Furfural is an organic compound with the formula C4H3OCHO. It is a colorless liquid, although commercial samples are often brown. It has an aldehyde group attached to the 2-position of furan. It is a product of the dehydration of sugars, as occur in a variety of agricultural byproducts, including corncobs, oat, wheat bran, and sawdust. The name furfural comes from the Latin word furfur, meaning bran, referring to its usual source.

Furfural is only derived from lignocellulosic biomass, i.e. its origin is non-food or non-coal/oil based. Aside from ethanol, acetic acid and sugar it is one of the oldest renewable chemicals. It is also found in many processed foods and beverages.

Production of Furfural

We mentioned that furfural was a renewable chemical feedstock. The reason this is the case actually stems from how it's made. Furfural can be produced on large industrial scales by taking plant mass and treating it with an acid. When this happens, the 5-carbon sugar molecules undergo a dehydration (loss of water) reaction to give furfural.

Depending on the type of plant matter that's used, anywhere between 3% and 10% of the original plant mass can be recovered as furfural. Obviously, plants are constantly growing and being produced, that's why furfural is considered a 'green' or renewable source of chemical feedstocks. It could potentially represent an important source of organic compounds once petroleum resources start to dry up.

Applications of Furfural

refining of lubricating oils & decolorizing agent

Furfural thanks several large scale applications to its solubility characteristics and its easy recuperation by steam distillation. Furfural has the unique property to dissolve aromatics and other unsaturated olefins. Today all major oil companies use furfural as selective solvent in the refining of lubricating oils. The first refining unit was built by a subsidiary of Texaco, the Indian Refining Company. This technology lead to production of high quality motor oil with improved temperature-viscosity properties. Aromatics, polar components, mercaptans are removed from petroleum by means of furfural extraction. Furfural can also be used as decolorizing agent to refine crude wood rosin.

purification technology for C4 and C5 hydrocarbons

During the Second World War the purification technology of butadiene was developed in the United States for the manufacture of synthetic rubber. By extractive distillation with furfural butadiene or isoprene can be separated from other C4 and C5 hydrocarbons, respectively.

reactive solvent and good wetting agent

Furfural is unusually effective as a solvent for phenolic resins. In the manufacture of abrasive wheels, brake linings and refractory products for the steel industry furfural is known as a reactive solvent and excellent wetting agent.

unique chemical feedstock for other furan derivatives

However, the main outlet of furfural is as chemical feedstock for the production of furfuryl alcohol and for other 5-membered oxygen-containing heterocycles, i.e. furan, methylfuran, acetylfuran, furfurylamine and furoic acid.