Mechanistic Insights of Ethanol Steam Reforming over Ni鈥揅eOx(111): The Importance of Hydroxyl Groups for Suppressing Coke Formation

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• 作者：Zongyuan Liu ; Tom谩拧 Ducho艌 ; Huanru Wang ; Erik W. Peterson ; Yinghui Zhou ; Si Luo ; Jing Zhou ; Vladimir Matol铆n ; Dario J. Stacchiola ; Jos茅 A. Rodriguez ; Sanjaya D. Senanayake
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：August 13, 2015
• 年：2015
• 卷：119
• 期：32
• 页码：18248-18256
• 全文大小：553K
• ISSN：1932-7455

文摘

We have studied the reaction of ethanol and water over Ni鈥揅eOb>2-xb>(111) model surfaces to elucidate the mechanistic steps associated with the ethanol steam reforming (ESR) reaction. Our results provide insights about the importance of hydroxyl groups to the ESR reaction over Ni-based catalysts. Systematically, we have investigated the reaction of ethanol on Ni鈥揅eOb>2-xb>(111) at varying Ce³⁺ concentrations (CeOb>1.8鈥?.0b>) with absence/presence of water using a combination of soft X-ray photoelectron spectroscopy (sXPS) and temperature-programmed desorption (TPD). Consistent with previous reports, upon annealing, metallic Ni formed on reduced ceria while NiO was the main component on fully oxidized ceria. Ni⁰ is the active phase leading to both the C鈥揅 and C鈥揌 cleavage of ethanol but is also responsible for carbon accumulation or coking. We have identified a Nib>3b>C phase that formed prior to the formation of coke. At temperatures above 600 K, the lattice oxygen from ceria and the hydroxyl groups from water interact cooperatively in the removal of coke, likely through a strong metal鈥搒upport interaction between nickel and ceria that facilitates oxygen transfer.