen in the tank containing no adsorbent V BP Volume of bulk hydrogen in the pores of the adsorbent V S Skeletal volume of the adsorbent V P Open pore volume V A Adsorbate volume f fill factor x packing factor of adsorbent Sharpe et al. Microporous and Mesoporous Materials, COPS-X Special Edition (submitted)
Adsorptive hydrogen storage Comparison energy stored Sharpe et al. Microporous and Mesoporous Materials, COPS-X Special Edition (submitted)
Adsorptive hydrogen storage Comparison energy stored 90 K 100 K Sharpe et al. Microporous and Mesoporous Materials, COPS-X Special Edition (submitted)
Adsorptive hydrogen storage Comparison energy stored 77 K 90 K Sharpe et al. Microporous and Mesoporous Materials, COPS-X Special Edition (submitted)
Adsorptive hydrogen storage Comparison energy stored 77 K 90 K Sharpe et al. Microporous and Mesoporous Materials, COPS-X Special Edition (submitted)
Adsorptive hydrogen storage Comparison energy stored TE7 Carbon beads at 89 K Sharpe et al. Microporous and Mesoporous Materials, COPS-X Special Edition (submitted)
Adsorptive hydrogen storage Comparison energy stored Sharpe et al. Microporous and Mesoporous Materials, COPS-X Special Edition (submitted)
Thermodynamics of adsorption Isosteric enthalpies of adsorption Enthalpies of adsorption Measure of the heat released upon adsorption Should be calculated over absolute adsorption, not excess Isosteric method Pressure at constant amount adsorbed Clapeyron equation (exact) P T n A S v P T n A h Tv ab ab Assume: Ideal gas Negligible molar volume for the adsorbate Enthalpy of adsorption is independent of temperature (Heat capacity of the adsorbed phase is zero) v ab v a v ab vb va RT P RT P v a Bimbo et al. Faraday Discuss (2011) 151, 59 Bimbo et al. Adsorption (2014), 20, 373-384
ln P / MPa Thermodynamics of adsorption Clapeyron and Clausius-Clapeyron Clausius-Clapeyron equation P T n A h Tv P T n A hab RT T P Ph RT ab 2 Integrating ln P 1 T n A h R ab 4 2 0-2 -4-6 -8-10 Loading / wt.% 0.1 0.5 1 2 4 6 7-12 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 1000/RT / mol kj -1 Isosteres for hydrogen adsorption in Cu 2 (tptc) (NOTT-101) fitted with the Clausius-Clapeyron approximation, 50-87 K range, up to 4 MPa Bimbo et al. Faraday Discuss (2011) 151, 59 Bimbo et al. Adsorption (2014), 20, 373-384
Thermodynamics of adsorption Clapeyron and Clausius-Clapeyron But we can calculate exact molar volumes from the model and solve the differential numerically NOTT-101 P T n A h Tv ab ab Bimbo et al. Faraday Discuss (2011) 151, 59 Bimbo et al. Adsorption (2014), 20, 373-384
MIL-101 AX-21 Czepirski and Jagiello, Chem Eng Sci (1989), 44, 797 Thermodynamics of adsorption Virial equation m j j j l j j j n b n a T n P 0 0 1 ln Both with m and l = 5 l j j j st n a R Q 0
Isosteric enthalpy, Q st / kj mol -1 Isosteric enthalpy, Q st / kj mol -1 Thermodynamics of adsorption The virial equation Clapeyron, Clausius-Clapeyron and virial MIL-101 AX-21 7 6 5 4 Clausius-Clapeyron Clapeyron equation virial equation (m=5, l=4) virial equation (m=5, l=5) 9 8 7 6 5 3 2 1 4 3 2 1 Clausius-Clapeyron equation Clapeyron equation virial equation (m=5, l=4) virial equation (m=5, l=5) 0-1 0 1 2 3 4 5 6 7 Absolute uptake / wt. % 0-1 0 1 2 3 4 5 6 Absolute uptake / wt. % Bimbo et al. Adsorption (2014), 20, 373-384
CH 4 gravimetric uptake wt. % Amount adsorbed, n / moles Other work Methane adsorption Hydrogen kinetics 12 10 8 6 210 K 230 K 250 K 273.15 K 300 K 325 K 350 K 150 140 130 120 Data Fitted LDF 4 110 2 100 0 90 0 2 4 6 8 10 12 14 16 18 Absolute Pressure, P / MPa 80 0 2 4 6 8 10 12 14 16 time, t / minutes Methane adsorption on HKUST-1 Kinetic curve for Hydrogen on AX-21 (90 K, P f = 2.517 kpa)
Acknowledgements Tim Mays Research Group (http://people.bath.ac.uk/cestjm) Funding and Facilites Valeska Ting and Andrew Physick (http://people.bath.ac.uk/vt233)
Acknowledgements Thank you!