An exhaust gas purification device of an internal combustion engine, comprising: a) a vapor separation module, comprising a cylindrical container with vertical rotation axis and having a lower part and an upper part, said vapor separation module having an inlet for introducing exhaust gas located in the lower part and provided with a fluid-tight valve; a cover which closes the upper end of said cylindrical container, an outlet being located on said cover for the exhaust gas treated in said vapor separation module; separation means for retaining water vapor and solid particles from the exhaust gas, wherein the separation means comprise filtering means in the form of a cooling liquid contained in the lower part of the cylindrical container, said cooling liquid being apt to be crossed by the exhaust gas so that it cools and releases any particles present in suspension in said exhaust gas into said lower part, and a series of partitions (5, 6, 7) where the exhaust gas surrenders the water vapor present in said gas through condensation by coming into contact with the surface of said series of partitions, whereby the vapor separation module is configured to remove water vapor and solid particles from said exhaust gas, thus obtaining dried gas which is dried and free from solid suspensions; b) an intake module comprising an inlet connected to the outlet of the vapor separation module, a radial blade fan with vertical rotation axis, an outlet, the intake module being configured to aspirate the dried gas through the inlet and expel it through the outlet; c) a dissociation module consisting of a photodissociation cell, said photodissociation cell being provided with an opening connected to the outlet of said intake module for introducing the dried gas, and with an opening for releasing the gas resulting from the photodissociation, the photodissociation cell comprising a first electrode which acts as an anode, formed by a plurality of filiform antennas, a second electrode, consisting of the wall of the photodissociation cell, a pulse generator connected to the first electrode and to the second electrode, the photodissociation cell being configured to generate ultraviolet rays by applying a unidirectional pulsating electric field to the first electrode and the second electrode by means of the pulse generator, whereby the dried gas is subjected in the dissociation module to a photodissociation process by means of which the carbon dioxide contained in said dried gas is split into its components. a) a vapor separation module, comprising a cylindrical container with vertical rotation axis and having a lower part and an upper part, said vapor separation module having an inlet for introducing exhaust gas located in the lower part and provided with a fluid-tight valve; a cover which closes the upper end of said cylindrical container, an outlet being located on said cover for the exhaust gas treated in said vapor separation module; separation means for retaining water vapor and solid particles from the exhaust gas, wherein the separation means comprise filtering means in the form of a cooling liquid contained in the lower part of the cylindrical container, said cooling liquid being apt to be crossed by the exhaust gas so that it cools and releases any particles present in suspension in said exhaust gas into said lower part, and a series of partitions (5, 6, 7) where the exhaust gas surrenders the water vapor present in said gas through condensation by coming into contact with the surface of said series of partitions, whereby the vapor separation module is configured to remove water vapor and solid particles from said exhaust gas, thus obtaining dried gas which is dried and free from solid suspensions; b) an intake module comprising an inlet connected to the outlet of the vapor separation module, a radial blade fan with vertical rotation axis, an outlet, the intake module being configured to aspirate the dried gas through the inlet and expel it through the outlet; c) a dissociation module consisting of a photodissociation cell, said photodissociation cell being provided with an opening connected to the outlet of said intake module for introducing the dried gas, and with an opening for releasing the gas resulting from the photodissociation, the photodissociation cell comprising a first electrode which acts as an anode, formed by a plurality of filiform antennas, a second electrode, consisting of the wall of the photodissociation cell, a pulse generator connected to the first electrode and to the second electrode, the photodissociation cell being configured to generate ultraviolet rays by applying a unidirectional pulsating electric field to the first electrode and the second electrode by means of the pulse generator, whereby the dried gas is subjected in the dissociation module to a photodissociation process by means of which the carbon dioxide contained in said dried gas is split into its components.