FIELD

The present disclosure relates generally to the production of furfurals, and more specifically to the production of 5-(halomethyl)furfural, including, for example, 5-(chloromethyl)furfural or 5-(bromomethyl)furfural, from renewable biomass resources (e.g., cellulose, hemicellulose, starch, and sugar).

BACKGROUND

Efforts to reduce dependence on fossil fuels for transportation fuel and as feedstock for industrial chemicals have been undertaken for decades, with a particular focus on enabling economic feasibility of renewable feedstocks. Heightened efforts are being made to more effectively utilize renewable resources and develop “green” technologies, due to continued long-term increases in the price of fuel, increased environmental concerns, continued issues of geopolitical stability, and renewed concerns for the ultimate depletion of fossil fuels.

Cellulose in biomass is commonly used as a feedstock for biofuel production. For example, cellulose can be used to produce ethanol. Cellulose can also be used to produce furan-based biofuels by way of 5-(halomethyl)furfural, such as 5-(chloromethyl)furfural (CMF). CMF can be converted into 5-(ethoxymethyl)furfural, a compound considered as a promising diesel fuel additive. Alternatively, CMF can also be converted into 5-methylfurfural, another compound considered as a promising a biofuel candidate.

The production of CMF from cellulose was first described in the early 1900s. Currently, various synthetic routes are known in the art to produce CMF from biomass using concentrated hydrochloric acid. For example, U.S. Pat. No. 7,829,732 describes a method of producing CMF from biomass using concentrated hydrochloric acid and 1,2-dichloroethane as a solvent. See also, Szmant & Chundury,J. Chem. Tech. Biotechnol.1981, 31, 205-212; Liu et al.,J. Phys. Chem. A,2011, 115, 13628-13641. The use of concentrated hydrochloric acid, however, can present several challenges on a commercial scale. For example, use of concentrated hydrochloric acid can cause corrosion of the reactors.

Thus, what is needed in the art are commercially viable methods to produce 5-(halomethyl)furfural from biomass, using lower acid concentrations.

BRIEF SUMMARY

Provided herein are methods for producing 5-(halomethyl)furfural, including 5-(chloromethyl)furfural (CMF) and 5-(bromomethyl)furfural (BMF), using lower acid concentrations than what is currently known in the art. Lower acid concentrations can provide process advantages for the commercial production of 5-(halomethyl)furfural. For example, lower acid concentrations can reduce corrosion of the reactors.

In one aspect, provided is a method for producing 5-(halomethyl)furfural by:a) combining a feedstock, an aqueous acid, and a salt in a reaction vessel to form a reaction mixture, wherein:the aqueous acid is a halogen-containing acid; andthe reaction mixture has a [H+] less than 12 M; andb) converting at least a portion of the feedstock in the reaction mixture to produce 5-(halomethyl)furfural.

In other embodiments, the method further includes isolating the 5-(halomethyl)furfural from the reaction mixture.

In some aspects, provided is also a composition that includes: a feedstock; an aqueous acid; and a salt, wherein:the aqueous acid is a halogen-containing acid; andthe composition has a [H+] less than 12 M.

In certain embodiments of the methods and compositions descried herein, the aqueous acid is hydrochloric acid or hydrobromic acid. In one variation, the aqueous acid is HX, wherein X is halo.

In certain embodiments of the methods and compositions descried herein, the salt has a formula Ar+(X−)r, where Ar+is a cation having charge r, wherein X is halo and X−is an anion. In some variations, [X−] is [Cl−] or [Br−].

In some embodiments that can be combined with any of the methods and compositions described herein, the feedstock, aqueous acid and salt are further combined with a solvent.

In some embodiments of the methods and compositions descried herein, the feedstock is selected from the group consisting of corn stover, rice hulls, peanut hulls, spent grains, paper sludge, cardboard, old corrugated containers (OCC), old newspaper (ONP), mixed paper, wheat straw, paper mill effluent, newsprint, municipal solid wastes, wood chips, forest thinnings, slash,miscanthus, switchgrass, sorghum, bagasse, manure, wastewater biosolids, green waste, and food or feed processing residues, or any combinations thereof. In other embodiments, the feedstock comprises glucose, fructose, sucrose, starch, inulin, cellulose, hemicellulose, cellulosic oligomers, cellobiose, or any combinations thereof.

