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Title: Relationship of Pt Particle Size with the NOx Storage Performance of Thermally Aged Pt/BaO/Al2O3 Lean NOx Trap Catalysts

Abstract

Relationship between Pt particle size and NOx storage performance was investigated over a model Pt/BaO/Al2O3 and an enhanced lean NOx trap catalyst (LNT). These catalysts were treated at elevated temperature to mimic the effect of thermal aging encountered during the desulfation step in NOx trap catalyst regeneration. Combination of in situ time-resolved X-ray Diffraction (TR-XRD), DRIFT measurement after CO adsorption and TEM observation over the thermally aged samples clearly shows the sintering behavior of Pt crystalline as a function of time and temperature. Under elevated temperatures, the crystalline growth of Pt occurs within a short time (e.g. 1.5 hr) followed by the gradual increase with time. NOx storage reaction performed after successive thermal treatments of catalyst under oxygen and in situ XRD experiment have allowed us to correlate the NOx storage performance with phase change. Comparing the simple Pt-BaO/Al2O3 sample with the enhanced one which shows much less Pt sintering, it was confirmed that the Pt crystalline size plays a critical role in determining the NOx storage activity, in other words, the retention of the small Pt particles after thermal aging is crucial to maintain a higher activity. In conclusion, the prevention of Pt sintering when operated at elevated temperaturemore » must be a key factor to design the more durable LNT catalyst, thus potentially implying the practical importance for the improvement of the LNT technology.« less

Authors:
; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
898102
Report Number(s):
PNNL-SA-49255
VT0401000; TRN: US200705%%412
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Industrial and Engineering Chemistry Research, 45(26):8815-8821
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; PLATINUM; PARTICLE SIZE; SORPTIVE PROPERTIES; NITROGEN OXIDES; ADSORPTION; AGING; CATALYSTS; PERFORMANCE; REGENERATION; BARIUM OXIDES; ALUMINIUM OXIDES; AIR POLLUTION CONTROL; Lean NOx trap; Pt-BaO/Al2O3; thermal aging; Pt sintering; in situ XRD; NOx storage; TEM

Citation Formats

Kim, Do Heui, Chin, Ya-Huei, Muntean, George G., Yezerets, Aleksey, Currier, Neal, Epling, William S., Chen, H.-Y., Hess, Howard .., and Peden, Charles HF. Relationship of Pt Particle Size with the NOx Storage Performance of Thermally Aged Pt/BaO/Al2O3 Lean NOx Trap Catalysts. United States: N. p., 2006. Web. doi:10.1021/ie060736q.
Kim, Do Heui, Chin, Ya-Huei, Muntean, George G., Yezerets, Aleksey, Currier, Neal, Epling, William S., Chen, H.-Y., Hess, Howard .., & Peden, Charles HF. Relationship of Pt Particle Size with the NOx Storage Performance of Thermally Aged Pt/BaO/Al2O3 Lean NOx Trap Catalysts. United States. doi:10.1021/ie060736q.
Kim, Do Heui, Chin, Ya-Huei, Muntean, George G., Yezerets, Aleksey, Currier, Neal, Epling, William S., Chen, H.-Y., Hess, Howard .., and Peden, Charles HF. Wed . "Relationship of Pt Particle Size with the NOx Storage Performance of Thermally Aged Pt/BaO/Al2O3 Lean NOx Trap Catalysts". United States. doi:10.1021/ie060736q.
@article{osti_898102,
title = {Relationship of Pt Particle Size with the NOx Storage Performance of Thermally Aged Pt/BaO/Al2O3 Lean NOx Trap Catalysts},
author = {Kim, Do Heui and Chin, Ya-Huei and Muntean, George G. and Yezerets, Aleksey and Currier, Neal and Epling, William S. and Chen, H.-Y. and Hess, Howard .. and Peden, Charles HF},
abstractNote = {Relationship between Pt particle size and NOx storage performance was investigated over a model Pt/BaO/Al2O3 and an enhanced lean NOx trap catalyst (LNT). These catalysts were treated at elevated temperature to mimic the effect of thermal aging encountered during the desulfation step in NOx trap catalyst regeneration. Combination of in situ time-resolved X-ray Diffraction (TR-XRD), DRIFT measurement after CO adsorption and TEM observation over the thermally aged samples clearly shows the sintering behavior of Pt crystalline as a function of time and temperature. Under elevated temperatures, the crystalline growth of Pt occurs within a short time (e.g. 1.5 hr) followed by the gradual increase with time. NOx storage reaction performed after successive thermal treatments of catalyst under oxygen and in situ XRD experiment have allowed us to correlate the NOx storage performance with phase change. Comparing the simple Pt-BaO/Al2O3 sample with the enhanced one which shows much less Pt sintering, it was confirmed that the Pt crystalline size plays a critical role in determining the NOx storage activity, in other words, the retention of the small Pt particles after thermal aging is crucial to maintain a higher activity. In conclusion, the prevention of Pt sintering when operated at elevated temperature must be a key factor to design the more durable LNT catalyst, thus potentially implying the practical importance for the improvement of the LNT technology.},
doi = {10.1021/ie060736q},
journal = {Industrial and Engineering Chemistry Research, 45(26):8815-8821},
number = ,
volume = ,
place = {United States},
year = {Wed Dec 20 00:00:00 EST 2006},
month = {Wed Dec 20 00:00:00 EST 2006}
}