Abstract Layered double hydroxides, mixed oxides, and pure oxides based on magnesium and calcium were evaluated as catalysts in the methyl transesterification of soybean oil in a batch reactor. The catalysts were prepared by continuous co-precipitation and characterized by specific surface area, thermogravimetric analysis, temperature-programmed desorption of CO2, and X-ray diffraction. The reactions were performed at 65 °C, methanol-to-oil molar ratio 9:1, catalyst dosage of 1 wt.%, and reaction time of 240 min. The biodiesel analysis was carried out by Fourier Transform Infrared spectroscopy (FTIR) and Gas Chromatography (GC). Calcium-based catalyst, pure oxide (CaO) and mixed oxide (CaAl), demonstrated higher activity for methyl transesterification than magnesium-based catalyst. Considering both groups of catalysts, the activity for transesterification was: pure oxide > mixed oxide >> LDH. These results were related to the strength of the basic sites. FTIR and GC results were similar, with the advantage of FTIR analysis being simple, fast, and economical.

中文翻译：

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用于监测多相催化剂生产生物柴油的 FTIR 光谱分析

摘要 以镁和钙为基础的层状双氢氧化物、混合氧化物和纯氧化物在间歇式反应器中作为豆油甲基酯交换反应的催化剂进行了评价。催化剂通过连续共沉淀制备，并通过比表面积、热重分析、CO2 程序升温脱附和 X 射线衍射表征。反应在 65 °C、甲醇与油的摩尔比 9:1、催化剂用量 1 wt.% 和反应时间 240 min 下进行。通过傅里叶变换红外光谱（FTIR）和气相色谱（GC）进行生物柴油分析。钙基催化剂，纯氧化物 (CaO) 和混合氧化物 (CaAl)，表现出比镁基催化剂更高的甲基酯交换活性。考虑到两组催化剂，酯交换活性为：纯氧化物>混合氧化物>>LDH。这些结果与基本位点的强度有关。FTIR 和 GC 结果相似，FTIR 分析的优点是简单、快速和经济。