Hydrothermally-treated Na-X as efficient adsorbents for butadiene removal

An efficient adsorbent for butadiene was synthesized via soft hydrothermal treatment (2 h in boiling water followed by 1 h calcination at 573 K) of industrial Na-X. The adsorption capacity of the zeolite was studied in the low concentration range (20–300 ppmv). Whereas original Na-X presents a very small adsorption, its treated counterpart shows a large capacity. The characterization of the zeolite suggests that the soft hydrothermal treatment dealuminates the zeolite leaving behind new OH-groups responsible for the adsorption of butadiene on the zeolite lattice. The adsorption isotherms were determined for the hydrothermally treated zeolites and the results were found to be consistent with the Dubinin–Astakhov (D–A) model. The adsorption enthalpy of butadiene on the treated Na-X was obtained from the D–A equation and from the modeling of temperature-programmed desorption profiles. Both methods gave a value of −45 kJ mol−1 suggesting chemical interactions of butadiene with the zeolite lattice. In summary, we report an efficient adsorbent for butadiene removal from diluted stream being valuable material for reducing butadiene emissions.