The quest for efficiency and productivity in the chemical and process industry is a 24/7 occupation. Extracting every ounce of potential is the goal. But it is not easy and some corners of our profession have big challenges.
Extracting the full potential of biomass is one example. Trees, plants and agricultural waste can provide a valuable source of fuel in the form of ethanol from cellulose.
But the same biomass also consists of lignin – a by-product of ethanol production. Although nearly as abundant as cellulose, its uses are more limited and is often just burnt to power ethanol plants.
If a cellulosic ethanol industry is to grow and be commercially successful, new processes will be needed to convert all of the input biomass into fuel. To improve the economic feasibility, a portion of the lignin needs to be converted to higher-values chemicals or materials.
The challenge has promoted a multi-disciplinary team at Purdue University to take a new look at breaking down the molecules in biomass – using rocket technology!
Take a look at this video which offers a great explanation of their work, including rocket technology which heats the biomass in a few hundredths of a second.
The new catalytic process is able to convert the lignin in the biomass into lucrative chemical products that can be used in fragrances, flavorings or to create high-octane fuel for race-cars and jets.
Mahdi Abu-Omar, the R.B. Wetherill professor of chemistry and professor of chemical engineering at Purdue says: “We are able to take lignin – which most biorefineries consider waste to be burned for its heat – and turn it into high-value molecules that have applications in fragrance, flavoring and high-octane jet fuels
“We can do this while simultaneously producing from the biomass lignin-free cellulose, which is the basis of ethanol and other liquid fuels. We do all of this in a one-step process.”
The Purdue team has developed a process that starts with untreated chipped and milled wood from sustainable poplar, eucalyptus or birch trees.
A catalyst is added to initiate and speed the desired chemical reactions, but is not consumed by them and can be recycled and used again.
A solvent is added to the mix to help dissolve and loosen up the materials. The mixture is contained in a pressurized reactor and heated for several hours.
The process breaks up the lignin molecules and results in lignin-free cellulose and a liquid stream that contains two additional chemical products, Abu-Omar said.
The liquid stream contains the solvent, which is easily evaporated and recycled, and two phenols, a class of aromatic hydrocarbon compounds used in perfumes and flavorings, such as vanilla.
The team also developed an additional process that uses another catalyst to convert the two phenol products into high-octane hydrocarbon fuel suitable for use as drop-in gasoline.
The fuel produced has a research octane rating greater than 100, whereas the average gas we put into our cars has an octane rating in the eighties.
Looking to the future, Mahdi says: “A biorefinery that focuses not only on ethanol, but on other products that can be made from the biomass is more efficient and profitable overall.
“It is possible that lignin could turn out to be more valuable than cellulose and could subsidise the production of ethanol from sustainable biomass.”
Let’s hope so. We wish them all the best as they look to reduce costs and scale-up their work.