Obtaining stable suspensions for washcoating in microchannels: Study of the variables involved and their effects on the catalyst

Abstract

La0.5Ca0.5CoO3-δ and La0.9Mg0.1Al0.9Ni0.1O3-δ perovskites were prepared for ethanol oxidation reaction and for ethanol steam reforming. The perovskites were mechanically ground and suspensions were subsequently prepared for washcoating. The physical and physicochemical modifications introduced in the mixed oxides after suspension, and their influence on the catalytic activity, were systematically studied in the suspended solids. The deposition of catalysts in metal microchannels was performed by washcoating. The mechanical milling was carried out in a high energy ball mill followed by measurements of particle size and isoelectric point (IEP). The samples were characterized by XRD, BET, TPR, XPS, FT-IR, TGA and catalytic tests. Both catalysts showed an excellent catalytic activity and high stability. In the oxidation reaction, indications of carbonaceous residues were obtained in the sample with organic additive, and the suspension without any additive presented the best stability. The samples that were evaluated in the ethanol reforming with steam showed good catalytic activity and stability. High yield of H2 was obtained and low selectivity values to CO and CH4 were observed. Polyvinyl alcohol was the additive that showed the best results. The catalytic films were characterized by SEM, EDX, and 3D confocal microscopy. Their stability were studied by adhesion test.