STRUCTURE AND TEXTURE OF FILAMENTOUS CARBONS PRODUCED BY METHANE DECOMPOSITION ON NI AND NI-CU CATALYSTS

Adsorption methods, mercury porosimetry, electron and tunneling micros copy, and diffraction techniques were used to study filamentous carbon produced by methane decomposition on coprecipitated Ni/alumina and Ni -Cu/alumina catalysts. The porous structure of carbons was generally c lassified as follows: 1) micropores on the filament surface; 2) mesopo res produced by filament surface roughness; 3) meso- and macropores in dense and loosely packed regions of the carbon granules. Adsorption o f the various hydrocarbons pointed to the slit-like micropores with ca 0.34 nm of width, uniformly distributed on the filament surface. It w as suggested that these micropores are responsible for abnormal adsorp tion at very low P/P-0. We supposed that the micropores were formed by the non-aligned and curved graphene layers of the edge planes of grap hite which cover about 10% of the total area, while the rest of the fi lament surface is covered by deformed basal planes producing closed-la yer structure. (C) 1997 Elsevier Science Ltd.