Study On Preparation And Performance Of Novel Cobalt-based Fischer-tropsch Catalysts Derived From MOF

Fischer-Tropsch(FT)synthesis is a technology that uses CO and H₂ to prepare liquid fuels and highly value-added chemicals.This technology can effectively improve energy shortages and other problems.Metal cobalt(Co)generates Fischer-Tropsch synthesis catalytic activity,high long-chain hydrocarbon selectivity,and low water-gas shift activity.In order to reduce costs,Co is usually loaded on a catalyst support material to be used in a Fischer-Tropsch plant.It is one of the commonly used catalyst components,and the properties of the support materials exert a significant impact on the catalytic performance of Co-based catalysts.In order to reduce the interaction between the carrier and the active metal and obtain a supported Co-based catalyst with high stability,good dispersibility and low deactivation rate,the porous carbon carrier derived from MOF has been drawing wide research interest in recent years.Two novel Co-based catalysts supported on porous carbon material were prepared using ZIF-67 as a template for application in Fischer-Tropsch synthesis reaction.In this paper,ZnCo-ZIF is used as a precursor to prepare a bimetallic organic framework structure(BMZIF)to study the effect of Zn/Co ratio on the structure of porous carbon support,and on the catalytic activity as well as.The porous structure,morphology and catalytic activity of BMZIF catalysts were compared with each other based on XRD,BET,SEM,TEM data and the reaction test results from a fixed-bed reactor.The results show that the specific surface area and pore size of the prepared BMZIF catalyst are larger than other samples.Among all the samples,BMZIF-1-P yields the largest specific surface area and the highest C₅₊selectivity of 91.6%,which is significantly higher than other MOF-derived FT catalysts.The increase in specific surface area is beneficial to synthesis gas and enhanced diffusion inside the pores to promote the formation of long-chain hydrocarbons.The loading of active metals in the Fischer-Tropsch catalyst produces a crucial effect on the catalytic activity.ZIF-67 was added in-situ on the CoAl-LDH material to obtain a composite CoAl-LDH/ZIF-67 structure and obtain a highly dispersed embedded porous nano-layered(CoPNP)Fischer-Tropsch catalyst through pyrolysis.CoPNP catalyst retains the desired particle size and Co dispersion with a Co metal loading over 50wt%.At the same time,the large specific surface area and abundant porous channels of the CoPNP catalyst promote the diffusion of syngas and thus enhance the long-chain hydrocarbon production,iyielding a positive effect on CO conversion and C₅₊selectivity.The evaluation of the CoPNP catalyst shows that the catalyst generates a superior CO conversion rate of71.6%and high C₅₊long-chain hydrocarbons selectivity of 70.2%.This research provides a good foundation for improved performance of the novel catalyst in Fischer-Tropsch synthesis and therefore helps the design and preparation of the catalysts for similar processes.