Supports strong metal-support interaction

It is now well established that spillover-backspillover phenomena play an important role in numerous catalytic systems. It is worth reminding that the effect of strong-metal-support interactions (SMSI), which was discovered by Tauster74 and attracted the intense interest of the catalytic community for the least a decade75 was eventually shown to be due to backspillover of ionic species from the Ti02 support onto the supported metal surfaces. 

S.J. Tauster, S.C. Fung, and R.L. Garten, Strong metal-support interactions. Group 8 noble metals supported on T1O2, JACS 100, 170-175 (1978). 

To Illustrate the utility of the technique, we have addressed the question of the anomalous chemlsorptlve behavior of tltanla-supported group VIII metals reduced at high temperatures. The suppression of strong H2 chemisorption on these catalysts has been ascribed to a strong-metal-support Interaction (SMSI) ( ). It has also been found that the reaction activity and selectivity patterns of the catalysts are different In normal and SMSI states... 

The structure of supported rhodium catalysts has been the subject of intensive research during the last decade. Rhodium is the component of the automotive exhaust catalyst (the three-way catalyst) responsible for the reduction of NO by CO [1], In addition, it exhibits a number of fundamentally interesting phenomena, such as strong metal-support interaction after high temperature treatment in hydrogen [21, and particle disintegration under carbon monoxide [3]. In this section we illustrate how techniques such as XPS, STMS, EXAFS, TEM and infrared spectroscopy have led to a fairly detailed understanding of supported rhodium catalysts. 

At the end of the seventies, scientists at Exxon discovered that metal particles supported on titania, alumina, ceria and a range of other oxides, lose their ability to chemisorb gases such as H2 or CO after reduction at temperatures of about 500 °C. Electron microscopy revealed that the decreased adsorption capacity was not caused by particle sintering. Oxidation, followed by reduction at moderate temperatures restored the adsorption properties of the metal in full. The suppression of adsorption after high temperature reduction was attributed to a strong metal-support interaction, abbreviated as SMSI [2]. 

We conclude that strong metal-support interaction is in fact an incorrect name for a phenomenon which is satisfactorily explained by the blocking of adsorption sites due to the covering of metal particles by mobile oxide species from the support. Additionally, these oxide species may act as promoters in catalytic reactions. 

Kalakkad, Datye, and coworkers—TEM indicates strong metal-support interactions in Pt/ceria and Pt/Ce/Al catalysts. Kalakkad et al 362,369 published TEM and probe reaction studies on 0.6%Pt/CeO2 catalysts relevant to ACC catalysis. The... 

The use of supports such as Ti02, where the effect of a strong metal-support interaction (SMSI) was observed at high reduchon temperature, is one of the recommended routes. It is proposed that TiO having coordinatively unsaturated Ti cations that could interact with the electron pair donor site of the C=0 bond, facilitates adsorption of the unsaturated aldehyde in a favorable way to produce UOL [74, 75]. As for the metaUic phase, both theoretical and experimental studies indicate that larger particles improve the selectivity to UOL. In effect, it has been... 

The phenomena which occur in metal-ceramic interface interactions are of great importance in catalysis. There are two types of interactions those which depend on the epitaxy between the metal and the support and those which are independent of it. Strong metal-support interactions are described by the term SMSI. 

Strong metal-support interactions (SMSI) and electronic structures In situ atomic resolution ETEM... 

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