Methods for furfural production from branched non-fermentable sugars in stillage or syrup
View Patent ↗Furfural is obtained selectively and in good purity from non-fermentable branched sugars found in soluble waste streams of lignocellulosic biomass. In a monophasic method, stillage or syrup is contacted with water and an acid catalyst under suitable reaction conditions to convert the branched non-fermentable branched sugars to furfural. Additionally, the stillage or syrup can be treated with a water-immiscible organic solvent to form a biphasic mixture comprising an aqueous phase and an organic phase. The furfural that is produced preferentially partitions into the organic phase, from which it may be recovered.
1. A method for producing furfural comprising the steps of:
a) providing stillage or syrup comprising non-fermentable branched sugars;
b) contacting the stillage or syrup with water to form a mixture;
c) acidifying the mixture of formed in step (b) to pH 1 or less with an acid catalyst;
d) contacting the acidic mixture with at least one water-immiscible organic solvent:
e) heating the mixture formed in step (c) at a temperature and for a time sufficient to convert the non-fermentable branched sugars to furfural;
f) optionally, recovering the furfural thereby produced,
wherein the at least one water-immiscible organic solvent is an aliphatic hydrocarbon, cycloalkane, aromatic hydrocarbon, polyether containing ester or ether end groups, or plant-derived oil.
2. The method of claim 1 , wherein steps (b) and (c) are performed concurrently.
3. The method of claim 1 wherein the product furfural is recovered by either distillation or selective extraction with a solvent.
4. The method of claim 1 , wherein the acid catalyst comprises a mineral acid, a heteropolyacid, an organic acid, or a combination thereof.
5. The method of claim 4 , wherein the acid catalyst comprises sulfuric acid, phosphoric acid, hydrochloric acid, phosphotungstic acid, molybdophosphoric acid, oxalic acid, formic acid, acetic acid, an alkyl sulfonic acid, an aryl sulfonic acid, a halogenated acetic acid, a halogenated alkylsulfonic acid, a halogenated aryl sulfonic acid, or a combination thereof.
6. The method of claim 1 , wherein the organic solvent is an aliphatic hydrocarbon comprising CF 3 CH 2 CH 2 CHF 2 , CF 3 CF 2 CFHCFHCF 3 , CF 3 CF 2 CHCl 2 , or mixtures thereof; a cycloalkane comprising cyclohexane, methylcyclohexane, or mixtures thereof; or an aromatic hydrocarbon comprising benzene, toluene, a xylene, trifluorotoluene, or mixtures thereof.
7. The method of claim 1 , wherein the organic solvent is a polyether comprising polyethylene glycol having ester or ether end groups, polypropylene glycol having ester or ether end groups, or mixtures thereof.
8. The method of claim 1 , wherein the organic solvent is a plant-derived oil selected from the group consisting of corn oil, coconut oil, palm kernel oil, palm oil, soybean oil, and cottonseed oil, or mixtures thereof.
9. The method of claim 1 , wherein the volume ratio of water to organic solvent is from about 95:5 to about 5:95.
10. The method of claim 1 , wherein the organic solvent comprises toluene, trifluorotoluene, or corn oil.
11. The method of claim 1 wherein the step of recovering furfural comprises separation of organic layer and evaporation of the organic solvent.