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Producing dimethyl carbonate (DMC) from CO2 and methanol offers significant potential for carbon utilization. Ceria (CeO2) is a key catalyst due to its abundant oxygen vacancies essential for CO2 activation, but enhancing its catalytic performance for practical applications remains challenging. While doping with REMs (rare earth metals) has been recognized as a potential strategy for modulating defect sites of ceria, incorporating praseodymium (Pr) into defect-rich nanostructured ceria to optimize DMC synthesis is still unexplored. Herein, we systematically synthesized a series of CeO2 catalysts using Ce containing metal–organic framework (MOF) templates, including Ce-MOF-808 and Ce-BTC, and further doped them with various rare earth metals (REMs) to evaluate their effectiveness in DMC conversion. Among them, Pr-doped CeO2 derived from Ce-BTC templates exhibited the highest reactivity for DMC formation in a gas-phase flow reaction system. High-resolution imaging (HAADF and ABF-STEM) and spectroscopic analyses (Raman, XANES and XPS) revealed that Pr-doped CeO2 from BTC exhibited significantly higher oxygen defect concentrations. Temperature-programmed desorption (TPD) of CO2 and NH3 showed that Pr-doped CeO2 possesses enhanced acidic and basic properties, attributable to higher oxygen vacancies. These facilitated the formation of key reaction intermediates, such as bicarbonates and methoxy species, observed in in situ DRIFTS, leading to improved DMC yields in gas-phase reactions. Density Functional Theory (DFT) calculations corroborated these experimental findings, highlighting the pivotal role of defect sites in the activation of CO2 and methanol, crucial for efficient DMC formation. [ABSTRACT FROM AUTHOR]

Although ethanol dry reforming is an attractive carbon utilization technology, problems of severe coke formation and low catalytic activity should be solved for realization of the technology. We demonstrate the effects of alkali metal additives (lithium, sodium, and potassium) on nickel catalyzed ethanol dry reforming. Potassium doped nickel catalyst (Ni/K2O-Al2O3) showed enhanced catalytic activity and durability in ethanol dry reforming. Thermogravimetric analysis (TGA) showed that Ni/K2O-Al2O3 had a high resistance to coke formation. The amounts of coke formed on Ni/K2O-Al2O3 were 1/3 lower than the amounts of coke formed on Ni/Al2O3. The total coke quantities were closely correlated to the number of basic sites of the nickel catalysts. Raman spectroscopy and transmission electron microscopy analyses revealed that the alkali metals control the coke formation on the catalysts. [ABSTRACT FROM AUTHOR]