Home Self Diffusivity of n-Dodecane and Benzothiophene in ZSM-5 Zeolites. Its Significance for a New Catalytic Light Diesel Desulfurization Process
Article
Licensed
Unlicensed Requires Authentication

Self Diffusivity of n-Dodecane and Benzothiophene in ZSM-5 Zeolites. Its Significance for a New Catalytic Light Diesel Desulfurization Process

  • María L. Ferreira , Saad A. Al-Bogami and Hugo I. de Lasa EMAIL logo
Published/Copyright: October 13, 2015
Become an author with De Gruyter Brill
Submit Manuscript Author Information
International Journal of Chemical Reactor Engineering
From the journal International Journal of Chemical Reactor Engineering Volume 14 Issue 3

Abstract

This study provides theoretical support to a recent promising ZSM5 catalyst used for the selective desulfurization of light diesel type compounds (Al-Bogami and de Lasa 2013; Al-Bogami, Moreira, and de Lasa 2013). With this end, Molecular Dynamics (MD) simulations employing a rigid silicalite structure are developed to calculate self-diffusivities of n-Dodecane (n-C12) and Benzothiophene (BZT) in a silicalite structure. The simulations are performed at 573 K, 623 K, 673 K and 723 K at a fixed loading of 1 molecule per unit cell to study the temperature effect on diffusivity coefficient. In addition, a number of simulations which are developed to investigate four molecule loadings (corresponding to 0.25, 0.5, 0.75 and 1 molecule per zeolite unit cell) at 723 K. MD simulations, show a self diffusivity of BZT one order of magnitude higher than that of n-C12 self diffusivity at all temperatures investigated. This is the case in spite of BZT having a critical molecular diameter of 6 Å when compared to the 4.9 Å diameter of n-C12. In addition, the self diffusivity coefficient is found to increase with temperature for both n-C12 and BZT. Furthermore, the results obtained show that the self diffusivity of n-C12 decreases as the number of n-C12 molecules per zeolite unit cell increases. On the other hand, it is observed that the self-diffusivity coefficient for BZT remains fairly constant and drops at a loading of 1 molecule per zeolite unit cell only. These coefficients show that differences in n-C12 and benzothiophene diffusivities favours desulfurization with selective benzothiophene adsorption and sulfur species removal as coke (Al-Bogami and de Lasa 2013).

Keywords: diesel; desulfurization; zeolite; catalyst; molecular simulation; self diffusion

Acknowledgments

The authors would like to acknowledge the financial contribution of the Natural Science and Engineering Research Council of Canada (NSERC). The authors also are very appreciative to Saudi Aramco Oil Company for providing the scholarship to Mr. Saad Al-Bogami and to the Consejo Nacional de Ciencia y Tecnologia (CONICET), for supporting Dr.M.L. Ferreira’s research at Plapiqui, Univ.Nacional del Sur,Argentina. In addition, we would like to thank Ms. F. de Lasa for her assistance on the preparation of this manuscript.

Notation

BZT

Benzothiophene

C

concentration

COMPASS

Condensed-Phase Optimized Molecular Potentials for Atomistic Simulation Studies

CREC

Chemical Reactor Engineering Centre

Ds

Self diffusivity coefficient

FCC

Fluid Catalytic Cracking

FTIR

Fourier Transform Infrared Spectroscopy

MD

Molecular Dynamics

MFI

Mordenite Framework Inverted

MSD

Mean square displacement

PFG NMR

Pulsed Field Gradient Nuclear Magnetic Resonance

NVE

constant number of particles, volume, and energy

NVT

constant number of particles, volume, and temperature

NHL

Nose-Hoover-Langevin

n-C12

n-Dodecane

QENS

Quasi-Elastic Neutron Scattering

r

coordinate of a particle

Si/Al

silica to alumina ratio

t

simulation time

TST

Transition State

u.c

unit cell

ΔR(t)

change of particle coordinates with simulation time

Units

Å

Angstrom

°C

Celsius

cm2

Squared centimetres

fs

Femtoseconds (10−15 s)

K

Kelvin

m2

Squared metres

nm

nanometre

ps

Picoseconds (10−12 s)

s

seconds

References

1. Al-Bogami, S.A., de Lasa, H.I., 2013. Catalytic Conversion of Benzothiophene Over a H-ZSM5 Based Catalyst. Fuel 108, 490–501.10.1016/j.fuel.2012.11.008Search in Google Scholar

2. Al-Bogami, S.A., Moreira, J., de Lasa, H.I., 2013. Kinetic Modeling of Benzothiophene Catalytic Conversion Over a H-ZSM5 Based Catalyst. Ind. Eng. Chem. Res. 52, 17760–17772. DOI: 10.1021/ie401169k.Search in Google Scholar

3. Al-Khattaf, S., 2001. Diffusion and Reaction of Hydrocarbons in FCC Catalysts. PhD thesis, University of Western Ontario.10.1002/cjce.5450790306Search in Google Scholar

4. Auerbach, S.M., Carrado, K.A., Dutta, P.K., 2003. Handbook of Zeolite Science and Techology, Marcel Dekker Inc, New York.10.1201/9780203911167Search in Google Scholar

5. Bogdanov, B., Georgiev, D., Angelova, K., Hristov, Y., 2009. Synthetic Zeolites and Their Industrial and Environmental Applications, in: International Science Conference, Bulgaria.Search in Google Scholar

6. Bunte, S.W., Sun, H., 2000. Molecular Modeling of Energetic Materials: The Parameterization and Validation of Nitrate Esters in the COMPASS Force Field. J. Phys. Chem. B 104, 2477–2489.10.21236/ADA393318Search in Google Scholar

7. Catlow, C., Freeman, C.M., Vessal, B., Leslie, M., 1991. Molecular Dynamics Studies of Hydrocarbon Diffusion in Zeolites. J. Chem. Soc. Faraday Trans. 87, 1947–1950.10.1039/ft9918701947Search in Google Scholar

8. Contreras, R., Cuevas-Garcia, R., Ramirez, J., Ruiz-Azuara, L., Gutierrez-Alejandre, A., Puente-Lee, I., Castillo-Villalon, P., Salcedo-Luna, C., 2008. Transformation of Thiophene, Benzothiophene and Dibenzothiophene over Pt/HMFI, Pt/HMOR and Pt/HFAU: Effect of Reactant Molecular Dimensions and Zeolite Pore Diameter over Catalyst Activity. Catal. Today 130, 320–326.10.1016/j.cattod.2007.10.007Search in Google Scholar

9. de Lasa, H.I., 1992. Riser simulator U.S. Patent 5 102 628.Search in Google Scholar

10. de Lasa, H.I., Hernandez-Enriquez, R., Tonetto, G., 2006. Catalytic Desulfurization of Gasoline via Dehydrosulfidation. Ind. Eng. Chem. Res. 45, 1291–1299.10.1021/ie0506825Search in Google Scholar

11. Demontis, P., Suffritti, G.B., 2009. A Comment on the Flexibility of Framework in Molecular Dynamics Simulations of Zeolites. Microporous Mesoporous Mater. 125, 160–168.10.1016/j.micromeso.2009.03.032Search in Google Scholar

12. Dumont, D., Bougeard, D., 1995. A molecular dynamics study of hydrocarbons adsorbed in silicalite. Zeolites 15, 650–655.10.1016/0144-2449(95)00032-2Search in Google Scholar

13. Govind, N., Andzelm, J., Reindel, K., Fitzgerald, G., 2002. Zeolite Catalyzed Hydrocarbon Formation from Methanol: Density Functional Simulations. Inter. J. Mol. Sci. 3, 423–434.10.3390/i3040423Search in Google Scholar

14. Hagen, J., 2006. Industrial Catalysis a Practical Approach, 2nd ed. Wiley-Vch, New York.10.1002/3527607684Search in Google Scholar

15. Hernandez, E., Catlow, C., 1995. Molecular Dynamics Simulations of n-Butane and n-Hexane Diffusion in Silicalite. Proc. R. Soc. Lond. A. 448, 143–160.10.1098/rspa.1995.0010Search in Google Scholar

16. Hussain, I., Titiloye, J., 2005. Molecular Dynamics Simulations of the Adsorption and Diffusion Behavior of Pure and Mixed Alkanes in Silicalite. Microporous Mesoporous Mater. 85, 143–156.10.1016/j.micromeso.2005.06.017Search in Google Scholar

17. Jaimes, L., Badillo, M., de Lasa, H.I., 2011. FCC asoline desulfurization using a ZSM-5 Catalyst Interactive Effects of Sulfur Containing Species and Gasoline Components. Fuel 90, 2016–2025.10.1016/j.fuel.2010.12.041Search in Google Scholar

18. Jaimes, L., Ferreira, M.L., de Lasa, H.I., 2009. Thiophene Conversion under Mild Conditions over a ZSM-5 Catalyst. Chem. Eng. Sci. 64, 2539–2561.10.1016/j.ces.2009.01.070Search in Google Scholar

19. Jia, W., Murad, S., 2005. Separation of Gas Mixtures using a Range of Zeolite Membranes: A Molecular Dynamics Study. J. Chem. Phys. 122, 1–11.10.1063/1.1930829Search in Google Scholar

20. Jianfen, F., de Graaf, B., Xiao, H.M., Njo, S.L., 1999. Molecular Dynamics Simulation of Ethene Diffusion in MFI and H[Al]ZSM-5. J. Mol. Struct. 492, 133–142.10.1016/S0166-1280(99)00158-XSearch in Google Scholar

21. Jobic, H., 2000. Diffusion of Linear and Branched Alkanes in ZSM-5. A Quasi-Elastic Neutron Scattering Study. J. Mol. Catal. A: Chem. 158, 135–142.10.1016/S1381-1169(00)00057-1Search in Google Scholar

22. Jobic, H., Schmidt, W., Krause, C.B., Kärger, J., 2006. PFG NMR and QENS Diffusion Study of n-Alkane Homologues in MFI-Type Zeolites. Microporous Mesoporous Mater. 90, 299–306.10.1016/j.micromeso.2005.10.020Search in Google Scholar

23. Jobic, H., Theodorou, D.N., 2006. Diffusion of Long n-Alkanes in Silicalite. A Comparison between Neutron Scattering Experiments and Hierarchical Simulation Results. J. Phys. Chem. B 110, 1964–1967.10.1021/jp056924wSearch in Google Scholar

24. Jobic, H., Theodorou, D.N., 2007. Quasi-Elastic Neutron Scattering and Molecular Dynamics Simulation as Complementary Techniques for Studying Diffusion in Zeolites. Microporous Mesoporous Mater. 102, 21–50.10.1016/j.micromeso.2006.12.034Search in Google Scholar

25. June, R.L., Bell, A.T., Theodorou, D.N., 1992. Molecular Dynamics Studies of Butane and Hexane in Silicalite. J. Phys. Chem. 96, 1051–1060.10.1021/j100182a009Search in Google Scholar

26. Kärger, J., Pfeifer, H., 1987. NMR elf-Diffusion Studies in Zeolite Science and Technology. Zeolites 7, 90–107.10.1016/0144-2449(87)90067-4Search in Google Scholar

27. Leroy, F., Rousseau, B., Fuchs, A.H., 2004. Self-Diffusion of n-Alkanes in Silicalite using Molecular Dynamics Simulation: A Comparison between Rigid and Flexible Frameworks. Phys. Chem. Chem. Phys. 6, 775–783.10.1039/b310273dSearch in Google Scholar

28. Lins, J.O., Nascimento, M.A., 1997. Molecular Dynamics Studies of Light Hydrocarbon Diffusion in Zeolites. Mol. Eng. 7, 309–316.10.1023/A:1008279021220Search in Google Scholar

29. Liu, Z., Ottaviani, M.F., Abrams, L., Lei, X., Turro, N.J., 2004. Characterization of the External Surface of Silicalites Employing Electron Paramagnetic Resonance. J. Phys. Chem. A 108, 8040–8047.10.1021/jp049275hSearch in Google Scholar

30. Marcilly, C., 2001. Evolution of Refining and Petrochemicals: What is the Place of Zeolites. Oil Gas Sci. Technol.-Rev. IFP 56, 499–514.10.1016/S0167-2991(01)81185-XSearch in Google Scholar

31. McQuaid, M.J., Sun, H., Rigby, D., 2004. Development and Validation of COMPASS Force Field Parameters for Molecules with Aliphatic Azide Chains. J. Comput. Chem. 25, 61–71.10.1002/jcc.10316Search in Google Scholar PubMed

32. Nicholas, J.B., Trouw, F.R., Mertz, J.E., Iton, L.E., Hopfinger, A.J., 1993. Molecular Dynamics Simulation of Propane and Methane in Silicalite. J. Phys. Chem. 97, 4149–4163.10.1021/j100118a035Search in Google Scholar

33. Nose, S., 1984. A Unified Formulation of the Constant Temperature Molecular-Dynamics Methods. J. Chem. Phys. 81, 511–519. doi:10.1063/1.44733.Search in Google Scholar

34. Ravella, A., de Lasa, H.I., Mahay, A., 1987. Operation and Testing of a Novel Catalytic Reactor Configuration for the Conversion of Methanol to Hydrocarbons. Ind. Eng. Chem. Res. 26, 2546–2552.10.1021/ie00072a029Search in Google Scholar

35. Roque-Malherbe, R., Wendelbo, R., Mifsud, A., Corma, A., 1995. Diffusion of Aromatic Hydrocarbons in H-ZSM-5, H-Beta, and H-MCM-22 Zeolites. J. Phys. Chem. 99, 14064–14071.10.1021/j100038a043Search in Google Scholar

36. Rozanska, X., Van Santen, R.A., 2003. Reaction Mechanisms in Zeolite Catalysis. in: Auerbach, S.M., Carrado, K.A., Dutta, P.K. (Eds.), Handbook of Zeolite Science and Technology, Marcel Dekker Inc., New York. Chapter 15, 900–947.10.1201/9780203911167.ch15Search in Google Scholar

37. Rungsirisakun, R., Nanok, T., Probst, M., Limtrakul, J., 2006. Adsorption and Diffusion of Benzene in the Nanoporous Catalysts FAU, ZSM-5 and MCM-22: A Molecular Dynamics Study. J. Mol. Graphics Modell. 24, 373–82.10.1016/j.jmgm.2005.10.003Search in Google Scholar

38. Runnebaum, R.C., Maginn, E.J., 1997. Molecular Dynamics Simulations of Alkanes in the Zeolite Silicalite: Evidence for Resonant Diffusion Effects. J. Phys. Chem. B 101, 6394–6408.10.1021/jp970774aSearch in Google Scholar

39. Samoletov, A.A., Dettmann, C.P., Chaplain, M.A.J., 2007. Thermostats for Slow Configurational Modes. J. Stat. Phys. 128, 1321–1336.10.1007/s10955-007-9365-2Search in Google Scholar

40. Sastre, G., Raj, N., Catlow, C.R.A., Roque-Malherbe, R., Corma, A., 1998. Selective Diffusion of C8 Aromatics in a 10 and 12 MR Zeolite. A Molecular Dynamics Study. J. Phys. Chem. B 102, 3198–3209.10.1021/jp980053rSearch in Google Scholar

41. Satterfield, C.N., 1980. Heterogeneous Catalysis in Practice, McGraw-Hill Book Company, New York.Search in Google Scholar

42. Schuring, D., 2002. Diffusion in Zeolites: Towards a Microscopic Understanding. PhD Thesis, Eindhoven University of Technology.Search in Google Scholar

43. Smit, B., Daniël J.C. Loyens, L., Verbist, G.L.M.M., 1997. Simulation of Adsorption and Diffusion of Hydrocarbons in Zeolites. Faraday Discuss. 106, 93–104.10.1039/a701559cSearch in Google Scholar

44. Song, L., Sun, Z., Rees, L.V.C., 2002. Experimental and Molecular Simulation Studies of Adsorption and Diffusion of Cyclic Hydrocarbons in Silicalite-1. Microporous Mesoporous Mater. 55, 31–49.10.1016/S1387-1811(02)00394-3Search in Google Scholar

45. Sun, H., Ren, P., Fried, J.R., 1998. The COMPASS Forcefield: Parameterization and Validation for Polyphosphazenes. Comput. Theor. Polym. Sci. 8, 229–246.10.1016/S1089-3156(98)00042-7Search in Google Scholar

46. Szczygieł, J., Szyja, B., 2005. Computer Simulated Diffusion of C7 Hydrocarbons in Microporous Materials: Molecular Modeling. Microporous Mesoporous Mater. 83, 85–93.10.1016/j.micromeso.2005.02.004Search in Google Scholar

47. Tukur, N., Al-Khattaf, S., 2005. Catalytic Cracking of n-Dodecane and Alkyl Benzenes over FCC Zeolite Catalysts: Time on Stream and Reactant Converted Models. Chem. Eng. Process. 44, 1257–1268.10.1016/j.cep.2005.02.009Search in Google Scholar

48. Verlet, L., 1967. Computer Experiments on Classical Fluids. I. Thermodynamical Properties of Lennard-Jones Molecules. Phys. Rev. 159, 98–103.10.1103/PhysRev.159.98Search in Google Scholar

49. Xiao, J., 1990. The Diffusion Mechanism of Hydrocarbons in Zeolites. PhD Thesis, Massachusetts Institute of Technology.Search in Google Scholar

50. Xiao, J., Wei, J., 1992a. Diffusion Mechanism of Hydrocarbons in Zeolite I. Theory. Chem. Eng. Sci. 47, 1123–1141.10.1016/0009-2509(92)80236-6Search in Google Scholar

51. Xiao, J., Wei, J., 1992b. Diffusion Mechanism of Hydrocarbons in Zeolites—II. Analysis of Experimental Observations. Chem. Eng. Sci. 47, 1143–1159.10.1016/0009-2509(92)80237-7Search in Google Scholar

52. Yu, S., Waku, T., Iglesia, E., 2003. Catalytic Desulfurization of Thiophene on H-ZSM5 Using Alkanes as Co-Reactants. Appl. Catal. A: Gen. 242, 111–121.10.1016/S0926-860X(02)00507-0Search in Google Scholar

53. Zheng, S., 2002. Surface Modification of HZSM-5 Zeolites. PhD Thesis, Technische Universitat Mϋnchen.Search in Google Scholar

Appendix I Thiophene Adsorption on ZSM5 Zeolite

  1. During the unsteady reaction of benzothiophene in the CREC Riser Simulator, the benzothiophene conversion has to comply with species balances in the ZSM5 crystallite as follows:

(4)εDsr2∂∂rr2∂Cbt∂r=∂Cbt∂t+ScρckadsCbt1−θbt−θd−kdesθbt

and

(5)ScρckadsCbt1−θbt−θd−kdesθbt=ρcKbt∂Cbt∂t+Catalytic Reaction Rate

With εDs in m2/s representing the effective diffusivity, kads the intrinsic rate adsorption constant in m/s, kdes the intrinsic rate desorption constant in moles/ (m2 s), Cbt the benzothiophene concentration in mole/m3, Kbt the benzothiophene equilibrium adsorption constant in m3/g, Sc the specific crystallite area per unit weight in m2/g, ρc the apparent crystallite density in g/m3 and θbt and θd the dimensionless site fraction occupied by benzothiophene and n-dodecane.

As a result, one can notice that both benzothiophene and the n-dodecane occupied sites influence the adsorption processes.

  1. However, during the early stages of adsorption, one can postulate a simplified (eq. (1)) with: i) no sites occupied by dodecane species, θd = 0, ii) very small fractions of sites being occupied by benzothiophene θbt<< 1, and iii) catalytic reaction being negligible.

Thus,

(6)ϵDsr2∂∂rr2∂Cbt∂r=ε∂Cbt∂t+ScρckadsCbt

and

(7)Sc ρc[kads cbt]=ρcKbt∂Cbt∂t

One should notice that under these early unsteady conditions a large εDsr2∂∂rr2∂Cbt∂r leads to significant selective benzothiophene adsorption with no n-dodecane occupied sites.

Published Online: 2015-10-13
Published in Print: 2016-6-1

©2016 by De Gruyter

Articles in the same Issue

  1. Frontmatter
  2. Editorial
  3. In Honour of Professor Serge Kaliaguine
  4. Research Articles
  5. Core/Shell Nanostructured Materials for Sustainable Processes
  6. Photodegradation Efficiencies in a Photo-CREC Water-II Reactor Using Several TiO2 Based Catalysts
  7. Hydrotreatment of Light Cycle Oil Over a Dispersed MoS2 Catalyst
  8. Hybrid Ionic Liquid-Chitosan Membranes for CO2 Separation: Mechanical and Thermal Behavior
  9. Photo-oxidation of Tributyltin, Dibutyltin and Monobutyltin in Water and Marine Sediments
  10. Contribution of Pd Membrane to Dehydrogenation of Isobutane Over a New Mesoporous Cr/MCM-41 Catalyst
  11. Self Diffusivity of n-Dodecane and Benzothiophene in ZSM-5 Zeolites. Its Significance for a New Catalytic Light Diesel Desulfurization Process
  12. Staggered Grid Finite Volume Approach for Modeling Single Particle Char Gasification
  13. High Efficiency CeCu Composite Oxide Catalysts Improved via Preparation Methods for Propyl Acetate Catalytic Combustion in Air
  14. Hydrodesulfurization of Dibenzothiophene in a Micro Trickle Bed Catalytic Reactor under Operating Conditions from Reactive Distillation
  15. Surface Modification of the ZnO Nanoparticles with γ-Aminopropyltriethoxysilane and Study of Their Photocatalytic Activity, Optical Properties and Antibacterial Activities
  16. One-Pot Isomerization of n-Alkanes by Super Acidic Solids: Sulfated Aluminum-Zirconium Binary Oxides
  17. Photocatalytic Decomposition of Metoprolol and Its Intermediate Organic Reaction Products: Kinetics and Degradation Pathway
https://doi.org/10.1515/ijcre-2015-0129
Keywords for this article
diesel; desulfurization; zeolite; catalyst; molecular simulation; self diffusion

Articles in the same Issue

  1. Frontmatter
  2. Editorial
  3. In Honour of Professor Serge Kaliaguine
  4. Research Articles
  5. Core/Shell Nanostructured Materials for Sustainable Processes
  6. Photodegradation Efficiencies in a Photo-CREC Water-II Reactor Using Several TiO2 Based Catalysts
  7. Hydrotreatment of Light Cycle Oil Over a Dispersed MoS2 Catalyst
  8. Hybrid Ionic Liquid-Chitosan Membranes for CO2 Separation: Mechanical and Thermal Behavior
  9. Photo-oxidation of Tributyltin, Dibutyltin and Monobutyltin in Water and Marine Sediments
  10. Contribution of Pd Membrane to Dehydrogenation of Isobutane Over a New Mesoporous Cr/MCM-41 Catalyst
  11. Self Diffusivity of n-Dodecane and Benzothiophene in ZSM-5 Zeolites. Its Significance for a New Catalytic Light Diesel Desulfurization Process
  12. Staggered Grid Finite Volume Approach for Modeling Single Particle Char Gasification
  13. High Efficiency CeCu Composite Oxide Catalysts Improved via Preparation Methods for Propyl Acetate Catalytic Combustion in Air
  14. Hydrodesulfurization of Dibenzothiophene in a Micro Trickle Bed Catalytic Reactor under Operating Conditions from Reactive Distillation
  15. Surface Modification of the ZnO Nanoparticles with γ-Aminopropyltriethoxysilane and Study of Their Photocatalytic Activity, Optical Properties and Antibacterial Activities
  16. One-Pot Isomerization of n-Alkanes by Super Acidic Solids: Sulfated Aluminum-Zirconium Binary Oxides
  17. Photocatalytic Decomposition of Metoprolol and Its Intermediate Organic Reaction Products: Kinetics and Degradation Pathway
Sign up now to receive a 20% welcome discount
Institutional Access
How does access work?
Have an idea on how to improve our website?
Please write us.
© 2025 De Gruyter Brill
Downloaded on 26.9.2025 from https://www.degruyterbrill.com/document/doi/10.1515/ijcre-2015-0129/html
Scroll to top button