Optimizing Carbon Dioxide Uptake and Carbon Dioxide‐Methane Selectivity of Oxygen‐Doped Porous Carbon Prepared from Oxygen Containing Polymer Precursors

Abstract

AbstractThe reproducible synthesis is reported for oxygen containing porous carbons (OPC) by the KOH activation at 500–800 °C of two oxygen containing precursor polymers: polyfurfuryl alcohol (PFFA) and polyanisyl alcohol (PAA) yielding FFA‐OPC and AA‐OPC, respectively. Both OPCs exhibits good thermal stability and reproducible gas uptake properties over multiple cycles. The surface area and pore volumes of the OPC are independent of the precursor identity, but controlled by the activation temperature. Similarly, the uptake of CO2 is determined by the physical properties of the OPC: activation at 750 °C results in uptake that equals or out‐performs existing PCs for high pressure uptake (30 bar) at 24.0 °C (FFA‐OPC750: 117 wt%; AA‐OPC750: 115 wt%). The high uptake is related to a high relative percentage of pores <2 nm. The uptake of CH4 for both OPCs is greatest for samples activation at 750 °C, FFA‐OPC750 shows enhanced uptake compared to AA‐OPC750, 15.5 wt% versus 13.7 wt%, respectively. Uptake for CH4 appears to relate to a high relative percentage of pores 1–2 nm, which is observed for AA‐OPC750. As a consequence, AA‐OPC750 demonstrates superior selectivity for CO2 capture over CH4 uptake (AA‐OPC750: Vmass(CO2/CH4)=8.37 at 30 bar) as compared to reported PCs. A higher value for the isosteric heat of adsorption of CO2 (33 kJ mol−1) versus CH4 (11 kJ mol−1) suggests a new temperature dependent strategy for removing CO2 from natural gas via selective adsorption and desorption cycles.