2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/106254In this paper we prove the existence and uniqueness of the solution of a non-stationary problem that modelizes the behaviour of the concentrations and the temperature of gases going through a cylindrical passage of an automotive catalytic converter. This problem couples parabolic partial differential equations in a domain with one parabolic partial differential equation and some ordinary differential equations on a part of its boundary.Analysis of PDEs35M10, 35K65, 35Q80text