Effect of ethanedioic acid functionalization on Ni/Al2O3 catalytic hydrodeoxygenation and isomerization of octadec-9-enoic acid into biofuel: kinetics and Arrhenius parameters

The effect of ethanedioic acid (EdA) functionalization on Al2O3 supported Ni catalyst was studied on the hydrodeoxygenation (HDO), isomerization, kinetics and Arrhenius parameters of octadec-9-enoic acid (OA) into biofuel in this report. This was achieved via synthesis of two catalysts; the first, nickel alumina catalyst (Ni/Al2O3) was via the incorporation of inorganic Ni precursor into Al2O3; the second was via the incorporation nickel oxalate (NiOx) prepared by functionalization of Ni with EdA into Al2O3 to obtain organometallic NiOx/Al2O3 catalyst. Their characterization results showed that Ni species present in Ni/Al2O3 and NiOx/Al2O3 were 8.2% and 9.3%, respectively according to the energy dispersive X-ray result. NiOx/Al2O3 has comparably higher Ni content due to the EdA functionalization which also increases its acidity and guarantees high Ni dispersion with weaker metal-support-interaction leading to highly reducible Ni as seen in the X-ray diffraction, X-ray photoelectron spectroscopy, TPR and Raman spectroscopy results. Their activities tested on the HDO of OA showed that NiOx/Al2O3 did not only display the best catalytic and reusability abilities, but it also possesses isomerization ability due to its increased acidity. The NiOx/Al2O3 also has the highest rate constants evaluated using pseudo-first-order kinetics, but the least activation energy of 176 kJ/mol in the biofuel formation step compared to 244 kJ/mol evaluated when using Ni/Al2O3. The result is promising for future feasibility studies toward commercialization of catalytic HDO of OA into useful biofuel using organometallic catalysts. (C) 2016 Science Press and Dalian Institute of Chemical Physics. All rights reserved.