against four sets of ~3CO tracer data in a CSTR over
silica supported nickel catalyst, l represents an active
catalyst site where either adsorption/desorption or an
atomic or molecular surface exchange occurs. CO
adsorbs on sites l to form CO/. Then the adsorbed
CO dissociates to form the four adsorbed species Ni- 1,
Ni-2 and two O/'s. We distinguish between Ni-1 and
Ni-2 as two different species. Using 13CO tracer data
alone, one cannot differentiate between active sites I in
Eqs. (3.2) and (3.3), as 13CO cannot probe noncarbonaceous
species. Nor does this, in any way, as will be
shown later in this section, affect the modeling of
13CO tracer data.
This mechanism consists of two parallel paths each
of which contributes independently to the production
of methane. Using 13CO tracer data alone, it is not
possible to address the exact nature of Ni-1 and Ni-2.
We only assume that Ni-I and Ni-2 represent a pool of