Presidential Green Chemistry Challenge: 1999 Small Business Award
Biofine, Inc. (now DPS BioMetics, Inc.)
Conversion of Low-Cost Biomass Wastes to Levulinic Acid and Derivatives
Innovation and Benefits: Biofine developed a process to convert the waste cellulose in paper mill sludge, municipal solid waste, unrecyclable waste paper, waste wood, and agricultural residues into levulinic acid (LA). LA can be used as a building block for many other useful chemicals. LA made from waste cellulose reduces the use of fossil fuels and reduces the overall cost of LA from $4–6 per pound to as little as $0.32 per pound.
Summary of Technology: Replacing petroleum-based feedstocks with renewable ones is a crucial step toward achieving sustainability. When considering alternatives to traditional feedstocks, attention often focuses on plant-based materials. Renewable biomass conserves our dwindling supplies of fossil fuels and contributes no net CO2 to the atmosphere. Biofine has developed a high-temperature, dilute-acid hydrolysis process that converts cellulosic biomass to levulinic acid (LA) and derivatives. Cellulose is initially converted to soluble sugars, which are then transformed to levulinic acid. Byproducts in the process include furfural, formic acid, and condensed tar, all of which have commercial value as commodities or fuel. Feedstocks used include paper mill sludge, municipal solid waste, unrecyclable waste paper, waste wood, and agricultural residues.
Levulinic acid serves as a building block in the synthesis of useful chemical products. Markets already exist for tetrahydrofuran, succinic acid, and diphenolic acid, all of which are levulinic acid derivatives. The use of diphenolic acid (DPA) as a monomer for polycarbonates and epoxy resins is currently under investigation. An industry/government consortium has conducted research on two additional derivatives with commercial value: methyltetrahydrofuran (MTHF), a fuel additive, and δ-amino levulinic acid (DALA), a pesticide. The conversion of levulinic acid to MTHF is accomplished at elevated temperature and pressure using a catalytic hydrogenation process. MTHF is a fuel additive that is miscible with gasoline and hydrophobic, allowing it to be blended at the refinery rather than later in the distribution process. Using MTHF as a fuel additive increases the oxygenate level in gasoline without adversely affecting engine performance. MTHF also boasts a high octane rating (87) and a lower vapor pressure, thereby reducing fuel evaporation and improving air quality.
DALA can be obtained from levulinic acid in high yield using a three-step process. DALA is a broad-spectrum pesticide that is nontoxic and biodegradable. Its activity is triggered by light, selectively killing weeds while leaving most major crops unaffected. DALA also shows potential as an insecticide.
Diphenolic acid is synthesized by reacting levulinic acid with phenol. DPA has the potential to displace bisphenol-A, a possible endocrine disruptor, in polymer applications. Brominated DPA shows promise as an environmentally acceptable marine coating, while dibrominated DPA may find use as a fire retardant.
Currently, levulinic acid has a worldwide market of about one million pounds per year at a price of $4–6 per pound. Large-scale commercialization of the Biofine process could produce levulinic acid for as little as $0.32 per pound, spurring increased demand for LA and its derivatives. Using the Biofine process, waste biomass can be transformed into valuable chemical products. The ability to produce levulinic acid economically from waste biomass and renewable feedstocks is the key to increased commercialization of LA and its derivatives.