A breakthrough discovery in carbon capture conversion by The University of Illinois at Chicago: A review
Summary:
A team of researchers led by Meenesh Singh at the University of Illinois Chicago has discovered a way to convert 100% of carbon dioxide captured from the industrial exhaust into ethylene, a key building block for plastic products.
Why it is an outstanding invention
Water?is?a?poor?solvent?for CO2.?While?CO2?dissolves?to?form?carbonic?acid in the water, H2CO3 is?not?a?stable?molecule?thermodynamically. It generates negative entropy and positive Gibbs free energy. And because?of this, it?decomposes?immediately?back?to?CO2 + H20??with?less?than?1%?conversion.
UIC process
An?electric?current?is?passed?through?a?cell,?half?of?which?is?filled?with?captured?carbon?dioxide?and?the?other?half?with?a?water-based?solution,?in?UIC's?approach.?An?electrified?catalyst?attracts?charged?hydrogen?atoms?from?water?molecules?into?the?other?half?of?the?unit,?which?is?separated?by?a?membrane,?where?they?combine?with?charged?carbon?atoms?from?carbon?dioxide?molecules?to?form?ethylene.
UIC?avoided?direct?CO2?contact?with?H2O?in?favor?of?combining?CO2?and?H2.
Why did UIC choose CO2 to ethylene conversion as a challenge?
Among manufactured chemicals, ethylene ranks third in terms of carbon emissions, trailing only ammonia and cement. Ethylene is used to make plastic products for the packaging, agricultural, and automotive industries, as well as chemicals used in antifreeze, medical sterilizers, and vinyl siding for houses.
Ethylene is typically produced through a process known as steam cracking, which requires enormous amounts of heat. Cracking emits about 1.5 metric tonnes of CO2 per tonne of ethylene produced. Every year, manufacturers produce approximately 160 million tonnes of ethylene, resulting in more than 260 million tonnes of CO2 emissions worldwide.
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What is carbon capture: A brief review
There are two ideas. [1] Carbon capture and storage (CCS), also known as carbon capture and sequestration (CCS), and [2] carbon capture. It is a centuries-long process of capturing carbon dioxide (CO2) before it enters the atmosphere, transporting it, and storing it (carbon sequestration) in an underground geological formation. The goal is to reduce CO2 emissions from heavy industry in order to mitigate the effects of climate change. Although CO2 has been injected into geological formations for decades for a variety of purposes, including enhanced oil recovery, long-term CO2 storage is a relatively new concept. CCS is a relatively expensive process that produces a product with a low intrinsic value (i.e., CO2). As a result, carbon capture makes more economic sense when combined with a utilisation process in which the cheap CO2 is used to produce high-value chemicals, offsetting the high costs of capture operations. CO2 can be directly captured from an industrial source, such as a cement kiln, using a variety of technologies such as absorption, adsorption, chemical looping, membrane gas separation, or gas hydration. CCS will capture approximately one-thousandth of global CO2 emissions by 2020. The majority of projects are industrial.
Global proposed (grey bars) vs. implemented (blue bars) annual CO2 sequestration.
More than 75% of proposed gas processing projects have been implemented, with corresponding figures for other industrial projects and power plant projects being about 60% and 10%, respectively.
About the article picked up from the paper
A team of researchers led by Meenesh Singh at the University of Illinois Chicago has discovered a way to convert 100% of carbon dioxide captured from the industrial exhaust into ethylene, a key building block for plastic products. The UIC team's approach is the first to achieve nearly 100% utilization of carbon dioxide to produce hydrocarbons. Their system uses electrolysis to transform captured carbon dioxide gas into high purity ethylene, with other carbon-based fuels and oxygen as by-products. The process can convert up to 6 metric tons of carbon dioxide into 1 metric ton of ethylene, recycling almost all carbon dioxide captured. Because the system runs on electricity, the use of renewable energy can make the process carbon negative.
According to Singh, his team's approach surpasses the net-zero carbon goal of other carbon capture and conversion technologies by actually reducing the total carbon dioxide output from the industry. "It's a net negative," he said. "For every 1 ton of ethylene produced, you're taking 6 tons of CO2 from point sources that otherwise would be released to the atmosphere."
Challenges
Previous attempts at converting carbon dioxide into ethylene have relied on reactors that produce ethylene within the source carbon dioxide emission stream. In these cases, as little as 10% of CO2 emissions typically converts to ethylene. The ethylene must later be separated from the carbon dioxide in an energy-intensive process often involving fossil fuels.
Process
In UIC's approach, an electric current is passed 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 the water molecules into the other half of the unit separated by a membrane, where they combine with charged carbon atoms from the carbon dioxide molecules to form ethylene.