Integrated bi-modal fluidized bed reactor for butane dehydrogenation to corresponding butylenes

The direct butane dehydrogenation to corresponding butenes (1-butane and/or iso-butene) is the most economical route. The reaction is complex as reaction engineering constraints are very much tide up with engineering constraints due to high endothermic requirements, equilibrium limitations and selectivity control. The state-of-the-art idea of bi-modal particle gas–solid–solid fluidization (GSS–FBR) system was introduced in order to overcome light alkane dehydrogenation reaction barriers (i.e. continuous heat input for endothermic reaction) in a fluidized bed technology. In this study, both n-butane and iso-butane dehydrogenation reactions were studied in an integrated fluidized bed reactor (see Fig. 1), using Pt–Sn/Al2O3–SAPO-34 novel catalyst at 590 °C. The results of integrated bi-modal particle fluidized bed reactor were compared with fixed bed micro-reactor, and parametrically characterized. The results showed that above 95% total olefins selectivity with feed conversion between 20 and 40 wt.% from end-of-run (8 h) to the start-of-run (10 min) in GSS–FBR. This significant enhancement is achieved for continuous longer reaction duration by using novel bi-modal particle fluidization system, owing to uniform heat transfer throughout the reactor and transfer of coke from principal catalyst to secondary catalyst, which increases principal catalyst’s stability. The secondary catalyst (fine particles), i.e. heat carrier and may serve as a catalyst in secondary reactor for olefin inter-conversion reaction and/or cracking, if integrated setup is designed. Experimental investigation reveals that the novel Pt–Sn/Al2O3–SAPO-34 catalyst and proposed intensified design of fluidized bed reactor is a promising commercialization opportunity for light alkane (in particular propane, n-butane, and iso-butane, etc.) dehydrogenation to the corresponding olefins, with both economic and operational benefits.