An Mg–Al hydrotalcite with a Mg/Al molar ratio of 3 was prepared via co-precipitation. The XRD and FTIR analyses proved the presence of the hydrotalcite structure in the uncalcined solid, its destruction after calcination and its reconstruction after rehydration. TG-DSC analyses revealed a higher thermal stability of the rehydrated solids compared to the uncalcined solid. CO₂-TPD analyses showed the presence of stronger and more abundant basic sites for the rehydrated solids. All prepared solids were then tested in the transesterification of sunflower oil [catalyst to oil ratio (CTOR) of 10 wt%, methanol to oil molar ratio (MOMR) of 12:1, temperature of 60 °C and reaction time of 2 h]. The uncalcined and calcined solids all exhibited low activities as evidenced by very low FAME yields (<1.5%). The catalytic activity was significantly improved for most of the rehydrated solids due to their higher basicity. Calcination of the fresh Mg–Al solid at 450 °C followed by subsequent rehydration (Mg₆Al₂-450RH) allowed the obtainment of a FAME yield of 56%. No biodiesel was formed in the presence of the rehydrated catalysts previously calcined at temperatures greater than 500 °C due to a reduced “memory effect”. The effects of reaction conditions such as the duration of rehydration treatment, reaction temperature, MOMR and CTOR on the activity of Mg₆Al₂-450RH were also studied. The obtained results in this work demonstrate the potential of rehydrated Mg–Al solids for biodiesel production. They could also be useful for optimizing the preparation conditions of reconstructed hydrotalcites as basic catalysts and contribute to the search for ideal conditions for biodiesel production.

通过共沉淀制备了 Mg/Al 摩尔比为 3 的 Mg-Al 水滑石。XRD 和 FTIR 分析证明未煅烧固体中存在水滑石结构，其在煅烧后被破坏，在再水合后重建。TG-DSC 分析表明，与未煅烧的固体相比，再水化的固体具有更高的热稳定性。CO ₂-TPD 分析表明存在更强和更丰富的再水化固体的碱性位点。然后在向日葵油的酯交换中测试所有制备的固体[催化剂油比 (CTOR) 为 10 wt%，甲醇油摩尔比 (MOMR) 为 12:1，温度为 60 °C，反应时间为 2 h] . 正如非常低的 FAME 产率 (<1.5%) 所证明的那样，未煅烧和煅烧的固体都表现出低活性。由于碱度较高，大多数再水合固体的催化活性得到显着提高。在 450 °C 下煅烧新鲜的 Mg-Al 固体，然后再水合（Mg ₆ Al ₂-450RH) 允许获得 56% 的 FAME 产率。由于“记忆效应”降低，在预先在高于 500°C 的温度下煅烧的再水合催化剂存在时没有形成生物柴油。还研究了复水处理时间、反应温度、MOMR和CTOR等反应条件对Mg ₆ Al ₂ -450RH活性的影响。在这项工作中获得的结果证明了再水化的 Mg-Al 固体在生物柴油生产中的潜力。它们还可用于优化作为基本催化剂的重构水滑石的制备条件，并有助于寻找生产生物柴油的理想条件。