Abstract
In this work, the mass and energy balances and the economic analysis of a continuous process for the reduction of CO2 (captured as NaHCO3) into sodium formate using Zn as the reductant are studied. The reaction in hydrothermal media has the advantage of easily integrating the conversion system with the CO2 capture process by absorption in basic solutions. The process conditions (pressure, Zn/NaHCO3 molar ratio, and residence time) were theoretically optimized. A reaction temperature of 275 °C was selected, obtaining formate yields greater than 70%. A continuous process design was proposed based on available information and on our experimental experience in the process. Mass and energy balances were solved and the potential for an energy integration was studied. Additionally, both capital and operating costs for a plant treating 1000 kg/h of CO2 were estimated. The cost calculated for transforming CO2 was EUR 1.28/kg CO2.
Highlights
A major consequence of the combustion of fossil fuels is the continuous and significant increase in atmospheric concentration of CO2, a greenhouse gas
CO2 industrial applications as a C1 building block are currently still limited to a few applications, such as the synthesis of urea and its derivatives, the production of salicylic acid and organic carbonates, the Solvay process for the synthesis of NaHCO3− Na2CO3, and the synthesis of methanol using syngas enriched with CO2.2,3
The kinetic constants obtained in previous work by this research group[21] were used to develop a model of the continuous reactor based on reactions R1−R4. This model was used to optimize the reaction conditions that enhance the yield of HCOONa produced.[21]
Summary
A major consequence of the combustion of fossil fuels is the continuous and significant increase in atmospheric concentration of CO2, a greenhouse gas. In the past decades CO2 has gained great attention as a potential raw material due to its abundance, lack of toxicity, and relatively low price,[1] rather than considering it as just a waste substance. CO2 industrial applications as a C1 building block are currently still limited to a few applications, such as the synthesis of urea and its derivatives, the production of salicylic acid and organic carbonates, the Solvay process for the synthesis of NaHCO3− Na2CO3, and the synthesis of methanol using syngas enriched with CO2.2,3
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