(571c) Multi-Step Condensation Enhanced Carbon Utilization (Multi-CECU): A Unified Paradigm for Process Intensification in CO2 Conversion

The chemical industry is increasingly focusing on CO₂ utilization to reduce emissions and create sustainable production pathways. CO₂-derived fuels and chemicals, such as methane, methanol, dimethyl ether (DME), Fischer-Tropsch hydrocarbons, and alcohols are the backbone of a circular carbon economy [1]. However, a fundamental challenge across nearly all these conversion routes is the formation of water as a byproduct: uncontrolled water accumulation shifts thermodynamic equilibria, inhibits reaction rates, and accelerates catalyst deactivation, reducing efficiency and hindering the industrial scalability of CO₂ conversion processes [2].

This work introduces multi-step Condensation Enhanced Carbon Utilization (multi-CECU) as an innovative process intensification approach that systematically removes water and other condensable species at strategic points along the reaction pathway [3]. Unlike other strategies that rely on in situ water management via adsorbents or membranes, the multi-CECU approach integrates selective condensation shortly after each reaction stage. By shifting equilibrium limitations, this methodology allows deeper CO₂ conversion and reduces the formation of undesired by-products, while optimizing energy recovery. These beneficial effects are demonstrated through a combination of thermodynamic analysis, Aspen Plus modeling, and kinetic evaluations, applied to a case study on direct DME synthesis from CO₂. Furthermore, techno-economic and life cycle assessments provide preliminary insights into the sustainability potential of multi-CECU and its possible viability as a scalable and cost-effective strategy for CO₂ conversion.

By addressing one of the key challenges in CO₂ utilization - i.e., water formation and removal - the multi-CECU configuration represents an innovative approach that can be integrated into multiple industrial processes. Its applicability extends far beyond the production of e-fuels to various CO₂-based chemical processes, including methanation (Sabatier process), methanol and higher alcohol synthesis, direct and indirect synthesis of dimethyl ether (DME), and Fisher-Tropsch process. Therefore, this study establishes multi-CECU as a unifying strategy for CO₂ hydrogenation and conversion technologies, offering a pathway towards more efficient, scalable, and sustainable chemical production.

[1] S. Valluri, V. Claremboux, S. Kawatra, Opportunities and challenges in CO₂ utilization, Journal of environmental sciences 113 (2022) 322–344.

[2] J. van Kampen, J. Boon, F. van Berkel, J. Vente, M. van Sint Annaland, Steam separation enhanced reactions: Review and outlook, Chemical Engineering Journal 374 (2019) 1286–1303.

[3] A. D’Ambrosio, M. Facchino, S. Tatarelli, V. Piemonte, M. Capocelli, M. De Falco, Carbon capture utilization through a novel multistage configuration for dimethyl ether synthesis, Journal of Cleaner Production 490 (2025) 144658.