Synthesis, Characterization, and Use of NbV/CeIV-Mixed Oxides in the Direct Carboxylation of Ethanol by using Pervaporation Membranes for Water Removal

• Published in: Chemistry : a European journal 2012-08, Vol.18 (33), p.10324-10334
• Main Authors: Dibenedetto, Angela, Aresta, Michele, Angelini, Antonella, Ethiraj, Jayashree, Aresta, Brunella Maria
• Format: Article
• Language: English
• Subjects: carbon dioxide; carboxylation; Chemistry; diethylcarbonate; Membranes; niobium; pervaporation membranes
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201201561

New catalytic systems based on ceria have been used in the direct carboxylation of ethanol. The catalytic behavior of Al2O3 and Nb2O5 loaded ceria is compared, the latter showing a better performance. A morphological and structural study has been carried out on Nb2O5/CeO2 catalysts in order to explain their behavior in catalysis. Pervaporation membranes have been used for water separation. The synthesis of diethylcarbonate (DEC) has been carried out either in a liquid phase (ethanol) pressurized with CO2 or in supercritical conditions. A set‐up has been developed that allows the production of quite pure DEC (>90 %) with recycling of CO2 and ethanol. Continuous carboxylation of ethanol to diethylcarbonate has been obtained by using NbV‐loaded‐CeO2 mixed oxides under water removal by pervaporation (see figure). These catalysts showed a higher activity compared with other CeO2‐based catalysts. XRD analyses have demonstrated that NbV substitutes CeIV with up to 11 % molar ratio in the CeO2 lattice, causing a severe change of the acid–base properties.