Synthesis of carbon nanofiber/graphite-felt composite as a catalyst

Abstract

Carbon nanofiber/graphite-felt composite with desirable shape and size has been synthesized by the method of catalytic chemical vapor deposition (CCVD) through the growth of carbon nanofibers (CNFs) on the surface of the graphite microfibers of the felt. Scanning electron microscopy (SEM), N 2-physisorption, and a mechanical strength test have been used to characterize the morphology, the texture properties, and the mechanical strength of the CNF/graphite-felt composites, aiming at a detailed understanding of the relationship between structure and property. The physico-chemical properties, especially the mechanical strength of the composites, have been investigated as a function of the ratio (w/w) between the CNFs and the graphite felt. Both the compressive strength and the apparent density of the composites were found to vary with the CNF yield (w/w). Their maximum values are reached at a CNF yield of about 6. Very few fragments are desquamated from the composite with a CNF yield below 5 under vigorous agitation, indicating stable anchorage of CNFs on the graphite microfibers. A distinct mesoporous character, a large external surface area and high mechanical strength make CNF/graphite-felt composites attractive as a catalyst for the oxidative dehydrogenation of ethylbenzene to styrene (ODE). An optimized ratio of 4.5 between the CNF and graphite felt in the composites exists for the catalyst in the ODE reaction with respect to both the styrene yield and mechanical strength. Moreover, the composite exhibits much greater catalytic stability than activated carbon.