Biodiesel production from soybean oil deodorizer distillate usingcalcined duck eggshell as catalyst

•Calcined DES was used as catalyst for biodiesel production from SODD.•The obtained CaO was characterized by XRD, FT-IR, SEM and the optimal calcination temperature was 900°C.•The biodiesel yield was 94.6% at the optimal transesterification conditions.•The biodiesel yield was above 80% after five times usage. Biodiesel production from soybean oil deodorizer distillate (SODD) using calcined duck eggshell (DES) as catalyst was studied. An inexpensive and environment-friendly catalyst was prepared from waste DES which is a source of calcium carbonate. The calcium carbonate could be changed to calcium oxide (CaO) under high temperatures. The obtained CaO was characterized by X-ray diffraction (XRD), Fourier Transmission Infrared Spectra (FT-IR), Scanning Electron Microscopy (SEM). XRF was used to determine the elemental composition of the catalyst. BET analysis was performed to determine specific surface area, pore volume and particle size of the catalysts. Results showed that at 800°C and 900°C the calcium carbonate in DES was changed to CaO. The pre-esterification of SODD was conducted under the following conditions: H2SO4 concentration (v/w, based on oil weight) 1.5%, methanol to oil molar ratio 12:1, reaction time 120min and reaction temperature 60°C. Thephytosterols were removed by cooling down step by stepand temperature steps were 15°C, 5°C, −5°C. The process of biodiesel production from pre-esterified SODD using the obtained CaO as catalyst was studied and the optimal conditions were: calcination temperature of 900°C, catalyst amount of 10wt.%, methanol to oil ratio of 10:1, reaction temperature of 60°C and reaction time of 80min and the biodiesel yield was 94.6% at these conditions. The reusability of the DES-derived catalyst was tested and the results showed that the biodiesel yield was above 80% after five times usage and was lower than 60% after 8 times usage.