Adsorption Equilibria of Dimethyl Carbonate and Ethyl Methyl Carbonate onto Activated Carbon

Abstract

Increasing usage of lithium‐ion batteries requires new recycling strategies. Dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) represent about 50 % of the electrolyte and need to be captured from recycling exhaust gas. This study identifies adsorption as an advantageous method. Single component isotherms of DMC and EMC are presented applying the model of Tóth. Model parameters are used to calculate binary adsorption isotherms with the ideal adsorbed solution theory. Comparison with experimental data shows good agreement in respect to selectivity, temperature dependence and overall gas loading.

Adsorptive Exhaust Gas Cleaning for Recycling of Li-Ion-Batteries

“…31 Experiments at 30 • C show a linear relation between carbon loading and gas loading. The results of batch experiments of previous works 17 suggest that the carbon loading is reaching a saturation state at higher gas loadings with a significant discrepancy between batch and fixed-bed experiments. One reason for this discrepancy can be the decomposition of DMC.…”

“…24 The composition of the inlet gas stream was analyzed by gas chromatography prior to each experiment and only DMC was detected. The gas loading at the exit of the adsorber was analyzed by gas chromatography as described by Stehmann et al 17 during the operation time of the experiments. Although only DMC and nitrogen were fed to the adsorber, methanol was also detected at the adsorber exit.…”

“…Since sufficient cleaning of the exhaust gas with condensation leads to very low condensation temperatures, and therefore a very high energy demand, the final purification can be done by adsorption. 13,17 Experiments of the recycling process have been carried out in a demonstration plant on the complete process from discharging to separation. 15,16 This was complemented by theoretical flow sheet simulation studies to establish consistent material and energy balances and to support a targeted process optimization.…”

Adsorptive Exhaust Gas Cleaning for Recycling of Li-Ion-Batteries

“…It is formed in pellets with a diameter of 4 mm. It has a specific surface area of 1121 m² g -1 and a pore volume of 0.55 mL g -1 [3] .…”

“…Since sufficient cleaning of the exhaust gas with condensation leads to very low condensation temperatures, and therefore a very high energy demand, the final purification can be done using adsorption. [3,4] This contribution addresses the process steps of producing and treating the off-gas. The off-gas composition and flow are calculated using a common flow sheet simulation.…”