1 / 60

Presentation outline

Effects of Geometrical Corrugation and Energetical Heterogeneity of Graphene Pore Walls on Adsorption in Nanoporous Carbons . PSD Characterization Jacek Jagiello Micromeritics Corporation, Norcross GA, USA. Relationship between assumed carbon pore model and calculated PSD

azizi
Download Presentation

Presentation outline

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Effects of Geometrical Corrugation and Energetical Heterogeneity of Graphene Pore Walls on Adsorption in Nanoporous Carbons.PSD CharacterizationJacek Jagiello Micromeritics Corporation, Norcross GA, USA

  2. Relationship between assumed carbon pore model and calculated PSD Standard slit pore model based on Steele potential Artifacts resulting from this model Modifications of the model finite pores energetically heterogeneous pore walls geometrically corrugated (rough) walls incorporation of both effects Improvements in PSD analysis Presentation outline

  3. Fluid Density Calculated by DFT for Ar on Graphite

  4. How the PSD is calculated Theoretical Isotherms (Kernel) ∫ Experimental Isotherm Linear Fredholm integral equation of the first kind

  5. Model NLDFT isotherms and density profiles are calculated using Tarazona approach [1, 2]. Attractive fluid-fluid interactions are modeled by Weeks-Chandler-Andersen potential [3]. Pore walls are constructed by structureless graphene sheets. External solid-fluid interaction potential is determined by numerical integration of the 12-6 Lennard-Jones potential over the graphene geometries. Outline of 2D-NLDFT calculations • ______________________________ • Tarazona, P.; Marini Bettolo Marconi, U.; Evans R. Mol Phys 1987; 60, 573. • Lastoskie, C.; Gubbins, K.E.; Quirke N. J Phys Chem 1993; 97, 4786-96. • Weeks, J. D.; Chandler, D.; Andersen, H. C. J. Chem. Phys. 1971; 54,5237.

  6. Carbon Slit Pore Model (History) Rosalind E. Franklin Proceedings of The Royal Society of London Series A. Mathematical and Physical Sciences 1951, 209, 196-218 Steele WA. The Interactions of Gases with Solid Surfaces, Pergamon, Oxford, 1974 N. A. Seaton, J. P. R. B. Walton and N. Quirke Carbon ,1989, 27, 853-861 C. Lastoskie, K.E. Gubbins, N. Quirke, Langmuir, 1993, 9, 2693. J.P. Olivier, W.B. Conklin, M.V. Szombathely, in Characterization of Porous Solids (COPS-III) Proceedings, ed. by F. Rodriguez-Reinoso, J. Rouquerol, K.S.W. Sing, K.K. Unger (Amsterdam, 1994)

  7. Artifacts of Carbon Slit Pore Model(NLDFT and Molecular Simulations) Ustinov, E.A., Do, D.D., Fenelonov, V.B. Carbon2006, 44, 653-663. Neimark, A.V., Lin, Y., Ravikovitch, P.I., Thommes, M. Carbon2009, 47, 1617-1628. Lueking, A.D.; Kim, H.-Y.; Jagiello,J., Bancroft, K., Johnson, J.K., Cole, M.W. J. Low Temp. Phys.2009,157, 410–428. NLDFT adsorption N2 isotherms for uniform flat slit pores (kernel) Kernels by GCMC and NLDFT Are qualitatively similar. 4 Å 7 Å 10 Å 15 Å 30 Å Source of Numerical Problem

  8. HRTEM Images of Activated Carbons Skeletonized images -> Atul Sharma, Takashi Kyotani, Akira Tomita, Carbon 38 (2000) 1977–1984

  9. Bright Field STEM Image of UMC (Westvaco) Carbon (Oak Ridge National Lab) Jagiello, J., Kenvin J., Olivier J.P., Lupini A.R., Contescu C.I., Ads. Sci & Tech. 29,2011, 769-780.

  10. STEM Image - Atomic Resolution Annular dark-fi eld (ADF) STEM images of UMC (a,b) and PFAC (c,d) processed to remove high-frequency noise and probe tail effects. The in-plane carbon atoms are clearly resolved, and large areas of hexagonal lattice (marked in blue) with a few five- and seven-atom ring defects (marked in red) can be seen. (Oak Ridge National Lab) Guo J, Morris JR, Ihm Y, Contescu CI, Gallego NC, Duscher G, Pennycook SJ, Chisholm MF. Small 2012;8:3283-3288.

  11. Strip pore x L, length Width, H y Partially closed strip pore (channel) L H Finite slit shape pores Effective pore width, w=H-3.4 Ǻ -∞ ∞ Disc pore Marini Bettolo Marconi, U.; van Swol, F. Phys. ReV. A 1989, 39, 4109–4116. Monson, P. A. J. Chem. Phys. 2008, 128, 084701. Kozak, E., Chmiel, G., Patrykiejew, A., Sokolowski, S. Phys. Lett. A1994, 189, 94-98. Wongkoblap, A, Do, D.D. J. Phys. Chem. B2007, 111, 13949-13956 Jagiello, J., Olivier, J. P. J. Phys. Chem. C 2009, 113, 19382-19385. Jagiello, J., Kenvin J., Olivier J.P., Lupini A.R., Contescu C.I., Ads. Sci & Tech. 29,2011, 769-780

  12. Density profiles across the pores H=27.6 Ǻ (w=24 Ǻ), L=30 Ǻ, p/p0=0.001 Disc pore Strip pore Channel

  13. Density profiles across the pores H=27.6 Ǻ (w=24 Ǻ), L=30 Ǻ, p/p0=0.01 Disc pore Strip pore Channel

  14. Density profiles across the pores H=27.6 Ǻ (w=24 Ǻ), L=30 Ǻ, p/p0=0.05 Disc pore Strip pore Channel

  15. Density profiles across the pores H=27.6 Ǻ (w=24 Ǻ), L=30 Ǻ, p/p0=0.1 Disc pore Strip pore Channel

  16. Density profiles across the pores H=27.6 Ǻ (w=24 Ǻ), L=30 Ǻ, p/p0=0.2 Disc pore Strip pore Channel

  17. Density profiles across the pores H=27.6 Ǻ (w=24 Ǻ), L=30 Ǻ, p/p0=0.3 Disc pore Strip pore Channel

  18. Density profiles across the pores H=27.6 Ǻ (w=24 Ǻ), L=30 Ǻ, p/p0=0.5 Disc pore Strip pore Channel

  19. Density profiles across the pores H=27.6 Ǻ (w=24 Ǻ), L=30 Ǻ, p/p0=0.7 Disc pore Strip pore Channel

  20. NLDFT Adsorption N2 Isotherms for Slit Pores Finite Pores, L=30 Ǻ Infinite Slit Pores Strip Channel

  21. PSD Analysis for UMC (Westvaco) Carbon using Infinite and Finite Pore Models (Mix) Calculated PSDs Fits of N2 Adsorption Isotherm Fitting error=16.8 10-5<p/p0<10-2 Fitting error = 4.2 UMC sample kindly provided by Dr. Frederic Baker

  22. Simple energetically and geometrically heterogeneous carbon infinite slit pore model • The model is derived from the Steele potential where the geometrical • heterogeneity is introduced only to the surface layer. • Objective: • Introduce minimal modifications to Steele potential that are necessary to improve the model. • Carbon pore heterogeneity may be considered a combined effect of: • Chemical composition (surface chemical groups) • Variation of local density • Variations of pore wall thickness • Geometry (curvature, roughness)

  23. External potential in heterogeneous pore The solid-fluid interaction potential of a gas molecule interacting with the graphitic surface: For a uniform infinite graphitic surface: esf, ssf –solid-fluid interaction parameters rs –solid surface density D – distance between graphitic layers For a pore wall consisting of 3 graphitic surfaces: The total external interaction potential in the pore Vext:

  24. Surface energy distributionUnit cell in periodic boundary conditions Solid-fluid interaction parameter, esf External potential at 1st adsorbed layer, Vext

  25. Experimental and calculated adsorption isotherms on nongraphitized carbon black surfaceCabot BP280

  26. N2 local densitiesin heterogeneous and uniform slit pores with w=24 Ǻ p/p0=0.00001

  27. N2 local densitiesin heterogeneous and uniform slit pores with w=24 Ǻ p/p0=0.0001

  28. N2 local densitiesin heterogeneous and uniform slit pores with w=24 Ǻ p/p0=0.0005

  29. N2 local densitiesin heterogeneous and uniform slit pores with w=24 Ǻ p/p0=0.001

  30. N2 local densitiesin heterogeneous and uniform slit pores with w=24 Ǻ p/p0=0.01

  31. N2 local densitiesin heterogeneous and uniform slit pores with w=24 Ǻ p/p0=0.05

  32. N2 local densitiesin heterogeneous and uniform slit pores with w=24 Ǻ p/p0=0.1

  33. N2 local densitiesin heterogeneous and uniform slit pores with w=24 Ǻ p/p0=0.2

  34. N2 local densitiesin heterogeneous and uniform slit pores with w=24 Ǻ p/p0=0.3

  35. N2 local densitiesin heterogeneous and uniform slit pores with w=24 Ǻ p/p0=0.4

  36. N2 local densitiesin heterogeneous and uniform slit pores with w=24 Ǻ p/p0=0.5

  37. NLDFT Adsorption N2 Isotherms forUniform and Heterogeneous Slit Pores Uniform pores Heterogeneous pores 4 Å 7 Å 4 Å 10 Å 7 Å 10 Å 15 Å 15 Å 30 Å 30 Å

  38. Effect of pore geometry on external wall potential Uniform flat wall Uniform cylindrical wall Curved (corrugated) wall

  39. Pore geometry (roughness)Unit cell - periodic boundary conditions Pore wall: 3 graphene layers Surface layer: z=0.3*sin(x) H

  40. External potential in flat slit and curved (rough) pores The solid-fluid interaction potential of a gas molecule interacting with a graphene surface: For a flat infinite graphene: For a curved surface is obtained by numerical integration. For a pore wall consisting of 3 graphene surfaces: The total external interaction potential in the pore Vext: esf, ssf –solid-fluid interaction parameters rs –solid surface density D – distance between graphitic layers

  41. N2 Isotherms measured for standard reference carbon blacks, graphitized carbon black Carbopak F and the standard NLDFT model

  42. Experimental and calculated adsorption isotherms on nongraphitized carbon black surfaceCabot BP280

  43. N2 local densitiesin curved and flat slit pores with w=24 Ǻ p/p0=0.00001

  44. N2 local densitiesin curved and flat slit pores with w=24 Ǻ p/p0=0.0001

  45. N2 local densitiesin curved and flat slit pores with w=24 Ǻ p/p0=0.0005

  46. N2 local densitiesin curved and flat slit pores with w=24 Ǻ p/p0=0.01

  47. N2 local densitiesin curved and flat slit pores with w=24 Ǻ p/p0=0.05

  48. N2 local densitiesin curved and flat slit pores with w=24 Ǻ p/p0=0.1

  49. N2 local densitiesin curved and flat slit pores with w=24 Ǻ p/p0=0.2

  50. N2 local densitiesin curved and flat slit pores with w=24 Ǻ p/p0=0.3

More Related