Jose G.A. Pacheco

Flash Pyrolysis of Oleic Acid as a Model Compound Adsorbed on Supported Nickel Catalysts for Biofuel Production

Flash pyrolysis of oleic acid was studied over 10 wt.% nickel catalysts supported on silica and alumina. The catalysts were impregnated with 10 wt.% oleic acid. The dried precursors and the catalysts containing oleic acid were characterized by thermogravimetric analysis. The calcined catalysts were analyzed by X-ray diffraction (XRD) and temperature programmed reduction (TPR). Samples containing adsorbed oleic acid were submitted to flash pyrolysis up to 650 °C. Whereas pyrolysis of oleic acid without catalyst converted only about 10%, the pyrolysis of oleic acid adsorbed on catalysts allowed practically a complete conversion. NiO/alumina yielded a higher amount of liquid hydrocarbons than NiO/silica. The main products obtained with NiO/silica were 1-alkenes, whereas the main products obtained with NiO/alumina were alkene isomers and aromatics. Small amounts of oxygenated compounds were also observed, principally alcohols. The flash pyrolysis of oleic acid adsorbed on different catalyst surfaces appears as a useful way to distinguish activity trends of different catalyst samples.

Characterization and Acidic Properties of AlMCM-41 Prepared by Conventional and Post-Synthesis Alumination

The catalysts analysed in the current work are variations of MCM-41. The properties of these highly ordered mesoporous aluminosilicates were adjusted by an isomorphous substitution of Si by a trivalent cation, in this case Al3+, generating catalysts of the AlMCM-41 type. The materials were synthesized with a silicon/aluminium ratio of 40, through two methods of impregnation of the metal: conventional and post-synthesis alumination. With the aim of determining the density of the acid sites of the Al40MCM-41 prepared by post-synthesis and conventional alumination, studies of the adsorption of n-butylamine probe molecule were carried out. Further, the studied material was characterized by thermogravimetry measurements, providing the profile of decomposition of the samples, which allowed calculation of the densities of the acid sites. The model-free kinetic algorithms were applied in order to determinate conversion and apparent activation energy. Comparison of energy-dispersive X-ray fluorescence and X-ray photoelectron spectroscopy measurements indicated that the post-synthesis method was more favourable based on the metal positioning, ‘anchored’ in the surface of the catalyst. The textural properties of the calcined Al40MCM-41 prepared by post-synthesis and conventional alumination were characterized by X-ray diffraction, N2 isothermal adsorption measurements (Brunauer–Emmett–Teller and Barrett–Joyner–Halenda), transmission electron microscopy, and X-ray photoelectron spectroscopy.

Comprehensive near infrared study of Jatropha oil esterification with ethanol for biodiesel production

This work presents a comprehensive near infrared study for in-line monitoring of the esterification reaction of high acid oils, such as Jatropha curcas oil, using ethanol. Parallel reactions involved in the process were carried out to select a spectral region that characterizes the evolution of the esterification reaction. Using absorbance intensities at 5176cm(-1), the conversion and kinetic behaviors of the esterification reaction were estimated. This method was applied to evaluate the influence of temperature and catalyst concentration on the estimates of initial reaction rate and ester conversion as responses to a 2(2) factorial experimental design. Employment of an alcohol/oil ratio of 16:1, catalyst concentration of 1.5% w/w, and temperatures at 65°C or 75°C, made it possible to reduce the initial acidity from 18% to 1.3% w/w, which is suitable for transesterification of high free fatty acid oils for biodiesel production. Using the proposed analytical method in the esterification reaction of raw materials with high free fatty acid content for biodiesel makes the monitoring process inexpensive, fast, simple, and practical.