A novel hybrid catalyst for the esterification of high FFA in Jatropha oil for biodiesel production

M Sagir,I M Tan,M Mushtaq,M Suleman Tahir,M Pervaiz

doi:10.3989/gya.0216161

Abstract

The synthesis and application of a hybrid catalyst for the esterification of free fatty acids (FFA) in Jatropha oil is reported. Three catalysts, namely silica sulfuric acid, silica supported boron trifluoride and a combination of the two in the weight ratio of 1:1, the hybrid catalyst, were investigated. Jatropha oil samples with a wide range of FFA values i.e. 6.64 to 45.64% were prepared and utilized for the experimental work. This study revealed that silica sulfuric acid and silica supported boron trifluoride were not very effective when used independently. However, a strong synergistic effect was noted in the catalytic activity of the hybrid catalyst which reduced the FFA value from 45.64 to 0.903% with a conversion efficiency of 98%. Reusability of the catalyst was also tested and the results were promising in up to three cycles of use when used with lower amounts of FFA (6.64%) in the oil. Under the influence of the catalyst, the reaction was found to follow first order kinetics. Activation energy was calculated to be 45.42 KJ·mol-1 for 2 wt.% of hybrid catalyst. The products were analyzed by FT-IR and NMR spectroscopic techniques and the results are reported.

Highlights

The most convenient feedstock for fatty acid alkyl esters is plant oils and animal fat
The current study focuses on the usage of heterogeneous catalysts based on BF3 and SO3 groups attached to silica to esterify very high amounts of free fatty acids (FFA) to methyl esters
In this study three solid catalysts namely silica sulfuric acid (SSA), silica supported boron trifluoride (SSB) and a hybrid catalyst (HC),which was a 50-50 mixture of SSA and Silica supported-BF3 (SSB), were evaluated for the esterification of high FFA in Jatropha curcas oil

Summary

Introduction

The most convenient feedstock for fatty acid alkyl esters is plant oils and animal fat. It is pertinent to find a feedstock which has no competition with food grade oils In this context many inedible oils such as Jatropha curcas, Karanja, Neem and Babassu, along with unconventional feedstock, for example, poultry fat, waste cooking oil, algae, fungi, latexes and yellow grease are explored for biodiesel production (Lee et al, 2008; Kim 2009; Shahid and Jamal 2011; Wittayakun et al, 2011; Kevin et al, 2012; Chen et al, 2012; Mushtaq et al.,2013). A two-step approach is usually applied for biodiesel production; in the first step the FFA value is reduced by using an acid catalysts at less than 1% and in the second step, a base catalyzed transesterification step is launched (Tellez et al, 2010; Mushtaq et al, 2014). As methanol is not very reactive with fatty acids under normal processing conditions, acid catalysts are usually employed for the esterification reaction, sometimes at high temperature and pressure conditions

Methods

Results

Conclusion