Combinatorial computational chemistry approach to the design of catalysts

Combinatorial chemistry is an efficient technique for the synthesis and screening of a large number of compounds. Recently, we introduced the combinatorial approach to computational chemistry for a catalyst design and proposed a new method called 'a combinatorial computational chemistry' [K. Yajima et al., Appl. Catal. A, in press.]. In the present study, we have applied this 'combinatorial computational chemistry approach' to the design of deNO_x catalysts. Various ion-exchanged ZSM-5 are good candidates as catalysts for removal of nitrogen oxides (NO_x) from the exhaust gases in the presence of excess oxygen. Here we described the screening of the exchange cations in ion-exchanged ZSM-5 which are strong against poisons. In the deNO_x reaction NO₂ molecules play an important role in the formation of reaction intermediates with reductants. Here, we estimated adsorption energies of NO₂ on various ion-exchanged ZSM-5 catalysts. The difference in the adsorption energies of NO₂ and poisons such as water and SO_x molecules has been compared. Cu⁺, Ag⁺, Au⁺, Fe²⁺, Co²⁺ and Cr³⁺-ZSM-5 were found to have a high resistance to water and SO_x molecules during the deNO_x reaction.