A revolutionary discovery in the conversion of carbon capture for the production of ethylene

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

Their findings are published in Physical Sciences Cell Reports.

While researchers have been exploring the possibility of converting carbon dioxide to ethylene for more than a decade, the UIC team’s approach is the first to achieve nearly 100% carbon dioxide utilization for produce hydrocarbons. Their system uses electrolysis to turn captured carbon dioxide into high-purity ethylene, with other carbon-based fuels and oxygen as byproducts.

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

According to Singh, his team’s approach exceeds the net zero carbon goal of other carbon capture and conversion technologies by actually reducing the industry’s total carbon dioxide output. “It’s a net negative,” he said. “For every ton of ethylene produced, you take 6 tons of CO₂ from point sources that would otherwise be released to the atmosphere.”

Previous attempts to convert carbon dioxide to ethylene have relied on reactors that produce ethylene in the source carbon dioxide emission stream. In these cases, as little as 10% CO₂ emissions generally convert to ethylene. The ethylene must then be separated from carbon dioxide in an energy-intensive process often involving fossil fuels.

In the UIC approach, an electric current passes through a cell, half of which is filled with captured carbon dioxide, the other half with a water-based solution. An electrified catalyst draws charged hydrogen atoms from water molecules into the other half of the membrane-separated unit, where they combine with charged carbon atoms from carbon dioxide molecules to form ethylene.

Among the chemicals manufactured in the world, ethylene ranks third in carbon emissions after ammonia and cement. Ethylene is used not only to create plastic products for the packaging, agricultural and automotive industries, but also to produce chemicals used in antifreeze, medical sterilizers and plastic coatings. vinyl for homes.

Ethylene is usually made in a process called steam cracking which requires huge amounts of heat. Cracking generates approximately 1.5 metric tons of carbon emissions per ton of ethylene created. 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 to industry through their electrolysis approach. They have also achieved very high solar energy conversion efficiency, converting 10% of the energy from the solar panels directly into the production of carbon products. This is well above the standard 2% peak. For all the ethylene they produced, the solar energy conversion efficiency was about 4%, about the same rate as photosynthesis.