Methane adsorption on carbonaceous microporous materials prepared from cellulose and lignin: Equilibrium and kinetic studies

Abstract

The present investigation highlights methane adsorption on synthesized Activated Carbons (ACs) based upon hydrothermally treated cellulose and lignin followed by chemical activation utilizing ZnCl2 as the activating agent. The inuence of effective parameters such as hydrothermal pretreatment, precursor type, carbonization temperature, and impregnation ratio on the textural properties of synthesized materials as well as adsorption capacities of methane was examined. Thermal stability and decomposition procedures of cellulose and lignin were determined through the TGA technique while all prepared ACs were characterized via N2 adsorption-desorption analysis utilizing BET-BJH surface area measurement and Field Emission Scanning Electron Microscopy (FESEM). Amongst all prepared materials, the AC that was produced through impregnating hydrothermally treated cellulose with ZnCl2 with the ratio of 1 and carbonized at 600°C revealed improved surface and textural properties and enhanced methane storage. Furthermore, hydrothermal pretreatment provided micro-pore diameters ranging from 1.8 to 2.2 nm. This resulted in 6.42 mmol.g-1 of methane adsorbed at 298 K and 3.65 MPa. In order to systematically understand behaviors of adsorbents in the process at hand, several kinetic and isotherm models were investigated.