Method for removing mineral acid from levulinic acid
The invention describes processes to selectively remove or reduce the mineral acid content substantially from compositions comprising a solvent and levulinic acid, wherein the levulinic acid was derived from the reaction between various biomass materials and a mineral acid or an organic acid catalyst.
1. A method to prepare a levulinic acid composition substantially without an acid catalyst present comprising the steps:
preparing an aqueous levulinic acid composition comprising levulinic acid, an acid catalyst and water;
combining the aqueous levulinic acid solution with an immiscible organic solvent to form a mixture;
partitioning the mixture into an aqueous phase and an organic phase; and
washing the organic phase with an aqueous treatment solution comprising one or more monosaccharides, one or more disaccharides, or a mixture thereof to reduce the acid catalyst content in the organic phase.
2. The method of claim 1 , further comprising the step of separating the aqueous phase from the organic phase.
3. The method of claim 1 , wherein the reduction of acid catalyst in the levulinic acid composition after treatment with the aqueous treatment solution is at least two fold.
4. The method of claim 1 , wherein the reduction of acid catalyst in the levulinic acid composition after treatment with the aqueous treatment solution is at least ten fold or greater.
5. The method of claim 1 , wherein the concentration of acid catalyst that remains in the organic phase is less than 100 ppm.
6. The method of claim 1 , wherein the organic solvent is methyl-isobutyl ketone (MIBK), methyl isoamyl ketone (MIAK), cyclohexanone, o, m, and para-cresol, substituted phenols, for example, 2-sec butyl phenol, C4-C18 alcohols, such as n-pentanol, isoamyl alcohol, n-heptanol, 2-ethyl hexanol, n-octanol, 1-nonanol, cyclohexanol, methylene chloride, 1,2-dibutoxy-ethylene glycol, acetophenone, isophorone, o-methoxy-phenol, methyl-tetrahydrofuran, tri-alkylphosphine oxides (C4-C18) and ortho-dichlorobenzene and mixtures thereof or the like, more specifically, methyl isoamyl ketone (MIAK), o, m, and para-cresol, phenol, isoamyl alcohol, n-hexanol, n-heptanol, 2-ethyl hexanol, o-methoxy-phenol, 2-4 dimethyl phenol, methyl isobutyl carbinol, and mixtures thereof or the like, and even more specifically, phenol, all isomers of fluoro, chloro, bromo, and iodo phenols, bis-halogenated phenols, mixtures of halogenated phenols, xylenols, gamma-valerolactone, isoamyl alcohol, neopentyl alcohol, methyl isobutyl carbinol, and mixtures thereof.
7. The method of claim 1 , wherein the monosaccharide is glucose, fructose or mixtures thereof and/or the disaccharide is maltose, sucrose or mixtures thereof.
8. The method of claim 1 , wherein the concentration of monosaccharide and/or disaccharide present in the aqueous solution is from about 5% to about 80% by weight based on the total weight of the mixture.
9. The method of any of claims 1 through 8 , wherein the concentration of acid catalyst present is from about 0.01% to about 5% by weight based on the total weight of the mixture.
10. The method of claim 1 , wherein the concentration of levulinic acid present is from about 1% to about 30% by weight based on the total weight of the mixture.
11. The method of claim 1 , wherein the acid catalyst is sulfuric acid or hydrochloric acid.