Browsing by Author "Gleichmann, Kristin"
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- Adsorption equilibrium and dynamics of fixed bed adsorption of CH4/N2in binderless beads of 5A zeolitePublication . Silva, José A.C.; Ferreira, Alexandre; Mendes, Patrícia A.P.; Cunha, Adelino F.; Gleichmann, Kristin; Rodrigues, AlírioThe sorption equilibrium of methane (CH4) and nitrogen (N2) in binderless beads of 5A zeolite is presented between 305 and 373 K and pressures up to 3 bar in a static electronic microbalance. The adsorbed amount of CH4 and N2 is around 1.6 and 1.02 mol/kgads, respectively, at 305 K and 3 bar. A comparison of these values with the ones in literature shows that the adsorption capacity of the 5A binderless beads is 20% higher than that of the 5A binder commercial materials. The CH4 and N2 adsorption isotherms were fitted with the simplest Langmuir model with a prediction of the maximum amount adsorbed for both compounds of 5.0 mol/kg. The heats of sorption are -16.6 and -15.1 kJ/mol for CH4 and N2, respectively. In the overall pressure and temperature range the isotherms of N2 seems practically linear. However, it was observed that the experimental data of N2 at low coverage (below 0.2 bar) deviates slightly from Type I isotherms. Thereafter, the binary sorption of CH4 and N2 has been investigated in a fixed bed adsorber at 313 and 343 K and total pressures up to 5 bar for 50(CH4)/50(N2) and 75(CH4)//25(N2) mixture ratios diluted in an inert helium stream. A mathematical model was formulated to compute the dynamic behavior of the fixed bed adsorber using the extended binary Langmuir model, showing close agreement with the measured binary breakthrough experiments in the partial pressure range of the components above 0.2 and below 3 bar. © 2015 American Chemical Society.
- Fixed bed adsorption of CO2, CH4, and N2 and their mixtures in potassium-exchanged binder-free beads of Y zeolitePublication . Aly, Ezzeldin; Zafanelli, Lucas F.A.S.; Henrique, Adriano; Pires, Marcella Golini; Rodrigues, Alírio; Gleichmann, Kristin; Silva, José A.C.; Golini Pires, MarcellaThe adsorption of carbon dioxide (CO2), methane (CH4), and nitrogen (N2) has been studied on potassium-exchanged (95%) binder-free beads of Y zeolite through single, binary, and ternary fixed bed breakthrough experiments, covering the temperature range between 313 and 423 K and a pressure of up to 350 kPa. At 313 K and 350 kPa, the single-component data obtained showed that the amounts adsorbed of CO2, CH4, and N2 are around 6.42, 1.45, and 0.671 mol kg-1, respectively. The binary experiments CO2/N2 carried out under typical post-combustion conditions show a selectivity of CO2 over N2 around 104. The ternary experiments resulted in the selectivities of CO2 over CH4 and N2 around 19 and 45, respectively. The adsorption equilibrium data have been modeled by the dual-site Langmuir model, and the breakthrough experiments were numerically simulated with a suitable dynamic fixed bed adsorption model. The model predicts with good accuracy the systematic behavior of all breakthrough experiments. The results shown in the present work prove that the potassium-exchanged binder-free beads of Y zeolite enhance the amount adsorbed of CO2 at low partial pressure over other alkali metal-exchanged faujasites and efficiently separate it from binary (CO2/N2) and ternary (CO2/CH4/N2) mixtures by fixed bed adsorption.
- Separation of CO2/N2 in Ion-Exchange binder-free beads of zeolite NaY for Post-Combustion CO2 capturePublication . Aly, Ezzeldin; Zafanelli, Lucas F.A.S.; Henrique, Adriano; Gleichmann, Kristin; Rodrigues, Alírio; Freitas, Francisco A. da Silva; Silva, José A.C.Ion-exchange on bare commercial zeolites can offer improved adsorption processes. In the context of CO2/N2 separation for post-combustion CO2 capture (PCC), here, we report, the effect of ion-exchange on commercial binder-free NaY zeolite with alkali (K+) and alkaline earth (Ca2+) metal cations, achieving exchange levels of 23 %, 58 %, and 95 % for K+ and 56 % and 71 % for Ca2+. Adsorption isotherms of CO2 and N2 were measured over a temperature range of 306–344 K and pressures up to 350 kPa. At low pressures, the CO2 adsorption capacity increases as Na+ ions are exchanged to a higher level of K+, while a reverse trend is observed for Ca2+ exchange. At 25 kPa and 306 K, the CO2 loading (mol∙kg−1) follows the order 2.01-Ca(71)Y < 2.63-Ca(56)Y < 4.05-NaY < 4.29-K(23)Y < 4.59-K(58)Y < 4.72-K(95)Y. The selectivities of CO2 (15 %)/N2 (85 %) at 306 K and 101.3 kPa range from 52 for Ca(71)Y to 101 for K(23)Y, compared to 89 in the bare NaY zeolite. The working capacities for the most promising exchanged sample (K(23)Y) exhibit superior values of 4.51, 2.98, and 2.41 mol∙kg−1 considering regeneration pressures of 3, 10, and 15 kPa, relative to a feed pressure of 101.3 kPa, respectively. Dynamic simulations were conducted using the Aspen Adsorption package to accurately predict both single- and binary-component breakthrough curves.
- Vacuum pressure swing adsorption process using binder-free K(23)Y zeolite for post-combustion CO2 capturePublication . Aly, Ezzeldin; Zafanelli, Lucas F.A.S.; Henrique, Adriano; Gleichmann, Kristin; Rodrigues, Alírio; Freitas, Francisco A. da Silva; Silva, José A.C.This study presents the development of a Vacuum Pressure Swing Adsorption (VPSA) process utilizing binder- free K(23)Y zeolite for post-combustion CO2 capture. The ion-exchanged K(23)Y zeolite, characterized by a high CO2 selectivity of 97 over N2 at 10 kPa and an adsorption capacity exceeding 7 mol⋅kg− 1 350 kPa at 306 K, was evaluated under various operational conditions to optimize the VPSA process. Experimental and simulated breakthrough analyses provided essential data for adsorption equilibrium and sorption kinetics, which were modelled using Aspen Adsorption software. Optimization of key cycle steps, including pressurization, adsorption, blowdown, and evacuation, revealed that Light Product Pressurization significantly enhances process performance. Parametric studies demonstrated that reducing intermediate pressure from 0.2 bar to 0.07 bar increased CO2 purity from 84 % to 93 %, though it decreased recovery from around 99 % to 78 %, revealing a key trade-off. Similarly, extending adsorption time beyond 86 s enabled CO2 purity to exceed 90 %, though recovery decreased slightly. Under optimal conditions, the VPSA process achieved a CO2 purity and recovery of ~90 % and productivity of 0.367 molCO2⋅m− 3ads⋅s− 1 , with specific energy consumption of 144 kWh per ton of CO2 captured. The study demonstrates the viability of a simple 4-step VPSA configuration with binder-free K(23)Y, offering competitive performance and low energy consumption.