Investigations for the environmentally friendly production of Na2CO3 and HCl from exhaust CO2, NaCl and H2O

The conventional Solvay ammonia soda process is a net producer of CO2 and produces large quantities of ecologically doubtful side products. Therefore a possible solution for this problem was investigated. Theoretical and experimental data are given which show the feasibility of a modified ammonia soda process which delivers Na2CO3 and HCl by using exhaust CO2, NaCl and H2O. This modified ammonia soda process would not produce the byproduct CaCl2 as in the conventional Solvay ammonia soda process, would be completely recyclable and could be driven by solar thermal energy. Low maximum reaction temperatures of T ≤ 800 K and an estimated achievable solar efficiency of 10% show that this cycle is not only environmentally friendly but also energetically interesting. Kinetic constants of the main reactions are given which are similar to the ones in the conventional process. The principle of a simple solar thermo-chemical reactor is described. Preliminary economical considerations show that this new process might even be competitive when driven by solar thermal energy instead of using fossil fuels. If this novel process would be implemented worldwide approximately up to 3 × 107 tonne of CO2 could be omitted annually compared with the conventional Solvay ammonia soda process. This would correspond to 0.15% of the annual release of all anthropogenically produced CO2.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► New ecofriendly process produces Na2CO3 and HCl and uses exhaust CO2, NaCl and H2O. ► Kinetics similar to conventional Solvay ammonia soda process but no byproducts. ► Process runs at T ≤ 800 K, could be driven by solar thermal energy competitively. ► New simple solar thermo-chemical reactor proposed. ► Assumed solar efficiency 10% and 2.3–3 × 107 ton CO2 omitted annually if used worldwide.