二酸化炭素と水、電気からプラスチックを製造する新技術を開発（Making Plastic from Carbon Dioxide, Water, and Electricity）

2025-06-24 カリフォルニア工科大学（Caltech）

カリフォルニア工科大学（Caltech）の研究チームは、二酸化炭素（CO₂）、水、電気のみを用いてプラスチックを合成する二段階プロセスを開発した。第1段階ではCO₂を電気化学的に還元してエチレンと一酸化炭素を生成し、第2段階でそれらをパラジウム触媒下で共重合して耐久性の高いポリケトンプラスチックを製造。従来は化石資源を必要としたが、本手法は完全に再生可能資源由来で、カーボンニュートラルな製造が可能。今後は分子制御やスケールアップが課題となるが、CO₂資源化の新たな道を示す重要な技術である。

＜関連情報＞

CO2、水、電気からプラスチック：タンデム電気化学的CO2還元と熱化学的エチレン-CO共重合 Plastic from CO2, Water, and Electricity: Tandem Electrochemical CO2 Reduction and Thermochemical Ethylene-CO Copolymerization

Maxim Zhelyabovskiy, Hyuk-Joon Jung, Paula L. Diaconescu, Jonas C. Peters, Theodor Agapie
Angewandte Chemie International Edition Published: 07 April 2025
DOI:https://doi.org/10.1002/anie.202503003

Graphical Abstract

A new system of generating entirely CO₂-generated abiotic polymers by integrating electrochemical CO₂ reduction (eCO₂R) and organometallic polymerization catalysis is presented, having an overall CO₂-to-polymer conversion of 14% and current-to-polymer efficiency of 51%. A strategy for tuning the product composition obtained from eCO₂R by combining different electrocatalysts is introduced. CO-ethylene copolymerization activity in the presence of potential poisons from eCO₂R is retained.

Abstract

Converting CO₂ into industrially useful products is an appealing strategy for utilization of an abundant chemical resource. Electrochemical CO₂ reduction (eCO₂R) offers a pathway to convert CO₂ into CO and ethylene, using renewable electricity. These products can be efficiently copolymerized by organometallic catalysts to generate polyketones. However, the conditions for these reactions are very different, presenting the challenge of coupling microenvironments typically encountered for the transformation of CO₂ into highly complex but desirable multicarbon products. Herein, we present a system to produce polyketone plastics entirely derived from CO₂ and water, where both the CO and C₂H₄ intermediates are produced by eCO₂R. In this system, a combination of Cu and Ag gas diffusion electrodes is used to generate a gas mixture with nearly equal concentrations of CO and C₂H₄, and a recirculatory CO₂ reduction loop is used to reach concentrations of above 11% each, leading to a current-to-polymer efficiency of up to 51% and CO₂ utilization of 14%.