Methodology Development for Capturing CO₂ and Greenhouse Gas Precursors From Flex‐Fuel Internal Combustion Engine Exhaust

Largely derived from the combustion of automotive fuels, CO 2 and other greenhouse gas precursors are significant emission gases and warrant attention. This article proposes an adsorption‐based method for capturing and separating these gases directly from the exhaust of flex‐fuel vehicles. The technique is feasible, leveraging the solid adsorbents’ capacity and selectivity for CO 2 and precursor gases. Characterization of the utilized adsorbents, natural ZN2040 and synthetic Oxan_X, revealed unique characteristics, notably their high surface area, low‐pressure adsorption capabilities, stability in wet gas conditions, high‐temperature applicability, a high Si/Al ratio in their crystal structure, and the presence of elements, such as Fe, Ca, K, and S. The adsorbents were arranged in a horizontal fixed‐bed column, installed within the vehicle's front exhaust muffler. The synthetic Oxan_X zeolite, exhibiting improved performance, demonstrated average reductions of 2.20% for CO 2 and approximately 17% for precursor gases, primarily CO, for both gasoline (22% anhydrous ethyl alcohol [AEAC]) and ethanol combustion. Additionally, it also facilitated the reduction of other vehicular pollutants. In the long term, deploying a vehicular fixed‐bed column could contribute to a reduction of approximately 764,000 t of CO 2 and 23,300 t of CO when the vehicle operates on gasoline and 1,168,000 t of CO 2 and 18,000 t of CO when operating on ethanol. These projections are based on 1.4–2.0 L engine vehicles employing 2.0 kg of adsorbent. 2025 Society of Chemical Industry and John Wiley & Sons, Ltd.