Preparation and Characterization of Ce-Zr/Al-MCM-41 Bimetallic Catalyst for Transesterification of Jatropha Oil to Biodiesel

Abstract

Abstract.A series of bimetallic Ce-Zr heterogeneous catalysts supported on Al-MCM-41 aluminosilicate with cerium and zirconium loading ranging from 2.5 to 7.5 wt%, were prepared by co-impregnation method. The characterization of the catalysts obtained by various analytical methods; XRD, N2 adsorption-desorption, FESEM, EDX and TPD NH3. The result shows that metals were well incorporated in the framework of the support, catalysts retained the mesoporous character and stability of structure after impregnation. The catalysts were active in one step transesterification of non-edible jatropha oil to produce fatty acid methyl esters (FAME) with methanol to oil ratio 6:1 at 90˚C, after 4 h reaction time. The FAME yield was found to have the maximum activity, higher than 80% with catalyst 5 wt% Ce and 5 wt% Zr loadings supported by Al-MCM-41 with catalyst loading 5 wt%. The catalyst was recovered by simple filtration. IntroductionRecently, increasing attention has been paid to mesoporous molecular sieves having ordered hexagonal arrangements, high specific surface areas, and uniform pore diameters [1]. Modification of mesoporous aluminosilicates gives rise to a platform for wider application possibilities in industry and catalysis. The structurally stable mesoporous material, Al-MCM-41 has both hydrothermal stability and acidity properties unlike the parent material, MCM-41 [2].According to Avhad and Marchetti [3], an ideal catalyst should have superior activity and selectivity, be abundant, less expensive, durable, reusable, and be easy to separate. Although Al-MCM-41 have the requirements necessary for solid catalysts, the activity in alkyl ester conversion was found to be low and this weak performance was related to the acidity of the catalyst [4]. Active metals are incorporated into the framework of Al-MCM-41 as a support, in order to regulate the acidity. Moreover, catalyst efficiency depends on factors such as surface area, pore size and activity sites [5].Distribution of acid strength on the surface of molecular sieves is regulated to improve their activity, selectivity as well as the stability in biodiesel formation reaction processes. Ceria-zirconiaalumina samples synthesized by sol-gel process exhibited an increase in thermal instability at high temperature and high concentration of the ceria which was regulated with an increase in zirconia concentration [6]. According to the study conducted by Neto and Schmal [7] on iso-synthesis reaction with ceria and ceria-zirconia solid catalysts, strong basic sites and high selectivity was presented by ceria-zirconia as compared to ceria only.