Title : Obtaining biofuel from the deoxygenation of bio-oil using nanostructured catalysts
Abstract:
This study developed catalysts based on nano-sized zeolite Y (nanoZY) modified with transition metals (Ni, Mo) and rare earths (La, Ce), for the transformation of guaiacol and highly oxygenated bio-oil into bi-fuels with fossil fuel-like properties by catalytic hydrodeoxygenation (HDO).
Nanozeolite Y ( particle size <100 nm) was synthesized following the method described by Mendoza et al [1] followed by ion exchange with 0.25 M solutions of La(NO3)3·6H2O and Ce(NO3)3·6H2O. The modified supports (xZY x=La,Ce) were pelletized with γ-alumina (60:40 w/w) and sequentially impregnated with MoO? (15%) and NiO (3%) by incipient wet impregnation.
The catalysts obtained were characterized by X-ray diffraction and X-ray fluorescence, scanning electron microscopy, temperature programmed desorption of NH3 and adsorption of N2. XRD characterization confirmed the crystalline structure of nanoZY with a crystallite size of 24.6 ± 1.2 nm and crystallinity of 89%. X-ray fluorescence results corroborated an Si/Al ratio of 2.3 for nanoZY. Moreover, the catalysts showed a combination of type I and IV isotherms, typical of microporous materials such as zeolites and mesoporous materials such as γ-alumina, respectively. According to the NH3-TPD results, the HY and xZY (x=La,Ce) supports presented two desorption peaks, corresponding to the weak and strong acid sites.
The catalytic activity of the materials was evaluated in a fixed bed microreactor (PID Eng&Tech). Initially, it was carried out with guaiacol as a model molecule and subsequently with the bio-oil obtained. The space velocity was 1.0 h-1 and a pressure of 4 MPa in the presence of H2/N2 (Flow rate: 100 mL/min), at temperatures between 150-250°C. The resulting liquid products were analysed by gas chromatography (GC). The incorporation of metals such as La and Ce promoted the absorption of oxygenated compounds and favored the elimination of oxygen present in the bio-oil [2], while Ni and Mo generated active sites capable of dissociating molecular hydrogen, activating it and transferring it to participate in saturation reactions or C-O bond breaking [3].
