Novel heterogeneous SO₃Na-carbon transesterification catalyst for the production of biodiesel

Abstract

Glycerol, a major biodiesel by‐product, was valorised into a novel and highly stable heterogeneous carbon‐based solid base catalyst with transesterification activity. The SO₃H‐carbon catalyst developed previously by us from glycerol was modified into base catalyst by treating with aqueous alkali under controlled conditions. The reported solid base catalyst is first of its kind having polycyclic aromatic carbon sheets attached with ‐SO₃Na, ‐COONa and ‐ONa functionalities. The catalyst was characterized for its structural properties using XRD, FTIR, ¹³C‐MAS NMR, XPS, EDAX, SEM, TEM, TG/DTA, ICP‐OES and Raman spectral techniques. The SO₃Na‐catalyst was employed for the transesterification of sunflower oil to fatty acid methyl esters (biodiesel) in high yields (99%) at atmospheric pressure. The strong basic sites of the catalyst contributed to its remarkable performance and the activity was intact even after 8 cycles of reuse without any leaching, indicating its high structural stability. Thus, the reported SO₃Na‐carbon catalyst possessed the potential of green and economic biodiesel production from oils & fats apart from clean glycerol as by‐product.