Different Morphology Of Al2o3 Load Fee - Tropsch Catalyst Cobalt, Ruthenium Catalyst Performance Study

Fischer-Tropsch synthesis （FTS） is a very important chemical process forproducing clean transportation fuels and valuable chemicals by the conversion ofnatural gas, coal and biomas. Cobalt-based catalysts are one of the most importantcandidates as the active component for FTS catalysts because of the higherselectivity for long chain hydrocarbons, the longer catalyts life and the lower activityfor water-gas reaction （WGS）. Although iron and cobalt are the common metalsapplied for FTS, Ru catalysts have been widely used for mechanism studies aspossessing higher intrinsic activity and selectivity for long chain hydrocarbons. Thus,Ru catalysts are usually used as the model catalysts for the development of promisingnovel FTS catalysts.In this work, the different morphology of alumina support have been successfullysynthesized by hydrothermal synthesis method. Co/Al₂O₃and Ru/Al₂O₃catalystswere prepared by incipient wetness impregnation technique. Catalysts withcommercial alumina as support were also prepared for comparison. TEM, Nitrogenadsorption-desorption, XRD, TPR, TPD and oxgen titration were used to characterizethese catalysts.The main results are as follows:（1）The specific surface area and porous structure of alumina support dependson its morphology, this is because the morphology of alumina support has asignificant effect on the stacking and aggregation of alumina particles. The specificsurface area decreased as follows: alumina nanofiber、nanosheet and nanorods. Whenthe support has a higher specific surface area, the pore volume and pore size aresmaller.（2）The morphology of Al₂O₃support was also found to have a significanteffect on Co₃O₄crystallite size, catalyst reducibility and Fischer–Tropsch synthesisactivity. Alumina nanofiber with the highest specific surface area leads to the catalystwith highest dispersion and FTS activity among the three nanostructures. However, the commercial alumina supported cobalt catalyst, without uniform morphology,resulted in the lowest reducibility and FTS activity. Meanwhile, the pore size ofcatalyst have a significant effect on the selectivity for CH₄and C₅+. The pore size ofthe catalyst is higher, the selectivity to CH₄is lower and C₅+is higher.（3）A significant effect on the catalytic performance of Ru catalyst supportedon alumina with different morphology was found observed. The particle size of Rucatalyst varies with the morphology of alumina support. Ru/Al₂O₃-r-1on support withlarge particle size when calcined in air and shows better FTS performance thanRu/Al₂O₃-c-1and Ru/Al₂O₃-f-1.When the catalyst was calcined in hydrogen,Ru-based catalyst with rod-shape support also show higher activity.