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Development of SO2 Phase Change Absorption: Viscosity Change and Component Distribution Rules
journal contribution
posted on 2019-09-20, 21:30 authored by Shengchao Xu, Wenbo Zhao, Muyuan Chai, Tian Si, Yuan Chen, Qingming JiaAs
phase change absorption of CO2 could drastically
reduce energy consumption, a liquid–liquid phase change absorption
process of SO2 was developed in the present work using N,N-dimethylethanolamine (DMEA) as absorbent
and hexadecane as solvent. The homogeneous solution was split into
two immiscible phases when the absorption capacity reached 0.02 mol/mol.
The phase change mechanism was attributed to the formation of a zwitterionic
compound, through the reaction of SO2 with DMEA and its
separation from the solution. The viscosity of the absorption product
was related to the absorption capacity and temperature, which is described
by an Arrhenius-type equation. The gravimetric absorption capacity
was found to be 1.56 g SO2/g DMEA at 1.0 atm, which is
the highest value reported in the literature. At 0.02 atm, its capacity
still reached 0.59 g/g, which is also much higher than those of other
absorbents at similar conditions. The distribution of DMEA, hexadecane,
and SO2 in the two phases is described by two differential
equations and material balance. Ternary phase diagram representation
was used to provide an intuitive visual of the phase separation behavior.
High temperature was found to play a role in weakening phase separation.
Ultimately, DMEA was chemically regenerated by the reaction of the
absorption product and cyclohexene oxide.