Gas absorption in reactive solutions: Adapted instrumentation of a stirred cell for kinetic study and application to CO₂/amine systems

The elimination of impurities from natural gas (water, CO2, H2S, mercaptans) is an obligation: in Europe, a max. 20 mg/Sm3 total sulfur (at 15°C and 1 atm) allowed, as well 2.5 vol% CO2. It maximizes the calorific value delivered limits chemical risks (corrosion, toxicity) associated with this transition fuel to cleaner energy sources. Acid separation commonly performed by reactive gas-liquid absorption. Raw absorptive solution are brought into counter current contact absorber at 40-80°C 30-80 bar. Then acid-gas loaded solvent sent stripper where acid desorption takes place T between 105 140°C P ≤ aqueous base (e.g., amine) solution. A good has high reactivity dissolved during absorption low regeneration energy, hence advantage mixtures two amines. Here we study small amount piperazine (PZ) added methyldiethanolamine (MDEA). PZ reacts faster CO2 than MDEA, major reaction product hydrogen carbonate ion HCO3-, which lowers duty. This work aims characterising kinetics MDEA-PZ. Indeed, no consensus been found on mechanism amine mixture; synergies MDEA observed literature remain poorly explained. However, its knowledge essential optimize formulation industrial unit design.