Carbon dioxide, a renewable resource

ChemSusChem

As the result of new carbon capture technologies, carbon dioxide is increasingly becoming available in vast quantities and in high purity as an economically attractive resource for chemical syntheses. Our aim is to exploit this raw material for synthesizing polymer building blocks. The cover of ChemSusChem illustrates our vision to establish the greenhouse gas CO2 as feedstock for chemical production.

Link to publisher (review)


Waste product becomes raw material

Polymers made of carbon dioxide

It is a simple idea: If humans produce too much CO2 causing an imbalance in the natural carbon dioxide cycle, we could harness this greenhouse gas to create something useful and aid in correcting this environmental imbalance.

With this goal, scientists from CAT Catalytic Center are working on a sustainable utilization of CO2. Their primary aim is to technically exploit carbon dioxide as a building block for synthesizing polymers.


Today’s use of CO2

By implementing existing techniques, CO2 is already being used as raw material in a series of important chemical processes. For example, it is used as so-called C1-building block in the production of:

  • Methanol (CO2 consumption: 2 million tonnes per year),
  • Salicylic acid (CO2 consumption: 30,000 tonnes per year), and
  • Urea (CO2 consumption: 107 million tonnes per year).

The future of CO2 utilization

There are many innovative ideas on how to use this molecule as a C1-building block for chemical production in the near future.

Four interesting technologies are currently being discussed:

  • Incorporation of CO2 in polymers,
  • Hydrogenation of CO2,
  • Electrocatalytic activation, and
  • Photocatalytic activation.

Of these four technologies, the production of CO2-based polymers is particularly promising in the short term.


Evaluation criteria for efficient exploitation

There are several criteria, when assessing CO2-based synthesis routes. Crucial are:

  • Fixation potential,
  • Purity, and
  • Energy balance.

Concerning the fixation quantity and duration, polymers prove particularly effective in storing carbon dioxide, because substantial amounts of CO2 can be incorporated in products and, thus, during the products’ lifetime, become chemically bound for years or even decades.

Impurities in the applied carbon dioxide can affect the function of catalysts necessary for the chemical reaction. The purity of CO2 also determines the future application area of the product.

Fundamentally important is to assess the energy balance of the overall process. Along with the direct incorporation of CO2 into products, the efficient use of the gas can lead to a remarkable reduction of its emission in the overall balance. For a comprehensive assessment of new products and procedures, it is necessary to figure out complete energy and CO2 balances.


The use of catalysts for accelerating the reaction

To promote the incorporation of the thermodynamically stable CO2, one strategy is to use energy rich reaction partners in the chemical processes. By choosing apt catalysts, the respective chemical reaction is accelerated and steered in the desired direction, thereby helping to increase the cost-effectiveness of the process. Researchers at CAT Catalytic Center are thereby focussing on building up fundamental knowledge about catalyst performance to ensure optimal reaction performance.


„Dream Production“

CAT Catalytic Center is partner in the project „Dream Production“, which is promoted by the German Federal Ministry of Education and Research. In the context of “Dream Production“, carbon dioxide originated from coal and obtained from the flue gas stream of a lignite-fired power plant is to be made available as a building block for polymers. The technical and economical feasibility will be demonstrated in a pilot plant.

The specific aim of the research project is to develop processes for the technical utilization of CO2 to produce so-called polyether carbonates. These function as building blocks for the production of polyurethane plastics useful in a variety of application areas. The research at CAT Catalytic Center also aims to ensure that this “real“ CO2 is compatible with input materials and the catalysts applied in the chemical process.


Conclusion

Carbon dioxide – the waste product of the energy industry – is a reusable material with a highly attractive application profile and great potential to create added value for the chemical industry. Even though the usable quantities of CO2 are considerably smaller than the CO2-emissions from energy generation, the recycling of carbon dioxide is a welcome component in an innovative global strategy to both create economic value and mitigate its environmental impact as a greenhouse gas. Likewise, recycled CO2 poses exciting opportunities to create new products and also save energy through optimized production processes.

Find the entire article (in German) of the „RWTH Themen“ here:
RWTH Themenheft

The study (in German) commissioned by the Federal Ministry of Economics and Technology can be downloaded below
“Weltweite Innovationen bei der Entwicklung von CCS-Technologien und Möglichkeiten der Nutzung und des Recyclings von CO2

Innovationen bei CCS und CCU
Innovationen bei CCS und CCU - Kurzfassung