Adsorption Equilibrium and Dynamics of Fixed Bed Adsorption of CH₄/N₂ in Binderless Beads of 5A Zeolite

Abstract

The sorption equilibrium of methane (CH 4 ) and nitrogen (N 2 ) 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 CH 4 and N 2 is around 1.6 and 1.02 mol/kg ads , 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 CH 4 and N 2 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 CH 4 and N 2 , respectively. In the overall pressure and temperature range the isotherms of N 2 seems practically linear. However, it was observed that the experimental data of N 2 at low coverage (below 0.2 bar) deviates slightly from Type I isotherms. Thereafter, the binary sorption of CH 4 and N 2 has been investigated in a fixed bed adsorber at 313 and 343 K and total pressures up to 5 bar for 50(CH 4 )/ 50(N 2 ) and 75(CH 4 )//25(N 2 ) 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.

Ultramicroporous carbon granules with narrow pore size distribution for efficient CH4 separation from coal‐bed gases

“…Notably, this selectivity is higher than that of many top‐ranking adsorbents, such as ZK‐5 (~4.2), 20 CGUCs (5.4), 45 OMC (3.7), 46 and MIL‐100(Cr) (3.0) 47 . Furthermore, the high CH 4 /N 2 selectivity and CH 4 adsorption capacity were exhibited simultaneously by granular GOC‐2, as shown in Figure 3d 1,2,17,20,45‐55 . Thus, GOC‐2 sets a benchmark for CH 4 separation and concentration from low‐grade coal‐bed gas.…”

Prediction of adsorption isotherms from breakthrough curves

“…Therefore, simplifying assumptions are usually applied to facilitate the computational process without losing the predictive capability of mathematical models. During the last decades, several models with various simplifications have been proposed to reproduce and predict the experimental breakthrough curves for different systems [10,8,11,12,9,13,14]. Breakthrough curves estimated by many of these models are in good agreement with the experimental breakthrough curves [7,13,14].…”

Facile synthesis of ultramicroporous carbon adsorbents with ultra‐high CH4 uptake by in situ ionic activation

“…One potential strategy for accomplishing this goal involves the selective adsorption of dilute CH 4 from a stream of CH 4 /N 2 by porous materials, which would be both economically and operationally feasible, as well as highly energy efficient. In this regard, many adsorptive materials, including metal–organic frameworks (MOFs), zeolites, and carbon‐based adsorbents, have been examined for the separation of CH 4 /N 2 7‐10 . Specifically, MOFs comprise a new generation of porous materials that have recently demonstrated excellent CH 4 adsorption properties; for example, MOF‐177, 11 M 3 (HCOO) 6 (M = Co, Ni), 12 Co 3 (C 4 O 4 ) 2 (OH) 2 , 13 all exhibit high uptake values for CH 4 , or high CH 4 /N 2 selectivity.…”