Patent ID: 8268464

Claim:
A process for preparing a catalyst coated membrane (CCM), comprising the following steps: 1) formation of a first electrocatalytic layer on the surface of an inert support with the following steps: 1a) preparation of a first liquid dispersion comprising an ionomer, in acid or salified form, and the catalyst, wherein the ionomer concentration (in % by w.), ranges from 0.5% to 40%, the ratio by weight between catalyst and ionomer being from 0.5 to 4; 1b) the dispersion prepared in 1a) is placed on the surface of an inert support; 1c) removal of the solvent for at least 80% by weight with respect to the initial solvent of the dispersion, obtaining a first electrocatalytic layer having: an extractable ionomer percentage ≧80% by weight with respect to the total ionomer present in the layer; a catalyst amount in mg/cm 2 of electrocatalytic layer between 0.01 and 2 mg/cm 2 ; 2) on the first electrocatalytic layer formation of an ionomeric membrane through the following steps: 2a) preparation of a liquid dispersion of an ionomer in acid or salified form, equal to or different from that used in step 1a) and having a concentration (% by w.) on the total dispersion weight, from 3% to 40%; 2b) the liquid dispersion 2a) is placed on the free surface of the first electrocatalytic layer; 2c) solvent removal for at least 80% by weight as in 1c), obtaining an ionomeric membrane on the top of the first electrocatalytic layer; the ionomer percentage extractable after this step being ≧80% by weight with respect to the total ionomer present in the first catalytic layer and the membrane; 3) formation of a second electrocatalytic layer on the surface of the ionomeric membrane free from catalyst to obtain the raw CCM on the inert support through the following steps: 3a) preparation of a second liquid dispersion comprising an ionomer, in acid or salified form, and a catalyst, wherein the ionomer concentration is (% by w.) between 0.5% and 40%, the catalyst/ionomer ratio (by w.) being between 0.5 and 4; in said second dispersion the ionomer and/or the catalyst being equal to or different from those used in 1a) and in 2a); 3b) deposition of the liquid dispersion 3a) on the surface of the ionomeric membrane free from catalyst prepared in 2) to form the second electrocatalytic layer; 3c) solvent removal from the second dispersion for at least 80% by weight, as in 1c), until obtaining the second electrocatalytic layer, having: a catalyst amount as in 1c); the ionomer percentage extractable after this step from the raw CCM being 80% by weight with respect to the total weight of the ionomer present in the CCM; 4) annealing of the raw CCM supported on the inert support at temperatures from 120° C. to 280° C. and obtainment of the CCM by separation of the inert support from the CCM.