Ferrite catalysts

Two or more soHd catalyst components can be mixed to produce a composite that functions as a supported catalyst. The ingredients may be mixed as wet or dry powders and pressed into tablets, roUed into spheres, or pelletized, and then activated. The promoted potassium ferrite catalysts used to dehydrogenate ethylbenzene in the manufacture of styrene or to dehydrogenate butanes in the manufacture of butenes are examples of catalysts manufactured by pelletization and calcination of physically mixed soHd components. In this case a potassium salt, iron oxide, and other ingredients are mixed, extmded, and calcined to produce the iron oxide-supported potassium ferrite catalyst. 

Selective Oxidative Dehydrogenation of Butenes on Ferrite Catalysts... 

Iron oxide is an important component in catalysts used in a number of industrially important processes. Table I shows some notable examples which include iron molybdate catalysts in selective oxidation of methanol to formaldehyde, ferrite catalysts in selective oxidative dehyrogenation of butene to butadiene and of ethylbenzene to styrene, iron antimony oxide in ammoxidation of propene to acrylonitrile, and iron chromium oxide in the high temperature water-gas shift reaction. In some other reactions, iron oxide is added as a promoter to improve the performance of the catalyst. 

Finally, it has been found that isomerization generally proceeds more rapidly when a ferrite catalyst is too reduced to be active in oxidation. It has also been shown that even on oxidized ZnCrFe04 (79) and MgFe204 (15), isomerization is faster in the absence than in the presence of gaseous oxygen. From these results, it has been suggested that a surface Fe2 + ion is the active site for isomerization. 

Based on the data on butene oxidation on ferrite catalysts, a comparison can be made among several ferrite catalysts using data obtained under similar conditions, as is shown in Table VIII. Referring to the table, it is seen that the butadiene desorption temperatures are about the same for a-Fe203 and... 

Comparison of Different Ferrite Catalysts in Butene Oxidation ... 

Kwan and Fujita (7fi) investigated the adsorption of carbon dioxide on a copper ferrite catalyst of the composition CuO-Fe203, prepared by the usual precipitation method and ignited at 500°C. in vacuo for about one month. Special precautions were made in the adsorption studies for attaining true adsorption equilibria. The adsorption isotherm for the low... 

The spectra obtained upon adsorption of 1,3-butadiene over the Mg-ferrite catalyst are reported in Fig. 3. The spectrum obtained is similar to that previously reported for the adsorption of 1,3-butadiene over a-Fe203 [19]. The detection of the symmetric C=C stretching mode at 1636 cm (IR inactive in the gas) shows that the molecule is either in the non-centrosymmetric s-cis configuration, or its symmetry is strongly lowered by interaction with... 

Then we incorporated Cu into the Fe/M catalysts (M = Cr, Mn, Co, Ni, Cu, Zn and Ce) since Cu is a promoter for the Fe/Cr catalysts for the high-temperature WGS reaction in the industries [3-5]. Interestingly, Cu acts as a promoter for all the modified ferrite catalysts except Fe/Ce catalyst. It acts as an inhibitor for the Fe/Ce catalyst. These results show that all of the copper co-doped ferrites behave like Fe/Cr/Cu except Fe/Ce/Cu, which behaves differently for high-temperature WGS reaction. We explained this interesting behaviour of copper... 

G. K. Reddy, K. Gunasekara, P. Boolchand, P. Smimiotis, Cr- and Ce-doped ferrite catalysts for the high temperature water-gas shift reaction TPR and Mossbauer spectroscopic study, J. Phys. Chem. C 115 (2011) 920-930. 

Hwang CS, Wang NC. Preparation and characteristics of ferrite catalysts for reduction of CO2. Mater Chem Phys 2004 88 258. 

Rennard, R. and Kehl, W. (1971). Oxidative dehydrogenation of butenes over ferrite catalysts, J. Catal, 81, pp. 282-293. 

Chung, Y, Kwon,Y, Kim,T.,cfa/. (2009). Mixed manganese ferrite catalysts, method of preparing thereof and method of preparing 1,3-hutadiene using there of, patent WO/2009/075478. 

In early patents, it was claimed that various phosphate catalysts, including calcium/nickel phosphate and bismuth/molybdate, were active. A variety of other catalysts was also introduced, including the zinc and magnesium ferrites developed by Petrotex." The best ferrite catalyst included chromium to prevent excessive catalyst reduction." PhilUps described tin oxide catalysts that were promoted with 4% phosphate and 1% lithium as well as the bismuth/phosphate catalysts that were promoted with boron or lithium compounds. 

K.N. Harish, H.S. Bhojya Naik, P.N. Prashanth Kumar, R. Viswanath, Remarkable optical and photocatalytic properties of solar light active Nd-substituted Ni ferrite catalysts for environment protection, ACS Sustainable Chem. Eng. 1 (2013) 1143-1153. 

Nanosized nickel ferrite catalysts for CO2 reforming of methane at low temperature effect of preparation method and acid-base properties... 

Nanosized nickel ferrite catalysts for CO 2 reforming ofmethane... 

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