Abstract
The shorter driving range is the challenge of compressed natural gas (CNG) as a vehicular fuel. In this study, adsorbents were prepared from coconut shells and Poly Ether Ether Ketone (PEEK) using KOH microwave activation to overcome the challenge of CNG storage system. The CNG storage system has some disadvantages which include high-pressure operation with less safety guard, and heavy storage cylinders. The adsorbents were used as a potential Sorbents for methane (CH4) storage at different pressures. The coconut shell and PEEK were carbonized from ambient temperature to 700 ± 20 oC at 10 oC min-1 heating rate with 1 L min-1 N2 flow rate. The carbonization temperature of the precursor was determined using thermo-gravimetric and derivative thermogravimetric (TG/DTG) analysis. The activation was achieved with well modified microwave equipment operated at 500 W and 5 minutes. The adsorbents were characterized by Fourier transform infrared spectroscopy (FTIR), nitrogen adsorption and scanning electron microscopy (SEM). The CH4 adsorption characteristics were conducted using volumetric adsorption equipment at an ambient temperature and pressures of 5-17 bar. The highest CH4 uptake achieved from hybrid adsorbent at 5, 7.5, 11 and 17 bar are 2.35, 3.04, 4.80 and 7.15 mmol/g respectively. The experimental data simulated using three common adsorption models: Langmuir, Freundlich and Sips. The Freundlich, had high correlation coefficient up to 0.9989 and lower root mean square deviation (RMSD) which fitted our data better than others. The findings revealed the potential of coconut shell-PEEK as sorbents for CH4 adsorption applications and isotherm models equations used in adsorption

Key words: Hybrid, Non hybrid, Activated carbon, Adsorption, Isotherm