TAILIEUCHUNG - Reusability and regeneration of solid catalysts used in ultrasound assisted biodiesel production

Reusability of two heterogeneous catalysts in ultrasound (US) assisted biodiesel production was investigated in comparison to each other. An ultrasound (US) generator (200 W, 20 kHz) equipped with a horn type probe (19 mm) was used. Regeneration experiments were planned according to second order central composite design (CCD) method. After the eighth use of the catalysts, biodiesel yield decreased from to for calcined calcite (CaO) and from to for calcined dolomite (). Furthermore, regeneration of spent catalysts by calcination was investigated; optimum temperature and time were found as 750 °C and 90 min, lower than fresh catalyst preparation conditions. | Turkish Journal of Chemistry Turk J Chem 2021 45 342-347 http chem TÜBİTAK Research Article doi kim-2008-33 Reusability and regeneration of solid catalysts used in ultrasound assisted biodiesel production 1 2 1 Mahmut BAYRAMOĞLU İbrahim KORKUT Başak TEMUR ERGAN 1 Chemical Engineering Department Gebze Technical University Gebze Turkey 2 Chemical Engineering Department Sivas University of Science and Technology Sivas Turkey Received Accepted Published Online Final Version Abstract Reusability of two heterogeneous catalysts in ultrasound US assisted biodiesel production was investigated in comparison to each other. An ultrasound US generator 200 W 20 kHz equipped with a horn type probe 19 mm was used. Regeneration experiments were planned according to second order central composite design CCD method. After the eighth use of the catalysts biodiesel yield decreased from to for calcined calcite CaO and from to for calcined dolomite . Furthermore regeneration of spent catalysts by calcination was investigated optimum temperature and time were found as 750 C and 90 min lower than fresh catalyst preparation conditions. The regenerated catalysts were reused in a second process cycle biodiesel yield was calculated as for CaO and for . Finally the process showed that calcination is an energetically favorable regeneration process of spent catalysts. Key words Biodiesel ultrasound assisted transesterification calcium oxide calcined dolomite heterogeneous catalyst regeneration 1. Introduction Transesterification reaction transforms oil or fats with methanol CH3OH into biodiesel in presence of a catalyst with glycerol as a by-product 1 2 . Usually homogeneous basic catalysts such as potassium hydroxide KOH or homogeneous acidic catalysts such as sulfuric acid H2SO4 are used 3 . However the homogeneously catalyzed transesterification process has some drawbacks such as the

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