Preparation,Characterization and Effect of Ce-Zr Washcoat on Zn-Cr Monolithic Catalysts for Methanol Autothermal Reforming

The Ce-Zr colloid with a narrow particle size distribution was prepared by the sol-gel method and used as a washcoat of the Zn-Cr monolithic catalyst for methanol autothermal reforming to hydrogen. The particle size of the Ce-Zr colloid can be effectively adjusted by peptization treatment in order to obtain highly adhesive and uniform washcoat. TEM and XRD results confirmed that Ce-Zr solid solution was formed and the particle size of Ce-Zr composite oxide powder calcined at 1073 K was still maintained within 20 - 50 nm. To avoid coating flaking, different drying methods during coating process were investigated in details. The results indicated that the microwave method was more favorable for the drying of moisture in honeycomb channels, while the oven drying method caused washcoat severely cracking. The Zn-Cr/Ce-Zr monolithic catalyst was more stable than that of no Ce-Zr washcoat because of the unique redox property of Ce-Zr mixed oxide. The temperature of the catalyst bed indicated that Ce-Zr washcoat exhibited better energy match of exothermic reaction and endothermic reaction, avoiding the hot-spot and prohibiting active species sintering.