Reusability enhancement of combustion synthesized MgO/MgAl2O4 nanocatalyst in biodiesel production by glow discharge plasma treatment

Abstract

In this study, plasma technology was used to prepare the catalysts for biodiesel production. The base of MgO/MgAl2O4 particles was prepared by combustion synthesis method to attain suitable porosity for large molecules of triglyceride and then active phase of MgO was dispersed on the samples by impregnation method. The nanocatalysts were characterized by XRD, FESEM, EDX, BET-BJH, FTIR, TGA and Particle size distribution analyses. In order to evaluation the catalytic activity of the samples in biodiesel production, the transesterification reaction was performed under these conditions: reaction temperature=110°C, methanol-to-oil molar ratio=12, catalyst concentration=3wt.% and reaction time=3h. XRD and FTIR results confirm successful synthesis of MgO/MgAl2O4. Meanwhile, XRD and EDX analyses indicated that MgO in modified sample by plasma has suitable size distribution. FESEM and BET-BJH analyses reveal proper morphology in both samples and showed higher surface area and pore size in plasma treated sample. TG analysis showed that applying plasma on the catalyst leads to successful removal of unwanted functional groups remaining from synthesis process. By using catalysts for biodiesel production, it became clear that despite the almost same conversion (96.5% and 95.7% for treated and untreated catalysts, respectively) whereas treated sample exhibited better quality in terms of reusability so after 5 times reuse (the amount of deactivation was 5.6% and 17.1% for treated and untreated samples, respectively). The results of this study showed that plasma technology can improve the characteristics of the catalysts used in the biodiesel production process and it can also improve their economic susceptibility.