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This paper presented the effect of CO2 concentration in the gas feed to the CO2 absorption performance using a green solvent, potassium carbonate promoted with glycine (PCGLY). Recently, the performance of this solvent (with precipitates) was hindered by its poor mass transfer performance due to the blockage in packings and piping. Therefore, this study focused to study the CO2 absorption performance of non-precipitating potassium carbonate promoted with glycine. This green solvent contains aqueous blend of 15wt% potassium carbonate and 3 wt% glycine. The absorption performance of the solvent was obtained by demonstrated a few experimental works using a bench scale packed absorption column. The packing type was Sulzer metal gauze and the column consisted of six sampling point which located equidistance along the packing.The effect of CO2 concentration at the gas feed was assessed in term of its CO2 removal efficiency and concentration profile along the packing. The study shows the decreasing trend of CO2 removal as CO2 inlet concentration in the gas feed increases. The reason of this behavior is due to the limited reactant of liquid phase to absorb high CO2 concentration in gas phase. The main outcome of this study demonstrated the efficient absorption which can absorb up to 79.24 % of CO2 from natural gas using non-precipitated PCGLY.

Chemical absorption is the most common technology used for the process of CO2 removal from natural gas due to its ability to reduce the level of the acid gas to a very low level as well as higher mass transfer performance due to the chemical kinetic reaction. Higher solvent concentration resulted in higher capacity to remove CO2, however reduces the diffusivity as well as its ability to spread on the packing due to its high solvent viscosity. This has hindered the used of high viscosity solvent in the operation of conventional packed column. However, recent technology of using high frequency ultrasonic irradiation for absorption process has shown possibility to operate high viscosity solvent due to the absence of packing in the reactor. From this work, it is shown that high viscosity solvent does not affect the mass transfer performance under ultrasonic irradiation due to the presence of acoustic streaming, fountain and atomization that reduced the film resistance thus increases the diffusivity. This work has demonstrated that this technology has high flexibility of solvent selection for the absorption process.

The advancement of efficient carbon capture technology is vital for the transition to a net-zero carbon future. Critical developments in ultrasonic irradiation can be used to enhance the conventional CO2 absorption process. For example, sonophysical effects such as acoustic streaming, acoustic cavitation, acoustic fountain and atomization induced by the propagation of high-frequency ultrasonic waves in a liquid medium can enhance the mixing and create a larger interfacial area for gas–liquid mass transfer. In this study, the performance of a continuous ultrasonic-assisted CO2 absorption process using MDEA was investigated. The design of experiment (DOE) was used to study the effect of the gas flowrate, liquid flowrate and ultrasonic power on CO2 absorption performance. Based on the findings, ultrasonic power was the most significant parameter affecting the CO2 outlet concentration, liquid-to-gas ratio (L/G) and mass transfer coefficient (KGa), which confirmed that ultrasonic irradiation has a significant impact on the intensification of the CO2 absorption process. The optimum condition to achieve the target CO2 absorption performance was numerically determined and validated with experimental tests. The results from the verification runs were in good agreement with the predicted values, and the average error was less than 10%. [ABSTRACT FROM AUTHOR]