Esterification of Palm Fatty Acid Distillate for Biodiesel Production Catalyzed by Synthesized Kenaf Seed Cake-Based Sulfonated Catalyst

Shehu-Ibrahim Akinfalabi,Imededdine Arbi Nehdi,Umer Rashid,Mohamed Mossad Gewik,Thomas Yaw Choong Shean,Hassen Mohamed Sbihi

doi:10.3390/catal9050482

Abstract

Sulfonated kenaf seed cake (SO3H-KSC) catalyst, was synthesized to aid biodiesel production from palm fatty acid distillate (PFAD). It was chemically activated with phosphoric acid for an impregnation period of 24 h in order to enhance the porosity and the specific surface area of kenaf seed cake (KSC). After the carbonization and sulfonation, the resultant catalyst was characterized with powder X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscope (FESEM), NH3-temperature programmed desorption (NH3-TPD) and thermogravimetric analysis (TGA). The SO3H-KSC catalyst was amorphous in nature and had an acid density of 14.32 mmol/g, specific surface area of 365.63 m2/g, pore volume of 0.31 cm3/g and pore diameter of 2.89 nm. At optimum esterification conditions--reaction time 90 mins, temperature of 338 K, methanol:PFAD molar ratio of 10:1 and catalyst concentration of 2 wt.%—a free fatty acid (FFA) conversion of 98.7% and fatty acid methyl esters (FAME) yield of 97.9% was achieved. The synthesized SO3H-KSC catalyst underwent five reaction cycles while maintaining a fatty acid methyl esters (FAME) yield and free fatty acid (FFA) conversion of >90%. Thus, the SO3H-KSC catalyst was shown to be an excellent application of bio-based material as a precursor for catalyst synthesis for esterification of PFAD.

Highlights

Catalyst synthesis has become an interesting area of research in the production of biodiesel in recent times
The final sulfonated-kenaf seed cake (SO3 H-KSC), is an indication that H3 PO4 when used for chemical activation, can aid in surface area and pore development
This is due to the sulfonation process; upon sulfonation, the pores and surface area will slightly shrink as a result of the attachment of the functional group to its surface

Summary

Introduction

Catalyst synthesis has become an interesting area of research in the production of biodiesel in recent times. Homogeneous catalysts such as NaOH, KOH and H2 SO4 were more prevalent in conventional biodiesel production due to their high conversion rate and reduced reaction time [1]. Catalysts 2019, 9, 482 production of biodiesel These streams of heterogeneous catalysts require expensive materials, have complicated synthesis routes and record low catalytic activity, whereas catalysts derived from biomass (bio-based catalysts), have an easy synthesis route, are readily abundant and are environmentally benign. Bio-based catalysts emerged as the leading alternatives owing to their immense advantages, thereby reducing the total cost of biodiesel production, while reducing the global environmental threat and increasing their feasibility for industrial usage [3]

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