Hall Effect Generator回路を用いた磁気測定によるニッケル微粒子触媒のガス吸着の研究
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The effects of chemisorbed H<SUB>2</SUB>, CO<SUB>2</SUB> and CO on the saturation magnetization of nickel have been investigated on fine particles of nickel supported and not supported.<BR>Apparatus provided with "Hall Effect Generator" circuit and the permanent magnet of the intensity of 0.5T, was designed for in situ measurements of magnetization after gas adsorption.<BR>Change of magnetization with gas amount adsorbed at the room temperaure was measured. The reduction of magnetization by adsorbed gas causes solely from pairing of electron spins. The value of ε is numerically the number of spins cancelled per the hydrogen atom adsorbed on nickel by pairing in the d band. The values of ε for the various nickel particles have been determined. The obvious influence of particle size over the range 20 to 360Å in radius on ε for coprecipitates was not observed. But the magnetic data showed clear examples of support influence in changing the value of ε. The effect of chemisorbed hydrogen on ε appears to be almost independent of the surface coverage for supported nickel coprecipitate exhibiting the superparamagnetism. However, the values of ε decrease with the surface coverage of hydrogen for the samples contained larger metallic particles than the catalysts showing the superparamagnetic behavior. The ε value for nickel-zeolite impregnate is 0.85 and very close to that of massive nickel, Ni-Al<SUB>2</SUB>O<SUB>3</SUB>, or Ni-kaolin-supported samples in the range of low hydrogen coverage. A possible reason for the low value of ε in Ni-SiO<SUB>2</SUB>-Al<SUB>2</SUB>O<SUB>3</SUB> is explained by chemical interaction in the interfaces between the support and nickel metal.
- 社団法人 粉体粉末冶金協会の論文
- 1999-10-15