Development of a barium-modified zeolite catalyst for biodiesel production from waste frying oil: Process optimization by design of experiment

摘要

A barium-modified zeolite (Ba-ZEL) catalyst was developed via co-precipitation technique followed by thermal treatment (calcination) at different temperatures (600, 700 and 800 degrees C). The thermal stability, elemental composition, surface functional groups, crystallographic structure, textural characteristics, basic strength and surface morphology of the Ba-ZEL catalyst were determined using TGA/DTA, EDX, FTIR, XRD, BET, CO2-TPD and SEM techniques, respectively. The biodiesel production process conditions, such as catalyst loading, alcohol to oil ratio, temperature and time, were optimized using a central composite design approach. The Ba-ZEL composite calcined at 700 degrees C was selected as a representative catalyst due to its high activity for the waste frying oil (WFO) conversion, resulting in a maximum biodiesel yield of 93.17 +/- 0.02% under optimum conditions (3.0 wt% catalyst loading, 12:1 methanol to WFO ratio, 65.38 degrees C reaction temperature and 2 h reaction time). The produced biodiesel, which was characterized by the FTIR and GC-FID analyses, contained sufficient ester groups and was in accordance with the specifications of EN 14214. Additionally, its physicochemical properties met ASTM D6751 specifications. Moreover, the Ba-ZEL700 catalyst was reused for five cycles upon regeneration using n-hexane washing followed by reactivation at 110 degrees C for 12 h. (C) 2021 Elsevier Ltd. All rights reserved.