Asphaltenes, a byproduct of crude oil production, are a potentially hazardous waste material. Scientists at Rice University are determined to find it by converting a carbon-rich resource into useful graphene. Muhammad Rahman, an assistant research professor of materials science and nanoengineering at Rice, is converting asphaltenes instantly into turbostratic (loosely aligned) graphene and mixing it into composites for thermal, anti-corrosion, and 3D-printing applications using Rice’s unique flash Joule heating process.
The process makes good use of material that would otherwise be burned as fuel or disposed of in tailing ponds and landfills. Using at least some of the world’s more than 1 trillion barrels of asphaltene reserve as a feedstock for graphene would also be beneficial to the environment.
“Asphaltene is a big headache for the oil industry, and I think there will be a lot of interest in this,” Rahman said, describing the process as both scalable and sustainable in terms of reducing carbon emissions from asphaltene combustion.
We try to keep the carbon black content as low as possible because we want to maximize the utilization of asphaltene. The government has been putting pressure on the petroleum industries to take care of this.
Muhammad Rahman
Rahman is a lead corresponding author of the paper in Science Advances co-led by Rice chemist James Tour, whose lab developed flash Joule heating, materials scientist Pulickel Ajayan and Md Golam Kibria, an assistant professor of chemical and petroleum engineering at the University of Calgary, Canada.
Asphaltenes are 70% to 80% carbon already. The Rice lab combines it with about 20% of carbon black to add conductivity and flashes it with a jolt of electricity, turning it into graphene in less than a second. Other elements in the feedstock, including hydrogen, nitrogen, oxygen, and sulfur, are vented away as gases.
“We try to keep the carbon black content as low as possible because we want to maximize the utilization of asphaltene,” Rahman said. “The government has been putting pressure on the petroleum industries to take care of this,” said Rice graduate student and co-lead author M.A.S.R. Saadi. “There are billions of barrels of asphaltene available, so we began working on this project primarily to see if we could make carbon fiber. That led us to think maybe we should try making graphene with flash Joule heating.”
Assured that Tour’s process worked as well on asphaltene as it did on various other feedstocks, including plastic, electronic waste, tires, coal fly ash, and even car parts, the researchers set about making things with their graphene.
Saadi, who works with Rahman and Ajayan, mixed the graphene into composites, and then into polymer inks bound for 3D printers. “We’ve optimized the ink rheology to show that it is printable,” he said, noting the inks have no more than 10% of graphene mixed in. Mechanical testing of printed objects is forthcoming, he said.
