Synthesis Of Fe-SUZ-4 Zeolite And Application For N₂O Catalytic Decompositon

N₂O is a kind of strong greenhouse gas,it can strongly destroy the ozone layer. For reducing N₂O emissions,more efficient catalysts for catalyzing N₂O decomposeition at low temperature are required. Iron-containing zeolites are widely researched due to their high activity and catalytic stability for the reaction. As two Fe（II） cations locates at two adjacent p sites of the six-member ring in the eight-member ring channel, the Fe."Fe distance is fitter than that in other zeolites for N₂O catalytic decomposition. Therefore,Fe-FER zeolite exhibited much higher catalytic activity compared with the other zeolites containing same amount of iron. Because SUZ-4 zeolite not only has the topology similar to FER zeolite, but also has double six-member rings which contacts with double cages in the c axis direction,it can be speculated that the SUZ-4 zeolites will have more Fe —Fe active sites after modified by Fe ions. Consequently, the Fe-SUZ-4 zeolite, in which some Fe³⁺ ions isomorphously substituted Al³⁺ ions in the zeolite framework, was synthesized and studied for the N₂O decomposeition in this thesis. For the SUZ-4 zoelite synthesis, acidic silicasol was used as silicon source for the first time, as expected, it can effectively avoid alkaline silica sol reacting with iron ions. The main works and findings are listed as follows:1.The best initial gel is of 2.61TEAOH: 7.9KOH: 21.2Si0₂: AL₂O₃: 498.6H₂ O,form which 100% pure micron-sized rodlike SUZ-4 zeolite can be obtained after crystallization at180 for 12 hours.2.The crystallization process of the Fe-SUZ-4 synthesis was monitored by XRD and SEM, Similar to the synthesis of SUZ-4 zeolite, 100% pure micron-sized rodlike Fe-SUZ-4zeolite was obtained from the best initial gel mentioned above at 180 for 12 hours. With the Si/Fe ratio decreasing in Si/Fe ratio range of 20-100, the crystallization time required fox obtaining pure Fe-SUZ-4 zeolite was extend. It implies that the framework formation of iron is the rate determining step in the Fe-SUZ-4 zeolite crystallization process. BET results of the samples confirmed that the Fe-SUZ-4 zeolite obtained was a kind of microporous material and iron ions incorporated into the zeolite framework. On the other hand,pure Fe-SUZ-4zeolite with nano-rodlike morphology（40x440 nm） was obtained at 150。C from a initial gel with Si/Fe =100 after crystallization for 48 hours.3. H-Fe-SUZ-4 catalysts were studied for the first time in the N₂O decomposition, which showed more active than H-Fe-FER for the reaction. For the micron-sized rodlike H-Fe-SUZ-4 zeolite, which was synthesized from the initial gel of Si/Fe = 20,the temperature to reach complete N₂O conversion was 450...