NOTE A Study on the Chemical Heterogeneity of Active Surface of Solid Catalysts that there is a relation between the monolayer adsorption quantities on the solid particle surface [N (mmol/g)] and particle size [R (mm)] A method that can be used to characterize the chemical heterogeneity of active surface of solid catalyst is given. The chemical adsorption behavior of three adsorbates on Ni-W/F-Al 2 O 3 -SiO 2 N Ο° S g Ο° R D r 03 , [1] catalyst and supported Ni catalyst has been investigated. On the basis of fractal geometry, the roughness fractal dimension ( D r ) where S g is the apparent specific surface area [ m 2 / g] , and D r is the and the chemisorption fractal dimension (D c ) of two kinds of roughness fractal dimension, 2 Β°Dr Β°3, which is used to describe catalyst are estimated. We use the difference between D c and D r quantitatively the geometric accessibility or surface roughness of a solid to characterize the chemical heterogeneity of active sites on the particle surface. In cases not involving a physisorbed monolayer blanket, catalytic surface. As a result, the chemical heterogeneity of the Farin and Avnir ( 6 ) pointed out that if chemical interactions enter the acid sites of Ni-W/F-Al 2 O 3 -SiO 2 catalyst is very great. As for molecule / surface complex, selectivity of adsorption is dictated not only supported Ni catalyst, the chemical heterogeneity of active sites by geometric accessibility, but also by the chemical heterogeneity of the decreased when impregnating operation times in preparation of active surface to a certain extent. This is especially true for metal cata- the catalyst increased. After impregnated four times, the chemical lysts dispersed on porous supports; thus there is the following relation between chemical adsorption quantities [ N c ( mmol / g ) ] and solid particle heterogeneity of its active surface of supported Ni catalyst is elimisize [ R ( mm) ] : nated.