Synthesis of amine-functionalized activated carbon from novel barhi date kernels for superior CO₂/CH₄ selectivity
摘要
The development of sustainable, biomass-derived adsorbents is critical for efficient CO₂/CH₄ separation in biogas upgrading. In this study, activated carbons (AC) synthesized from waste Barhi date kernels via KOH activation were functionalized with various amine agents (DEA, TETA, and Urea). Physicochemical characterizations confirmed a critical design trade-off: while amine loading reduced the BET surface area by approximately 70% (from 1631 to 478 m2/g), it successfully induced a high density of basic nitrogenous sites. The diethanolamine-modified sample (AC-DEA) exhibited the highest basic site density (1.614 mmol/g) and achieved a CO₂ capacity of approximately 3.2 mmol/g at 298 K and 1 bar. Most importantly, under competitive binary gas conditions, AC-DEA demonstrated an outstanding CO₂/CH₄ selectivity of 12.5 at 1 bar (peaking at 43.5 at 1.6 bar), surpassing the industrial benchmark Zeolite 13X. Mechanistic insights derived from the isosteric heat of adsorption (ΔHst) revealed that this exceptional performance is driven by a synergistic effect between ultramicroporosity and surface chemistry. This work presents a robust route for producing high-performance adsorbents, providing deep mechanistic insights into the interplay between surface chemistry and porosity for next-generation gas separation materials.