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New Types of Nonclassical Iridium Carbonyls Formed in Ir-ZSM-5: A Fourier Transform Infrared Spectroscopy Investigation

“…This may be explained by the autoreduction of iridium and the formation of relatively big metallic particles. Indeed, as reported in the literature, the activation procedure for iridium-containing catalysts is decisive for the genesis of supported iridium species. That is why we performed a more gentle treatment before the adsorption experiments (slow heating to 523 K during evacuation), as was mentioned in the Experimental Section.…”

Reduction of NO by propene over supported iridium catalysts under lean-burn conditions: an in situ FTIR study

“…The selective catalytic reduction activity measurements were carried out in a down flow fixed-bed quartz reactor at atmospheric pressure, as already described [11,16]. Typically, 0.2 g of sample was used and the reactant gas mixture contained 1000 vpm NO, 2000 vpm C 3 H 6 , 500 vpm CO, 10 vol.% O 2 and He as a carrier gas (total flow rate 10 l h −1 ).…”

“…Iridium-based catalysts have been also reported to be active and durable catalysts for HC-SCR of NO x [6][7][8][9][10][11][12][13][14][15]. N 2 is formed between 623 and 873 K over Ir/Al 2 O 3 [16], i.e., at higher temperatures than over Pt-based catalysts which are active between 473 and 623 K. An advantage of Ir-based catalysts over Pt-based catalysts is that the selectivity of NO reduction toward N 2 formation is high.…”

“…A dispersion in the 0.08-0.15 range was found to be required to obtain the best activity in NO reduction into N 2 . Such a dispersion could be achieved after heating cycles in the reaction mixture up to 873 K. Highly dispersed Ir particles obtained after preparation of the fresh catalysts were found to sinter under reaction conditions, regardless of whether the catalyst was oxidised in O 2 or in situ reduced in H 2 [16] before reaction. Furthermore, it has been shown that, besides the size of Ir particles, the composition of the reaction mixture is another important factor influencing the activation of the Ir catalyst in the reduction of NO to N 2 .…”

Combinatorial Computational Chemistry Approach for Materials Design:Applications in deNOx Catalysis, Fischer-Tropsch Synthesis, Lanthanoid Complex, and Lithium Ion Secondary Battery

“…The TWC simultaneously converts HC's, CO and NO x into harmless chemical substances such as H 2 O, CO 2 , and N 2 [22][23][24][25]. For developing catalysts with longer lifetimes, supported precious metal catalysts are preferable and have been extensively studied for better catalytic activity toward the selective catalytic reduction of NO x [35][36][37][38][39][40]. The combinatorial computational chemistry approach was applied to cation-exchanged ZSM-5 catalyst, and several candidates for an active catalyst were successfully proposed [6], of which results were well supported by experiments [32][33][34][35][36][37].…”