Natural and Modified Montmorillonite Clays as Catalysts for Synthesis of Biolubricants.

In this study, natural and modified clays were evaluated as catalysts in an esterification reaction to obtain bio-based lubricants. The biolubricants are environmentally preferred to petroleum-based lubricants because they are biodegradable and non-toxic. Other advantages include very low volatility due to the high molecular weight and excellent viscosity properties with temperature variations. Modifications in natural clay were performed intending to obtain materials with different textural properties that could improve the reaction under study. The modified clays were obtained in two ways: by pillarization using Al13 Keggin polyoxocations or by acid treatments with H2SO4, HCl and HNO3. All samples were evaluated for the esterification reaction of fatty acids from castor oil (FACO) using 2-ethyl-hexanol. During the reaction step, a zeolite-based adsorbent was used for water removal to increase the reaction equilibrium conversion. Gas chromatography and nuclear magnetic resonance were performed to ensure the formation of the products. The highest conversion of fatty acids to esters was obtained using pillared clays. Adding adsorbent in the reaction medium (10 g of 3A zeolite to 100 g of FACO), the conversion improved from 74⁻88 wt % after 6 h at 50 °C.

Characterization of calcium oxide catalysts from natural sources and their application in the transesterification of sunflower oil.

The catalytic activities of calcium oxide obtained from natural sources (crab shell and eggshell) were characterized and evaluated in the transesterification of vegetable oil. These catalysts are mainly composed of calcium carbonate, which is partially converted into CaO after calcination (900°C for 2h). The catalysts have some advantages, such as abundant occurrence, low cost, porous structure, and nontoxic. The materials were characterized by XRD, FTIR, TG/DTG, CO2-TPD, XPS, SEM, and BET methods. The thermal treatment produces small particles of CaCO3 and CaO that are responsible for the catalytic activity. The conversion from triglycerides to methyl ester was not observed in transesterification carried out using natural crab shell and eggshell. Under optimized reaction conditions, the conversions to YFAME using the calcined catalysts were: crab shell (83.10±0.27 wt.%) and eggshell (97.75±0.02 wt.%). These results, showed that these materials have promising viability in transesterification for biodiesel production.