Synergistic Resource Utilization of Carbon Dioxide-Rich Off-Gas and Industrial By-Product Alkaline Salt

The capture and utilization of carbon dioxide (CO₂) from CO₂-rich off-gas streams play a vital role in mitigating carbon emissions. Chemical absorption, as a well-established and commercially deployed CO₂ capture technology, has attracted sustained research interest. Current efforts in this field are primarily directed toward developing cost-effective absorbents and energy-efficient processes. Meanwhile, industrial operations generate significant quantities of by-product alkaline salts, which often consist of mixtures containing two or more components such as sodium carbonate, sodium hydroxide, sodium sulfate, and sodium chloride. The use of these alkaline by-products for CO₂ absorption to produce value-added chemicals presents a promising and economically attractive carbon capture and utilization (CCU) strategy. In this work, an industrial salt by-product from a petrochemical plant, rich in sodium carbonate and sodium sulfate, was employed as an absorbent to simulate a CCU process. By controlling the mass transfer and crystallization behavior of CO₂ within the multicomponent system during carbon capture, it was feasible to produce sodium bicarbonate from CO₂. Concurrently, industrial-grade sodium sulfate was separated based on solubility differences. This study proposes an innovative integrated approach that combines the utilization of alkaline by-product salts, CO₂ capture from off-gas, and resource recovery in a single process.