Studio dell'idrogenazione catalitica selettiva di trigliceridi e dei loro derivati.

The proposed research for an industrial Ph.D regards Green Chemistry, in particular the study of selective catalytic hydrogenation of vegetable oils, to maximize oleic acid and expand the range of non-edible uses. Oleic acid is a carbossilic acid with 18 carbon atoms. It has the suitable characteristics for use as biodegradable lubricant and as a building block in the production of polymers from renewable resources, replacing and/or alongside to those obtained from mineral oils. It is considered a building block of the green polymer chemistry and its use in industry is expected to rise. This stimulates R & D towards the optimization of the production process. In Italy, must be emphasized the commitment of the CNR on the subject. The specific interest towards oleic acid is justified by its stability in the presence of oxygen and it remains liquid even at low temperatures. The oleic acid production is limited and only some oils with high oleic content can be used, limiting market availability. A review of the literature has revealed how to apply the selective hydrogenation to all the common oils on the market; both triglycerides and methyl esters can be hydrogenated. The main challenge of this study is represented by the application of heterogeneous catalyst which allows to saturate the double bonds available in C18 fatty acids, such as C18:2 (linoleic acid) and C18:3 (linolenic acid), with low formation of the stearic acid C18:0 and maximum yield of C18:1. Currently, the Ni-based catalysts do not allow it, they are commonly used in complete hydrogenation. The research activities concern of a selective catalytic process for the hydrogenation of natural vegetable oils, and validation of the production technology, still at laboratory scale, studying the most updated techniques for both preparation and characterization of catalysts, especially non-noble catalysts Cu and Ni and noble catalysts Pd, cited in literature about selective hydrogenation. In the framework of a wide literature of vegetable oils hydrogenation, Zaccheria et al. have shown how hydrogenating canola and soybean oils can achieve low levels of saturated acids and trans isomers with a Cu-based catalyst supported on amorphous silica. Other authors used different kinds of catalysts, both palladium and nickel based, working on operative conditions to obtain low content of unwanted reaction products. In the thesis, both one commercial and 11 synthesised catalysts were used in a hydrogenation laboratory scale plant to selective hydrogenate sunflower and canola oil. The catalysts were characterized by ICP, XRD, N2 adsorption BET, TPR, Raman spectroscopy, FTIR spectroscopy, XPS, SEM-EDS, and TEM. Reduced catalysts have also been characterized. Tests were carried out in a laboratory scale reactor (600 mL) reactor unit operated in semi-batch mode, feeding hydrogen. In order to analyze the composition at different reaction times, samples were taken from the reactor and transesterified and analyzed by GC-FID. In order to develop the hydrogenation procedure and the product analysis method, some tests were carried out with a commercial catalyst, Lindlar catalyst (reduced Pd supported on calcium carbonate poisoned with lead), normally used for hydrogenation reactions. Another Pd based catalysts, Pd supported on hydrotalcite (1% Pd/HT) was synthesized with a method proposed by Di Nicola et al., in this method the reduction of the Pd is obtained reacting with cyclohexene. Two Cu-based catalysts (5% and 10% by weight) on silicon oxide were synthesized by two synthesis methods proposed: Hydrolysis-Precipitation and Ammonia-Evaporation noted. In order to increase the activity of the catalysts while trying to maintain selectivity to oleic acid, bimetallic catalysts containing Cu and Ni or Cu and Pd have been synthesized. In addition the student performed the development and optimization of the entire innovation process, evaluating utilities and production costs of oleic acid.