Solid Acid Resin Amberlyst 45 as a Catalyst for the Transesterification of Vegetable Oil.

Commercial transesterification of vegetable oil to biodiesel using alkaline hydroxides requires expensive refined vegetable oil and anhydrous alcohols to avoid saponification. These issues are not present in the acid-catalyzed process; however, the challenge still lies in developing stable and active solid acid catalysts. Herein, Amberlyst 45, a resin for high-temperature application, was efficiently used for biodiesel production by the methanolysis or ethanolysis of vegetable oil. Yields of up to 80 and 84% were obtained for the fatty acid methyl ester and the fatty acid ethyl ester, respectively. Two processes are proposed and showed to be efficient: (i) incremental addition of alcohol along with the reaction for both methanolysis and ethanolysis; or (ii) one-pot reaction for ethanolysis using oil/ethanol molar ratio of 1/18. The catalytic system used also showed to be compatible with used oil (2.48 ± 0.03 mgNaOH g oil - 1 ) and to the presence of water (10-20 wt. % based on the alcohol), allowing the use of waste oil and hydrated alcohol.

Physicochemical characterization and surface acid properties of mesoporous [Al]-SBA-15 obtained by direct synthesis.

In this work, [Al]-SBA-15 samples were prepared by three different direct synthesis methods and one postsynthesis procedure, aiming to study the influence of the preparation procedures on their structural, textural, and physicochemical features. To this aim, samples were investigated by combining different experimental techniques (XRD, N(2) physisorption, (27)Al-MAS NMR, and IR spectroscopy). All preparation methods led to the formation of aluminum-containing SBA-15 samples. Nevertheless, depending on the preparation procedure, samples exhibited different structural, textural, and surface characteristics, especially in terms of Brønsted and Lewis acid sites content. [Al]-SBA-15(1) was synthesized by the pH-adjusting method and presented the lowest surface area and pore volumes. Its surface displayed three families of medium and one family of high strength Brønsted acid sites. The Brønsted/Lewis ratio was 3.49. [Al]-SBA-15(2) and [Al]-SBA-15(3) were synthesized by prehydrolysis of the silica and the aluminum precursors. In [Al]-SBA-15(2), ammonium fluoride was used as silica condensation catalyst. These two materials presented similar surface area, pore diameters and volumes, and Brønsted acidity. The Brønsted/Lewis acid sites ratio were 3.07 and 2.15 for [Al]-SBA-15(2) and [Al]-SBA-15(3), respectively. The [Al]-SBA-15(P) obtained by postsynthesis alumination displayed surface area similar to that of [Al]-SBA-15(3), Brønsted/Lewis acid sites ratio of 2.75, and Brønsted acidity similar to that of [Al]-SBA-15(1). The presence of extra-framework aluminum oxide was identified only on [Al]-SBA-15(3) and [Al]-SBA-15(P).