The absorption of SO2 by morpholine cyclic amines with sulfolane as the solvent for flue gas

The absorption properties of N-(2-hydroxyethyl) morpholine (HEM), morpholine (MP) and N-(2-aminoethyl) morpholine (AEM) for SO2 were studied using sulfolane (SUL) as solvent in this work. Among these solvent combinations, HEM/SUL shows the best cyclic absorption performance, and the capacity of HEM-SUL-40 (40 wt % of HEM and 60 wt% of SUL) to absorb 8580 mg/m(3) SO2 (the remainder is N-2) is 192.18 mg/g at 293.15 K. The absorption capacity of the second cycle is 97.5% of the first absorption cycle, which is higher than 70% of the Cansolv amine solution in a commercial application with similar experimental conditions. However, MP/SUL is difficult to desorb at high temperature, and the absorption capacity of AEM/SUL is much lower than HEM/SUL and MP/SUL. According to the FTIR, H-1 NMR and C-13 NMR, all three cyclic amines have charge transfer effects with SO2. The structure of HEM/SUL can be recovered after heating, but MP cannot be recovered. Delta rGm degrees in the reaction against HEM with SO2 increases significantly with increasing temperature. The Delta rGm degrees of HEM-SO2 and MP-SO2 at 353.15 K is -12.56 kJ/mol and -16.29 kJ/mol, respectively, which further explains the easy desorption of HEM-SO2 and the difficult desorption of MP-SO2 at high temperature.

Automated summary

This study found that N-(2-hydroxyethyl) morpholine has the best absorption performance for SO2 when used with sulfolane as a solvent, with its absorption capacity remaining above 97.5% of the first cycle in the second cycle. The other two absorbents, morpholine and N-(2-aminoethyl) morpholine, did not perform as well as the former.