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Highlights

Coconut coir husk derived sulfonated catalyst was prepared by a simple protocol.

Activation of the catalyst was confirmed by XPS and FTIR.

Prepared catalyst was able to produce biodiesel from waste palm oil (5.2% FFA).

Highest biodiesel yield of >89% was obtained in an autoclave reactor at 130 °C.

Catalyst can be reused for four cycles with >77% biodiesel yield.

Abstract

The present study investigates biodiesel production from waste palm oil (WPO) using coconut coir husk (CCH) derived solid acid catalyst. The catalyst was prepared by the direct in-situ concentrated sulfuric acid impregnation. The presence of active sites, such as sulfonic, carboxylic, and phenolic OH functional groups on the catalyst was confirmed by Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The highest biodiesel yield of 89.8% was obtained under optimum conditions of 10 wt % catalyst, 12:1 methanol:oil (molar ratio), after 3 h at 130 °C and 500 rpm, in a laboratory autoclave reactor. It was found that biodiesel yield increases with increasing reaction temperature, reaction time, and catalyst loading, up to an optimum value. The catalyst can be reused for four cycles and the biodiesel yield was >77%. Relatively higher activity may be due to the high acid density of the catalyst due to the presence of hydrophilic functional groups bonded to the hydrophobic carbon structure. It was found that, kinematic viscosity (2.9 mm2 s−1), pour point (−6 °C), heating value (38.1 MJ kg−1), and oxidation stability (3 h) of the produced biodiesel are in accordance with the international standards. Therefore, the produced biodiesel can be used.

Keywords

Autoclave reactor

Biodiesel

Carbon based solid acid catalyst

Direct sulfonation

Lignocellulose waste biomass

Waste palm oil

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