Behaviour of SOx-traps derived from ternary Cu/Mg/Al hydrotalcite materials

Cu/Mg/Al ternary HT-derived materials show significantly better SOx trap performances with respect to binary Cu/Al HT-derived materials and represent an interesting type of material either to protect NOx traps from the deactivation by sulphur or as SOx additives in fluid catalytic cracking (FCC) applications. The kinetics of SO2 uptake was studied at low (10 ppm) and higher (1000 ppm) SO2 concentration in a thermobalance (TG) apparatus. The results were compared with those obtained by measuring the SO2 breakthrough curves in a flow reactor under reaction conditions simulating those of autoexhaust gases, in particular regarding the use of high space-velocities and the presence of CO2 in the feed. The SOx trap performances depend on the feed composition and type of experiments. However, a similar ranking of the SOx trap performances was observed for the different configurations. Cu/Mg/Al = 1:1:2 shows the best performance and also improved hydrothermal stability with respect to Cu/Al binary samples.