Iron-modified zeolite

Aho A, Kumar N, Lashkul AV, et al. Catalytic upgrading of woody biomass derived pyrolysis vapours over iron modified zeolites in a dual-fluidized bed reactor. Fuel. 2010 89 1992-2000. 

Initial studies using cobalt-, nickel-, and iron-modified zeolites X and Y (241, 242) were, however, not particularly encouraging with relatively poor activities, selectivities, and stabilities. This situation has now changed dramatically with the discovery by Mobil Oil Corporation of a new series of synthetic high-silica zeolites. The so-called ZSM-5 zeolite (in the H form) is capable of converting methanol quantitatively to hydrocarbons and water (239), i.e.,... 

There is a major economic incentive to extend the current HC processes to enable heavier feedstocks to be converted to lighter, higher-value transportation fuels. Studies by Idemitsu indicate that iron-modified zeolite catalysts significantly enhance conversion when heavy oils such as long residue are hydroprocessed (65). Nevertheless, major technical barriers exist which make high conversions and product selectivities difficult to achieve with truly heavy feeds (end boiling points beyond 620 °C) - these include ... 

Iron modified zeolites and ordered mesoporous oxides have been studied as catalysts for the sulfur dioxide oxidation in sulfur rich gases. Both zeolitic materials and mesoporous oxides show very good activity in this reaction. Other than solid state or incipient wetness loaded MCM-41 materials, the zeolites do not show an initial loss of activity. However, they loose activity upon prolonged exposure to reaction conditions around 700°C. The zeolitic samples were analyzed via X-ray absorption spectroscopy, and the deactivation could be related to removal of iron from framework sites to result in the formation of hematite-like species. If the iron can be stabilized in the framework, these materials could be an interesting alternative to other iron based catalysts for the commercial application in sulfur rich gases. 

H. and Ochieng, A. (2003) Adsorption kinetics of arsenic removal from groundwater by iron-modified zeolite. Journal of Chemical Engineering of Japan, 36,1515-22,... 

Aho, A., Kumar, N., Lashkul, A. V, Eranen, K., Ziolek, M., Decyk, P, Salmi, T, Holmbom, B., Hupa, M., Murzin, D. Y. Catalytic upgrading of woody biomass derived pyrolysis vapors over iron modified zeolites in a dual-fluidized bed reactor. Fuel 2010, 89,... 

Iron-modified zeolites (Fe/ZSM-5) are highly efficient catalysts for a wide range of important processes than include the selective oxidation of benzene with N O (the Panov reaction) [37], catalytic decomposition of N O [38], selective catalytic reduction (SCR) of NOx [39], and many others. These unique properties stem from the presence of specific extra-framework iron-containing cationic species in the micropores of ZSM-5 zeolite [40]. Because of a very heterogeneous iron speciation in the zeolite catalyst, the direct determination of the catalytically active iron species and the mechanism of the catalytic reaction by experimental methods was not possible. The exact speciation will obviously depend on such parameters as the Fe loading, the method of iron introduction, and the history of the sample (calcination, reduction, etc.). Many studies have indicated that the reactivity of Fe/ZSM-5 for the selective benzene oxidation is mainly associated with the presence of highly dispersed Fe + extraframework cations [41]. On the contrary, the high catalytic activity in the N O decomposition... 

Iron-modified zeolite L nanocrystals were applied for the oxidation of phenol in the presence of acetic acid with the 93.4% conversion in 30min with selective formation of 77.5% of catechol and 22.5% of hydroquinone [144]. Acetic acid was oxidized by hydrogen peroxide to form peracetic acid, which served as a better oxidizing agent (Fig. 16). 

This technology is still under development. It is carried out essentially on Fe-or Mo-modified, zeolites. Very few investigators reported their work on vanadium and heteropolyacid based catalysts. Investigations using CaO catalysts also appear in the literature. The monomeric and dimeric ferric ions were found to be active in ODH of ethane with nitrous oxide giving a product selectivity of 40-60% at 350°C on Fe-modified zeolites (ferrierite and MFI). On the other hand, Fe oxide nanoclusters resulted in overoxidation of ethane and/or ethylene to C, CO and CO2 [88]. Iron modified zeolites of different structures viz., ZSM-5, zeolite Y and mordenite were tested in the ethane and propane ODH. The nature of zeolite dictated the catalytic activity. The best... 

Cells 1 and 2 of the barrier frame were filled with 8-14 SMZ while Cell 3, adjacent to the pilot-test tank wall, was filled with iron/surfactant-modified zeolite pellets (Fe/SMZ pellets, see below). During refilling, sheets of plywood were temporarily placed against the inner faces of the barrier frame to retain the fill material. The SMZ was transferred using a conveyor belt that ran from the outside the pilot-test tank to the appropriate cell. While the SMZ was loaded in the barrier frame the samplers were reinstalled in their original positions. The annular space between the plywood and the outer perforated metal of the frame was filled with aquifer sand. The plywood was then pulled out of the cell using a jack and appropriate blocking. 

Burt, T. A., Jones, H. K., Li, Z., Bowman, R. S., and Helferich, R. Perchloroethylene and chromate reduction using a surfactant-modified zeolite/zero-valent iron pellet. 1999 WERC Conf. on the Environment, Albuquerque, NM, (in press). 

Li Z, Jones HK, Bowman RS, Helferich R. Enhanced reduction of chromate and PCE by pelletized surfactant-modified zeolite/zerovalent iron. Environ Sci Technol 1999 33 4326-4330. 

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. 

As described above, it was found that physicochemical properties of the iron cluster supported on zeolite and the catalytic activity for toluene disproportionation were significantly affected by the preparation conditions. The catalyst which was prepared by modifying NH Y with 0.25M Fe(N03)3 solution at 323K showed the highest activity among the samples obtained. 

Zeolite (clinopti lolite-heulandite)-rich tuff modified with iron(lll) chloride solution Laboratory solutions 18 6 As(V) 0.1... 

EnviNOx Two related processes for removing N20 and NOx from the tailgases from nitric acid manufacture by the Ostwald process. Both variants use two beds of two zeolite catalysts modified with iron. The first variant is for gases hotter than 425°C and involves injecting ammonia between the beds. The second variant, for gases cooler than 425°C, injects ammonia before the first bed and a volatile hydrocarbon between the beds. Developed by Uhde in association with Agrolinz Melamine International. The first variant was installed in Linz, Austria, in 2003. The second variant was installed in Egypt in 2007. The catalysts are supplied by Sud-Chemie. 

Hexadecafluorophthalocyanine (FiePc) complexes of Ru(II) which were prepared by the reaction of tetrafluorophthalonitrile and Ru3(CO)i2, have been encapsulated in the supercages of zeolites NaX. The X type zeolites were synthesized around the RuFiePc complexes. The zeolites modified with the metal complexes were characterized by XRD, FT-IR and UV-Vis spectroscopy as well as elemental analysis. The oxidation of cyclohexane using t-butylhydroperoxide was catalyzed by the intrazeolite RuFiePc complexes. Complete conversion to cyclohexanone and cyclohexanol was achieved with nearly 3000 turnovers per day. These ship-in-a-bottle RuFisPc complexes show no signs of deactivation in contrast to the iron analogs, regardless of how the peroxide is administered during the reaction. 

We presented a facile route for the modification of zeolites and for the preparation of bifunctional catalysts possessing both acidic and hydrogenation functions via solid-solid reaction. Branched and higher hydrocarbons were obtained over such modified composite catalysts. Sodium migration from the surface of the iron-based catalyst to the zeolite during the solid-solid reaction accounts for the change of catalytic activity. XRD measurements exhibited evidence for Na migration. 

Fig. 12.47 Portion of the crystal structure of Prussian blue showing the bridging by ambidenlate cyanide ions. Circles represent iron(ll) (O), iron(lH) (O), and oxygen in water ( ). The remaining interstitial or "zeolitic water in the cubic sites has been omitted for clarity, as have most of the cyanide ions. In addition, some of the cyanide ions are replaced by water molecules coordinated to iron(IIl), and there are also vacancies in the structure. [Modified from Buser, H. J. Schwarzenbach, D. Better, W. Ludi, A. Inorg. Chem. 1977, 16, 2704-2710. Reproduced with permission.]...

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). 

---