Furfural Hydrodeoxygenation on iron and platinum catalysts

M. SOLEDAD ZANUTTINI; MARTIN GROSS; C.A. QUERINI

Santa Fe

Congreso; VI San Luis Conference on Surfaces, Interfaces and Catalysis; 2018

INTEC CONICET Santa Fe

Monometallic and bimetallic catalysts of platinum and iron supported on silica were studied with the aim of deoxygenate the molecule of furfural, model compound of bio-oil. These catalysts have been studied for the hydrodeoxygenation of other model compounds (cresol, anisole, phenol) in previous works with excellent results.Through Mossbauer spectroscopy, XRD and TPR technique it was possible to determine the iron status in each catalyst and explain the behavior in reaction. High octane compounds with low solubility in water are the desired products of furfural hydrodeoxygenation process. It is also important to achieve reaction paths with no loss of C to avoid a decrease in system efficiency. Among the possible reaction products, furfuryl alcohol and tetrahydrofurfuryl alcohol as well as tetrahydrofuran are not most suitable as a fuel molecule since they are totally miscible in water. Another possibility of reaction path without opening of the ring is the production of furan and 2-methylfurane, aromatic compounds with high octane number and low solubility in water. However, furan molecule implies the loss of a C. Therefore, this research focuses in maximizing the production of these two last compounds, trying to obtain the highest production of 2-methylfuran as possible, considering the total yield of the system and its properties as fuel. The complete hydrogenation of 2-methylfurane must be avoided, since it generates 2-methyltetrahydrofuran, with a lower octane rating and greater solubility in water.The catalytic activity was evaluated in gas phase at atmospheric pressure in the presence of hydrogen. A comparison of the results obtained with different catalysts studied under the same reaction conditions was made. Monometallic iron catalyst, Fe/SiO2, was more selective than the platinum one, Pt/SiO2, to the desired products due to its lower hydrogenation capacity, with 93% of initial selectivity to 2-MF. The formation of 2-MF occurs by the hydrogenation reaction of the C=O bond to the corresponding alcohol (furfuryl alcohol) catalyzed by metal, and then the alcohol dehydration and elimination of oxygen catalyzed by the acidity, although very low, of the support. Due to their electron configuration, iron atoms have a selective attraction to the O atom of the C=O bond and exhibit repulsion with the ring, allowing a high selectivity towards 2-methylfuran However, iron catalyst presented low stability, showing deactivation during the reaction run. On the other hand, the monometallic platinum catalyst, although less selective to 2-MF, presents greater stability. Based on these results, it was decided to work with Pt-Fe bimetallic catalysts. It was intended to improve the performance of the catalyst in terms of activity, selectivity and stability, based on the synergistic relationship between these two metals. Two bimetallic catalysts with different Fe-Pt (10 and 100) ratio were prepared by co-impregnation technique. The catalyst with Fe-Pt ratio 100 showed better stability than Fe/SiO2 and higher selectivity to the desired products than Pt/SiO2.Besides, a comparative study of regeneration of the catalysts and a quantification and characterization of the coke deposits were carried out.