CO<sub>2</sub> Chemical Conversion Using Catalytics Systems Based on Titanate Nanotubes

Abstract

CO2 is the most important greenhouse gas in terms of emitted quantities and its emission has increased significantly due to the action of anthropogenic sources. Among the alternatives for mitigation of this gas is the direct synthesis of propylene carbonate (PC), which requires efficient and selective catalysts. In this scenario the titanate nanotubes (TNT) are promising catalysts because they can be modified to become selective for the PC synthesis. The present work has the objective to develop titanate nanotubes with different metals (Na, Sn and Zn) as well as protonated titanate nanotubes (HTNT) and to test their efficiency in the direct synthesis of PC. The synthesized nanostructures were characterized by TEM, EDS, XRD and N2 adsorption-desorption. The results showed that the synthesized TNT have a specific surface area of 155, 232, 56 and 140 m2/g (NaTNT, HTNT, SnTNT and ZnTNT, respectively). Besides, the ion exchange of [Na+] by [Sn+2] and [Zn+2] decreased the crystallinity of nanostructure. On the catalytic tests, the system NaTNT/ZnBr2 showed the best results with a yield of 61% and a selectivity of 81% in PC. The catalytic system SnTNT/DMF and ZnTNT/DMF are promising to this reaction showing interesting yields and catalytic activity (59 and 53%; 295 and 265 mmol/g) for PC synthesis.