ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Optimization of process conditions for biodiesel production over CaO–Al₂O₃/ZrO₂ catalyst using response surface methodology

Mohammad Hojjat, Hamed Nayebzadeh, Mahmoodreza Khadangi-Mahrood, and Behgam Rahmani-Vahid

Department of Chemical Engineering, Quchan Branch, Islamic Azad University, Quchan, Iran

E-mail: hojjat@iauq.ac.ir

Abstract: CaO–Al₂O₃/ZrO₂ mixed oxide catalyst was prepared using free-solvent method. The catalyst was characterized using X-ray diffraction, BET surface area, acidity index (obtained by titration method), and scanning electron microscopy (SEM). With calcium aluminate and calcium zirconate been successfully formed, the mix exhibited small crystal size, high acidity, and large surface area, pore size, and pore volume, making it a catalyst of choice for biodiesel production. The activity of catalyst was evaluated in the course of esterification of oleic acid as well as transesterification of waste cooking oil (WCO) into biodiesel. Based on a four-variable central composite design (CCD), response surface methodology (RSM) was used to optimize effective variables on oleic acid conversion. The optimum yield of 94.68% was obtained at the following set of optimum conditions: reaction temperature of 120 °C, methanol/oleic acid molar ratio of 15.64, catalyst concentration of 2.94 wt%, and reaction time of 4 h; the result was in excellent agreement with the predicted values. Furthermore, under the optimum conditions, the catalyst succeeded to convert 93.48% of WCO into biodiesel.

Keywords: Calcium zirconate; Calcium aluminate; Esterification of oleic acid; Transesterification of waste cooking oil (WCO); Response surface methodology (RSM)

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-016-0096-1

Chemical Papers 71 (3) 689–698 (2017)