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CO Oxidation and Site Speciation for Alloyed Palladium–Platinum Model Catalysts Studied by in Situ FTIR Spectroscopy
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2017-11-16 00:00:00 , DOI: 10.1021/acs.jpcc.7b07611 Natalia M. Martin 1 , Magnus Skoglundh 1 , Gudmund Smedler 2 , Agnes Raj 3 , David Thompsett 3 , Peter Velin 1 , Francisco J. Martinez-Casado 4 , Zdenek Matej 4 , Olivier Balmes 4 , Per-Anders Carlsson 1
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2017-11-16 00:00:00 , DOI: 10.1021/acs.jpcc.7b07611 Natalia M. Martin 1 , Magnus Skoglundh 1 , Gudmund Smedler 2 , Agnes Raj 3 , David Thompsett 3 , Peter Velin 1 , Francisco J. Martinez-Casado 4 , Zdenek Matej 4 , Olivier Balmes 4 , Per-Anders Carlsson 1
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In situ Fourier transform infrared spectroscopy was used to study transient CO oxidation over a series of bimetallic Pd–Pt catalysts with different Pd:Pt molar ratios. The catalysts were found to contain both alloyed PdPt nanoparticles (particle sizes 25–35 nm) and monometallic Pd nanoparticles (sizes below 10 nm). For oxygen-free conditions, CO reduces the surface while simultaneously function as a chemical probe molecule whereby the CO adsorption sites can be characterized. Under these conditions, it is shown that adsorbed carbonyl species form both on the Pd and Pt. On platinum, CO adsorbs predominantly linearly on top, whereas on palladium it adsorbes in bridged configurations. This behavior is used for site speciation of the catalysts. The spectra from the bimetallic Pd–Pt catalysts are more complicated than a direct superposition of the spectra for the monometallic catalysts as a consequence of alloy formation and enrichment of Pd at the surface of the reduced catalysts. The temperature-programmed CO oxidation results show that the addition of Pd to the Pt catalyst supported on alumina shifts the CO-poisoned state to lower temperatures, therefore increasing the temperature range for the CO oxidation at low temperatures.
中文翻译：
原位FTIR光谱研究合金钯-铂模型催化剂的CO氧化和位点形态
原位使用傅里叶变换红外光谱研究了一系列具有不同Pd：Pt摩尔比的双金属Pd-Pt催化剂上的瞬时CO氧化。发现该催化剂既包含合金化的PdPt纳米颗粒（粒径为25-35 nm），也包含单金属的Pd纳米颗粒（粒径小于10 nm）。对于无氧条件，CO会还原表面，同时充当化学探针分子，从而可以表征CO的吸附位点。在这些条件下，显示出在Pd和Pt上均形成了吸附的羰基物质。在铂上，CO主要在顶部线性吸附，而在钯上，其以桥联结构吸附。该行为用于催化剂的位点形成。由于合金的形成和还原催化剂表面Pd的富集，双金属Pd–Pt催化剂的光谱比单金属催化剂的光谱直接叠加更为复杂。温度编程的CO氧化结果表明，将Pd添加到负载在氧化铝上的Pt催化剂中会将CO中毒状态转移到较低的温度，因此增加了低温下CO氧化的温度范围。
更新日期：2017-11-16
中文翻译：
原位FTIR光谱研究合金钯-铂模型催化剂的CO氧化和位点形态
原位使用傅里叶变换红外光谱研究了一系列具有不同Pd：Pt摩尔比的双金属Pd-Pt催化剂上的瞬时CO氧化。发现该催化剂既包含合金化的PdPt纳米颗粒（粒径为25-35 nm），也包含单金属的Pd纳米颗粒（粒径小于10 nm）。对于无氧条件，CO会还原表面，同时充当化学探针分子，从而可以表征CO的吸附位点。在这些条件下，显示出在Pd和Pt上均形成了吸附的羰基物质。在铂上，CO主要在顶部线性吸附，而在钯上，其以桥联结构吸附。该行为用于催化剂的位点形成。由于合金的形成和还原催化剂表面Pd的富集，双金属Pd–Pt催化剂的光谱比单金属催化剂的光谱直接叠加更为复杂。温度编程的CO氧化结果表明，将Pd添加到负载在氧化铝上的Pt催化剂中会将CO中毒状态转移到较低的温度，因此增加了低温下CO氧化的温度范围。
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