Immobilization of potassium-based heterogeneous catalyst over alumina beads and powder support in the transesterification of waste cooking oil

Abstract

In this work, the beads and powder potassium hydroxide (KOH) and potassium carbonate (K2CO3 ) supported on alumina oxide (Al2O3 ) were successfully prepared via incipient wetness impregnation technique. Herein, the perforated hydrophilic materials (PHM) made from low-density polyethylene (LDPE) was used as the catalyst reactor bed. The prepared catalysts were investigated using TGA, XRD, BET, SEM-EDX, TPD, FTIR while spent catalysts were analyzed using XRF and ICP-AES to study its deactivation mechanism. The catalytic performance of beads and powder KOH/Al2O3 and K2CO3/Al2O3 catalysts were evaluated via transesterification of waste cooking oil (WCO) to biodiesel. It was found that the optimum conditions for transesterification reaction were 1:12 of oil-to-methanol molar ratio and 5 wt.% of catalyst at 65◦C. As a result, the mesoporous size of beads KOH/Al2O3 and K2CO3/Al2O3 catalysts yielded 86.8% and 77.3% at 2 h’ reaction time of fatty acids methyl ester (FAME), respectively. It was revealed that the utilization of PHM for beads K2CO3/Al2O3 increase the reusability of the catalyst up to 7 cycles. Furthermore, the FAME produced was confirmed by the gas chromatography-mass spectroscopic technique. From this finding, beads KOH/Al2O3 and K2CO3/Al2O3 catalysts showed a promising performance to convert WCO to FAME or known as biodiesel.