Development of a Continuous System Based on Azeotropic Reactive Distillation to Enhance Triacetin Selectivity in Glycerol Esterification with Acetic Acid

Abstract

Glycerol esterification with acetic acid was carried out in a continuous, easy-to-scale-up system using toluene as the entrainer. A water separation system was designed and coupled to an optimized continuous system. The continuous system operated at a temperature of 100 °C, an acetic acid-to-glycerol mole ratio of 7, a pressure of 1 bar, and a feed flow rate of 0.5 mL min–1 over 3 g of Amberlyst 36. Under these conditions, the glycerol conversion was 100% with 43%, 44%, and 13% selectivities to monoacetin, diacetin, and triacetin, respectively. Formation of byproducts was not observed under these conditions. When this continuous system was coupled to the designed simultaneous reactor and water separation system, containing 3 g of Amberlyst 36, these values changed to 0%, 15%, and 80%, respectively. Byproduct formation was observed with a selectivity of only 5% after the feed was passed from the water separation system. Continuous removal of the water formed in the reaction was done with toluene. As a result of this process, the chemical equilibrium shifted toward the TA production. The maximum selectivities obtained from experiments were 85% for MA, and 65% for DA. Amberlyst 15 and Purolite PD206 also was used for esterification reaction. Amberlyst 15 and Amberlyst 36 exhibited similar performances. A mixture of MA and DA was obtained through esterification of glycerol with trapped acetic acid in a Dean–Stark apparatus.

Production of Triacetin by Microwave Assisted Esterification of Glycerol Using Activated Natural Zeolite

“…Triacetin is an alternative additive that could be used to improve cold and viscosity properties of biodiesel. Esterification of glycerol with acetic acid is reported using several solid catalysts, however the triacetin selectivity was rather low [8,9]. So far, no report is found on esterification of triacetin involving microwave as source of heating.…”

Dehydration of a Dilute Acetic Acid‐Water Mixture via Batch Heteroazeotropic Distillation

“…Many factories do not have sufficient raw materials all year around, which is especially true for the biorefinery plants using wood vinegar as the feedstock. In addition, for the upgrading of many existing small factories, a continuous distillation process is not always possible due to limited space or funding for auxiliary equipment, pipelines, and towers 23, 24. Batch distillation operation is appealing in these scenarios and has attracted much attention in recent years due to its strong flexibility and wide adaptability 25–28.…”

Continuous-Flow Process for Glycerol Conversion to Solketal Using a Brönsted Acid Functionalized Carbon-Based Catalyst

“…Glycerol excess from biodiesel production provides a good potential raw material for generation of value-added products, such as fuel additives, solvents or chemicals [1][2][3][4]. Thus, the strategies for glycerol valorization include a series of very different processes, such as acetalization, hydrogenolysis, esterification, etherification, reforming, pyrolysis or selective oxidation, as has been reported in the literature [5][6][7][8][9]. Glycerol acetalization, in particular, uses glycerol and carbonyl compounds, e.g., aldehydes or ketones yielding cyclic glycerol acetal/ketal molecules.…”