Catalytic performance of MgO /Fe2O3-SiO2 core-shell magnetic nanocatalyst for biodiesel production of Camelina sativa seed oil: Optimization by RSM-CCD method

Abstract

Many investigations have introduced MgO as a favorable solid base catalyst. Although magnesium oxide catalyst does not have as strong of basic sites as calcium oxide catalyst, it is stable under ambient conditions. Furthermore, magnesium oxide catalyst activity is not sensitive to the water content of the reactants, which makes magnesium oxide catalyst possible for commercial purposes. In addition, the use of the non-magnetic catalyst could be facilely recovered by magnetic and reusable several times without a notable decrease in catalytic activity. In the present study, MgO /Fe2O3-SiO2 core-shell magnetic nanocatalyst was synthesized by precipitation method for biodiesel production. This nanocatalyst was characterized by different techniques such as Fourier transform infrared (FT-IR) to recognize functional groups, measurement magnetic characteristics by vibrating sample magnetometer (VSM), identification of the phase and crystalline structure of nanocatalysts using X-radiation (XRD) and a survey of morphology and surface properties by scanning electron microscopy (SEM). Then, the synthesized catalyst was utilized to synthesis biodiesel from the transesterification reaction of camelina seed oil with methyl alcohol. A high biodiesel efficiency (99 %) was obtained under optimized conditions using the central composite design (CCD) based on the response surface methodology (RSM). The optimization was carried out in two separate parts; the initial part focuses on the optimization of the variables affecting the catalytic performance and the second part includes optimizing the variables affecting the reaction conditions of biodiesel production. The biodiesel was examined by GC- Mass spectra and physicochemical characteristics such as viscosity and refractive index. The optimum performance was achieved over MgO /Fe2O3-SiO2 core-shell magnetic nanocatalyst at calcination time 2.29 h, calcination temperature 650 ͦ C, 55.25 % w/w MgO to Fe2O3-SiO2 core-shell magnetic nanocatalyst, methanol to oil molar ratio 12/1, the catalyst to oil weight ratio 4.9 % w/w, reaction temperature 70 ͦ C and reaction time 4.1 h. Moreover, MgO /Fe2O3-SiO2 core-shell magnetic nanocatalyst could be removed facilely from the reaction system by a magnet and catalytic performance maintained for the four reused cycles. Based on the results, camelina seed oil could be utilized as a promising alternative biofuel for impressive, renewable and green production of biodiesel.