Tetraamine modified MOFs remove 90% of CO2 more efficiently and cheaply.
major advances in carbon extraction technology could provide an effective and inexpensive way for natural gas plants to remove carbon dioxide from their flue emissions, a necessary step in reducing gas emissions of greenhouse to slow global warming and climate change.
Developed by researchers at University of California, Berkeley, Lawrence Berkeley National Laboratory and ExxonMobil, the new method uses a very fast material called a metal-organic framework, or MOF, modified by nitrogen-containing molecules to obtain CO2 and low vapor temperature to eliminate CO2 for other uses or to sequel it underground.
In experiments, the method showed a six times larger capacity for CO removal2 from flue gas than current amine-based technology, and it is highly selective, getting more than 90% of CO2 released The process uses low vapor temperature to regenerate the MOF for repeated use, meaning less energy is required for carbon extraction.
“For CO2 capture, steam stripping – where you use direct steam contact to remove CO2 – is a kind of holy grain for the farm. This is rightly seen as the cheapest way to do this, “said senior researcher Jeffrey Long, professor of chemistry at UC Berkeley and chemical and biomolecular engineering and senior faculty scientist at the Berkeley Lab.” These materials, not at least from the experiments we’ve done so far, it seems very promising. “
Because there is little market for most of the captured CO2, power plants are likely to pump into the ground, or successively, where it would ideally be rock. The cost of scrubbing emissions needs to be facilitated by government policies, such as the carbon trade or a carbon tax, in order to accommodate the CO2 acquisition and order, something that has been implemented by many countries.
The work is funded by ExxonMobil, which works with both Berkeley team and startup Long, Mosaic Materials Inc., to develop, measure and test processes for CO removal.2 from the exit.
Long senior author of a paper describing the new technique published on July 24, 2020, journal issue Science.
“We made the first discovery and, through research and testing, obtained a material that in lab experiments demonstrated the potential not only to capture CO2 under extreme conditions present in the discharge of exhaust gases from natural power plants, but to do so without loss of order, “said co-author Simon Weston, associate associate research and project leader at ExxonMobil Research and Engineering Co. ” We have shown that these new materials can be recycled with low vapor for repeated use, providing the path for a viable solution for extracting carbon at scale.
Carbon dioxide emissions by burning fossil vehicles, electricity generating plants and industry account for approximately 65% of the gases driving climate change, rising above Earth’s average temperature of 1.8 degrees Fahrenheit (1 degree Celsius) since 19ika century. Without a decrease in these emissions, climate scientists predict warmer temperatures, more wrong and violent storms, more sea level rise and rising rainfall, flooding, fire, famine and conflict .
“In fact, in the kinds of things the Intergovernmental Panel on Climate Change says we need to do to control global warming, CO2 acquisition is a big part, “Long said.” We have no equipment for most CO2 that we need to stop coming out, but we need to do it. “
Power plants strip CO2 from today’s flue emissions by dissolving flue gases through organic amines in water, which binds and draws carbon dioxide. The liquid is then heated to 120-150 C (250-300 F) to release CO2 gas, after which the liquids are reused. The whole process consumes about 30% of the energy generated. Seizure of CO2 the underground costs an additional, albeit small, fraction of it.
Six years ago, Long and his team at the UC Berkeley’s Center for Gas Separations, funded by the U.S. Department of Energy, discovered a modified chemical MOF that easily catches CO2 from flue concentrated power plant flue, potentially reduce cost acquisition by half. They added moles to a magnesium-based MOF to enable the formation of CO polymer chains2 which is then cleaned by flushing a moist stream of carbon dioxide.
Because MOFs are so heavy, in this case like a honeycomb, an amount of weight of a paper clip has an internal area equal to a football field, all available for adsorbing gas.
A major advantage of MOFs combined with amine is that amines can be tweaked to obtain CO2 at different concentrations, from 12% to 15% typical emissions of coal plants to 4% typical of natural gas plants, or even lower concentrations in the surrounding air. Mosaic Materials, built and led by Long, were made to use this technology extensively in power and industrial plants.
But the 180 C stream of water and CO2 need to flush the captured CO2 eventually the diamine molecules are expelled, shortening the life of the material. The new version uses four amine molecules – a tetraamine – that are more stable at high temperatures and in the presence of steam.
“Tetraamines are so strongly bound within the MOF that we can use a very concentrated stream of water vapor with zero CO.2, and if you have tried the previous adsorbents, the steam will start to destroy the material, “Long said.
They showed that direct contact with steam at 110-120 C – slightly above boiling water – works well to release CO2. Steam at that temperature is readily available in natural gas power plants, whereas 180 C CO2-Mixing the water needed to regenerate the previously modified MOF required heating, which wastes energy.
When Long, Weston and their colleagues first thought about replacing diamines with tougher tetraamines, it seemed like a long shot. But the crystal structures of MOFs containing diamine have suggested that there may be ways of connecting the two diamines to produce a tetraamine while maintaining the material’s ability to polymerize CO2. When UC Berkeley graduate student Eugene Kim, the first author of the paper, chemically created the tetraamine-appended MOF, it released the diamine-appended MOF on the first test.
Researchers next studied the structure of the modified MOF using Berkeley Lab’s Advanced Light Source, which announced that CO2 the polymers that line the pores of the MOF are actually linked by tetraamines, like a ladder with tetraamines as rungs. Basic principles of calculating the theory of basic principles using a Cori supercomputer at the National Energy Research Scientific Computing Center (NERSC) of the Berkeley Lab, which are computing resources at the Molecular Foundry and resources provided by the Berkeley program Campus Research Computing confirmed this amazing structure initiated by Long’s team initially. .
“I’ve been researching Cal for 23 years now, and it was one of those times where you had a seemingly crazy idea, and it worked right away,” Long said.
References: “Cooperative coal cooperative and steam regeneration in metal-organic metal-organic compounds” by Eugene J. Kim, Rebecca L. Siegelman, Henry ZH Jiang, Alexander C. Forse, Jung-Hoon Lee, Jeffrey D. Martell, Phillip J. Milner, Joseph M. Falkowski, Jeffrey B. Neaton, Jeffrey A. Reimer, Simon C. Weston and Jeffrey R. Long, 24 July 2020, Science.
DOI: 10.1126 / science.abb3976
Co-authors with Long, Kim and Weston are Joseph Falkowski from ExxonMobil; Rebecca Siegelman, Henry Jiang, Alexander Forse, Jeffrey Martell, Phillip Milner, Jeffrey Reimer and Jeffrey Neaton from UC Berkeley; and Jung-Hoon Lee from Berkeley Lab. Neaton and Reimer are also senior faculty scientists at the Berkeley Lab.