Synthesis of oxygenated fuel additives via glycerol esterification with acetic acid over bio-derived carbon catalyst

Abstract

Glycerol derived from biodiesel (BD) production is oversupplied and requires urgent utilization. Hence, crude bio-derived glycerol was utilized as a carbon precursor for heterogeneous solid acid catalyst synthesis via partial sulphonation and carbonization in a single step. The as-synthesized catalyst was utilized to catalyze glycerol acetylation reaction with acetic acid to produce oxygenated fuel additives (diacetin and triacetin) and monoacetin. Under reaction conditions of 110°C, glycerol-to-acetic acid molar ratio of 3, 2wt% catalyst dose, and 3h reaction time, 88% combined DAG and TAG selectivity was attained with a corresponding glycerol conversion of 99%. The high surface acid sites density of the catalyst primarily contributed to its enhanced catalytic performance. The catalyst displayed sufficient heterogeneity and robustness in polar reaction media despite high hydrophilic acid sites density. Hence, it was reused in seven cycles of the experiment without experiencing significant deactivation.