Fe-Co catalyst

Suslick KS, Fang M, Fly eon T, Cichowlas AA, Gonsalves KE, Chow GM, Xiao TO, Cammarata RC (1994) Nanostructured Fe-Co catalysts generated by ultrasound. Molecular Design Nanostruct Mater 351 443 148... 

Hydrocarbon production and selectivities at comparable CO conversion are given in Table 19.2. The ultrafine iron oxide catalyst had a very poor C2-C4 olefin selectivity while the olefin selectivity of the precipitated catalyst was slightly higher than the iron carbide catalyst. This is surprising because Rice et al. report higher olefin selectivity for a similar iron carbide catalyst than a conventional Fe/Co catalyst.6 Soled et al. have subsequently reported that the conventional catalyst contains acidic sites which... 

A similar concept was followed independently by researchers at Toulouse (72), who synthesized dual CoMgOx oxides, which decomposed under reaction conditions when exposed to methane. While methane is typically less selective than CO for SWNT production, it can also produce a high-quality material with a broader distribution of chiralities and diameters. Methane has also been used as a feed for the production of double-waUed nanotubes. A novel type of feed was used by Maruyama et al. (73, 74), who obtained high yield and high selectivity towards SWNT by decomposition of ethanol on Fe-Co catalysts at low pressures and moderate temperatures (i.e. lower than 800°C). 

College of Chemical Engineering investigated fused iron catalysts containing cobalt oxide and found that the activity increased significantly. Work of ICI in UK was noticeable for cobalt containing catalysts, and patented the Fe-Co catalysts. 

Assuming that the activity of catalyst without cobalt is 100, the activities of Fe-Co catalysts at 40 bars at different temperatures would be as follows 134 at 450°C, 144 at 400°C, and 160 at 350°C, respectively. 

In 1985, Fuzhou University in China successfully developed A201 Fe-Co catalyst for ammonia synthesis. Compared with AllO-3 without cobalt, A201 increases net ammonia concentration by about 0.5%-l% under the same conditions. In 1995, they added rare earth oxide and reduced cobalt content, which is called as A202 catalyst. Moreover, the Research Institute of Nanjing Chemical Industry Company and Zhengzhou University developed Fe-Co catalysts, and applied in industry. 

Table 1.10 shows a comparison between the wiistite based and the magnetite based catalyst. It is shown that the wiistite (Fei xO) based catalyst is a new generation of ammonia synthesis catalyst that is completely different from the magnetite (Fe304) based catalyst (including Fe-Co catalyst) in the chemical composition, crystal structure, physical-chemical property, and producing principle etc. 

The spent and discharged catalyst from converter in ammonia plant is called as waste catalyst. The waste catalyst is mainly composed of 65% 80% of metallic iron, 10%-20% of iron oxide and 8%-10% of promoter oxides such as AI2O3, K2O, CaO, CoO etc. At present, they are generally abandoned or are interred in the scrapheap. This is not only a waste of resources, but also leads to environmental pollution, especially for the catalyst containing precious metals such as cobalt which has great recycling value. Example, the content of CoO and promoters in Fe-Co catalysts is illustrated in Table 4.13. 

The ICI-AMV process was developed by the ICI Company for its 74-1 Fe-Co catalyst, where the process was designed by ICI and the engineering was designed by Uhde Company, Germany. The core of the synthesis loop at low-pressure is the radial-flow converter with three beds of catalysts using 74-1 catalyst of small-particle and indirect interchanger, and in series an inverted U-shaped waste heat boiler. " The process flow is shown in Fig. 9.5. The main technical parameters are shown in Table 9.2. 

Volume of catalyst was increased by 122 m and the operation pressure was declined to 10-12 MPa due to using small particles of 74-1 Fe-Co catalysts. 

CO. Alkynes will react with carbon monoxide in the presence of a metal carbonyl (e.g. Ni(CO)4) and water to give prop>enoic acids (R-CH = CH-C02H), with alcohols (R OH) to give propenoic esters, RCH CHC02R and with amines (R NH2) to give propenoic amides RCHrCHCONHR. Using alternative catalysts, e.g. Fe(CO)5, alkynes and carbon monoxide will produce cyclopentadienones or hydroquinols. A commercially important variation of this reaction is hydroformyiation (the 0x0 reaction ). 

Although supported Pd catalysts have been the most extensively studied for butadiene hydrogenation, a number of other catalysts have also been the object of research studies. Some examples are Pd film catalysts, molybdenum sulfide, metal catalysts containing Fe, Co, Ni, Ru, Rh, Os, Ir, Pt, Cu, MgO, HCo(CN) on supports, and LaCoC Perovskite. There are many others (79—85). Studies on the weU-characteri2ed Mo(II) monomer and Mo(II) dimer on siUca carrier catalysts have shown wide variations not only in catalyst performance, but also of activation energies (86). 

The 0X0 process is not limited to simple olefins. The terrninal-to-branched ratio of products can be controlled by ligand addition (130). Butanol is produced from propylene and CO using a similar process (see Butyl alcohols). The catalyst in this case is Fe(CO) (131). 

Reactions of acetylene and iron carbonyls can yield benzene derivatives, quinones, cyclopentadienes, and a variety of heterocycHc compounds. The cyclization reaction is useful for preparing substituted benzenes. The reaction of / fZ-butylacetylene in the presence of Co2(CO)g as the catalyst yields l,2,4-tri-/ f2 butylbenzene (142). The reaction of Fe(CO) and diphenylacetylene yields no less than seven different species. A cyclobutadiene derivative [31811 -56-0] is the most important (143—145). 

Meta/ Oxides. The metal oxides aie defined as oxides of the metals occurring in Groups 3—12 (IIIB to IIB) of the Periodic Table. These oxides, characterized by high electron mobiUty and the positive oxidation state of the metal, ate generally less active as catalysts than are the supported nobel metals, but the oxides are somewhat more resistant to poisoning. The most active single-metal oxide catalysts for complete oxidation of a variety of oxidation reactions are usually found to be the oxides of the first-tow transition metals, V, Cr, Mn, Fe, Co, Ni, and Cu. 

Fig. 5. Diameter distributions of nanotubes produced via different methods (a) Fe catalyst in an Ar/CH4 atmosphere, adapted from Ref. 2 (b) Co catalyst in He atmosphere, adapted from Ref. 5 (c) Co catalyst with sulfur, about 4 at. % each, adapted from Ref. 5.

The laser-ablation method can produce SWCNT under co-evaporation of metals like in the electric arc-discharge method. As metallic catalyst Fe, Co or Ni plays the important role and their combination or addition of the third element such as Y produces SWCNT in an efficient manner. But it is still difficult in the laser-ablation method to produce gram quantity of SWCNT. Nonetheless, remarkable progress in the research of physical properties has been achieved in thus synthesized SWCNT. 

To accelerate the polymerization process, some water-soluble salts of heavy metals (Fe, Co, Ni, Pb) are added to the reaction system (0.01-1% with respect to the monomer mass). These additions facilitate the reaction heat removal and allow the reaction to be carried out at lower temperatures. To reduce the coagulate formation and deposits of polymers on the reactor walls, the additions of water-soluble salts (borates, phosphates, and silicates of alkali metals) are introduced into the reaction mixture. The residual monomer content in the emulsion can be decreased by hydrogenizing the double bond in the presence of catalysts (Raney Ni, and salts of Ru, Co, Fe, Pd, Pt, Ir, Ro, and Co on alumina). The same purpose can be achieved by adding amidase to the emulsion. 

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