INORGANIC FUNCTIONAL MATERIALS FOR ENVIRONMENTAL PROTECTION

摘要

Nitrogen oxides (NO_x) are harmful to the environment as well as human beings. Among various NO_x removal methods, direct catalytic decomposition into non-toxic N_2 and 0_2 is one of ideal ways, because the process is simple and any reductants are not necessary. The predominant NO_x species in the emitted gas at elevated temperatures is thermodynamically stable nitrogen monoxide, NO. Therefore, the research should be directed on the NO direct reduction. Rare earth oxides hold three phases as shown in Figure 1. The lighter lanthanides have A-type phase. In contrast, the heavier lanthanides hold C-type phase. The intermediate oxides are stable to hold B-type phase. Among three phases, C- type phase is the most loose in its structure and seems to have suitable pores to absorb gas species, like NO.