Study On The Stability Of The Catalyst For Ethylbenzene Dehydrogenation In The Presence Of CO₂

The process of ethylbenzene dehydrogenation in the presence of CO2 (CO2-EBDH) could reduce the energy consumption, improve the equilibrium conversion and provide a new approach for CO2 utilization. However, the main problem at present is that catalysts for CO2-EBDH ususlly deactivate rapidly and have a short lifespan. The key to this process is the preparation of high-performance catalyst, especially with high stability.In present work, deactivation reasons of Fe2O3/y-Al2O3 catalyst for ethylbenzene dehydrogenation in the presence of CO2 were investigated though a series of regeneration experiments and characterization means. The effects of different supports/promoters, operation conditions and preparation conditions on activity and stability of the catalyst were studied. The catalytic performance of other types of catalysts for CO2-EBDH was also evaluated.Coke deposition, reduction of the active center, sintering and poisoned by H2O, all could lead to the catalyst deactivation. Over reduction of the active center (reduction of Fe3+ to Fe2+) was the main reason for the catalyst deactivation; coke deposit formed in long period was another important factor leading to the deactivation.The addition of K, Ce, Ca, Mg and Mo promoters could improve the catalytic activity or styrene selectivity to some extent. Moreover, the adding of Ca with a certain amount could restrain the catalyst deactivation and improve the catalyst stability. Proper calcination temperature and EB flow rate could also help to slow down the catalyst deactivation rate. Fe2O3/γ-Al2O3 catalyst exhibited better performance compared with other types of catalysts for ethylbenzene dehydrogenation in the presence of CO2.