What is a Carbon Capture Sorbent?

The newly released IEA World Energy Outlook 2024 highlights the crucial role of CCUS technologies in addressing climate change, particularly for hard-to-abate emissions, and at the heart of these systems are sorbents. As the world shifts towards renewable energies to reduce reliance on fossil fuels, effective carbon capture becomes essential for managing emissions that cannot be easily eliminated. Sorbents are specialized materials that capture carbon dioxide (CO₂) either by absorbing it into their structure or adsorbing it onto their surface. Sorbents are commonly used in carbon capture applications across various industries. They are crucial in determining the efficiency and performance of carbon capture technologies. 

However, conventional sorbents come with significant limitations. They often require energy-intensive pre-drying and high amounts of energy during the regeneration process—when the captured CO₂ is released and the sorbent is restored for reuse. These inefficiencies become especially problematic in low-concentration environments, where conventional sorbents struggle to perform effectively. 

As a result, sorbents play a significant role in the overall costs of carbon capture. In post-combustion capture (PCC) systems, the capture stage accounts for 45-65% of the total costs, while in direct air capture (DAC) systems, it can reach 80-90%. The performance of the sorbents used in these stages is a major cost driver. Improving sorbent efficiency is crucial to reducing both energy consumption and the overall expense of CCUS technologies, making it a key focus for the future of carbon capture. 

Sorbents used in carbon capture fall into two main categories: liquid sorbents and solid sorbents. Each type functions in a different way, but both are designed to “attract” CO₂ molecules and prevent them from being released into the atmosphere. 

CO₂ absorption by Liquid Sorbents  

These are typically chemical solvents, such as amines, that react with CO₂, capturing it by forming a chemical bond. In absorption, CO₂ molecules are taken up into the bulk of the liquid sorbent, integrating chemically within the solvent itself. Liquid solvents are commonly used in industrial settings, where they are often applied to flue gases emitted from power plants or other heavy industrial processes.  

CO₂ adsorption by Solid Sorbents

These include materials like zeolites, activated carbons, and advanced reticular materials such as Metal organic Frameworks (MOFs) and Covalent Organic Frameworks (COFs).   
Solid sorbents work by adsorbing CO₂ onto their surface, meaning that the CO₂ molecules stick to the sorbent rather than becoming absorbed into the material’s internal structure. Advanced sorbents can undergo chemical modification to improve their CO₂ capture performance, efficiency and durability in various environmental conditions. 

Each type of sorbent has its advantages, depending on the specific application, and the choice of sorbent can significantly impact the efficiency and cost of carbon capture. 

As the technology landscape for CCUS continues to evolve, the need for more advanced, energy-efficient sorbents becomes even more pressing. A recent survey conducted by Atoco has provided valuable insights into the challenges and opportunities in this critical field, offering a roadmap for future innovation. The survey revealed that while 56% of Original Equipment Manufacturers (OEMs) currently rely on liquid solvents as their primary sorbent technology, there is growing optimism about the potential of next-generation sorbents. 

Innovations in materials like Metal organic Frameworks (MOFs) and Covalent Organic Frameworks (COFs) (referred to as reticular materials) hold great promise, offering the potential for more efficient CO₂ capture at lower costs and with reduced energy consumption. These advanced materials can be engineered at the molecular level to optimize CO₂ capture under various conditions. 77% of the respondents believe that nano-engineered materials and advanced sorbents like MOFs and COFs will drive significant improvements in the carbon capture industry over the next 5 to 10 years. OEMs also anticipate a shift toward solid adsorbents, which can be seamlessly integrated into existing systems, providing easier upgrades and greater scalability. 

Atoco is a leader in climate technology, founded by Professor Omar Yaghi, the pioneer of Reticular Chemistry. Atoco leverages reticular materials such as Metal Organic Frameworks (MOFs) and Covalent Organic Frameworks (COFs) to develop breakthrough solutions for carbon capture and atmospheric water harvesting. These technologies, designed with atomic precision, are engineered to tackle global and most pressing challenges: climate change and water scarcity. 

Atoco’s solid-state carbon capture technology, including solid-state PCC (Post-Combustion Carbon Capture) and solid-state DAC (Direct Air Capture) modules, tackles the challenges of post-combustion and DAC by using highly efficient reticular materials. This approach allows for reduced energy consumption and scalable deployment across industries, making it a vital tool in addressing global carbon emissions and the fight against climate change.