ИСТИНА

Expanded graphite (EG), a low-dense carbon material, found great application as a source for gasket materials whereas the unique combination of its properties allows to consider it as a promising sorbent, electrode material, gas-storage container etc. Porous structure of expanded graphite is represented by pores with a wide pore size distribution, although macropores and mesopores prevail. Due to such a pore distribution, EG surface area is of 20-60 m2/g and could be developed up to 100 m2/g using electrochemical technique. The development of porous structure allows to widen EG application. Recently, EG was reported as a catalyst support in several processes and it was mentioned that catalyst size strictly depends on EG morphology. Thus, the aim of this work was to develop a route to obtain expanded graphite combining high porosity and variable amount of metal oxide of a desirable size and distribution. Two activation techniques were applied. The first one lies in pre-treatment of natural graphite with a solid alkali at a temperature of 800 oC in a nitrogen flow for 1-8 hours. Second one is a steam activation of expanded graphite. EG modification with nickel oxide was carried out by 1) graphite anodic polarization in diluted solutions of nickel salts (Ni(NO3)2, (Ni(HCOO)2) followed with exfoliation; 2) Ni(HCOO)2 precipitation on expandable graphite followed with thermal treatment; 3) EG impregnation with nickel salt solutions followed by thermal treatment. XRD, Raman Spectroscopy, low-temperature nitrogen adsorption, SEM etc. were used for samples characterization. It was shown, that electrochemical treatment has a strong influence on graphite structure, makes it more receptive to any activation route. Thus, expanded graphite with a developed pore structure and variable content of nickel oxide was prepared. Porous structure, morphology and electrical properties of the samples were studied. EG was shown to be a perspective metal support that could be used both as catalyst or electrode material in various processes.