Effect of the CeZrNd mixed oxide synthesis method in the catalytic combustion of soot

• CeZrNd oxides were prepared by nitrates calcination, coprecipitation and microemulsion.
• The microemulsion catalyst (147 m2/g) is the most active for soot combustion.
• The nitrates calcination catalyst is only slightly less active and very convenient.
• Nitrates calcination leads to the best Nd doping into the parent ceria framework.
• The nitrates calcination catalyst has much more oxygen vacancies than the others.

Ce0.64Zr0.27Nd0.09Oδ mixed oxides have been prepared by three different methods (nitrates calcination, coprecipitation and microemulsion), characterized by N2 adsorption, XRD, H2-TPR, Raman spectroscopy and XPS, and tested for soot combustion in NOx/O2. The catalyst prepared by microemulsion method is the most active one, which is related to its high surface area (147 m2/g) and low crystallite size (6 nm), and the lowest activity was obtained with the catalyst prepared by coprecipitation (74 m2/g; 9 nm). The catalyst prepared by nitrates precursors calcination is slightly less active to that prepared by microemulsion, but the synthesis procedure is very straightforward and surfactants or other chemicals are not required, being very convenient for scaling up and practical utilization. The high activity of the catalyst prepared by nitrates calcination can be attributed to the better introduction of Nd cations into the parent ceria framework than on catalysts prepared by coprecipitation and microemulsion, which promotes the creation of more oxygen vacancies.

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