Synergistic integration of zeolite engineering and fixed-bed column design for enhanced biogas upgrading: Adsorbent synthesis, CO2/CH4 separation kinetics, and regeneration assessment

• Published in: Separation and purification technology Vol. 355; p. 129772
• Main Authors: Sidabutar, Rivaldi, Trisakti, Bambang, Irvan, Michael, Michael, Vanness, Vanness, Alexander, Vikram, Natasya, Yenny, Pasaribu, Della Sri Kristina, Alamsyah, Vandria, Zaiyat, M. Ziniddin Zidan, Syafriandy, Syafriandy, Fath, M. Thoriq Al, Dalimunthe, Nisaul Fadilah, Abdul, Peer Mohamed, Takriff, Mohd Sobri
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-03-2025
• Subjects: Biogas upgrading; CO2/CH4 separation; Fixed bed; Regeneration; Zeolite modification; Zeolite modification; Regeneration; Biogas upgrading; CO2/CH4 separation; Fixed bed
• DOI: 10.1016/j.seppur.2024.129772
• ISSN: 1383-5866

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•Zeolite system produces near-pure methane for enhanced fuel applications.•Modified zeolites upgrade biogas from 69% to 99.29% CH4.•Dual-chemical activation boosts zeolite adsorption in fixed-bed column.•Dual chemically-activated zeolites achieve 97.77 ± 0.01 % CO2 adsorption.•Optimal conditions: 30-min adsorption, 17-min desorption at 40 °C.
Biogas, a renewable energy vector derived from anaerobic digestion of organic waste, requires CO2 separation to enhance its calorific value for engine fuel. This study integrates CO2/CH4 separation in biogas using a novel approach integrating dual chemically-activated zeolites and fixed-bed column purification. Biogas produced via CSTR/ultrafiltration (69 % CH4, 30 % CO2, 14 ppm H2S) was further upgraded using HCl + NaOH and H2SO4 + NaOH activated zeolites. Optimal absorption capacity of 97.77 ± 0.01 % was achieved at 140 mesh, 60-minute H2SO4 + NaOH activation, 2-hour calcination (400 °C), and 200 mL/min flow rate. Breakthrough was observed at 18.12 min. Langmuir isotherm (R2 = 0.9992) and Elovich kinetics (R2 = 0.9846) best described the adsorption process. XRD analysis showed significant crystal size reduction post-activation (53.31 nm to 16.90 nm). Notably, BET analysis revealed enhanced surface properties surface area of 286.71 m2/g, pore volume of 0.213 cc/g, and pore diameter of 3.532 Å. An innovative dual-column system with non-isothermal TSA protocol optimized CO2 adsorption (30 mins) and desorption (17 mins, 40 °C, 100 mL/min), yielding superior near-pure methane biogas (99.29 % CH4, 0.66 % CO2, trace H2S). A methane loss of 2.75 % during upgrading demonstrated high CO2 selectivity. This synergistic approach presents a promising solution for sustainable biogas purification and engine fuel applications.