Iron-containing zeolites

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). 

As time moved on, the Mossbauer studies of iron-containing zeolites started to involve different aspects of zeolite chemistry, most notably in the area of catalysis. In addition, other new preparations were revealed as well as experiments that were designed to obtain superparamagnetic iron oxide particles in zeolites. Garten, Gallard-Nechschein and Boudart (5) studied iron mordenites in the reverse of the water-gas shift reaction and the ammoxidation of propylene. Collins and Mulay (6) reported that Fe(C0)5 and FeClj when thermally treated in air would form fine particles of Fe2<)3. 

Other recent reports of the use of Mossbauer in the characterization of iron-containing zeolites involve the study of coordination complexes synthesized in zeolites. One such study carried out by Lunsford and coworkers (12) involved the study of tris(2,2 bipyridine) iron(II) complexes In zeolite Y. These materials were reacted with chlorine gas in order to oxidize the iron. Another study done by Banerjee (13) involved the Mossbauer analysis of lron(II)phenanthrollne complexes sorbed on zeolite 3A. These are most of the Mossbauer studies of iron-containing zeolites that we have found, although some earlier work has not been Included since reviews (14) are available. 

The research reported here is very much related to all of the above studies. Our goals are to develop new preparations of Iron-containing zeolites, to stabilize iron in a highly dispersed and metallic state, and to explore the photochemical and thermal activation of these materials. Of major Interest to us are the reports of Derouane and coworkers (15), Ballivet-Tkatchenko and Coudurier (16), Good (17), and Scherzer and Fort (18). 

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 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. 

In the present work a series of synthesis was carried out in order to obtain iron-containing zeolites with a pore channel system larger than that of the MFI type zeolite. Attention was paid in particular on the BEA and MOR type zeohtes. 

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. 

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