Mônica Antunes Pereira da Silva

Estolides Synthesis Catalyzed by Immobilized Lipases

Estolides are vegetable-oil-based lubricants obtained from oleic acid or any source of hydroxy fatty acids. In this work, the estolides synthesis from oleic acid and methyl ricinoleate (biodiesel from castor oil), using immobilized commercial lipases (Novozym 435, Lipozyme RM-IM, and Lipozyme TL-IM) in a solvent-free medium was investigated. Acid value was used to monitor the reaction progress by determining the consumption of acid present in the medium. Novozym 435 showed the best performance. Water removal improved the conversion. Novozym 435 was more active at atmospheric pressure. Novozym 435 was reused four times with conversion reaching 15% after the fourth reaction at 80°C. Estolides produced under the reaction conditions used in this work presented good properties, such as, low temperature properties as pour point (−24°C), viscosity (23.9 cSt at 40°C and 5.2 cSt at 100°C), and viscosity index (153).

Reduction of NO by CO on Pt-MoO3/γ-Al2O3 catalysts

Abstract This work is concerned with the interaction between platinum and molybdenum oxide for Pt-MoO 3 /γ-Al 2 O 3 catalysts. Two types of characterization techniques were used: thermal analysis; and NO and H 2 desorption at programmed temperature. The results of thermal analysis as well as those of hydrogen desorption suggest bronze formation for catalysts with Mo. The NO desorption data show that Mo is the main responsible for the N 2 selectivity. The activity of the catalysts was evaluated with reduction of nitric oxide by carbon monoxide. A synergic behavior was observed between Pt and Mo. Product selectivity of the NO reduction by CO is function of the prevailing treatment and reaction conditions and suggests significant changes of surface sites during the reaction.

Enzymatic synthesis of monolaurin

The aim of this study was to produce monolaurin utilizing a commercial immobilized lipase (Lipozyme IM-20; Novo Nordisk, Bagsvaerd, Denmark) through the direct esterification of lauric acid and glycerol in a solvent-free system. The influence of fatty acid/glycerol molar ratio, temperature, and Lipozyme (IM-20) concentration on the molar fraction of monolaurin were determined using an experimental design. The best conditions employed were 55°C, lauric acid/glycerol molar ratio of 1.0, and 3.0% (w/w) enzyme concentration. The final product, obtained after 6 h of reaction, was 45.5% monolaurin, 26.8% dilaurin, 3.1% trilaurin, and 24.6% lauric acid. The reusability of the enzyme was also studied.

The effect of pressure on promoted Ru and Re-Co/Niobia catalysts in the Fischer-Tropsch synthesis

Abstract Co/Nb2O2, Co-Ru/Nb2O5 and Co-Re/Nb2O5 catalysts were prepared and characterized by TPR. The catalysts were investigated on CO hydrogenation under 0.4, 2 and 4Mpa. The total pressure has an important effect on the product distribution. The selectivity toward diesel and C5+ hydrocarbons achieves a maximum at reaction pressure of 2.0Mpa. The catalysts had good stability over 50h on stream at reaction conditions.