Glycerol esterification with acetic acid produces a mixture of mono, di, and triacetins, which are commercially important value-added products with a wide range of industrial uses including their application as fuel-additives, thus contributing to environmental sustainability and economic viability of the biorefinery concept. Glycerol esterification with acetic acid was studied using a range of nitrogen-based Brønsted-acidic ionic liquids. Cost-effective and easily synthesized Brønsted-acidic ionic liquids based on alkyl-pyrrolidone and alkyl-amine cations were synthesized and characterized using 1H NMR spectroscopy. The catalytic activity of the Brønsted-acidic ionic liquids produced were investigated for the production of di and triacetin from glycerol and acetic acid. Amongst all ionic liquids evaluated in this study, N-methyl-2-pyrrolidinium hydrogen sulfate [H-NMP]­[HSO4] was found to be the most active and cost-effective catalyst. The effect of significant reaction parameters on selectivity to the trisubstituted product, triacetin, was modeled using a design of experiment (DoE) approach with a response surface methodology involving a central composite design. The esterification process was optimized to maximize the production of triacetin. Optimizing the process this way naturally leads to lower levels of mono and diacetin. Amongst the reaction parameters evaluated, temperature had the greatest influence on product selectivity, followed by the glycerol to acetic acid molar ratio, and the model also showed dependence on the synergistic interaction between the temperature and mole ratio. It is worth noting that agitation speed had minimal influence on product selectivity. Under optimized reaction conditions, >99% glycerol conversion was achieved with 42.3% selectivity to triacetin, and a combined di and triacetin selectivity of >95% within 1 h.

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Glycerol acetins (mono-, di-, and tri) are produced via esterification with acetic acid. The acetins are commercially important industrial chemicals including their application as fuel additives, thus significant to environmental sustainability and economic viability of the biorefinery industry. Glycerol esterification with acetic acid was studied using partial tin exchanged tungstophosphoric acid supported on montmorillonite K-10 as catalysts. Partially exchanging the H+ ion of DTP with Sn (x = 1) increased the acidity of the catalyst and showed an increase in the catalytic activity as compared to the DTP/K-10 catalyst. A series of tin exchanged tungstophosphoric acid (20% w/w) supported on montmorillonite K-10 clay (Sn x -DTP/K-10, where x = 0.5–1.5) were synthesized and thoroughly characterized by using BET, XRD, FT-IR, UV–vis, and titration techniques. Among various catalysts, Sn1-DTP/K-10 was found to be the most active catalyst for glycerol esterification. Effects of different reaction parameters were studied and optimized to get high yields of glycerol triacetin. A suitable kinetic model of the reaction was fitted, and the Langmuir–Hinshelwood (L-H) dual-site model was able to describe the experimental data with high agreement between the experimental and calculated results. The prepared catalyst could be recycled at least four times without significant loss of activity. The overall process is green and environment friendly.

To decrease the dependence on crude oil, biomass derived liquid transportation fuels are highly desirable. Butyl levulinate is potential cellulose-derived biofuel additive with properties similar to diesel and low water solubility. Herein we report direct one-pot production of levulinic acid ester, butyl levulinate from furfuryl alcohol by alcoholysis using n-butanol.The partial tin exchanged tungstophosphoric acid (TPA) supported on montmorillonite K-10 catalysts showed facile alcoholysis of furfuryl alcohol to levulinate ester under mild temperature conditions. Partially, exchanging the H + ion of TPA with Sn (x = 1) resulted in enhanced acidity of the catalyst and showed an increase in the catalytic activity as compared to TPA/K-10 catalyst. A series of tin exchanged tungstophosphoric acid (20% w/w) supported on montmorillonite K-10 clay (Snx-TPA/K-10, where x = 0.5-1.5) were synthesized and thoroughly characterized by using XRD, FT-IR, UV-VIS, titration and SEM techniques. Among various catalysts, Sn1-TPA/K-10 was found to be the most active catalyst for butyl levulinate synthesis. Two different clay supports and varying tin loadings were used to study the effects on surface acidity as well as catalytic activity in butyl levulinate synthesis. Effects of different reaction parameters were studied and optimized to get high yields of butyl levulinate. Under mild reaction conditions at 110°C, complete conversion of furfuryl alcohol with 98% selectivity to butyl levulinate was achieved. The prepared catalyst could be recycled at least five times without significant loss of activity. The overall process is green and clean.

Glycerol is a valuable feedstock, produced in biorefineries as a byproduct of biodiesel production. Esterification of glycerol with acetic acid yields a mixture of mono-, di-, and triacetins. The acetins are commercially important value-added products with a wide range of industrial applications as fuel additives and fine chemicals. Esterification of glycerol to acetins substantially increases the environmental sustainability and economic viability of the biorefinery concept. Among the acetins, diacetin (DA) and triacetin (TA) are considered high-energy-density fuel additives. Herein, we have studied the economic feasibility of a facility producing DA and TA by a two-stage process using 100,000 tons of glycerol per year using Aspen Plus. The capital costs were estimated by Aspen Process Economic Analyzer software. The analysis indicates that the capital costs are 71 M$, while the operating costs are 303 M$/year. The gross profit is 60.5 M$/year, while the NPV of the project is 235 M$ with a payback period of 1.7 years. Sensitivity analysis has indicated that the product price has the most impact on the NPV.