Effect of temperature on the adsorption of short alkanes in the zeolite ssz-13-adapting adsorption isotherms to microporous materials

Tao Jiang, Florian Göltl, Rosa E. Bulo, Philippe Sautet

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

Understanding the diffusion and adsorption of hydrocarbons in zeolites is a highly important topic in the field of catalysis in micro-and mesoporous materials. Especially, the properties of alkanes in zeolites have been studied extensively. A theoretical description of these processes is challenging, because two interactions are involved: the alkane physisorbs to the zeolite wall and chemisorbs weakly to the active centers. At room temperature, the alkane remains physisorbed almost all the time, but the chemical bond to the active sites is regularly broken. In this work, we study this behavior using ab initio molecular dynamics simulations for the adsorption of methane, ethane, and propane in SSZ-13, the zeolite with the smallest unit cell, at temperatures of 250, 275, 325, and 350 K. We find a temperature dependence of the adsorption energy and the probability of the alkane to be close to the active site, which corresponds to chemisorption. We derive a temperature-dependent expression for these probabilities or active site coverages, which have the energy difference between physisorbed and chemisorbed state as the main variable. The methodology derived in this work will be highly useful in correlating static electronic structure calculations to finite temperature coverages, which, following the Sabatier principle, is a key step to understand the performance of catalysts under reaction conditions and a prerequisite to computationally design such materials.

Original languageEnglish (US)
Pages (from-to)2351-2358
Number of pages8
JournalACS Catalysis
Volume4
Issue number7
DOIs
StatePublished - Jul 3 2014
Externally publishedYes

Keywords

  • ab initio molecular dynamics
  • confinement effects
  • coverage
  • ethane
  • methane
  • propane

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)

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