Ru-CeO2 Nanocatalysts with Weak Metal-Support Interactions for Ethylene Methoxycarbonylation

In this work, Ru-CeO2 prepared by a "melting" method and used as a heterogeneous catalyst for ethylene methoxycarbonylation was investigated, together with two other catalysts prepared by impregnation and aerosol methods. The Ru-CeO2 (1%-M) catalyst demonstrates activity significantly higher than that of the other catalysts with the same Ru content. The XPS and Raman analysis results suggest that the Ru-CeO2 (1%-M) oxygen vacancy content is not the highest among the catalysts prepared using the three methods, even though the content oxygen vacancies have been reported to play a crucial role in carbonylation when using a Ru-CeO2 catalyst. It was discovered that the available Ru-0 (Ru-0 in the freshly prepared sample plus that being transformed from Run+ during reduction) is the other decisive factor in determining the catalyst's performance. We further investigated the high reducibility of the catalyst prepared by using the melting method and discovered that a weak metal-support interaction could be obtained because of the independent formations of Ru and CeO2 crystals with graphite carbon as the barrier. Removing carbon under the optimal conditions could facilitate the as-formed Ru crystals anchored onto CeO2; therefore, there is no strong interaction between Ru and CeO2.