Physicochemical Characterization of Highly Dispersed Platinum and Chromium on Zeolite Beta

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• 作者：Yoshiyuki Izutsu ; Yuki Oku ; Yusuke Hidaka ; Naoki Kanaya ; Yoshiki Nakajima ; Jun Fukuroi ; Kaname Yoshida ; Yukichi Sasaki ; Yasushi Sekine ; Masahiko Matsukata
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：May 22, 2014
• 年：2014
• 卷：118
• 期：20
• 页码：10746-10753
• 全文大小：397K
• 年卷期：v.118,no.20(May 22, 2014)
• ISSN：1932-7455

文摘

Structures of platinum and chromium supported on zeolite beta were investigated by XAFS, XPS, UV鈥搗is, NH₃-TPD, XRD, CO chemisorption, and molecular dynamics simulation. Both platinum and chromium were uniformly dispersed in the micropore of zeolite beta. Loading of chromium helped platinum to disperse highly and stabilized in the micropore of beta. Major species of platinum on PtCr/beta after calcination at 773 K was Pt²⁺ forming a Pt鈥揙 bond. The Pt鈥揙 bond disappeared, and a Pt鈥揚t bond did not appear by reducing PtCr/beta in hydrogen, accompanying formation of Pt⁰. Chromium was loaded as chromate anion in the micropore of zeolite. Results of molecular dynamics simulation showed that Pt²⁺ associated with CrO₄^{2鈥?/sup> in the micropore of zeolite beta was more stable than those in the absence of chromium species. We concluded that CrO₄2鈥?/sup> electrostatically stabilizes Pt2+ and inhibits migration and aggregation of platinum.}