  The analysis performed as well as extensive numerical simulations have
revealed the possibility of the generation of homoclinic orbits as a result of
homoclinic bifurcation in a porous pellet. A method has been proposed for the
development of a special type of diagrams - the socalled bifurcation diagrams.
These diagrams comprise the locus of homoclinic orbits together with the lines
of limit points bounding the region of multiple steady states as well as the
locus of the points of Hopf bifurcation. Thus, they define a set of parameters
for which homoclinic bifurcation can take place. They also make it possible to
determine conditions under which homoclinic orbits are generated. Two kinds of
homoclinic orbits have been observed, namely semistable and unstable orbits. It
is found that the character of the homoclinic orbit depends on the stability
features of the limit cycle which is linked with the saddle point. Very
interesting dynamic phenomena are associated with the two kinds of homoclinic
orbits; these phenomena have been illustrated in the solution diagrams and
phase diagrams.
