Quantum chemical prediction of hydrocarbon cracking reactions

Xiaobo Zheng, Paul Blowers

Research output: Contribution to conferencePaper

Abstract

For many years, researchers have been developing theoretical methods of estimating reaction rates and energetics when experimental measurements are not available. Recent advances have led to composite energy methods with near chemical accuracy. The performance of these new methods for predicting activation energies and rate constants have not been evaluated for large hydrocarbon cracking reactions. In this work, ab initio methods are used to study the transition state structures and activation energies of ethane cracking, hydrogen exchange and dehydrogenation reactions catalyzed by zeolites. The reactant and transition state structures are optimized by HF and MP2 methods and the final energies are calculated using a Complete Basis Set composite energy method. The computed activation barriers are 71.39 kcal/mol for cracking, 31.39 kcal/mol for hydrogen exchange and 75.95 kcal/mol for dehydrogenation using geometries optimized with the MP2 method. The cluster effect and acidity effect on the reaction barriers are also investigated. The relationship between activation barriers and zeolite deprotonation energies for each reaction are proposed so that accurate activation energies can be obtained when using different zeolites as catalysts.

Original languageEnglish (US)
Pages10693-10700
Number of pages8
StatePublished - Dec 1 2004
Event2004 AIChE Annual Meeting - Austin, TX, United States
Duration: Nov 7 2004Nov 12 2004

Other

Other2004 AIChE Annual Meeting
CountryUnited States
CityAustin, TX
Period11/7/0411/12/04

Keywords

  • CBS method
  • Cluster approach
  • Ethane
  • Zeolite

ASJC Scopus subject areas

  • Engineering(all)

Fingerprint Dive into the research topics of 'Quantum chemical prediction of hydrocarbon cracking reactions'. Together they form a unique fingerprint.

  • Cite this

    Zheng, X., & Blowers, P. (2004). Quantum chemical prediction of hydrocarbon cracking reactions. 10693-10700. Paper presented at 2004 AIChE Annual Meeting, Austin, TX, United States.