What are the advantages and disadvantages of the solvents used in aromatic extraction?

Several solvents exhibit different operating conditions during extraction, as well as varying properties of the raw materials and products along with different yields.

N-methylmaline, N-methylpyrrolidine may also introduce “N””

Commonly used solvents include: diglycol, triglycol, tetraglycol, dimethyl sulfoxide, N-methylpyrrolidone, and N-methylmorpholine. In terms of physical properties: the relative density of these solvents is all greater than 1.0, with sulfolane having the highest relative density at 1.26 ； Except for sulfolane and dimethyl sulfoxide which have relatively high freezing points, all glycol-based solvents have freezing points below 0°C ； The viscosity is lowest for dimethyl sulfoxide, moderate for sulfolane, and relatively high for glycol-based solvents ； Dimethyl sulfoxide has the worst thermal stability, beginning to decompose at 120°C, while cyclosulfone and tetraglycol have the best thermal stability, starting to decompose at 220°C and 237°C respectively ； The specific heat is lowest for sulfolane, while the values of the other solvents are similar; the latent heat of vaporization is lowest for tetraethylene glycol and sulfolane. Based on a comprehensive consideration of the above physical properties, sulfolane and tetraethylene glycol have numerous advantages as aromatic extraction solvents, making them suitable candidates for preferred use. In terms of solvent solvency and selectivity: sulfolane has the advantages of strong solvency and high selectivity. In terms of the source and price of solvents: glycol-based solvents are produced from ethylene oxide, are readily available, and have low prices ； Sulfolane is produced from butadiene and is relatively expensive.