Decarbonisation Technology May 2025 Issue

Solid-state adsorbent technology for carbon capture A pathway to low-cost carbon capture from a wide range of sources using an energy-efficient process

Nigel Campbell and Shane Telfer Captivate Technology

C arbon capture adoption is recognised by the United Nations Intergovernmental Panel on Climate Change (IPCC) as vital for mitigating harmful carbon dioxide (CO₂) and other greenhouse gas emissions to achieve net-zero goals, particularly in sectors like power generation, cement, steel, and biogas upgrading. Capturing CO₂ not only eliminates emissions from these processes; it also reduces the need for fossil fuel extraction, with fuels and products increasingly being manufactured from CO₂ as a raw material. Despite the growth of renewable energy, hydrocarbons will continue to be used for the foreseeable future. Hydrocarbons remain necessary for our daily lives and the growing needs of developing countries. Carbon capture plays a key role in mitigating the damaging effects of hydrocarbon combustion and can reduce the need for fossil-sourced hydrocarbons. Increasingly, refineries and petrochemical plants are able to secure carbon feedstock from non-fossil sources. CO₂ separation is a necessary part of many hydrocarbon processes but has historically had high capital and operating costs. Methods using chemical absorption of CO₂ with solvents have been used for more than a century and involve significant chemical process equipment (such as large processing towers) and massive amounts of heat (commonly fuelled by further fossil fuel combustion and emissions) for CO₂ recovery from the solvent. Naturally occurring CO₂ in fossil gas and CO₂ produced in hydrogen manufacture must be separated, and costs flow through to be included the price of the product.

With the fairly recent adoption of CO₂ separation to reduce the emissions in power generation or product manufacture, chemical absorption methods using solvents have proven to be costly in both economic and environmental terms. This is due to the nature of working with solvents. They are prone to side reactions, are volatile, are difficult to handle, and have environmental concerns. In response, and driven by industry and government commitments to net zero, there is a surge of interest, technology development, and investment in lower-cost methods for CO₂ separation. One such method used by Captivate Technology employs a solid-state adsorbent that provides a low-cost process for CO₂ separation. Adsorption of CO₂ in Captivate’s process occurs at ambient temperature and pressure, eliminating the need to use energy to compress the entire emissions stream at the start of the process. The emissions stream may only contain in the order of 10% CO₂, depending on the source. In the adsorption process used by Captivate, energy use is significantly less than solvent absorption because energy is only used

Captivate low- cost capture technology

CO gas emitted

CO use

Synthetic fuels Valued added materials

Figure 1 Circularity of CO₂