Catalyst-assisted Conversion of Pyrolysis Bio-oil into Fuels

The aldol condensation of model compounds furfural and acetone on the selected base catalysts have been performed. The activity of MgO was compared with industrially produced hydrotalcite and the series laboratory prepared hydrotalcites. Si×MAl2O4 hydrotalcites (M = Mg, Zn, Ni, Co, Cu, and Fe) were prepared by the solgel method at low calcination temperature of 300°C. The properties of the catalysts were evaluated by XRD and BET technique and they had a mesoporous structure. The aldol condensation was performed in the liquid phase preferably in N2 atmosphere, the temperature range of 25-140°C and at elevated pressure. The main condensation products were C8 FAc monomer and C13 F2Ac dimer. The first intermediate FAcol was readily dehydrated and higher temperatures favoured the reaction. The furfural (F) conversion into the C8 product (FAc) from 55.9 up to 94.5% with the selectivity 41.079.5% was reached. In the comparative tests of MHT hydrotalcites performed at 140° C, the best results were obtained in the case of Zn and Mg hydrotalcites despite their low specific surface. High selectivity to F2Ac was observed with Ni and Co hydrotalcites as catalysts with the specific surface area of 178 and 246 m2/g, respectively. As the key parameter for the high conversions the ratio catalyst/furfural close to 0.3 was notified.