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Diesel engine is one the effective solutions for reducing CO2 and recognized as a leading candidate for mitigating global warming. To comply with increasingly stringent emission standards, all diesel engines require some sort of NOx control systems such as selective catalytic reduction (SCR) systems. The SCR catalyst for reducing NOx from diesel engines is classified into two groups, urea-SCR and HC-SCR catalyst, respectively. Although the urea-SCR catalyst is widely recognized as promising de-NOx technology in respect to the NOx conversion efficiency, it have some outstanding issues such as ammonia slip, urea injection, storage space, freezing and some infrastructures for supplying urea water solutions. In an attempt to overcome the inherent shortcoming of existing urea-SCR catalyst, hydrocarbons have been considered as alternative reducing agents for SCR process, instead of NH3.

Multi-step water splitting with Mn-ferrite(MnFe2O4)/sodium carbonate(Na2CO3) system accompanying endothermic reaction was investigated for converting solar energy into chemical energy. This water splitting is caused by the oxidation-reduction of manganese ion in the Mn-ferrite. Multi-water splitting with MnFe2O4/Na2CO3 system was consisted of three steps. The first step was hydrogen generation at 1073K. The second step was oxygen release at 1273K. The third step was Na2CO3 reproduction at 873K. The mechanism of multi-water splitting has been considered by XRD, chemical analysis of colorimetry and back titration. The temperature range 873 to 1273K is quite lower than those studied on the solar furnace reaction (O2 releasing step) in two-step water splitting (1500-2300K). This lower temperature range would permit further progress in converting the direct solar energy into chemical energy.