Precursors iron acetate

Fe precursor, while larger Fe loadings (up to about 2 wt%) could still increase the ORR activity when the Fe precursor was a porphyrin (ClFeTMPP). All catalysts in Figure 3.15 were prepared by the adsorption of the Fe precursor on PTCDA. The resulting material was then pyrolyzed at 900°C in H2 Ar NH3. The difference between iron acetate and porphyrin precursors was interpreted in terms of a better interaction of the PTCDA with the Fe-porphyrin than with iron acetate, leading to a better dispersion of the iron ions on the carbon precursor. 

Table 3.1. Relative Abundance in % of FeN Cy" " Ions as a Function of the Pyrolysis Temperature for Catalysts Using Iron Acetate (0.2 wt% Fe) as Fe precursor (Reproduced from ref. [105] with Permission of the American Chemical Society)...

Figure 3.22. Relative abundance, according to ToF SIMS results, of the two catalytic sites (Fe-N2/C and Fe-N4/C) as a function of the heat treatment temperature of the catalysts obtained with iron acetate (panel A) and with CLFeTMPP (panel B) as Fe precursors. The catalysts were obtained by adsorbing either iron acetate (0.2 wt% Fe) or ClFeTMPP (0.2 wt% Fe) on prepyrolyzed PTCDA and heat treating that material in inert atmosphere at various temperatures, ranging from 400 to 1,000°C. Prepyrolyzed PTCDA was obtained by heat treating PTCDA at 900°C in H2 Ar NH3 (1 1 2) (according to Figure 5 in ref. [105] reproduced with permission of the American Chemical Society).

Before ending this section, it is worth mentioning two particular cases for which the carbon support was made from a carbon precursor during the pyrolysis step that also generated the catalyst. The first case was that of PTCDA, which was introduced in Section 2.2.3. Active catalysts were produced by adsorbing a metal precursor on that carbon precursor, then heat treating the resulting material, usually at 900°C in NH3 atmosphere. Our best results in fuel cells were obtained with catalysts made by this procedure, either with iron acetate (0.2 wt% Fe), or with ClFeTMPP (2 wt% Fe) as an Fe precursor. ... 

The apparent number of electrons transferred during ORR, , has been measured for several Fe-based catalysts obtained by the pyrolysis of various Fe precursors, including Fe-N4 chelates, iron phenanthroline or salts such as iron acetate. Values of n and the associated yields of hydrogen peroxide, %H202, are reported in Table 3.2 for Fe precursors and in Table 3.3 for Co precursors. %H202 is obtained from the following equation " %H202 = 100 (4 - n)tl. 

In the previous section, we came to the conclusion that two catalytic sites were always obtained simultaneously, but not in the same proportions, when an Fe precursor and an N precursor were present at the same time in the pyrolysis reactor. This demonstration was performed with the help of ToF SIMS analysis of either heat-treated iron acetate or CIFeTMPP adsorbed on N-enriched prepyrolyzed PTCDA . The two catalytic sites were labeled Fe-N4/C and Fe-N2/C, according to the relative abundance of their typical ions detected by ToF SIMS. While Fe-N4/C corresponds to the catalytic site proposed by van Veen and illustrated in Figure 3.5, the full coordination of Fe-N2/C, illustrated in Figure 3.19, is not completely known. Possible Fe-N2+2/C catalytic structures have been proposed by various authors > but have not yet been confirmed. In the following discussion we will continue to use the Fe-N4/C and Fe-N2/C labels to identify these catalytic sites. 

Figure 3.30. Correlation between the relative abundance of Fe-N2/C in non-noble metal catalysts (A open circles), the catalytic activity for O2 reduction (B), the value of n (C), and the value of %H202 (D) for catalysts made with iron acetate (0.2 wt% Fe) as Fe precursor. The catalysts were the same as those used in Figures 3.20, 3.21, and 3.22A. The relative abundance of Fe-N4/C in the catalysts is given by stars in panel A (according to Figure 6 in ref. [114] reproduced with permission of Elsevier).

Fig. 9.2 Schematic illustration of the micropore filling technique and active site formation during NPMC synthesis, (a) Two adjacent graphitic crystallites hosting a slit micropore in the BP carbon support, (b) cross section view of the empty micropore, (c) micropore after being filled with 1,10-phenanthroline and iron acetate precursors, and (d) active site formation and nitrogen-doped graphitic carbon deposition after subsequent heat treatments in argon and ammonia (from [28] with permission from AAAS)...

ToF-SIMS results obtained for catalysts made with ClFeTMPP as the iron precursor in similarly made catalysts show that FeNVC is the major type of catalytic site present. However, the two other active sites are also present in these catalysts, N-FeN2 + 2/C being here in smaller proportion. The opposite is true when the iron precursor is iron acetate. 

For catalytic applications, the associated iron ions present inside the zeolite framework may provide better precursors for catalytic centres than single ions [6]. Thus, the present iron acetate - Y zeolite system seems to be a promising candidate for catalytic application, in preliminary experiments the 620 K treated sample did not exerted the expected activity in conversion of CO - now the characterization of samples obtained at lower temperature treatments is in progress. 

Fe[MeC(NEt)(NBu )l2, was isolated starting from different iron(II) precursors such as acetylacetonate, acetate, and chloride. 

In the early work on the thermolysis of metal complexes for the synthesis of metal nanoparticles, the precursor carbonyl complex of transition metals, e.g., Co2(CO)8, in organic solvent functions as a metal source of nanoparticles and thermally decomposes in the presence of various polymers to afford polymer-protected metal nanoparticles under relatively mild conditions [1-3]. Particle sizes depend on the kind of polymers, ranging from 5 to >100 nm. The particle size distribution sometimes became wide. Other cobalt, iron [4], nickel [5], rhodium, iridium, rutheniuim, osmium, palladium, and platinum nanoparticles stabilized by polymers have been prepared by similar thermolysis procedures. Besides carbonyl complexes, palladium acetate, palladium acetylacetonate, and platinum acetylac-etonate were also used as a precursor complex in organic solvents like methyl-wo-butylketone [6-9]. These results proposed facile preparative method of metal nanoparticles. However, it may be considered that the size-regulated preparation of metal nanoparticles by thermolysis procedure should be conducted under the limited condition. 

Polymer and precursors (FeCl3, iron(III) acetate, titanium isopropoxide, silicon tetraethoxide, and copper(II) chloride) dissolved in organic solvent (acetone, ethyl acetate) and cast onto microscopic slides precursors in situ hydrolyzed... 

Synthetically useful routes to dibenzo[c,e J[l,2]dithiins are normally based on cyclizations of biphenyI-2,2 -disulfonyl chlorides. A method applied successfully to the parent compound reduces the precursor with zinc in acetic acid to generate the bis thiol, which is then gently oxidized to the dithiin using iron(II) chloride (66HC(21-2)952). An alternative one-step reductive cyclization, which has been applied to the preparation of the 2,9- and 3,8-dinitro derivatives, involves reduction of the appropriate bis sulfonyl chlorides with hydriodic acid in acetic acid (68MI22600). Yet another reductive cyclization uses sodium sulfite followed by acidification, and these conditions lead to dibenzo[c,e][1,2]dithiin 5,5-dioxide. The first step of the reaction is reduction to the disodium salt of biphenyl-2,2 -disulfinic acid which, on acidification, forms the anhydride, i.e. dibenzo[c,e][l,2]dithiin 5,5,6-trioxide. This is not isolated, but is reduced by the medium to the 5,5-dioxide (77JOC3265). Derivatives of dibenzo[c,e] [1,2]dithiin in oxidation states other than those mentioned here are obtainable by appropriate oxidation or reduction reactions (see Section 2.26.3.1.4). 

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