Solubility of carbon dioxide, methane and ethane in fourteen promising physical solvents for gas sweetening

Carbon dioxide removed from coal gasification effluents is used as a solvent in enhanced oil recovery processes. Proper solvent tailored specifically to the gas composition would result in more efficient separation. Contrary to chemical solvents, physical solvents are not limited in their absorption capacity by the stoichiometry of a reaction, which means lower amounts of circulating solvent, and much lower energy consumption required for regeneration. Physical solvents are also able to absorb mercaptans, sulfur compounds, and other impurities. This chapter presents a comprehensive solubility study that tests the capacity of absorption of twelve new glycol ether solvents. The solubilities of carbon dioxide in a polyethylene glycol dimethyl ether (PEGDME) mixture and n-formyl morpholine (NFM) and the solubilities of ethane and methane in the best solvents were measured. The results of these experiments have been presented in this chapter in a form of Henry's law constants at three different temperatures. The screening study concludes that the best solvents for CO₂ are PEGDME 250 and Selexol, both mixtures of polyethylene glycol dimethyl ethers.