In this study, metal-doped niobates and perovskites were obtained by a solid-state reaction. The solids were evaluated in the esterification of glycerol in the presence of acetic acid to produce valuable esters of glycerol. The structural features of the solids indicated the ZnNb₂O₆, Pb_2.8Nb₂O_7.8 and CuNb₂O₆ columbite main phases and La₂MnFeO₆ double-perovskite. Density functional theory (DFT) studies of Pb_2.8Nb₂O_7.8 clearly confirmed the existence of a robust orthorhombic structure and its electronic properties were correlated with the Nb and Pb interactions. The morphological and elemental analyses also indicated that not all surface elements, as well as morphology, were crucial for catalytic properties. All solids were active and selective toward triacetin formation upon glycerol esterification with acetic acid. The catalytic performance depends mainly on the availability of the surface and its structural stability, as well as defects formation. Recyclability studies indicated that the La₂MnFeO₆ double-perovskite was an efficient catalyst, achieving glycerol conversion of 68% and triacetin selectivity of 25% up to 4 cycles of use in the reaction. The structural defects near the Mn⁴⁺/Mn³⁺ surface sites resulted in the diffusion of anions and an increased concentration of oxygen vacancies contributed to the stable performance of the solid in glycerol ester production.

中文翻译：

---

用于甘油增值的金属掺杂铌酸盐烧绿石和双钙钛矿：结构和电子特性以及 DFT 计算

在这项研究中，通过固相反应获得了金属掺杂的铌酸盐和钙钛矿。在乙酸存在下的甘油酯化中评价固体以产生有价值的甘油酯。固体的结构特征表明ZnNb ₂ O ₆、Pb _2.8 Nb ₂ O _7.8和CuNb ₂ O ₆铌铁矿主相以及La ₂ MnFeO ₆双钙钛矿。 Pb _2.8 Nb ₂ O _7.8的密度泛函理论（DFT）研究清楚地证实了稳健的斜方结构的存在，并且其电子性质与Nb和Pb相互作用相关。形态和元素分析还表明，并非所有表面元素以及形态都对催化性能至关重要。当甘油与乙酸酯化时，所有固体均具有活性并选择性地形成三醋精。催化性能主要取决于表面的可用性及其结构稳定性以及缺陷的形成。可回收性研究表明，La ₂ MnFeO ₆双钙钛矿是一种高效的催化剂，在反应中使用4个循环后，甘油转化率达到68%，三醋精选择性达到25%。 Mn ⁴⁺ /Mn ³⁺表面位点附近的结构缺陷导致阴离子扩散和氧空位浓度增加，有助于固体在甘油酯生产中的稳定性能。