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Browsing by Author "Cheikh, Ikram Ben"

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  • Adsorption of co2, ch4 and n2 in powder and binder-free zeolite 13x
    Publication . Cheikh, Ikram Ben; Silva, José A.C.
    The increasing concentration of greenhouse gases (GHGs), particularly CO2, is a main driver of climate change, demanding effective mitigation strategies. Carbon Capture and Storage (CCS) technologies, especially adsorption-based processes using porous materials, offer an efficient route to reduce CO2 emissions from industrial sources. Zeolite 13X has gained prominence due to its high surface area, well-defined pore structure, and strong affinity toward CO2. While typically synthesised in powder form, the use of commercial binder-free Zeolite 13X (13X-BF) beads may offer potential advantages over conventional structures, including improved mechanical strength, enhanced mass transfer, and a higher effective capacity due to the reduced presence of inert components. This work systematically investigates the adsorption equilibrium of CO2, CH4, and N2 on both lab-agglomerated powder (13X-P) as synthesised and commercial binder-free (13X-BF) forms of zeolite 13X. A custom fixed-bed unit was used to measure breakthrough curves at temperatures of 308,328 and 348 K and partial pressures ranging from 10 to 350 kPa to measure adsorption equilibrium isotherms. The experimental equilibrium data were rigorously fitted using the Langmuir model for N2 and CH4 and the Dual-Site Langmuir (DSL) model for CO2. The 13X-BF material exhibited a superior thermodynamic performance comparable to the pure lab-agglomerated powder (13X-P) as synthesised. Adsorption equilibrium capacities followed the order CO2 > N2 > CH4. At 308 K and 150 kPa, the maximum uptake reached 7.57 mol⋅kg−1 for 13X-BF, even outperforming the 7.11 mol⋅kg−1 observed on 13X-P. Under typical post-combustion conditions (15% CO2, 308K, 101kPa), 13X-BF achieved a superior CO2/N2 selectivity of 70, comparable to 61 observed for the 13X-P. The working capacity performance parameter (important for cyclic processes such as PSA and TSA) highlighted also a critical operational trade-off: 13X-BF exhibited a working capacity of 3.10 mol.kg−1 under aggressive deep vacuum regeneration (in the pressure range 100 to 3 kPa at 308 K) compared to 2.56 mol.kg−1 to the 13X-P. However, 13X-P performed slightly better under milder vacuum regeneration (10 kPa and 15 kPa). Overall, the results indicate that commercial binder-free Zeolite 13X preserves the intrinsic adsorption characteristics of the powder form while providing comparable adsorption capacity, selectivity, working capacity and mechanical viability, suggesting its potential suitability for adsorption processes such as PSA and VPSA for CO₂ capture and biogas purification.
    2025Master thesis Open access Show more