Biodiesel Production with Nanotubular Sodium Titanate Doped with Potassium as a Catalyst
- PDF / 382,364 Bytes
- 6 Pages / 432 x 648 pts Page_size
- 75 Downloads / 173 Views
Biodiesel Production with Nanotubular Sodium Titanate Doped with Potassium as a Catalyst Elena Martínez-Klimova1, Patricia Hernández-Hipólito2 and Tatiana E. Klimova3 1 Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México (UNAM), Cd.Universitaria, Coyoacán, México D.F., 04510, México 2 Instituto de Química, Universidad Nacional Autónoma de México (UNAM), Cd.Universitaria, Coyoacán, México D.F., 04510, México 3 Facultad de Química, Universidad Nacional Autónoma de México (UNAM), Cd.Universitaria, Coyoacán, México D.F., 04510, México ABSTRACT In the present work, sodium titanate nanotubes doped with potassium were synthesized by the Kasuga method and tested as catalysts for biodiesel production. Potassium was added to the nanotubes in order to increase their basicity and, consequently, improve their performance in the transesterification of soybean oil with methanol. In the synthesis, the NaOH:KOH molar ratio was changed from 9:1 to 7:3 in order to increase potassium loadings in the obtained nanotubular solids. Synthesized catalysts were characterized by N2 physisorption, powder XRD, scanning electron microscopy (SEM-EDX), transmission electron microscopy (TEM), FT-IR, FT-Raman and CO2 temperature-programmed desorption (CO2-TPD). Obtained results showed that sodium trititanate nanotubes containing 1.5 wt. % of potassium were obtained when 10 M alkali solution with NaOH:KOH molar ratio of 9:1 was used. In this case, the proportion of sodium and potassium in the synthesized material was similar to that used in the synthesis. An increase in the proportion of KOH to 20 and 30 molar % in the NaOH-KOH solutions used in the synthesis allowed obtaining titanate nanotubes with larger potassium loadings (3.2 and 3.3 wt. %, respectively). As it was expected, potassium addition to the sodium titanate nanotubes resulted in an increase in the amount of medium and strong basic sites. Potassium-containing nanotubes showed higher catalytic activity in the transesterification reaction than the pure sodium counterpart used as a reference. The best results were obtained with the samples containing 3.23.3 wt. % of potassium where a biodiesel yield of about 94-96 % was obtained at 80 oC and 1 h reaction time. INTRODUCTION Nanotubular materials are of great interest because of their exceptional electronic and mechanical properties. Among different oxide nanotubes, TiO2-based nanotubes are particularly interesting because of their large specific surface area and novel properties. Titania nanotubes have already been reported as high-performance photocatalysts and catalytic supports, adsorbents in environmental purification, as well as catalysts for decomposition of pollutants, generation of hydrogen, etc. [1]. The synthesis of titania nanotubes by a hydrothermal treatment of a TiO2 precursor with an alkali solution was reported for the first time by Kasuga et al. [2,3]. It was found that prepared nanotubular structures are formed by hydrated sodium titanate phase (generally accepted to be Na2Ti3O7·xH2O), from which
Data Loading...
