- Hot potassium carbonate, commonly referred to in industrial applications as “hot potash,” is an aqueous solution of potassium carbonate (K₂CO₃) maintained at elevated temperatures.
- It is widely used in gas treating processes, particularly in carbon dioxide (CO₂) and hydrogen sulfide (H₂S) removal from natural gas, syngas, and flue gases. The compound itself is a white, water-soluble salt that forms a strongly alkaline solution. When heated, its chemical reactivity and absorption capacity are significantly enhanced, making it suitable for high-efficiency scrubbing in various industrial systems.
- In its typical application, the hot potassium carbonate process—often referred to by its commercial names like the Benfield Process—is used to selectively absorb acid gases from gas streams. The basic mechanism involves the reaction of CO₂ with carbonate ions in solution to form bicarbonate ions, which can later be regenerated by releasing the CO₂ through heating. The use of elevated temperatures, usually ranging from 100°C to 140°C, increases the rate of reaction and absorption capacity, while also reducing the viscosity of the solution, aiding in mass transfer efficiency.
- Compared to amine-based solvents, hot potassium carbonate offers several advantages. It is less corrosive, more environmentally benign, and has lower degradation rates. Additionally, since it is a physical-chemical solvent, it does not rely solely on chemical bonding and therefore requires less energy for regeneration, leading to potential operational cost savings. However, its efficiency in acid gas removal is more favorable under high partial pressures of CO₂, making it ideal for high-pressure gas streams but less effective for low-pressure applications unless enhanced with additives or promoters such as DEA (diethanolamine), MDEA (methyldiethanolamine), or piperazine.
- The process also has significant advantages in terms of thermal stability and longevity, which reduces the need for frequent solvent replacement. Furthermore, potassium carbonate is non-toxic and readily available, making it a more sustainable option for long-term use in large-scale industrial operations. Modern developments have improved the process by incorporating inhibitors to prevent corrosion and foaming, thus broadening its utility in complex and demanding gas treatment scenarios.
