Isobutane Dehydrogenation Assisted by CO2 over Silicalite-1-Supported ZnO Catalysts: Influence of Support Crystallite Size

of main observation and conclusion The ZnO catalysts supported on Silicalite-1 zeolites with different crystallite sizes (0.08, 0.35, 1 and 1.7 mu m, respectively) and 5% Zn were synthesized via an incipient wetness method. The catalysts were characterized by XRD, N-2 adsorption, SEM, TEM-EDX, DRIFT spectra and NH3-TPD, and their catalytic performance in isobutane dehydrogenation assisted by CO2 was investigated. The catalytic activity is strongly dependent on the crystallite size of Silicalite-1 support. The ZnO/S-1-0.35 catalyst with ca. 0.35 mu m crystallite size displays the highest activity, affording an initial isobutane conversion of 51.0% and 74.5% isobutene selectivity. This can be attributed to a higher amount of acid sites present on this catalyst as well as the largest amount of nest silanols possessed by the S-1-0.35 support.