Preparation of pineapple waste-derived porous carbons with enhanced CO2 capture performance by hydrothermal carbonation-alkali metal oxalates assisted thermal activation process

The pineapple waste-derived porous carbons with enhanced CO2 adsorption performance were successfully prepared by a facile hydrothermal carbonation and followed thermal activation using facile alkali metal oxalates instead of KOH or K2CO3 for chemical activation. Compared with macroporous-mesoporous carbons activated by Li2C2O4 and Na2C2O4, the microporous carbon activated by K2C2O4 at 700 °C with a relatively high specific surface area of 1076.3 m2 g−1 and big pore volume of 0.92 cm3 g-1 for narrow micropores (<1 nm)for narrow micropores (<1 nm) shows the highest adsorption capacities of 5.32 mmol g-1 at 0 °C, and 4.25 mmol g-1 at 25 °C under 1 bar, respectively. Furthermore, all the samples show high selectivities from 18.24 to 38.42 for CO2/N2 separation, stable cyclic capability with adsorption loss of 12.6–17.8% after twelve cycles at 25 °C and reasonable isosteric heat of CO2 adsorption. Especially, the microporous carbon activated by facile K2C2O4 at 700 °C shows speedy adsorption dynamics and excellent dynamic adsorption performance for simulated flue gas based on its breakthrough curve. In combination with the low-cost carbon source, the above advantages make the pineapple waste-derived porous carbons exceptionally potential sorbent to capture and separate CO2 under real conditions.