An economically efficient one-step lactide synthesis process has been developed by using a low-price commercialized catalyst of SiO₂/Al₂O₃ in a packed-bed reactor. Under the optimized conditions of preheater temperature 160 °C, reactor temperature 240 °C, and WHSV 3 h^–1, 90% lactic acid conversion and 99% lactide selectivity were obtained. Filling of glass beads underneath the catalyst bed proved to be quite effective in improving reaction performance. The catalyst stably maintained its activity for as long as 120 h showing no noticeable changes in its structure and chemical composition of the surface although a small amount of byproduct oligomers covered the surface. Oligomers deposited on the catalyst surface could be effectively removed by calcination at 600 °C.

中文翻译：

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使用固体催化剂经济有效地合成丙交酯

通过在填充床反应器中使用SiO ₂ / Al ₂ O ₃的低价商业化催化剂，已经开发了一种经济有效的一步丙交酯合成方法。在预热器温度160°C，反应器温度240°C和WHSV 3 h ^–1的最佳条件下，获得了90％的乳酸转化率和99％的丙交酯选择性。事实证明，在催化剂床下面填充玻璃珠对提高反应性能非常有效。尽管少量的副产物低聚物覆盖了表面，但该催化剂稳定地维持了其活性长达120小时，显示其表面结构和化学组成没有明显变化。沉积在催化剂表面的低聚物可通过在600°C下煅烧而有效去除。