Synthesis and application of carbon based heterogeneous catalysts for ultrasound assisted biodiesel production

Abstract

In the present work, carbon based heterogeneous acid catalysts have been prepared using various synthesis approaches based on the use of sustainable starting materials. The properties of the catalysts have been investigated using Fourier transformed infra-red (FTIR), scanning electron microscopy (SEM), temperature-programmed desorption (NH3-TPD), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The screening studies for catalytic activity in biodiesel production have established that a catalyst prepared by the approach of hydrothermal carbonation followed by sulfonation from the commercial cellulose showed the best catalytic performance and hence was used in a detailed parametric study for the ultrasound assisted (low frequency 20 kHz horn with power of 120 W) synthesis of biodiesel. The study also involved the use of palm fatty acid distillate (PFAD) as the sustainable feedstock. The obtained optimum conditions were a molar ratio of alcohol to oil of 6:1, catalyst concentration of 3 wt%, temperature as 333 K and power dissipation of 120 W with a reaction time of 3 h. Use of different co-solvents (0.2% of PFAD feedstock) was investigated where THF was found to be the best co-solvent. Overall the novelty of the work can be established in terms of the use of sustainable approaches for catalyst synthesis and its subsequent application for biodiesel synthesis based on the use of sustainable feedstock as a PFAD.

Keywords

• biodiesel
• esterification
• heterogeneous catalyst
• intensification
• ultrasound