USA: Exxon and GIT Develop New Technology Reduced Energy Consumption in Plastics Production

Editor: Alexander Stark

Scientists from Exxon Mobil and the Georgia Institute of Technology have developed a new technology that could significantly reduce the amount of energy and emissions associated with manufacturing plastics. Results of the research were published in the peer-reviewed journal Science.

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A molecular-level filter could revolutionize energy-intense chemical processes. (sample image)
A molecular-level filter could revolutionize energy-intense chemical processes. (sample image)
(Source: Exxon Mobil)

Irving/USA — The company claims that if brought to industrial scale, this technology could reduce industry’s global annual carbon dioxide emissions by up to 45 million tons, which is equivalent to the annual energy-related carbon dioxide emissions of about five million U.S. homes. It could also reduce global energy costs used to make plastics by up to $ 2 billion a year. Using a molecular-level filter, the new process employs a form of reverse osmosis to separate para-xylene, a chemical building block for polyester and plastics, from complex hydrocarbon mixtures. The current commercial-scale process used around the world relies on energy and heat to separate those molecules.

“Through collaboration with strong academic institutions like Georgia Tech, we are constantly exploring new, more efficient ways to produce the energy, chemicals, and other products consumers around the world rely on every day," said Vijay Swarup, vice president of research and development at Exxon Mobil Research and Engineering Company. “If advanced to commercial-scale application, this technology could significantly reduce the amount of greenhouse gas emissions associated with chemical manufacturing.”

The research demonstrated that para-xylene can be separated from like chemical compounds known as aromatics by pressing them through a membrane that acts as a high-tech sieve, similar to a filter with microscopic holes. Commercially practiced separations involve energy-intensive crystallization or adsorption with distillation. Globally, the amount of energy used in conventional separation processes for aromatics is equal to about 20 average-sized power plants. Chemical plants account for about eight percent of global energy demand and about 15 percent of the projected growth in demand to 2040.

The team first developed a new carbon-based membrane that can separate molecules as small as a nanometer. The membrane was then incorporated into a new organic solvent reverse osmosis process, during which aromatics were pressed through the membrane, separating out para-xylene. The researchers claim that their carbon-based membrane was about 50 times more energy efficient than the current state-of-the-art membrane separation technology. Because the new membrane is made from a commercially available polymer, the company believes it has potential for commercialization and integration into industrial chemical separation processes. The new organic solvent reverse osmosis process is believed to be the first use of reverse osmosis with carbon membranes to separate liquid hydrocarbons.

“By applying pressure at room temperature, the membrane is able to concentrate para-xylene from a mixture at high rates and low energy consumption relative to state-of-the-art membranes,” said Ryan Lively, an assistant professor in Georgia Tech’s School of Chemical & Biomolecular Engineering and the lead researcher. “This mixture could then be fed into a conventional thermal process for finishing, which would dramatically reduce total energy input.”

However, according to Exxon, the technology still faces challenges before it can be considered for commercialization and use at an industrial scale. The membranes used in the process would need to be tested under more challenging conditions, as industrial mixtures normally contain multiple organic compounds and may include materials that can foul membrane systems.

“The implications could be enormous in terms of the amount of energy that could be saved and the emissions reduced in chemical and product manufacturing,” said Benjamin McCool, an advanced research associate at ExxonMobil and co-author of the research. “Our next steps are to further the fundamental understanding in the lab to help develop a plan for pilot plant-scale demonstration and, if successful, proceed to larger scale. We continue to work the fundamental science underlying this technology for broader applications in hydrocarbon separations.”