Even though the carbon-based Fischer-Tropsch synthesis (FTS) catalysts deliver excellent performance owing to the outstanding physicochemical property of carbon materials, the poor mechanical strength and difficulty in formability are the bottlenecks for their practical and industrial applications, especially in a fixed-bed reactor. To tackle this obstacle, we propose a stepwise heat treatment protocol to successfully fabricate a biomass-derived monolithic carbon material with favorable mechanical strength. The carbon monolith can be employed as promising Fe-based active sites carrier to boost the olefins production performance of FTS. Compared with the powdered counterpart under the same reaction conditions (260 °C, 3 MPa, CO:H 2 = 1:2, GHSV = 3000 mL g cat −1 h −1 ), the catalytic activity of the monolithic catalyst is significantly increased from 37.2 % to 64.3 % while maintaining the high selectivity of olefin products (68.1 %), therefore the maximum olefin space–time yield approaching to extremely high value of 666 mg g Fe3O4 -1 h −1 (260 °C, 3 MPa, CO:H 2 = 1:2, GHSV = 6000 mL g cat −1 h −1 ). Multiple characterizations reveal that the formation of interconnected monolithic structure can be attributed to the dehydration-polymerization reaction between the biomass carbon and binder. Based on the heat and mass transfer simulations, it is obvious that the monolithic catalyst possesses superior mass and heat transfer performance and better reactants diffusion behaviors, which contribute to the formation of more χ-Fe 5 C 2 active phase for C-O bond activation and C-C bond coupling. This work will shed new light on the rational design of highly efficient monolithic FTS catalyst with remarkable strength for practical application at large scale.
Graphical Nanofiber Catalysis : Hexagonal boron nitride has been regarded as a potential inorganic nonmetallic catalyst for the oxidative dehydrogenation of propane. Herein, a novel nanofiber catalyst consisting of hexagonal boron nitride/silica oxide ( h -BN/SiO 2 ) was prepared via electrospinning method, which exhibited remarkable 24.9 g olefins ⋅ g BN −1 ⋅ h −1 productivity of olefins in oxidative dehydrogenation of propane. Fibrous nanomaterials have drawn considerable attention in the field of catalysis due to the promoted utilization of the surface and facilitated mass transfer process. In this study, we prepared one-dimensional nanofiber catalysts consisting of hexagonal boron nitride/silica oxide ( h -BN/SiO 2 ) via electrospinning method. The key is to prepare uniform sols consisting of exfoliated h -BN. The diameters of the nanofiber catalysts can be tuned in the range of 150–300 nm through h -BN loading change. When used in oxidative dehydrogenation of propane (ODHP), the obtained nanofibrous catalysts exhibited a 12.4 % conversion of propane and 85.1 % selectivity towards propylene, with remarkable olefins productivity of 24.9 g olefins ⋅ g BN −1 ⋅ h −1 , which is more than 5 times higher than that of bulk ODHP catalysts reported to date. This study shines light on the specific one-dimensional fibrous structure containing dispersed h -BN as well as a new strategy of preparing more efficient boron-based catalysts in the ODHP process.
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