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Using Molecular Dynamics Simulation for Investigation of Sulfuric Compounds Adsorption on Zeolite

Ramezani Shabolaghi, Kianoush | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52647 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Mohammadi, Aliasghar
  7. Abstract:
  8. There are different sulfur compounds in the crude oil, and after combustion all of these sulfuric compounds produce sulfur dioxide, this sulfur dioxide cause acid rain, deactivation of catalysts and also environmental bad effects. So the amount of sulfur that is released should be controlled and this is done by removing sulfuric compounds before combustion. zeolites as adsorbent of sulfuric compounds has been used widely by researches and had given good results. molecular dynamics simulation as an effective way for describing the behavior of these compounds in the molecular level and in scales of angstrom has been used and the effect of van der waals and electrostatic forces between sorbates and sorbents atoms on sorption process has been investigated. In this thesis, diffusion and adsorbtion of ethanethiol in three types of zeolites (MFI, FAU and ZSM-5) has been done by means of molecular dynamics simulation. Because the diffusion in zeolites is strongly dependent on non-structural ions, two types of ions (sodium and silver) that are more used in literature has been selected and their effects has been studied. Dependency of diffusion and sorption on temperature and loading of mercaptan molecules by means of three different forcefields (DREIDING,PCFF and CVFF) has been studied and self diffusivity, activation energy and also the coordination number of mercaptan molecules by means of radial distribution functions and mean square displacement figures had calculated. Mercaptan molecules in channels and cages of zeolites and in presence of non-structural ions has been tracked and their behavior completely analyzed. In these thesis the extraordinary effect of silver ion with respect to sodium ion and also advantages of using the FAU zeolite with respect to MFI and ZSM-5 zeolite has been shown. Perfect selectivity of silver ion provides the condition for sorption of mercaptans in zeolites and exerts a force on mercaptan molecules to separate them from other alkanes
  9. Keywords:
  10. Molecular Dynamics ; ZSM-5 Zeolite ; MFI Zeolite ; Ethyl Mercaptan ; Desulfurizing

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