Scientists at Texas A&M University in Qatar have developed a way of taking carbon dioxide (CO2) out of the process of energy production and turning it into carbon nanotubes (CNTs) — rolled sheets of graphene, sometimes called the ‘miracle material’. CNTs are being planned for use in photovoltaics and batteries to store renewable energy to, and one day, perhaps, a space elevator.
Qatar is one of the world’s top producers of natural gas, and turning the CO2 emitted during processing the gas into usable products. But a novel process could help Qatar process its natural gas, while reducing the country’s carbon footprint, possibly spawning a new industry of producing high-quality materials feeding a range of vital industries.
Developed in Qatar, the CARGEN reactor technology was conceived and designed by Nimir O. Elbashir and his research team at Texas A&M’s Qatar campus, in collaboration with Mahmoud M. El-Halwagi and his co-worker Debalina Sengupta from the Artie McFerrin Department of Chemical Engineering at Texas A&M’s main campus in College Station, Texas (USA). This technology is believed to be the first of its kind that processes natural gas (methane) and captures CO2 to produce both syngas — a valuable precursor to numerous hydrocarbon feedstocks — and high-quality solid CNTs. Unlike conventional processes, this method doesn’t release more CO2 into the atmosphere.
Elbashir’s research focuses on converting natural gas into hydrocarbon products, including ultraclean fuels or useful chemicals, in a process called gas-to-liquid conversion, or GTL. A major drawback of GTL processing is that it produces a lot of CO2, which increases Qatar’s carbon footprint and has led to the tiny country being named the world’s leading producer of CO2 per capita.
Under the umbrella of the Texas A&M University Engineering Experiment Station (TEES) Gas and Fuels Research Center (GFRC) headquartered at the Qatar Foundation, Elbashir and researchers at both campuses have focused on how to reduce CO2 emissions and reduce Qatar’s carbon footprint. Elbashir directs the GFRC, one of the largest TEES research centers and a major initiative, bringing together 32 multidisciplinary scientists and professors from Texas A&M’s campuses in Texas and Qatar, all working from different angles to speed up technology development in natural-gas processing.
The CARGEN — or CARbon-GENerator — technology was developed to advance the dry reforming of natural gas, which is especially attractive as it converts methane and CO2 through a reactor to produce syngas, which is a mixture of carbon monoxide and hydrogen that is then processed to make liquid hydrocarbons and ultraclean fuels. This process, however, requires a lot of heat to drive the chemical reactions. This heat — the reactions happen at more than 1,000° Celsius — usually comes from burning fuels, which emits even more CO2.
Elbashir’s team has designed the novel CARGEN reactor, a second reactor added to the reforming process, along with a catalyst to drive the chemical reactions to produce expensive CNTs and syngas from CO2 and methane. These high-quality CNTs can be used in several industries, including steel and cement, while the syngas can be turned into ultra-clean fuels and value-added products. The process can be driven by electric or solar power, eliminating the need to burn fuel and thereby resulting in much lower CO2 emissions than conventional technologies.
“We are making Qatar CO2 emissions into two products that are important to the economy in Qatar and will broaden the role of hydrocarbons in Qatar’s manufacturing facilities,” Elbashir said. “CNTs are very expensive and extremely versatile, and can be used to manufacture products such as computers and other high-quality materials. And at the same time, we are also producing syngas, which can then be used to make the chemicals Qatar’s processing industries rely on.”
The CARGEN reactor is a result of a nearly US$5 million Exceptional Proposal grant from the Qatar National Research Fund’s National Priorities Research Program, said Ph.D. student Mohamed Sufiyan Challiwala, who has been a significant contributor to the project. Challiwala started working on the project as a master’s student in chemical engineering at Texas A&M at Qatar before pursuing his Ph.D. through the main campus and beginning his doctoral research in Qatar.
Challiwala said, “CARGEN provides a new perspective on the implementation of natural gas–reforming technology. Rather than considering carbon or ‘coke’ formation as a process challenge, CARGEN treats it as an opportunity to convert at least 65% of CO2 per pass with 50% lower energy requirements. Most importantly, it produces CNTs and fibers that are considered to be next-generation materials with tremendous applications. This process is now patented with the support of Qatar Foundation.”
Hanif Choudhury, a research scientist in Elbashir’s group, said, “The CARGEN concept of CNT generation has been validated at the micro-, milli- and gram scales, with the quality of the carbon nanotubes controlled and preserved at every scale.”
The next step is partnering with industry collaborators to scale up the technology even further.
“This is a major achievement in the way people will look at CO2 utilization in the future,” Elbashir said. “It’s a homegrown technology based on Qatar’s interest in utilizing and sequestering CO2 and reduce the country’s carbon footprint. We are producing material out of it, not just liquid fuel that will be burned to produce something else or power a car, for example, which then puts CO2 back into the atmosphere.”
4 SURPRISING USES FOR CARBON NANOTUBES
Carbon nanotubes (CNTs) are hollow cylinders made of graphite carbon atoms at nanoscale (10−9 meters), much smaller than the width of a human hair. Discovered more than 50 years ago, the potential of CNTs is only now starting to be realized. So how could CNTs be used?
Researchers have found ways to unzip CNTs into atom-thick sheets of graphene. Like silicon, graphene is a semi-conductor. With their nanoscale size, CNTs can pack much more computing power in one place — or even use CNTs as “quantum wires” able to switch a single electron — to make computing more powerful.
Because of the properties of CNTs interacting with electrons, researchers have been exploring ways to use this material to significantly increase the efficiency of photovoltaic cells. In addition, a team at the Massachusetts Institute of Technology pioneered a way to use CNTs to store 10,000 times more energy with solar thermal systems than with previous methods.
MOLECULAR SYRINGES AND CANCER TREATMENT
Biotechnology researchers have been finding ways to exploit CNTs to direct drugs or genes into individual cells. In one study, CNTs were injected into kidney tumors in mice and then a near-infrared laser was aimed at the cancer cells, making the CNTs vibrate. With the highest “dose” of CNTs and 30 seconds of laser light, the tumors disappeared in 80% of the mice.
Because of the incredible strength and light weight of CNTs, researchers have explored ways to create extremely tough and flexible materials. Some experts imagine that 62,000-mile-long cables made of CNTs stretching out of the atmosphere and connected to a geosynchronous “captured” asteroid could be used to lift people and supplies from the Earth’s surface and into orbit.
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