Using Carbon Dioxide to Create 'Biodegradable Plastic'

Development of Catalyst for Simultaneous Production of Lactic Acid and Formic Acid Using Waste Glycerol from Biodiesel and Discarded Greenhouse Gas Carbon Dioxide

A catalytic technology that can simultaneously produce lactic acid and formic acid, chemical raw materials, from the greenhouse gas carbon dioxide and glycerol, a byproduct of biodiesel, has been selected as the cover paper of the December issue of the international materials science journal Chemistry of Materials.

[Asia Economy Reporter Hwang Junho] A catalytic technology has been developed that can simultaneously produce lactic acid and formic acid, chemical raw materials, from the greenhouse gas carbon dioxide and glycerol, a byproduct of biodiesel. This technology is about 10 to 20 times more active than existing catalysts and can increase the production volume of each substance by about twice. The research team expects it to be an eco-friendly method for reducing greenhouse gases.

The joint research team, including Hwang Younggyu, head of the Chemical Process Research Division at the Korea Research Institute of Chemical Technology, and Professor Kwon Youngwook of Sungkyunkwan University, announced the research results as the cover paper of the December issue of the international journal in the field of materials, 'Chemistry of Materials,' on the 30th.

Removing Hydrogen from Glycerol to Carbon Dioxide

Metal-Organic Frameworks Used in the Study

The research team developed a new catalyst that simultaneously induces the dehydrogenation reaction of glycerol and the hydrogenation reaction of carbon dioxide even when added in very small amounts. The reaction of removing hydrogen atoms from organic compounds is called dehydrogenation, and adding the removed hydrogen atoms to another compound is called hydrogenation.

The team introduced a molecular compound (trimer) containing three ruthenium (Ru) atoms into a metal-organic framework and then burned it (carbonization process) to create a nano catalyst with dispersed ruthenium metal (Ru/NCT). A metal-organic framework is a porous material where metal ions or metal clusters are connected by organic molecules.

This catalyst showed about 10 to 20 times higher activity than existing catalysts, and the production yield of lactic acid and formic acid was about twice as high. When measuring how quickly the developed catalyst can convert reactants (TOF), the newly developed catalyst recorded 548 for lactic acid and 164 for formic acid. Existing catalysts had activities of about 19 and 10, respectively. The space-time yield (STY) achieved was 422 g/L·day for lactic acid and 64 g/L·day for formic acid. The lactic acid production rate per unit time from the conventional glucose fermentation process is about 100-150 g/L·day.

Eco-friendly Greenhouse Gas Reduction Method

An illustration showing the simultaneous conversion of glycerol and carbon dioxide into lactic acid and formic acid through the reaction of a newly developed catalyst.

The research team plans to study ways to further increase the production yield of formic acid and lactic acid through catalyst candidate exploration using computational chemistry. Lactic acid can be used as a raw material for biodegradable plastics, and formic acid can be used as a hydrogen storage material for fuel cells, in leather and feed additives, or converted into chemical products through additional catalytic processes.

Hwang Younggyu, head of the division, said, "Based on the newly developed simultaneous conversion catalyst system for glycerol and carbon dioxide, active research on carbon dioxide conversion catalytic reactions using various biomass will be conducted," and added, "It is expected to have a significant impact on petrochemical, fine chemical, and biochemical processes."

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