A class of complex reaction networks with deficiency from two to six, involving isothermal catalytic reactions in a continuous flow stirred tank reactor (CSTR), is determined to have the capacity to admit multiple positive steady states by implementation of the combination of the Deficiency One Algorithm and the Subnetwork Corollary. A set of Tate constants and two corresponding positive steady stales, one stable and the other one unstable, are constructed for four examples.