Effective synthesis route of renewable activated biocarbons adsorbent for high CO2, CH4, H2, N2, C2H4 gas storage and CO2/N2, CO2/CH4, CO2/H2, C2H4/CH4 selectivity

Abstract

This study explores the feasibility of producing activated carbons (ACs) from abundant fern leaves to enhance their adsorption capabilities. The process involves activation with H3PO4 followed by thermal conversion at temperatures ranging from 700 to 900 °C. Adsorption isotherms for CO2, CH4, H2, N2, and C2H4 were systematically measured at 25 °C under pressures up to 45 bar for all specimens. These data formed the basis for calculating the separation selectivity of CO2/N2, CO2/CH4, CO2/H2, and C2H4/CH4 at various pressures. ACs synthesized at 800 °C (FERN800) exhibited superior characteristics, including a specific surface area of 438 m2/g, a total pore volume of 0.300 cm3/g, and a micropore volume of 0.236 cm3/g. This resulted in significant gas uptake values: 4.21 mmol/g for CO2, 3.14 mmol/g for CH4, 1.19 mmol/g for H2, 2.04 mmol/g for N2, and 3.36 mmol/g for C2H4, at 25 °C and 45 bar. The research demonstrates the potential of fern-derived ACs for high-pressure gas adsorption, particularly in mitigating greenhouse gas emissions and advancing gas separation technologies for applications such as flue gas treatment (post-combustion), syngas production (pre-combustion), biogas upgrading, and hydrocarbon mixtures. Notably, ACs showed a high selectivity of 146 for CO2 over N2 at 1 bar in flue gas containing 15 % CO2, and a selectivity of 90 for CO2 over H2 at 1 bar. ACs produced from fern leaves activated by H3PO4 also show promise in capturing CO2 from biogas and natural gas, as well as C2H4 from natural gas. Additionally, the calculated cost of producing 1 kg of the AC was found to be 2.45 € (19 CNY), positioning it competitively in the market. This research highlights the innovative use of fern-derived ACs as effective and sustainable adsorbents in various environmental and industrial applications.