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Microporous Carbon : Their Molecular Sieving Properties

Microporous Carbon : Their Molecular Sieving Properties. Department of Chemical and Biomolecular Engineering N orth C arolina S tate U niversity. Jeremy Palmer, Surendra Jain, Thomas Roussel, Keith Gubbins. Environemental and Energetical Interest. The emission of CO 2 /CH 4 and

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Microporous Carbon : Their Molecular Sieving Properties

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  1. Microporous Carbon : Their Molecular Sieving Properties Department of Chemical and Biomolecular Engineering NorthCarolinaStateUniversity Jeremy Palmer, Surendra Jain, Thomas Roussel, Keith Gubbins

  2. Environemental and Energetical Interest The emission of CO2/CH4 and there Green House effect on global warming is one of the key environmental issues http://www.chemistryland.com/CHM107/GlobalWarming/EarthSweating.jpg http://www.rite.or.jp/English/lab/sequestration/sequestration.jpg NSIDC – National Snow and Ice Data Center Synthesized Picture made from NASA data recorded between 1979 and 2005. (NASA)

  3. Microporous Filters for Gas Burying • a) A. Vishnyakov, et al, Langmuir, 1999, 15, 8736. • b) S. Cavenati, et al, J. Chem. Eng. Data, 2004, 49, 1095. c) L.Huang et al, J. Chem. Phys. C, 2007, 111, 11912. • http://images.blog-24.com/700000/698000/698166.jpg

  4. How to control the Pore Size of MicroPorous Carbon ? 1) By Activation of Microporous Carbon in oxidizing Air and at High Temperature : Activated Carbon Heated at 1000 C in atm. of CO2 Surendra J., et al Carbon 2000, 38, 269. 2) By Templating Method using a microporous and crystalline host : Zeolites Kyotani, T.et alCarbon 2000, 38, 269. Ryoo, et al J. Phys. Chem. B 1999, 103, 7743

  5. Disordered Vs Ordered Microporous Carbon Disordered Microporous Carbon : CS 400 CS1000 CS1000 Exp/sim. :J.Pikunic,et al, Langmuir, 19, 8565-8582, (2003)

  6. Disordered Vs Ordered Microporous Carbon An Order based on Well-controlled/organized pore size Disordered Microporous Carbon : Ordered Microporous Carbon : CS 400 CS1000 CS1000 Exp/sim. :J.Pikunic,et al, Langmuir, 19, 8565-8582, (2003) Exp : T.Kyotani, Bulletin of Chemical Society of Japan, 79, 9, 1322-1337, (2006) ;Awards Accounts‘’ Synthesis of Various Types of Nano Carbons Using the Template Technique’’

  7. Modelling Well-Controled Ordered Microporous Carbon Alumino-silicate : EMT : Hexagonal • xNa-(Al2O3)y-(SiO2)z • Interconnected cages • Pore size : ~ 7.3 Å • Windows : ~ 7.5 x 6.5 Å Simulation Box : [24.85 x 24.85 x 24.85] Å3 FAU : Cubic • xNa-(Al2O3)y-(SiO2)z • Interconnected cages • Pore size : ~ 10 Å • Windows : ~ 7 Å Simultaion Box : [17,35 x 30.11 x 28.34] Å3

  8. a) Alumino-Silicate Cubique (FAU) Microporous Carbon in-zeolite-templated Replica Microporous Carbon with a Well-controlled Pores Thomas Roussel, Thesis (2007 - France) Simulation GCMC of Carbon Condensed Phases : ¤ C-C Interactions : REBO Potential ¤ C-Zeolite Interactions : PN-TrAZ Carbon infiltration Pristine Replica after etching the zeolite and/or carbonisation Structure Synthesized Numerically (GCMC) Zeolite as a Template Nanocomposite Carbon/zeolite b) Alumino-Silicate Hexagonale (EMT) T.Roussel, (Thesis - 2007) T.Roussel, et al, J. Phys. Chem. C, 111, 15863-15876, (2007).

  9. Cubic and Hexagonal Faujasite Carbon Replica (C-FAU) & (C-EMT) C-FAU : [24.85 x 24.85 x 24.85] Å3 PSD Calculation based on Gelb and Gubbins method PSD : Sharp and Centered 10-11 Å C-EMT : [34,7 x 30.11 x 28.34] Å3 • FAU & EMT Replicas : • Faujasite Carbon Replicas are Allotropic Phases (Interconnected nanotube-like) • Good Mechanical Properties - low densities • Cost much higher than Disordered Carbon PSD : bimodal4- 9 Å

  10. Modelling Disordered Microporous Carbon CS1000a Radial Distribution Function for CS1000a PSD of CS1000a (using Ar as a probe)* g (r) [25x25x25] Å3 r (Å) UMC PSD : Broad distribution9-12 Å Radial Distribution Function for UMC PSD of UMC (using Ar as a probe) g (r) PSD : Broad and Centered on 9 Å [30x30x30] Å3 r (Å) *See Surendra K. Jain Thesis – NCSU - 2008

  11. Modeling Mixtures Isotherms and Selectivity (GCMC) + LJ model Change in composition of confined phase is often expressed as a Selectivity* (b = bulk, p = pore): Parameters are adjusted to the gas-liquid Transition in Bulk for pure components (i = j) Lorentz-Berthelot Mixing Rule for Mixtures : H2 : Tc = 30.3 K Pc = 1.3 MPa CO2 : Tc = 304.2 K Pc = 7.38 MPa CH4 : Tc = 190.4 K Pc = 4.60 MPa • Z.Tan, K.Gubbins, J.Phys.Chem., 96, 845-854, 1992

  12. Binary Mixture in Disordered Carbon (at 298 K) Snapshots of mixture is CH4/CO2 (transparent and opaque beads respectively) Snapshots of CH4/CO2 in CS1000a (left) and UMC (right) at 10 atm and Room temperature.

  13. CO2/CH4 Selectivity (at 298 K) DisOrdered Microporous Carbon Selectivity of CO2 / CH4 in CS1000a Selectivity of CO2 / CH4 in UMC Selectivity Selectivity Pi(CH4) / Ptot Relative Partial Pressure of CH4 in the Mixture Pi(CH4) / Ptot Relative Partial Pressure of CH4 in the Mixture

  14. Mixture (A/B) in Ordered Carbon Replica Snapshots of mixture is CH4/CO2 (transparent and opaque molecules respectively) Snapshots of CH4/CO2 in C-FAU (left) and C-EMT (right) at 10 atm.

  15. CO2/CH4 Selectivity(at 298 K) Ordered Microporous Carbon Selectivity of CO2 / CH4 in C-EMT Selectivity of CO2 / CH4 in C-FAU Selectivity Selectivity Pi(CH4) / Ptot Relative Partial Pressure of CH4 in the Mixture Pi(CH4) / Ptot Relative Partial Pressure of CH4 in the Mixture

  16. H2/CH4 Selectivity (at 298 K) DisOrdered Microporous Carbon Selectivity of H2 / CH4 in CS1000a Selectivity of H2 / CH4 in UMC Selectivity Selectivity Pi(CH4) / Ptot Relative Partial Pressure of CH4 in the Mixture Pi(CH4) / Ptot Relative Partial Pressure of CH4 in the Mixture

  17. H2/CH4 Selectivity (at 298 K) Ordered Microporous Carbon Selectivity of H2 / CH4 in C-EMT Selectivity of H2 / CH4 in C-FAU Selectivity Selectivity Pi(CH4) / Ptot Relative Partial Pressure of CH4 in the Mixture Pi(CH4) / Ptot Relative Partial Pressure of CH4 in the Mixture

  18. Isoteric Heat of adsorption (pure Fluid-Wall) C-FAU C-EMT CO2 CO2 CH4 CH4 Qst (KJ/mol) Qst (KJ/mol) H2 H2 N2 N2 Temperature (K) Temperature (K) CS1000a UMC CO2 CO2 CH4 CH4 Qst (KJ/mol) Qst (KJ/mol) H2 H2 N2 N2 Temperature (K) Temperature (K)

  19. CONCLUSION • Microporous Carbon have potentially a very good selectivity of CO2/CH4 and H2/CH4 mixtures • Such Materials are greater than previous nanoporous materials studied (Zeolite, Activated Carbon, even Nanotubes …) • Carbon Replica are much more attractive for such issues. • By comparing well-controlled pore size distribution, we can define an optimum for 3-Dimensionally interconnected nanopores (a pore size < 1 nm is recommanded) • Such materials can also be efficient in term of Energy transportation (CH4/H2 mixtures). • Recent works are pursued the CO2/N2 or CH4/N2 mixtures sieving, in order to entrap CH4 and CO2.

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