Magnesium Oxide Samples Research Articles

Effect of Hydrogen-Ion Bombardment on the Oxides of Aluminium and Magnesium

COMMERCIAL high-purity, polycrystalline samples of aluminium oxide and magnesium oxide have been subjected to bombardment by a 300-µamp. beam of hydrogen ions having an energy distribution with a maximum at 500 eV. At this energy, the maximum penetration into the substances would be of the order of 100 Å., and therefore any changes of property observed would, in the main, be confined to these regions. Changes in electrical resistance have been recorded as a convenient means of following the effect of the bombardment.

Effect of the method of making modifying additions on the properties of oxide catalysts

1. A study was made of the catalytic and adsorptive properties of magnesium oxide samples containing additions of stennic oxide introduced in quantities of 0.01–6.4% by various methods: by application to prepared magnesium oxide via organic and inorganic tin compounds, and by coprecipitation. 2. It was shown that the introduction of stannic oxide into magnesium oxide by impregnation with tetraphenyl tin or stannic chloride results in a modification of the action of the magnesium oxide catalyst in the decomposition of hydrogen peroxide.The main effect is already brought about by the very smallest additions of stannic oxide. As the temperature of the catalytic process is lowered from 90' to. 5% the modification curves change is form, becoming flattened out. 3. The dependence on stannic oxide content of the activity of catalysts prepared by the coprecipitation of magnesium and tin salts is expressed by a curve having a minimum and a maximum. Minimum catalytic activity corresponds to a stannic oxide content of 0.02% and maximum activity to a stannic oxide content of 1%. 4. It was shown that the introduction of stannic oxide into magnesium oxide by impregnation with tetraphenyl we showed previously-results in a marked change in the adsorptive properties of the catalyst. When stannic oxide is introduced into prepared magnesium oxide. the adsorptivity and specific surface of the sample Increases with increase in additive content. When stannic oxide is introduced into magnesium oxide by coptecipitation, the adsorptivity and specific surface of the products are almost unaffected by increase in additive content 5. On the basis of a comparison of the catalytic and adsorptive properties of the catalysts studied, we have advanced the hypothesis that the ways in which additions of stannic oxide are incorporated into magnesium oxide are of two different types and that the manner in which the additions act depends on the method by which they are introduced into the catalyst.