Potassium-promoted iron oxide is the primary catalyst used to produce styrene by dehydrogenation of ethylbenzene (EB). In industry, this reaction is operated with excess steam (steam/oil molar ratio = 8-12) at high temperature, which requires significant energy input. An economically advantaged process would involve performing this dehydrogenation reaction at a lower steam/oil ratio. However, significant catalyst deactivation occurs at low steam/oil conditions. To develop an improved catalyst, it is essential to understand the catalyst deactivation mechanism. The reaction system is complicated with a range of gas phase concentrations in addition to the potential for formation of “coke” on the catalyst surface. The stability of potassium promoted iron oxide catalyst materials steam, H₂, CO₂, and ethylbenzene environments were studied in this work. Reactions were performed in a thermogravimetric analyzer (TGA) and X-ray diffraction (XRD) was applied to characterize the phase changes. For comparison, unpromoted iron oxide and specially prepared KFeO₂, which is widely believed to be the catalytically active phase, were also examined. The results demonstrate the critical importance of the gas phase composition on the chemical state of the catalytic material.

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