Mass-spectrometic Study of the Synthesis of NH3 on Iron Tips

✍ Scribed by Dr. W. A. Schmidt

• Publisher: John Wiley and Sons
• Year: 1968
• Tongue: English
• Weight: 143 KB
• Volume: 7
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/anie.196801391

✦ Synopsis

In spite of the great importance of heterogeneous catalytic processes and of the large amount of work devoted to its study, the surface processes occurring on the catalyst are not yet satisfactorily clarified. We have attempted to apply, in the case of NH3 synthesis, the results of field ion mass spectrometry on ionization of NH3 and N2/& mixtures on iron to the solution of this problem. Field ionization makes it possible to ionize molecules that are interacting with a metal (tips) from the gas phase (pressure of ca. 10-4 torr) and to analyze them mass-spectrometrically. In view of the high sensitivity of the mass spectrometer, it seems reasonable to expect that even ions formed from molecules adsorbed on the metal surface will be detectable. The apparatus used was a 60' sector field mass spectrometer[zl. The residual gas pressure was reduced to < 10-9 mm; there was no disturbance from water vapor during the mass spectrometric measurements. 1 2 28 29 Table 1. Types of ions and intensities in the field ion mass spectrum of NH3 on an iron tip.