Characteristic evaluation of activated carbon applied to a pilot-scale VSA system to control VOCs

This work investigates the characteristics of activated carbon sampled after repeated adsorption/desorption cycles to indirectly evaluate the performance of a 30 m3/min pilot-scale VSA system installed in a paint factory. The onsite pilot VSA system was operated continuously for 20 adsorption/desorption cycles during a 40 day period. Samples of commercial activated carbon (raw) and regenerated activated carbon after 10 cycles and 20 cycles (10A, 10B, 20A, 20B) were prepared. The changes in physical properties were analyzed based on N2 adsorption-desorption. Changes in the adsorption capacity were measured using a toluene adsorption test and DTG analysis. Depending on the VSA cycle increase, minimal physical changes in the activated carbon were observed, except for a decrease in the BET surface area. As a result of the toluene adsorption test, at 20 cycles at least 85% of the performance of activated carbon was maintained. However, as the VSA cycles were increased from 10 cycles to 20 cycles, the toluene adsorption capacity was found to be slightly reduced or maintained. Based on the DTG analysis, the cause of the performance degradation seems to be the formation of a heel, which is the non-desorbed physisorption observed for regenerated activated carbon.