Effect of carbonization temperature on the physical properties and CO2 adsorption behavior of petroleum coke-derived porous carbon

Abstract

Cost-effective porous carbons for CO2 capture were developed from petroleum coke using KOH as an activating agent. In particular, the effect of the carbonization temperature on the physical properties and CO2 adsorption behavior of the prepared porous carbons was investigated while keeping the other conditions constant during KOH activation. The highest specific surface area and total pore volume of 1470 m(2)/g and 0.60 cm(3)/g were obtained for the porous carbon carbonized at 500 degrees C, with higher carbonization temperatures resulting in reduced porosities. XRD and FTIR analyses revealed that the structural disorder and amount of surface functional groups, both of which are favorable for porosity development during activation, had opposite trends with increasing carbonization temperature. Therefore, an optimal carbonization temperature existed for the maximum porosity. The porous carbon carbonized at 500 degrees C exhibited the highest CO2 adsorption capacity of 4.17 mmol/g at 25 degrees C and 1 bar owing to its highest narrow micropore volume (pore size of less than 0.8 nm). In addition to its high CO2 adsorption capacity, the prepared porous carbon presented good selectivity for CO2 over N-2, moderate heat of adsorption, fast adsorption kinetics, facile regeneration, and stable adsorption working capacity during consecutive adsorption and desorption cycles, indicating its promise in practical CO2 capture applications.