دانلود رایگان مقاله کاتالیست اکسید اسپینل فریت مس برای methanolysis روغن نخل

Abstract

Copper ferrite spinel oxide (CuFe2O4) samples with calcination temperatures ranging from 500 to 900 °C were synthesized using the sol-gel combustion method with citric-nitrate precursors. Each calcined sample was further characterized and carefully analyzed for its structure, morphology, porosity, magnetic property and reducibility. For the first time, the catalytic performance of the ferrite spinels was examined for palm oil methanolysis. The characterization results from X-ray diffraction (XRD), extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) analyses revealed that the major part of the active species was divalent ions of Cu2+ and Fe2+ and that they played a crucial role in the activity of the considered spinel catalysts. The catalytic behaviors strongly depended on the crystallinity of spinel structures and operating parameters, such as the catalyst loading and methanol to oil molar ratio. The CuFe2O4 calcined at 700 °C was the most active and selective for methanolysis with palm oil. No activity decline was observed over the catalyst after it was reused for 5 cycles without any post-treatment. Easy and effective catalyst separation could be obtained when magnetization was applied to the magnetic spinel catalysts.

4. Conclusions

Copper-ferrite spinel catalysts have been developed for the heterogeneous transesterification of palm olein oil to biodiesel. The calcination temperature played a crucial role in determining the catalyst properties. The X-ray analysis results demonstrated that the major part of the active species was divalent ions of Cu2+ and Fe2+, which played a significant role in the activity. Leaching and the dissolution of the spinel was observed over the catalyst with a low degree of crystallization calcined at 500 ◦C, while the high calcination temperature of 900 ◦C gave insufficient surface area for the reaction. CuFe2O4 calcined at 700 ◦C having tetragonal spinel phase with excellent crystallinity and good ferromagneticity was the most active catalyst without any deactivation under the testing conditions. High FAME contents (above 90%) were obtained using a methanol:oil molar ratio of 18:1 at 220 ◦C for 7 h.