Making methane from Carbon Dioxide: Carbon capture grows more affordable

Newswise: Making Methane from CO2: Carbon Capture Grows More Affordable
Just as important as understanding how best to capture CO2 is understanding how to use it. A new study details how CO2 can be converted into methane, the primary component of synthetic natural gas. Here, Jotheeswari Kothandaraman, PNNL chemist and author of the new study, holds a sample of methanol, which has an even greater number of applications than methane.
(Photo by Andrea Starr | Pacific Northwest National Laboratory)

For a long time, scientists have been interested in converting the global-warming chemical carbon dioxide into something of a useful fuel. Several scientists and researchers are wrangling with how to conserve hydrogen, which is an excellent energy transporter. Carbon dioxide reacting with hydrogen to form methane, a fuel, is a technique to kill two birds with one stone. Researchers at the Tata Institute of Fundamental Research (TIFR) reportedly devised a more efficient and cost-effective method of converting CO2 to methane.

The process is enabled by EEMPA, a crucial chemical actor. EEMPA is indeed a PNNL-developed surfactant that attracts  CO2 through power plant exhaust gas and binds it, allowing it to be transformed into valuable compounds. Researchers from PNNL demonstrated earlier this year that utilizing EEMPA within energy plants may reduce carbon capture prices by 19 percent compared to typical industry expenses, the lowest price yet observed for carbon capture. The team now discloses a new incentive—cheaper natural gas—to further reduces expenses in a research published in the journal ChemSusChem on Friday, August 21. When compared to the traditional technique of methane transformation, the new approach requires a 32 percent lower initial expenditure. The cost of operation and maintenance is reduced by 35%, lowering the price of artificial natural gas by 12%.

The function of methane in carbon capture

According to Polshettiwar, silica is a far superior catalyst over metallic nanoparticles, which are unstable. For the first time, a “metal-free, ligand-free” catalyst is used in this procedure. The method now requires 400°C heat, but “we are working on developing a ‘room temperature’ technique utilizing sunlight,” he added. This method offers a number of distinct benefits over others. The ‘defective silica’ serves two purposes: it rips hydrogen molecules into the 2 individual atoms of the element and it ‘activates’ carbon dioxide, boosting its reaction capability. According to a release from TIFR, “metallic nanoparticles also weren’t required, as well as the flaw sites alone functioned as catalyst surface for CO2 activation and hydrogen dissociation, and their combined action converted  CO2 to methane.” They also discovered that now the catalysts were cycled, more methane was produced. After eight regeneration cycles, methane emissions had doubled.

Cost-benefit analysis and carbon capture

To investigate the usage of EEMPA in turning  CO2 into methane, Kothandaraman along with her coauthors looked into the reaction’s molecular foundations before calculating the cost of scaling up the process in a 550-megawatt nuclear plant. Plant operators may now capture CO2 by dousing flue gas with specific solvents before it is released from plant chimneys. However, because these conventional solvents have a high water content, methane conversion is challenging.

Instead, using EEMPA lowers the amount of energy required to power such a reaction. The savings are due in part to EEMPA’s ability to dissolve  CO2 more easily, requiring less pressure to complete the conversion. The scientists discovered further cost reductions when they discovered that CO2 collected by EEMPA may be transformed into methane on spot.  CO2 is traditionally extracted from liquid solvents and sent off-site to be transformed or buried. Captured  CO2 is combined with sustainable hydrogen as well as a catalyst inside a small chamber, then warmed to 1/2 the pressure required in traditional methane production processes.

According to the scientists, the process is effective, converting over 90% of collected CO2 to methane; however, the final greenhouse gas footprint is dependent on what the methane is utilized for. Furthermore, EEMPA absorbs approximately 95% of  CO2 produced in the flue gas. Excess heat is also produced by the new method, which is used to produce steam for energy production.        

Getting more  CO2 out of it

Although it would be too early to call the method a Nobel Prize contender, this really does seem to be a step forward. Various techniques for turning carbon dioxide into methane abound in the scientific literature; however, they all need rare metals or are inefficient. Yasushi Sekine of Waseda University devised a method in February that used cerium oxide nanoparticles as a catalyst and an uncommon, inert metal called Ruthenium as a catalyst. The procedure necessitated the use of an electric field. A team of researchers from France’s University Paris Diderot and Argentina’s Universidad National de Córdoba identified a chemical mechanism that may convert carbon dioxide to methane a year ago. The method is inefficient, however, because the substance generated is 82 percent carbon monoxide, according to the researchers. It’s also extremely inefficient, producing only 12 grams of methane each hour. As a result, TIFR’s method is a huge step forward in science.

According to Kothandaraman, the chemical process detailed in the article is one of several where collected  CO2may be utilized like a feedstock for synthesizing other valuable compounds. “I’ll be happy when I can get this technique to operate as well for methanol as it would for methane,” she added. “That is my long-term objective.” Methanol has far more uses than methane, according to Kothandaraman, who has spent the last decade trying to figure out the catalytic processes that might create methanol from  CO2. Another avenue the team intends to pursue is the creation of polymers from collected CO2. “It’s critical that we not only capture  CO2 but also discover useful uses for it,” said Ron Kent, SoCalGas’ Advanced Technologies Development Manager, “and this study provides a cost-effective road toward producing something value out of waste CO2.”

Sources :

Research paper: David Heldebrant, Jotheeswari Kothandaraman, Johnny Saavedra Lopez, Yuan Jiang, Eric D. Walter, Sarah D. Burton, Robert A. Dagle. Integrated Capture and Conversion of CO2 to Methane using a Water‐lean, Post‐Combustion CO2 Capture SolventChemSusChem, 2021; DOI: 10.1002/cssc.202101590

https://www.sciencedaily.com/releases/2021/09/210903095311.htm

https://www.thehindubusinessline.com/news/science/tifr-scientist-develops-new-way-of-producing-methane-from-carbon-dioxide/article31323963.ece

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