SrO‐MnO/Ceramic: A Novel Bifunctional Catalyst for Biodiesel production via Simultaneous Transesterification‐Esterification of Waste Frying Oil

The strontium‐manganese supported over ceramic was synthesized through wet impregnation method and investigated as a solid catalyst for its catalytic performance in transesterifying‐esterifying low‐grade waste frying oil with methanol in a batch reactor; parameters for synthesis of catalyst and transesterification reaction were also optimized. The maximum biodiesel yield of 93.66 % was attained by SrO‐MnO/Ceramic catalyst under normal process conditions. The synthesized catalyst reusability potential was also evaluated for 12 runs with regeneration carried out after the 7th run only and it revealed that the catalyst showed great stability for the initial five cycles offering yield of over 90 %. The fresh and used SrO‐MnO/Ceramic catalysts were characterized to address the mechanism of catalytic behavior and deactivation using scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDS), X‐ray diffraction (XRD), benzoic acid and n‐butylamine titration method, and Hammett indicators. The alteration in surface morphology; Mn solubility in glycerol and methanol; occupation of energetic centers by organics might be the reasons for diminished activity or deactivation of solid catalyst after repeated reuse. In this work, a stable, reusable, and active bifunctional solid catalyst was implemented in one‐step production of biodiesel from acidic waste frying oil. The SrO‐MnO/Ceramic catalyst synthesized at the molar ratio of 1 : 3 and calcinated at 600 °C for 120 min reached peak biodiesel yield of 93.66 % under these process conditions as catalyst dosage of 2.5 wt ⋅ % (based on catalyst/oil, w/w), alcohol : oil molar ratio of 16 : 1, temperature and duration of 75 °C and 150 min, respectively.