用于费托合成的骨架Co@HZSM-5核壳催化剂

Fischer-Tropsch Synthesis over Skeletal Co@HZSM-5 Core-Shell Catalysts

We used skeletal Co as the core to prepare a skeletal Co@HZSM-5 core-shell catalyst by growing an HZSM-5 membrane on skeletal Co via hydrothermal synthesis. The physicochemical properties of the catalyst were determined using elemental analysis, N₂ physisorption, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and NH₃ desorption. In gas-phase Fischer-Tropsch synthesis (FTS), the skeletal Co@HZSM-5 core-shell catalyst was more efficient than a physically mixed skeletal Co-HZSM-5 catalyst in cracking long-chain hydrocarbons, giving higher selectivity for C₅-C₁₁ gasoline products. The thickness of the zeolite shell on the skeletal Co@HZSM-5 core-shell catalyst was easily tuned by adjusting the hydrothermal time. At a suitable zeolite shell thickness, the long-chain hydrocarbons were cracked completely, with high FTS activity, leading to high selectivity for the gasoline fraction. Increasing the reaction temperature resulted in higher FTS and cracking activities, but the product distribution shifted to short-chain hydrocarbons. For the optimum skeletal Co@HZSM-5 core-shell catalyst, which was subjected to hydrothermal treatment for 4 d, selectivity for the gasoline fraction reached 79% at 250 ℃, which shows an excellent synergistic effect between the FTS active sites and the acidic sites on this catalyst.