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Effect of heating profile on desorption curve in temperature programmed desorption analysis: Case study of acid sites distribution of SAPO-34

Izadbakhsh, A ; Sharif University of Technology | 2009

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  1. Type of Document: Article
  2. DOI: 10.1007/s10934-008-9237-4
  3. Publisher: 2009
  4. Abstract:
  5. Comparison of the traditional linear heating method of TPD with an original stepwise heating scheme was reported for the first time. Stepwise heating TPD was carried out by keeping the temperature constant as soon as ammonia desorption signal rises until the signal returns to the baseline. More ammonia desorption peaks on a SAPO-34 catalyst were identified using TPD with stepwise heating. The effect of temperature ramp on desorption peak broadening in TPD curve was also addressed. The more distinct ammonia desorption peaks in stepwise TPD indicates that ammonia adsorbs in about five or six different ways on SAPO-34, and attribution of different adsorptions may be explained considering some known features of SAPO's acidity; including adsorption on the bridge hydroxyl groups Brønsted acid sites with different acid strength resulting from different silicon environment of SAPO molecular sieves, adsorption on terminal hydroxyl groups Brønsted acid sites, and by multiple adsorption of ammonia on acid sites. © 2008 Springer Science+Business Media, LLC
  6. Keywords:
  7. Acidity ; Heating profile ; SAPO-34 ; Stepwise ; TPD ; Acid site ; Acid sites distribution ; Acid strengths ; Desorption peaks ; Desorption signals ; Effect of temperature ; Hydroxyl groups ; Linear heating ; SAPO-34 ; Stepwise ; Stepwise heating ; Temperature constant ; Temperature programmed desorption analysis ; TPD ; Acids ; Ammonia ; Gas adsorption ; Heating ; Molecular sieves ; Sieves ; Thermal effects ; Temperature programmed desorption
  8. Source: Journal of Porous Materials ; Volume 16, Issue 5 , 2009 , Pages 599-603 ; 13802224 (ISSN)
  9. URL: https://link.springer.com/article/10.1007/s10934-008-9237-4