Amazing discovery in converting carbon capture to produce ethylene

Abstract illustration of atoms passing through water and an electrified membrane under bright sunlight. Credit: Minish Singh

A team of researchers led by Minch Singh at the University of Illinois at Chicago has discovered a way to convert 100% of the carbon dioxide captured from industrial exhaust into ethylene, a building block for plastic products.

Their findings were published in Cell Reports Physical Sciences.

While researchers were exploring the possibility of conversion Carbon Dioxide to me ethylene For more than a decade, the UIC team’s approach has been the first to achieve nearly 100% use of carbon dioxide for hydrocarbon production. Their system uses electrolysis to transform the pickup carbon dioxide gas into high purity ethylene, with other carbon fuels and oxygen as by-products.

This process can convert up to 6 metric tons of carbon dioxide into 1 metric ton of ethylene, recycling nearly all of the carbon dioxide captured. Since the system runs on electricity, using renewable energy can make the process carbon negative.

According to Singh, his team’s approach goes beyond the net zero carbon goal of other carbon capture and conversion technologies by effectively reducing total carbon dioxide output from the industry. “It’s net negative,” he said. “For every ton of ethylene produced, you take in 6 tons of carbon dioxide2 from specific sources that would otherwise be released into the atmosphere.”

Previous attempts to convert carbon dioxide to ethylene have relied on reactors that produce ethylene within the source carbon dioxide emission stream. In these cases, less than 10% of carbon dioxide2 The emissions are typically converted to ethylene. Ethylene must then be separated from carbon dioxide in an energy-intensive process that often involves fossil fuels.

In the UIC approach, the . file electric current It passes through a cell, half filled with captured carbon dioxide, and the other half with an aqueous solution. The electrocatalyst draws a charge hydrogen atoms From water molecules The other half of the unit is separated by a membrane, where it combines with the charge carbon atoms from carbon dioxide molecules to form ethylene.

Among chemicals manufactured worldwide, ethylene ranks third in carbon emissions after ammonia and cement. Ethylene is used not only in construction plastic products For the packaging, agricultural and automotive industries, but also for the production of chemicals used in antifreeze, medical sterilizers and vinyl siding for homes.

Ethylene is usually made in a process called steam cracking, which requires huge amounts of heat. Cracking generates about 1.5 metric tons of carbon emissions for every ton of ethylene produced. On average, manufacturers produce about 160 million tons of ethylene each year, resulting in more than 260 million tons of carbon dioxide emissions worldwide.

In addition to ethylene, UIC scientists have been able to produce other carbon-rich products useful for industry through an electrolysis approach. They have also achieved a very high efficiency in solar energy conversion, converting 10% of the energy from Solar Panels Direct to carbon product production. This is well above the more recent 2% level. For all the ethylene produced, the solar energy conversion efficiency was about 4%, which is about the same as the rate of photosynthesis.

The conversion process turns carbon dioxide into money

more information:
Aditya Prajapati et al, High-purity CO2-free ethylene from CO2 electrosorption of 4% solar to ethylene and 10% solar to carbon, Cell Reports Physical Sciences (2022). doi: 10.1016/j.xcrp.2022.01053

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