Lithium orthosilicate (Li₄SiO₄) is a promising solid catalyst for biodiesel synthesis. However, Li₄SiO₄ is traditionally prepared by a solid‐state reaction, which results in the unstable activity for the reaction. In the present study, Li₄SiO₄ was successfully prepared using a simple sol‐gel method and employed as an efficient solid alkali catalyst for biodiesel synthesis. The molar ratio of precursors and calcination temperature were optimized for the synthesis of Li₄SiO₄ by using the sol‐gel method. The physical and chemical properties were determined using X‐ray diffraction, scanning electron microscopy, laser diffraction particle size, and thermogravimetric analysis. The as‐prepared Li₄SiO₄ catalyst had much smaller particle size, pore volume, and pore size, but higher surface area and basicity than Li₄SiO₄ catalyst prepared by the solid‐state reaction. It was then used to transesterify methanol and soybean oil into biodiesel. The effect of reaction factors (reaction time from 1 to 3 hours, catalyst concentration from 3 to 9%; molar ratio of methanol to oil from 6:1 to 18:1, and temperature from 55°C to 75°C) on the Li₄SiO₄‐catalyzed transesterification was systematically examined. The highest biodiesel conversion of 91% was reached under the following conditions: reaction time of 2 hours, Li₄SiO₄ concentration of 6%, 12:1 methanol:oil molar ratio, and temperature of 65°C. Notably, Li₄SiO₄ could be efficiently reused for at least 10 times without significant loss of its activity; this suggests that the sol‐gel synthesized Li₄SiO₄ is a potential solid alkali catalyst for biodiesel synthesis.

中文翻译：

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溶胶凝胶合成的原硅酸锂可作为生物柴油生产中可重复使用的固体催化剂

原硅酸锂（Li ₄ SiO ₄）是用于生物柴油合成的有前途的固体催化剂。然而，传统上通过固态反应制备Li ₄ SiO ₄，这导致该反应的活性不稳定。在本研究中，使用简单的溶胶凝胶法成功制备了Li ₄ SiO ₄，并将其用作生物柴油合成的有效固体碱催化剂。优化了前驱体的摩尔比和煅烧温度以合成Li ₄ SiO _4。通过使用溶胶凝胶法。使用X射线衍射，扫描电子显微镜，激光衍射粒度和热重分析法确定其物理和化学性质。所制备的锂₄的SiO ₄的催化剂具有更小的粒径，孔体积和孔尺寸，但更高的表面积和碱性除Li ₄的SiO ₄由固相反应制备的催化剂。然后将其用于将甲醇和大豆油酯交换为生物柴油。反应因素（反应时间为1至3小时，催化剂浓度为3至9％；甲醇与油的摩尔比为6：1至18：1，温度为55°C至75°C）的影响Li ₄ SiO ₄系统检查了催化的酯交换反应。在以下条件下，生物柴油的最高转化率达到91％：反应时间为2小时，Li ₄ SiO ₄浓度为6％，甲醇：油的摩尔比为12：1，温度为65°C。值得注意的是，Li ₄ SiO ₄可以有效地重复使用至少10次，而不会显着降低其活性。这表明溶胶凝胶合成的Li ₄ SiO ₄是生物柴油合成的潜在固体碱催化剂。