EFFECT OF CALCINATION ON CO-IMPREGNATED ACTIVE-CARBON

Active carbon (AC) from apricot shells with known characteristics has been impregnated with a 9.88% Co(NO3)2 · 6H2O solution. The samples are destroyed in air at 200, 300, 400, and 550°C. The processes accompanying the thermal treatment are studied by DTA. Two processes are established during calcination of Co-impregnated active carbon: (i) destruction of the support as a result of oxidation catalyzed by the impregnated cobalt and (ii) interaction of the active phase (Co3O4) with the support (AC), during which Co3O4 is reduced to CoO and Co. The presence of Co3O4 and CoO phases is proved by X-ray measurements, while that of metal Co is established by magnetic measurements. The porous structure changes are investigated by adsorption studies. The characterization of the samples is performed by physical adsorption of N2 (77.4 K) and CO2 (273 K). The poresize distribution curves are plotted over the range 0.4-10 nm by the methods of Pierce (for the mesopores) and Medek (for the micropores). The micropore volume is determined by two independent methods: t /F method and D-R plot. The results from adsorption studies indicate a decrease of SBET, Vmi and, especially, the supermicropores of the samples. © 1993 by Academic Press, Inc.