Acid-Promoter-Free Ethylene Methoxycarbonylation over Ru-Clusters/Ceria: The Catalysis of Interfacial Lewis Acid–Base Pair

Abstract

The interface of metal-oxide plays pivotal roles in catalytic reactions, but its catalytic function is still not clear. In this study, we report the high activity of nanostructured Ru/ceria (Ru-clusters/ceria) in the ethylene methoxycarbonylation (EMC) reaction in the absence of acid promoter. The catalyst offers 92% yield of MP with TOF of 8666 h, which is about 2.5 times of homogeneous Pd catalyst (∼3500 h). The interfacial Lewis acid-base pair [Ru-O-Ce-Vö], which consists of acidic Ce-Vö (oxygen vacancy) site and basic interfacial oxygen of Ru-O-Ce linkage, acts as active site for the dissociation of methanol and the subsequent transfer of hydrogen to the activated ethylene, which is the key step in acid-promoter-free EMC reaction. The combination of H MAS NMR, pyridine-IR and DFT calculations reveals the hydrogen species derived from methanol contains Brönsted acidity. The EMC reaction mechanism under acid-promoter-free condition over Ru-clusters/ceria catalyst is discussed.

Insight Observation of Simultaneously Enhanced CO Tolerance and Stability of Pt Electrocatalysts Decorated with Oxygen Vacancy Rich Cerium Oxide

“…Pt−O−Ce bond can be therefore generated on the interfaces between CeO x and Pt. Pt−O−Ce bond was observed at 71.9 eV clarified by Mori et al ., which was also similar to the reported Ru‐O−Ce bond . Pt−O−Ce bonds in C/PBI/Pt@CeO x were supposed to be formed during the hydrothermal process, agreeing well with previous report .…”

Morphology‐Tuned Activity of Ru/Nb2O5 Catalysts for Ketone Reductive Amination

“…1635 cm À 1 appeared in the spectrum of Nb 2 O 5 À L, which can be assigned to the coordination of carbonyl group of CPO with Lacid sites. [17] In the case of 1 %Ru/Nb 2 O 5 À L, the broad peak at around 1635 cm À 1 still exists, suggesting that CPO is indeed adsorbed on the support. However, two new peaks at 1592 cm À 1 and 1558 cm À 1 appear in the spectrum of 1 %Ru/ Nb 2 O 5 À L. The former one can be assigned to the carbonyl group in CPO adsorbed on the surface of Ru particles, and the latter one can be considered as the carbonyl group of the aldol condensed by-products (Figure 5a, others) coordinated to Lacid sites.…”

“…It can be seen only one broad band at ca. 1635 cm −1 appeared in the spectrum of Nb 2 O 5 −L, which can be assigned to the coordination of carbonyl group of CPO with L‐acid sites . In the case of 1 %Ru/Nb 2 O 5 −L, the broad peak at around 1635 cm −1 still exists, suggesting that CPO is indeed adsorbed on the support.…”

“…However, two new peaks at 1592 cm −1 and 1558 cm −1 appear in the spectrum of 1 %Ru/Nb 2 O 5 −L. The former one can be assigned to the carbonyl group in CPO adsorbed on the surface of Ru particles, and the latter one can be considered as the carbonyl group of the aldol condensed by‐products (Figure a, others) coordinated to L‐acid sites . The wavenumber of C=O groups shows an approximately 40 cm −1 red‐shift over Ru species than that over the pristine Nb 2 O 5 support, demonstrating that Ru species show a stronger ability to activate the C=O group.…”

The Synthesis of Quinazolinones from Olefins, CO, and Amines over a Heterogeneous Ru‐clusters/Ceria Catalyst

“…In ap revious study,w e reported the excellent catalytic performance of Ru-clusters/ ceria in the carbonylation of ethylene to methyl propionate. [15] Thus,the Ru-clusters/ceria was also applied in the synthesis of quinazolinones from olefins,C O, and amines.T he results showed that the reaction could proceed smoothly with a38% yield (by GC) of product 3.The yield increased to more than Scheme 1. Different catalytic systems for the synthesis of quinazolinones.…”