The research of rare earth modification on solid acid SO42−/ZrO2 catalysts

Rare earth modified SO₄^2-/ZrO₂ solid acid catalysts were prepared by coprecipitation and impregnation methods respectively. The properties of the samples were characterized by XRD, FT-IR, and N₂ adsorption-desorption techniques. And their catalytic performances were evaluated and investigated by transesterification of waste oil with methanol. The results showed that the catalyst containing 4% La and calcined at 600°C displayed the highest production rate and the better reuse ability than the others. 64.68% yield of fatty acid methyl ester was achieved. An analysis of XRD patterns reveal that the incorporation of rare earth into tetragonal zirconia stabilizes the compound, and the calcination at 600°C increases the reactivity of the catalyst by producing a greater fraction of active tetragonal zirconia with a larger surface area. It can be seen from the FT-IR spectra that superacids structures are formed in the catalysts and the acidity is strengthened remarkably and the activated centre of the catalyst were increasesed.