Iron containing zeolite catalysts

Destruction of N20 can be carried out at lower temperatures by adding a reductant. In this case an iron-containing zeolite catalyst is used for the selective catalytic reduction of N20 using hydrocarbons as a reductant. The catalyst did not deactivate in a 2000-hour test under demanding conditions (450°C, 6% H20). Hydrocarbons such as propane (or LPG) and methane (widely available as natural gas) can be used as the reducing agent221. 

Iron-containing zeolites are somewhat expectional in that the specific activity of FeY is independent of the iron content (18,19) (in the range 0.4 5 wt.%) and although less active than a-Fe203, the activation energies for the zeolite and oxide catalysts are the same (18 kcal/mol). 

We have reported here the preparations and treatment conditions that are needed to reduce Iron Ions to metallic Iron In zeolites. Although we have not Isolated highly-dis-spersed superparamagnetic Iron particles In zeolites, we have shown that these iron-containing zeolites are active catalysts in Fischer-Tropsch and in olefin isomerization reactions. The added insight that stems from the use of in-situ Mossbauer experiments has led to the preparation of new active catalysts that can be selectively activated. We presently are studying photochemical reactions of other metal carbonyl complexes in zeolites and believe that increased selectivity is a major benefit in these types of reaction. 

The first step of the process involves the cyclodimerization of butadiene to 4-vinylcyclohexene. The reaction is exothermic and can be catalyzed by either a copper-containing zeolite catalyst or an iron dinitrosyl chloride catalyst complex. Although both vapor-phase and liquid-phase processes have been studied, it appears that liquid-phase reactions are preferred because they achieve higher butadiene conversion levels. The second step is oxidative dehydrogenation of the 4-vinylcyclohexene to produce styrene. Dow has led the research effort in this area and has... 

The selective insertion of an oxygen atom into a benzene carbon-hydrogen bond to yield phenol is not a classical organic chemistry reaction. The first process for such a reactions was the Solutia process, based on discoveries by Panov and coworkers at the Boreskov Institute of Catalysis in Novosibirsk and then developed in close cooperation with Monsanto. In this process, the oxidant is nitrous oxide, N2O, while an iron-containing zeolite is used as the catalyst (Equation 13.4) ... 

In the last years a great interest was paid to the catalytic properties of iron-containing zeolites that show interesting activities in different industrial reactions. The Fe-BEA zeolite is reported to be a good catalyst in the vapour phase alkylation processes [1], the Fe-TON zeolite shows very high activity and selectivity in the olefin isomerization [2, 3]. Finally, new applications of zeolitic catalysts in the partial oxidation catalysis, such as the Solatia Inc. processes for benzene hydroxylation to phenol using Fe-MFI, open a novel route for the use of zeolites in oxidation processes [4, 5]. On the other hand, the catalytic properties of the metal-modified MOR type zeolite in the isomerization process are well known. 

P-25 - Iron containing zeolites and mesoporous silica as sulfuric acid catalyst... 

The catalytic oxidation of benzene to phenol in iron-containing zeolites is known as the Panov reaction The ZSM-5 zeolitic system is the preferred matrix. There are several ways in which the catalyst can be activated for this reaction. 

Series of zeolite-supported iron-containing catalysts with weight percent iron (% Fe) varying from 1 to 17% Fe have been prepared from Fe3(CO) 2 and the synthetic zeolites ZSM-5, mordenite and 13X by an extraction technique. The zeolites ZSM-5 and mordenite were used in the acid form, 13X in the sodium form. 

The recent introduction of zeolite catalysts m SCR applications (gas-fircd cogeneration plants) has to be mentioned Iron- or copper-containing zeolites guarantee high DeNOxmg performances up to temperatures of 600°C, where metal oxides become thermally unstable [12,13] The use of zeolite-based NO reduction catalysts with distinct structures has been covered in the patent literature, namely, mordenite, clinoptilotite, faujasite (both types X and Y), and pentasil [14,15]... 

The catalyst is an iron-containing ZSM-5 zeolite. Its half-life is three to four days so that, periodically, catalytic activity must be restored by passing air through the deactivated catalyst at high temperature no performance deterioration has been reported after more than 100 regeneration cycles. 

Study of Copper - and Iron - containing ZSM-5 zeolite catalysts ESR spectra and initial transformation of NO... 

In conclusion, the copper or iron containing MFI zeolite exhibits significant activity in the NO conversion due to the redox properties of the exchanged cations, and these catalysts can be utilized for treatment of lean exhaust gases. 

There is considerable interest in isomorphous substitution of aluminium in the zeolite framework by other elements and some papers have described the synthesis of MFI zeolites containing boron, gallium, titanium and iron as lattice elements (ref.1-3). The replacement of Al ions with the ions of another element can modify both the acidity and pore size features of the zeolite (ref.4, 5), resulting in modification of the catalytic property of zeolite catalysts (ref.6-8). 

The results presented evidence possibilities of tailoring uniform iron sites in FeMFI zeolites, under specific synthesis and activation conditions. Preparation of steam-activated Fe-silicalite containing mainly isolated iron species in extraffamework positions is essential to derive stmcture-activity relationships in various N2O conversion reactions over iron zeolite catalysts. The activity of the cluster-free Fe-silicalite was significantly higher in N2O reduction with CaHg and CO. However, some level of association of iron species leads to higher activities in direct N2O decomposition. Due to the intrinsic reaction mechanism, this result demonstrates the sensitivity of reactions for the form of the iron species in Fe-zeolites, rather than the existence of a unique active site. 

Adsorption and reaction of methanol and CO on reduced iron-containing L-type zeolites, (prepared with and without potassium-doping, K,Fe/L and Fe/L, respectively) were investigated by IR spectroscopy in a study by Park et al. [897]. The reaction produced methyl formate. Accordingly, it was shown by the authors that over the same catalyst, K,Fe/L, when used for methanol synthesis via hydrogenation of CO2, from the products CO and CH3OH methyl formate was formed in a secondary reaction. 

Lazar, K. Micheaud, N. Mihalyi, M. R., Pal-Borbely, G. and Beyer, H. K., Attempts to exchange iron into H-Y and H-ZSM-5 zeolites by in situ formed chloride-containing mobile species, Reaction Kinetics and Catalysis Letters 74(2), 289-298 (2001). Kucherov, A. V. and Slinkin, A. A., Zeolite modification by in situ formed reactive gas-phase species. Preparation and properties of Mo-containing zeolites, Studies in Surface Science and Catalysis 118(Preparation of Catalysts VII), 567-576 (1998). 

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