Paula Lobo Accioly

Paula Lobo Accioly

Federal University of Pernambuco, Brazil

Title: Evaluating alkaline activated carbon for methane enrichment of biogas


Paula Lobo Accioly is pursuing her Master’s degree in Chemical Engineering at the Federal University of Pernambuco, where she was also graduated in Chemical Engineering. She has interest in research related to biogas production, purification and enrichment.


Anaerobic decomposition of organic matter generates biogas, a renewable energy source. The primary components of biogas are methane and carbon dioxide at concentrations varying from 40-75% and 15-60% respectively. Biogas enrichment to 95-97% of CH4 and 1-3% of CO2 produces biomethane, which is a direct substitute for natural gas. The production of biomethane requires separating CH4 from CO2. Among many, pressure swing adsorption (PSA) is a common technology, which captures carbon dioxide by adsorption on a solid surface. Activated carbons (AC) are porous solids adsorbents of low cost, abundant and with a high CO2 adsorption capacity. In the interest of increasing carbon dioxide load and considering the weak acid characteristic of CO2, AC was impregnated in sodium and calcium hydroxide solution, separately, named AC1 and AC2, respectively. Saturation curves were obtained from packed bed reactor operating at 1 bar and 24 °C, which allow determining the carbon dioxide capacity for biomethane production. The results revealed that both AC1 and AC2 are capable of separating the mixture CO2/CH4 and the amount of carbon dioxide retained by each were 0.49 and 0.32 mmol/g. Activated carbon impregnated with sodium hydroxide has the highest CO2 adsorption load in comparison with calcium hydroxide. The packed bed reactor, utilizing AC1, has a breakthrough time of approximately 3.6 minutes. From the initial operation of the fixed bed reactor until the breakthrough time, the column delivers an output gas with methane concentration similar to natural gas.