Bimetallic synergistic effect of chromium‑gallium nanoparticles on ZSM-5 framework for robust propane dehydrogenation

Bimetallic CrGaO x /ZSM-5 catalyst balances activity-selectivity trade-off in propane dehydrogenation. • Ga species modulates the Cr-O-Cr coordination environment, facilitates C H bond activation and simultaneously stabilizes the Cr 6+ /Cr 3+ redox cycle. • In-situ DRIFTS reveals Cr Ga synergy promotes propyl intermediate formation at low temperature. • O 2 regeneration effectively restores Cr 6+ active sites and removes coke deposits, ensuring sustained catalytic performance. Developing highly active and stable catalysts for propane dehydrogenation (PDH) is crucial for propylene production, yet it is normally hampered by the trade-off between C 3 H 8 conversion and C 3 H 6 selectivity. Herein, we construct a series of bimetallic CrGaO x /ZSM-5 catalysts to mitigate this intrinsic challenge. The optimized Cr 3 Ga 3 O x /ZSM-5 catalyst achieves a propane conversion of 38.7% with a propylene selectivity of 84.3% at 600 °C and maintains stable propylene productivity over 40 h of continuous operation. Results reveal that Ga 3+ incorporation modifies the Cr-O-Cr coordination environment, thus enhancing propane activation and formation of propyl intermediates. The structural modification suppresses Cr 3+ over-reduction to Cr 0 , maintaining the Cr 6+ /Cr 3+ redox cycle over extended reaction periods. Furthermore, O 2 regeneration effectively removes coke deposits and restores active sites. This work provides mechanistic insights into the Cr Ga electronic and structural synergy and offers a design strategy for stable chromium-based PDH catalysts. The incorporation of Ga 3+ modulates the Cr-O-Cr coordination environment, facilitating C H bond activation while suppressing undesired C C bond cleavage, and simultaneously stabilizes the Cr 6+ /Cr 3+ redox cycle by preventing over-reduction of Cr 6+ to inactive Cr 0 . O 2 -mediated regeneration effectively restores active Cr 6+ sites and removes coke deposits, enabling a reversible deactivation-regeneration cycle. The optimized Cr 3 Ga 3 O x /ZSM-5(300) catalyst achieves a propane conversion of 38.7% with a propylene selectivity of 84.3% at 600 °C under standard conditions, and delivers a superior performance of 62.1% conversion with 90.6% selectivity under lower WHSV. Download: Download high-res image (126KB) Download: Download full-size image