An international research group, including the Department of Chemical and Pharmaceutical Sciences of the University of Trieste, has discovered a new mechanism for the photocatalytic activation of hydrogen, making it possible to selectively convert CO₂ into ethylene. This breakthrough paves the way for more efficient and sustainable production without the use of fossil fuels or petroleum derivatives.

The results of the study have been published in the prestigious journal Science and could have major implications for industry and decarbonisation processes.

An international team of researchers has discovered a new photocatalytic mechanism for hydrogen activation, used to design a novel process for producing ethylene from carbon dioxide (CO₂) and hydrogen.

Ethylene is a key component in the production of plastics used in packaging, food, textiles, coatings, electrical insulation, automotive tyres and medical equipment. Annual global production exceeds 150 million tonnes and currently relies on the catalytic conversion of fossil hydrocarbons, which contributes to rising greenhouse gas emissions.

The study has been published in the prestigious journal Science and could have major implications for industry and decarbonisation processes.

Among the co-authors of the study is Paolo Fornasiero, professor in the Department of Chemical and Pharmaceutical Sciences at the University of Trieste, Associate at the Institute of Chemistry of Organometallic Compounds (ICCOM-CNR) in Florence, and member of the National Interuniversity Consortium for Materials Science and Technology (INSTM).

The research carried out by professor Fornasiero and colleagues proposes a new way of activating hydrogen, that is, making it more reactive and ready to form new chemical bonds through the formation of electric dipoles induced by ultraviolet radiation on the surface of gold-based photocatalysts deposited on titanium dioxide. The discovery was applied to the hydrogenation of carbon dioxide with the aim of transforming this greenhouse pollutant into high-value products. The research is based on the awareness that green hydrogen will soon be available in large quantities, produced by electrolysis using electricity from renewable sources. The overall photocatalytic process developed leads to the selective formation of ethylene from carbon dioxide and hydrogen.

Among the co-authors of the study is Paolo Fornasiero, professor at the University of Trieste, Associate at the ICCOM-CNR Institute in Florence and member of the INSTM consortium, who comments: "In the perspective of an increasingly sustainable economy, less polluting and less energy-intensive, our study suggests the possibility of producing ethylene through an innovative and sustainable method. This would drastically reduce dependence on fossil fuels, decoupling its cost from the price of raw materials and energy, particularly oil and natural gas".

At present, ethylene is produced through catalytic cracking of hydrocarbons in the presence of steam. This process involves heating hydrocarbons such as ethane, propane, naphtha and gas oil to very high temperatures (typically 750-950 °C) with steam. Steam reduces the undesirable formation of carbon deposits on the surface of the catalysts and participates in breaking down larger hydrocarbons into smaller ones, including ethylene. The resulting mixture is then separated by compression and distillation to isolate ethylene. Production costs are heavily dependent on the type and availability of hydrocarbon feedstock, as well as on transport issues and competition with energy markets. The possibility of using carbon dioxide, green hydrogen, light and a suitable photocatalyst to produce ethylene could therefore not only offer economic and environmental benefits but also reduce the increasingly critical dependence on raw materials unevenly distributed worldwide.

The researchers successfully demonstrated their findings under conditions close to those of industrial interest, developing a first prototype.

The international research team includes, alongside professor Paolo Fornasiero, professors Nenchao Luo and Feng Wang from the Dalian Institute of Chemical Physics (China).

Professor Fornasiero’s research is currently funded by the European Commission (HORIZON-WIDERA-2021-ACCESS-03-01 and HORIZON-EIC-2023-PATHFINDEROPEN-01).

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Full study published in Science

Photochemical H2 dissociation for nearly quantitative CO2 reduction to ethylene

Ping Jin,1,3 Pu Guo,1 Nengchao Luo,1,3,* Hui Zhang,4,5 Chenwei Ni,1,3 Ruotian Chen,1 Wei Liu,1 Rengui Li,1 Jianping Xiao,1 Guoxiong Wang,6 Fuxiang Zhang,1 Paolo Fornasiero,2,* Feng Wang1,3,*

1. State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.

2. Department of Chemical and Pharmaceutical Sciences, Centre for Energy, Environment and Transport Giacomo Ciamiciam, INSTM Trieste Research Unit and ICCOM-CNR Trieste Research Unit, University of Trieste, Via Licio Giorgieri 1, Trieste 34127, Italy.

3. University of Chinese Academy of Sciences, Beijing 100049, China.

4. Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, China.

5. National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China.

6. Department of Chemistry, Fudan University, Shanghai 200438, China.