Synergistic modulation of electronic and acid–base properties of loaded Pt–Fe–Zr oxide catalyst for ethylbenzene oxidative dehydrogenation under low-oxygen conditions

Abstract

In the process of ethylbenzene dehydrogenation to styrene catalyzed by Fe-based catalysts, the easy reduction of Fe³⁺ in the reaction atmosphere and the over-strong acidity of traditional Fe-based catalysts are the two significant reasons for catalyst deactivation and coke deposition. In this study, we developed a novel Pt–Fe–Zr oxide catalyst loaded on alumina (simplified as Pt–Fe–Zr/Al₂O₃), aiming to increase the stability of Fe³⁺ and regulate the acidity simultaneously. In addition to the comprehensive control experiments, XPS, H₂-TPR, TPD, and CO-DRIFTS were employed to reveal the Pt–Fe–Zr interactions. On the one hand, the introduction of Zr species serves as a medium that significantly enhances electron transfer from Fe species to Pt species, thereby stabilizing the valence state of Fe³⁺, and simultaneously suppresses the sintering of Pt nanoparticles. On the other hand, the introduction of Zr species remarkably reduces the number of strong acid sites, effectively inhibiting coke deposition. The co-modulation of electron transfer and catalytic acidity delivers both enhanced catalytic performance and reduced coke deposition. Catalytic tests indicate that under low-oxygen conditions (O₂/EB molar ratio = 0.9, O₂ concentration < 10%), the Pt–Fe–Zr/Al₂O₃ catalyst achieved an ethylbenzene conversion of 45.9% and styrene selectivity of 97.2%, as well as significantly low coke deposition. The synergistic modulation of both electron transfer and acid–base properties in this study provides new insights for multi-metal catalyst design and promotes energy-efficient industrial styrene production.