Dehydrogenation of ethylbenzene with CO2 to produce styrene over Fe-containing ceramic composites

The activity of Fe-containing ceramic composites for the dehydrogenation of ethylbenzene in the presence of CO2 was studied. Ceramic composites containing Fe, Cu, Cr, Pb and/or Ti were obtained by solid-state reaction method. The materials were characterized by XRD, textural properties, chemical analysis, SEM, Mössbauer spectroscopy, TPR, CO2-TPD analyses and electrical measurements. A low conversion was obtained using CaTiO3, due to the loss of the Ca species and coke production. The improvement of styrene selectivity with iron content, as well as the high stability of Cr0.75Fe1.25O3, resulted in a better activity when using this solid. Fe2+ is continuously reoxidized to Fe3+ by CO2 in the Fe–Ti active phase from the Fe0.5Cu0.75Ti0.75O3 sample. The latter catalyst exhibited high selectivity but limited stability towards styrene production. The ceramic composites appeared to be quite promising candidates for the dehydrogenation of ethylbenzene under CO2, in comparison with the conventional Fe–K doped catalysts, due to the highly stable Fe3+ in a ceramic matrix.

The preparation of ceramic composites, as well as the Fe3+ environments (Mössbauer spectra), exerts a significant influence on the catalytic activity for the dehydrogenation of ethylbenzene with CO2 to produce styrene. The high catalytic activity of Cr0.75Fe1.25O3 was a result of the optimal balance between Fe2+ and Fe3+, which are continuously oxidized by the CO2.Figure optionsDownload high-quality image (81 K)Download as PowerPoint slide