The Roles of the Structure and Basic Sites of Sodium Titanates on Transesterification Reactions to Obtain Biodiesel

Abstract

Sodium titanates were evaluated as heterogeneous catalysts for biodiesel production. Materials were prepared using an experimental design considering NaOH and TiO2 concentrations and hydrothermal and calcination temperatures as input variables. Materials characterization was carried out by DRX-Rietveld refinement, CO2-TPD, and XPS. Statistical analysis of the experimental results indicates that the calcination temperature is the most influential factor in the formation of sodium titanates with high catalytic performance in transesterification reactions. Further analysis of the oil-to-biodiesel conversion revealed that the catalytic activity of sodium titanates is directly correlated to the catalyst associated species and to the density of medium-strong basic sites on the surface of the material, obtaining up to 95% conversion to biodiesel at 60 °C using 3.6% weight catalyst with respect to oil.

Biodiesel Production Using Lithium Metasilicate Synthesized from Non-Conventional Sources

“…Biodiesel production. The detailed procedure has been described elsewhere [ 17 ], the reactor was initially filled with methanol and a certain amount (1 wt.% and 5 wt.%) of catalyst. The reactor was heated for 30 min at a temperature of 60 °C under vigorous stirring.…”

“…Moreover, alternative materials with better physicochemical properties have been explored to replace CaO as heterogeneous catalysts in transesterification reactions. Among them, several materials and composites such as CaTiO 3 , CaZrO 3 , CaO–CeO 2 , CaMnO 3 , Ca 2 Fe 2 O 5 , KOH/Al 2 O 3 , sodium titanates, lithium compounds (silicates and carbonates), have been explored [ 8 , 16 , 17 , 18 ]. For instance, lithium silicates, inorganic materials with good thermal and chemical stability have been proposed as potential heterogeneous catalysts in biodiesel production due to its basic sites strength, high melting point (1200 °C), and good stability toward ambient conditions, this is mainly due to its low CO 2 absorption rate at temperatures below 250 °C [ 19 ].…”

Developments in Titanium‐Based Alkali and Alkaline Earth Metal Oxide Catalysts for Sustainable Biodiesel Production: A Review

“…In this report, a combinatorial approach was used to correlate the sodium titanate structures and basic sites for the transesterification catalysis. This method could be applied to other chemical reactions involving sodium titanate catalysts [144] . Another research group [145] performed the transesterification of sunflower oil catalyzed by sodium titanate nanotubes (Na 2 Ti 3 O 7 ) and the catalyst showed highest efficiency to achieve 95.97 % biodiesel yield with 1.5 wt.% catalyst dosage at 80 °C for 120 minutes.…”

“…This method could be applied to other chemical reactions involving sodium titanate catalysts. [144] Another research group [145] performed the transesterification of sunflower oil catalyzed by sodium titanate nanotubes (Na 2 Ti 3 O 7 ) and the catalyst showed highest efficiency to achieve 95.97 % biodiesel yield with 1.5 wt.% catalyst dosage at 80 °C for 120 minutes. In the reaction mechanism, the adsorption of methanol and triglycerides (myristic acid) on the surface of Na 2 Ti 3 O 7 nanotubes is shown in Figure 9(a) and (b).…”

Biodiesel Production via Transesterification Reaction over Mono- and Bimetallic Copper-Noble Metal (Pt, Ru) Catalysts Supported on BEA Zeolite

“…The main disadvantages of homogeneous catalysts include the difficulty or impossibility of their reuse and susceptibility to deactivation in the presence of water and free fatty acids in the starting raw material [17]. To avoid problems associated with the use of homogeneous catalysts in the transesterification of triglycerides, a viable solution is to replace them with heterogeneous catalysts [18]. Compared to homogeneous catalysts, the use of a heterogeneous catalyst in the transesterification reaction has great advantages, because it can be more easily separated from the products and the biodiesel can be purified more easily after the reaction [19].…”