The interface of metal-oxide plays pivotal roles in catalytic reactions, but its catalytic function is still not clear. Although tremendous advances have been achieved on the interfacial catalysis on metal sites, little attention has been paid to the role of interfacial acid-base catalysis of metal-oxide systems. Recently, we have found that the interfacial Lewis acid−base pair [Ru-O-Ce-Vo], which consists of acidic Ce-Vo site and basic interfacial oxygen of Ru-O-Ce linkage, is readily formed on the Ru-clusters/ceria and plays important roles in catalytic reactions. Based on this discovery, the concept of “Interfacial Acid-Base Pair” is proposed for the first time in the synthesis of methyl propionate via ethylene methoxycarbonylation reaction. The catalyst exhibits 2.5 times higher TOF value than the homogeneous Pd catalyst. The combination of 1H MAS NMR, pyridine-IR and DFT calculations reveals that the interfacial site [Ru-O-Ce-Vo] adsorbs and dissociates methanol, forming interfacial hydroxyl [Ru-<b>O</b>(H)-Ce-Vo] as acidic sites to react with ethylene. This explains why the present system synthesizing methyl propionate does not require mineral acid additives. Further study finds that the quinazolinones can be synthesized over heterogeneous Ru-clusters/ceria catalyst, extending the application of the concept of “Interfacial Acid-Base Pair”. Mechanism research shows that amide species formed during the reaction is verified to be the reaction intermediate. And then the target product quinazolinone is easily obtained <i>via</i> the dehydration of intermediate amide, which can be catalyzed by acid sites on ceria support.

Ru/Ceria catalyzes the C-C/C-N bond formation reactions

2019 Fall National Meeting

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