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This content will become publicly available on February 19, 2019

Title: Understanding the Reactive Adsorption of H 2S and CO 2 in Sodium-Exchanged Zeolites

Purifying sour natural gas streams containing hydrogen sulfide and carbon dioxide has been a long-standing environmental and economic challenge. In the presence of cation-exchanged zeolites, these two acid gases can react to form carbonyl sulfide and water (H 2S+CO 2H 2O+COS), but this reaction is rarely accounted for. In this work, we carry out reactive first-principles Monte Carlo (RxFPMC) simulations for mixtures of H 2S and CO 2 in all-silica and Na-exchanged forms of zeolite beta to understand the governing principles driving the enhanced conversion. The RxFPMC simulations show that the presence of Na + cations can change the equilibrium constant by several orders of magnitude compared to the gas phase or in all-silica beta. The shift in the reaction equilibrium is caused by very strong interactions of H 2O with Na + that reduce the reaction enthalpy by about 20 kJmol -1. The simulations also demonstrate that the siting of Al atoms in the framework plays an important role. Lastly, the RxFPMC method presented here is applicable to any chemical conversion in any confined environment, where strong interactions of guest molecules with the host framework and high activation energies limit the use of other computational approaches to study reactionmore » equilibria.« less
Authors:
 [1] ;  [1] ;  [2] ;  [3] ;  [1]
  1. Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Chemistry and Chemical Theory Center
  2. Argonne National Lab. (ANL), Argonne, IL (United States). Leadership Computing Facility
  3. Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Chemical Engineering and Materials Science
Publication Date:
Grant/Contract Number:
AC02-06CH11357; FG02-12ER16362; SC0008688
Type:
Accepted Manuscript
Journal Name:
ChemPhysChem
Additional Journal Information:
Journal Volume: 19; Journal ID: ISSN 1439-4235
Publisher:
ChemPubSoc Europe
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
03 NATURAL GAS; Monte Carlo simulation; density functional theory; reactive equilibria; sour natural gas
OSTI Identifier:
1426239
Alternate Identifier(s):
OSTI ID: 1422250