Supported Iron Oxide Research Articles

X-ray photoelectron spectroscopic studies of unsupported and supported rhenium using argon-ion bombardment

Identification of 4f binding energies of rhenium in various valencies has been attempted using X-ray photoelectron spectroscopy in conjunction with successive in situ reduction by means of argon-ion bombardment. For the first time a valency state attributable to oxidic ReIII has been identified. Ion bombardment has also proved useful in probing catalyst–support interaction and the effects of catalyst promoters. The iron oxide support interacted strongly with part of the supported rhenium of several valencies, making it difficult to reduce the rhenium by ion bombardment, while the weakly interacting rhenium was easily reduced. When potassium ion was present in the Re/iron oxide system, rhenium interacting strongly with the support was mainly in the 7+ valence state.

Iron-57 mössbauer spectra of supported iron oxides and hydroxides

Supported α-Fe 2O 3 is readily obtained by heating microgram quantities of iron-57 on magnesium oxide in vacuo. Treatments which produce heavier iron coatings give hydrolysed iron(III) species which may be difficult to distinguish and which dehydrate less readily. Thin layers of supported α-Fe 2O 3 are reduced by hydrogen to an iron(II) species whereas materials containing thicker layers of hydrolysed iron(III) are partially converted to metallic iron.

Immobilisation of α‐Amylase on Polyaromatic and Titanium Compounds Incorporating a Magnetic Material

AbstractThree methods of preparing immobilised α‐amylase on supports which incorporate magnetic properties have been developed. The use of diazotized 1,3‐diaminobenzene coated on magnetic iron oxide, which was itself either uncoated or coated with hydrous titanium (IV) oxide, was found to result in higher bound activities of the immobilised enzyme. The immobilised enzyme prepared from diazotized 1,3‐diaminobenzene coated magnetic iron oxide support showed excellent stability towards freeze drying. A preparation of immobilised enzyme using magnetic iron coated with hydrous titanium (IV) oxide resulted in a greater thermostability. This support can be prepared in situ, overcoming the problem of loss of activity of the freeze dried immobilised enzyme.

The catalytic chemistry of nitric oxide: I. The effect of water on the reduction of nitric oxide over supported chromium and iron oxides

The reduction of NO with CO over alumina supported iron oxide and chromium oxide is a relatively fast process. The reaction is strongly inhibited over both catalysts by small amounts (~0.7 mole %) of water. The reduction of NO by H 2 appears to be significantly slower than by CO, although this was shown to be due to inhibition by H 2O, which is a primary product of the NOH 2 reaction. The product distribution from competitive experiments with mixtures of CO and H 2, shows that H 2 reacts preferentially to CO, over iron oxide. The water-gas shift reaction occurs more readily over iron oxide than chromium oxide and the H 2 formed reduces NO to NH 3. The produet distribution from the NOH 2 reaction differs with the two catalysts. Over iron oxide the major product is NH 3, while with chromium oxide it is N 2. Since chromium oxide neither decomposes NH 3 nor promotes the NONH 3 reaction with any greater ease than Fe 2O 3, it is concluded that the reduction of NO with H 2 occurs by different mechanisms over the two catalysts.