Iron modifiers

Christokova St. G., Stoyanova M., and Georgieva M. 2001. Low-temperature iron-modified cobalt oxide system. Part 1. Preparation and characterisation. Appl. Catal. A Gen. 208 235 2. 

Nitric oxide coordinated to iron modifies, in a striking manner, the properties and reactivity of free NO (Sec. 6.2). Probably the most famous such coordinated entity is the nitroprusside ion, Fe(CN)5NO . An incisive review of its reactions particularly related to its hypertensive action (it reduces blood pressure of severely hypertensive patients) is available. Nitroprusside ion reacts with a variety of bases... 

Although this report describes the preparation of a wide variety of oxidation catalysts, only the iron modified bismuth molybdates will be described in detail. Other preparations are described in this section through an indication of the starting soluble salts and their synthesis temperatures which are the key process parameters. Other aspects of their HTAD preparations are similar to that described for the iron bismuth molybdates which follows. 

Re-1870s evolution diagram for 16 iron meteorites from diverse chemical groups. The line is the best-fit correlation for the IIA and MB irons. Modified from Shen et al. (1996) using X = 1.666 x... 

Iron-modified light-expanded Laboratory solutions Ambient 6.0 As(V)... 

Haque, N., Morrison, G., Cano-Aguilera, I. and Gardea-Torresdey, J.L. (2008) Iron-modified light expanded clay aggregates for the removal of arsenic(V) from groundwater. Microchemical Journal, 88(1), 7-13. 

Although cyclohexane oxidation dominates the market, because of cheaper raw materials, the hydrogenation of phenol remains competitive, offering better selectivity with fewer environmental and safety problems. In addition, this process allows efficient valorization of phenol-rich wastes from coal industries. Recently built plants make use of this technology, as reported by the engineering group Aker-Kvaerner (www.kvaerner.com, 2004). The availability of low-price phenol is the most important element for profitability. Besides the well-known cumene process, a promising route is the selective oxidation of benzene with N20 on iron-modified ZSM-5 catalyst [12]. In this way, the price of phenol may become independent of the market of acetone. 

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. 

FIGURE 10,24 Electron flow in Thiobacillus grown in medium with ferrous iron. (Modified from Madigan and Martinko, 2006.)... 

The iron catalyst can also be assembled in situ. The Na+ form of fluorotetrasilicic mica was ion exchanged with Fe +, then the iron-modified clay was treated with a solution of a bis(imino)pyridine ligand in l-butanol.i Formation of the intercalated metal complexes was inferred by the appearance of the characteristic u(C = N) mode at 1588cm i and an increase in the basal spacing of the clay from 1.0 to 1.6nm for XXIII and XXIV. The bulkier XXII apparently did not form due to the inability of the ligand to penetrate the interlayer space. 

Kabwadza-Corner P., Matsue N., Johan E., Henmi T. Mechanism of Diazinon Adsorption on Iron Modified Montmorillonite. American Journal of Analytical Chemistry 5, 70-76 (2014). 

Table 10. Structural Parameters of the First Coordination Shell around Fe Atom in the Template-Free Microporous and Mesoporous Iron-Modified Aluminophosphate Structures...

The iron-modified ferrierite was prepared by impregnation method, followed by calcination [10S3]. The cationic Fe and oxidic iron species were identified. Monomeric and dimeric iron ions have been obtained, being active in oxidative dehydrogenation of ethane to ethene. The iron oxide nanoclusters are active too and overoxidize ethane and/or ethene to C, CO, and CO2. 

Adsorption of As by AC can be improved by impregnation of AC emplo)dng suitable chemicals (e.g., sulfur contain textile dyes for As(III) and Fe(III) salts for removal of As(V) from aqueous solutions (Ansari, 2007). Recently, an interesting study was carried out by Ahna et al. (2013) on the As removal from water using activated carbon (AC). The authors tested different activated carbons modified with iron hydroxide for their ability to adsorb As from water. They concluded that iron modified activated carbons are efficient adsorbents for As at concentrations lower than 300 [xg. According to Mohan and Pittman (2007) Activated carbon can remove 60% As(V) and As(III) but this removal percentage of As is not sufficient to reach drinking water quality. However, sedimentation or filtration processes are required in case of powdered activated carbons, which in turn adds extra cost to the technology. 

Figure 7-75. Iron modified by 0.7 monolayers of octadecyltrichlorosilane (n-OTS). (a) SEM map (b) Volta potential map bright area surface covered by OTS dark area surface not covered (Stratmann et al., 1995).

Figure 7-76. Volta potential map of iron modified by 1 monolayer of dimethylhexadecylsilanol. (a) immediately after scratching the surface (b) surface scratched after 20 h corrosion in a humid S02-containing atmosphere (Stratmann et al., 1995).

Figure 7-79. Delamination rate on iron, iron modified by AI2O3 and iron modified by AI2O3 and 1 monolayer...

Li KZ, Wang H, Wei YG, Yan DX (2009) Selective oxidation of carbon using iron-modified cerium oxide. J Phys Chem C 113 15288-15297... 

Figure 5 Rate of oxygen reduction on iron (O) and iron modified by one monolayer of n-decylmercaptan ( ).

Figure 24 (a) Map of the Volta potential of iron modified by one monolayer of... 

Madaleno, L., R. Pyrz, L. R. Jensen, J. J. C. Pinto, A. B. Lopes, V. Dolomanova, J. Schjpdt-Thomsen, and J. C. M. Ranhe. 2012b. Synthesis of clay-carbon nanotube hybrids Growth of carbon nanotnhes in different types of iron modified montmoiillonite. Comp. Sci. Technol. 72 377-381. 

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