Thermal behavior of crosslinking polystyrene resin to carbon material by one-step carbonization

Abstract

Crosslinking polystyrene (CPS), which is an inexpensive porous resin synthesized by waste polystyrene and CCl4, can be precursor for carbon material. Carbonization with KOH or steam activation was usually needed for the carbonization, but that without any activation was rarely reported. By the carbonization (room temperature to 900 °C; heating rate of 3 °C/min; N2 atmosphere), the carbon prepared had no pores. Interestingly, the carbonization modified by five temperature platforms (150 °C, 200 °C, 300 °C, 400 °C and 500 °C) before 900 °C can produce the porous carbon with high surface area (SBET = 849 m2/g) and rich micropores (Vmic = 0.306 cm3/g). The thermal behavior of the CPS was studied under different carbonization conditions. The temperature platforms that made the heating milder was found to be crucial for the porous structure. They promoted the hydrolysis of Ph2CCl2 to Ph2C=O stabilizing the skeleton and slowed down the escape of the pore-creating substances, i.e., Ph2C=O, PhCOOH and –[CH–CH2]n–. Thereby, the carbonization with the temperature platforms not only kept the pores but also constructed the new pores. Moreover, the porous carbon prepared had the rich micropores from 0.6 to 0.8 nm and from 1.0 to 1.2 nm, showing a high S-capacity (34.2 mg S/g) for the adsorption of dibenzothiophene from oil.