Adsorption Of Ethylbenzene Research Articles

Study of the oxidative dehydrogenation of ethylbenzene: III. Mechanism for styrene formation

The reaction mechanism of oxidative dehydrogenation of ethylbenzene has been investigated using the pulse technique, isotope exchange reaction, and ESR measurement. Collecting the effluents of the pulse reaction has shown the reversible adsorption of ethylbenzene. The deuterium exchange reaction has shown that the adsorbed intermediates of ethylbenzene are dissociated at the α position. Neutrally adsorbed molecular oxygen species and O − species are observed on the prereduced SiAl catalysts by the ESR measurement, showing the ability of the catalysts to activate gaseous oxygen. The reaction of the oxygen species with ethylbenzene has shown the active oxygen species to be O − species. The O − species consumed by the reaction are supplied from gaseous oxygen through O 2ad species. The reversible adsorption of ethylbenzene and the correlation between the turnover frequency and basicity suggest that the rate of the overall reaction at above 723 K is determined by the reaction of adsorbed ethylbenzene species and O − in abstracting the β-hydrogen. From the above results, a reaction mechanism is proposed as follows: the acid site of H 0 between 1.5 and −5.6 adsorbs ethylbenzene, reversibly abstracting the α-hydrogen at the basic OH adjacent to the acid site, and the base site of p K a between 17.2 and 26.5 activates gaseous oxygen to form O − which abstracts the β-hydrogen.

Control of micropore diffusivities of molecular sieving carbon by deposition of hydrocarbons

Adsorption of ethylbenzene and styrene at 150–400°C followed by heat treatment at 400°C was tried for controlling diffusivities in micropores of Molecular Sieving Carbon. The amount of carbon deposited after heat treatment is a function of adsorption temperature. Diffusivities of oxygen and nitrogen were measured using the Chromatographic method and found to decrease sharply with the small increase of the amount of carbon deposited. The ratio of O 2 N 2 diffusivities, however, was little affected by this treatment.