The efficiency of a heterogeneous potassium fluoride (KF)/clay catalyst in continuous ester production from residual frying oil using pressurized ethanol is evaluated. Reactions without catalysts are conducted to determine the effect of the catalyst on ester yield. To verify the performance of the catalyst, the reactions are conducted for 3 h with determination of the ester yield every 30 min and characterization of the catalyst after each reaction. The influence of the temperature, catalyst mass used in the catalytic bed, and the residence time are evaluated. KF/clay is found to be efficient in ester synthesis and provides better results compared with non‐catalytic reactions and the formation of esters is favored on increasing the temperature. The ester yields remain stable over time at 275 and 300 °C but at 225 and 250 °C the yields decrease by 48.42% and 38.40%, respectively. This may be due to the lower diffusion coefficient at these temperatures, implying that the reaction occurs preferentially at the catalyst surface. There is an increase in yield with an increase in the catalyst mass up to 2 g. The catalyst maintains its morphological characteristics after the reaction and the average mass loss in each reaction is <8%.

中文翻译：

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KF /粘土催化的煎炸残油与乙醇的连续酯交换反应

评估了非均质氟化钾（KF）/粘土催化剂在使用加压乙醇从残留煎炸油连续生产酯中的效率。进行没有催化剂的反应以确定催化剂对酯收率的影响。为了验证催化剂的性能，反应进行3小时，每30分钟测定一次酯收率，并在每次反应后表征催化剂。评价温度，催化床中使用的催化剂质量和停留时间的影响。与非催化反应相比，发现KF /粘土在酯合成中是有效的，并提供更好的结果，并且酯的形成有利于提高温度。酯的收率在275和300°C下随时间保持稳定，但在225和250°C时，收率分别下降48.42％和38.40％。这可能是由于在这些温度下较低的扩散系数，这意味着该反应优先在催化剂表面发生。随着催化剂质量的增加，直到2g，产率增加。反应后催化剂保持其形态特征，每个反应的平均质量损失小于8％。