A synergistic effect of the activated limestone-based catalyst (LBC) and microwave irradiation on the transesterification of waste cooking oil (WCO) was screened using a two-level factorial design and response surface methodology. The catalyst was prepared using a wet-impregnation method and was characterised for its surface element, surface morphology, surface area and porosity. The reaction was performed in a purpose-built continuous microwave assisted reactor (CMAR), while the conversion and yield of biodiesel were measured using a gas chromatography. The results showed that the catalyst loading, methanol to oil molar ratio and the reaction time significantly affect the WCO conversion. The optimum conversion of oil to biodiesel up to 96.65% was achieved at catalyst loading of 5.47 wt%, methanol to oil molar ratio of 12.21:1 and the reaction time of 55.26 min. The application of CMAR in this work reduced the transesterification time by about 77% compared to the reaction time needed for a conventional reactor. The biodiesel produced in this work met the specification of American Society for Testing and Materials (ASTM D6751). Engine test results shows the biodiesel has a lower NOx and particulate matters emissions compared to petrodiesel.

中文翻译：

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在连续微波辅助反应器中，由废食用油合成的生物柴油减少了PM和NOx排放。

使用二级因子设计和响应面方法筛选了活化石灰石基催化剂（LBC）和微波辐射对废食用油（WCO）酯交换作用的协同效应。使用湿浸渍法制备该催化剂，并对其表面元素，表面形态，表面积和孔隙率进行表征。该反应在专用的连续微波辅助反应器（CMAR）中进行，而生物柴油的转化率和产率则使用气相色谱法进行测量。结果表明，催化剂负载量，甲醇与油的摩尔比和反应时间显着影响WCO转化率。在催化剂负载量为5.47 wt％，甲醇与油的摩尔比为12.21的情况下，油向生物柴油的最佳转化率达到96.65％：1，反应时间为55.26分钟。与常规反应器所需的反应时间相比，CMAR在这项工作中的应用使酯交换时间减少了约77％。这项工作中生产的生物柴油符合美国材料试验学会（ASTM D6751）的规范。发动机测试结果表明，与石油柴油相比，生物柴油的NOx和颗粒物排放量更低。