Novel SnZr oxides nanomaterials synthesized by ultrasonic-assisted co-precipitation method: Application in biodiesel production and DFT study

Abstract

Novel solids as Sn2O3-ZrSnO4 nanoparticles were prepared by ultrasonic- assisted co-precipitation method and were characterized by several techniques. The catalytic efficiency of the sonicated SnZr oxide catalysts was evaluated by biodiesel production through a stearic acid esterification reaction with methanol. Also, the optimization conditions and the kinetic study for the esterification reaction were practically implemented. The optimized catalyst (SnZr15m) gave stearic acid conversion of 88.5% at the optimum conditions with pseudo- first order kinetic reaction and the thermodynamic parameters of the esterification reaction were inspected theoretically and compared with the practical data. Furthermore, the recycling experimental results and the theoretically DFT data proved that the stability of the SnZr15m catalyst in the esterification process was reasonable and possess useful quality. The different phases for tin zirconium oxides have been studied using density functional theory (DFT) calculations at the DFT/B3LYP level of theory, using the GENECP basis set in the gas phase. DFT modeling indicated that the stability of the Sn2O3-ZrSnO4 (Sn3ZrO7) phase is higher than the other phases of SnZr oxide which catalyzed the esterification process. The electronic parameters; dipole moment of these compounds in the ground state theoretically were analyzed by computing HOMO and LUMO pictures. Using frontier molecular orbital (FMO) analysis, non-linear optical (NLO) properties and quantum chemical parameters were evaluated. The charge transfer of the electron density in the studied compounds was characterized by natural bond orbital analysis (NBO). For understanding of the reactivity points, the molecular electrostatic potential surfaces (MEPS) plots have been computed. Finally, Illustration for the proposed interaction between stearic acid, the catalyst (Sn3ZrO7), and methanol to produce the biodiesel was proposed.