Effect of potassium addition on bimetallic PtSn/h-Al2O3 catalyst for dehydrogenation of propane to propylene

Title
Effect of potassium addition on bimetallic PtSn/h-Al2O3 catalyst for dehydrogenation of propane to propylene
Authors
정광덕이미현나가라자프라카쉬크롱녹단윤성호이관영
Keywords
K(PtSn)/h-Al2O3 catalyst; Propane dehydrogenation; Propylene; PtSn alloy formation
Issue Date
2016-01
Publisher
Research on chemical intermediates
Citation
VOL 42, 123-140
Abstract
PtSn/h-Al2O3 catalysts with different amounts of K (0.14, 0.22, 0.49, 0.72, and 0.96 wt%) are prepared to investigate the K effects on the PtSn catalyst in propane dehydrogenation (PDH). KPtSn catalyst with 0.xx wt% K, 0.5 wt% Pt and 0.75 wt% Sn is designated as xx-KPtSn. PDH was performed at 873 K and a gas hourly space velocity (GHSV) of 53,000 mL/gcat h. The temperature-programmed desorption (NH3-TPD), temperature-programmed reduction (TPR) and CO chemisorption of the KPtSn catalysts with K added revealed the potassium addition blocked the acid sites, promoted the reduction of Sn oxide and decreased the Pt dispersion. The formations of cracking products and higher hydrocarbons on acid sites were suppressed by the K effect of blocking the acid sites. In contrast, K addition at more than 0.72 wt% rather increased cracking products and the amount of coke, resulting in the severe deactivation of catalysts. The high cracking products on the KPtSn catalysts with the high amount of K should not be related to the acid sites, because the acid sites were monotonously decreased with an increase in the amount of K. Instead, the potassium affected the characteristics of PtSn. The interaction between Pt and Sn could be weakened by enriching the reduced Sn, because the K component promoted the reduction of Sn oxide in the TPR experiments. Therefore, the 14-KPtSn catalyst with the low amount of K exhibits the highest stability and selectivity among the prepared KPtSn catalysts due to the compromise of the advantageous (blocking the acid sites) and bad (weakening the interaction between Pt and Sn) effects of the K addition in PDH.
URI
http://pubs.kist.re.kr/handle/201004/59236
ISSN
09226168
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KIST Publication > Article
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