Design of a hierarchical Co@ZSM-5/SiC capsule catalyst for direct conversion of syngas to middle olefin
Fischer-Tropsch (FT) synthesis as a strongly exothermic reaction has diffusely manufactured clean fuels from syngas. However, it is difficult to obtain the concentrated product distributions. Here, we design ZSM-5 encapsulated cobalt particles on the thermal conductivity of the SiC matrix. The Co@NaZSM-5/SiC capsule catalyst with hierarchical structure is ingeniously assembled through a solvent-free synthesis route. Due to the joint functions of acidic zeolite , SiC thermal conductivity and macropores, the olefin selectivity enhances to 32.3% on the Co@NaZSM-5/SiC catalyst. Moreover, the ratio of O 5-11 /C 5-11 approaches 49.1% suggesting the elevated middle olefin proportion. The H + ion-exchanged Co@HZSM-5/SiC capsule catalyst shows a high isoparaffin selectivity of 27.3%, since the olefin isomerization reaction is accelerated over strong acid sites. Besides, Co 2 C phase is readily formed during the FT reaction, which is an activity center for olefin synthesis. The capsule catalyst with the proper acidity, thermal conductivity, and hierarchical structure is a promising prospect for tuning production distribution in FT reaction.
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