(92f) Carbon Nano-Tube Addition to Improve the Conductivity of a Molecular Sieve Adsorbent

During resistive heating regeneration, an electric current passed through an adsorbent with sufficiently low

resistivity (typically, 0.1 – 10 Ω.m) and heat is generated by the Joule effect. This method allows for

rapid adsorbent regeneration, as the heat flow is decoupled from the purge gas flow. Molecular sieves

are effective adsorbents because they have tailored and structured pore size distributions. Unlike

carbonaceous materials, however, molecular sieves have high electrical resistivity that prevents their

regeneration by resistive heating. In this study, carbon nano tube (CNT) was added to zeolite Y (high

resistivity, >E+7 Ω.m) to decrease its resistivity. CNT was added by CH4 decomposition on cobalt

impregnated zeolite Y. Different cobalt impregnation conditions and decomposition temperatures were

used for CNT growth on zeolite Y. Modified samples were characterized using bulk elemental (CHN)

analysis, scanning electron microscopy (SEM), X-ray diffraction (XRD), and resistivity measurements.

CHN and SEM confirmed the addition of carbon onto zeolite Y in the form of CNT. Resistivity

measurements showed that CNT growth decreased the resistivity of zeolite Y by up to 8 orders of

magnitude. The results were compared to the resistivity of samples physically mixed with powdered

carbon in different ratios. It was found that the resistivity can be decreased more efficiently by adding

carbon directly to the structure of zeolite in the form of CNT. Finally, the modified samples were

heated resistively, suggesting that CNT addition to Zeolite Y allows faster and more energy efficient

heating compared to conductive-convective heating.