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The separation of ethylene from ethane is particularly complex due to their similar physical properties. Cryogenic distillation is the most common technology employed for this separation and is one of the most expensive operations in industry, being the driving force for the ongoing research to find a more cost-effective alternative. In the present work, a gas-phase simulated moving bed (SMB) bench unit was employed to produce polymer-grade ethylene from ethane/ethylene mixtures, using binderless 13X zeolite beads as adsorbent, and propane as desorbent. The achieved performance parameters demonstrated the high efficiency of the current technology, since ethylene was obtained with a purity of 99.8%, a recovery of 99.8%, and a productivity of 59.7 kg C2H4 Áh 21 Ám 23 adsorbent . Considering the encouraging results obtained it is fair to say that the gas-phase SMB is a competitive and strong candidate as alternative to the conventional process, especially when combined with enhanced performance adsorbents, such as binderless zeolites.

Zeolite molecular sieves are used in industrial applications since more than 60 years, mainly as highly efficient adsorbents for separation processes in gas or liquid phase. Zeolite molecular sieves may be applied in powder form, preferably in static applications, but to a much larger extent as shaped material in both static and dynamic (flowing media) applications. Many shaping technologies for molecular sieves have been developed over the last decades, reflecting the different requirements for molecular sieves in different applications. This review deals with the influence of the applied zeolite synthesis and shaping methods for hydrophilic zeolite molecular sieves (procedures, materials, recipes) on the potential industrial applications; thereby considering powders, binder-containing shapes as well as binderless shapes (including compact structures such as honeycombs, multi-channel, and foam-like structures). Due to new challenges from the market, more specialized, tailor-made types of zeolite molecular sieves are required. Such a higher specialization can be achieved by applying new types of zeolites or zeolite-like materials, modified synthesis and/or post synthesis treatments, and by modified, to the needs of the application adjusted shaping processes.

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.

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