Ammonia synthesis over rhenium

Fig. 7. Structure sensitivity in the ammonia synthesis over rhenium single-crystal faces. The turnover frequencies (TF) are given as NH3 molecules/cm2/s (PIotai = 20 atm, H2 N2 = 3 1, Tcryslai = 870 K). Schematics of the atomic structure of each surface are given above each bar. From Ref. 85.

Figure 4.4. The structure sensitivity of ammonia synthesis over rhenium single-crystal surfaces/ Schematics of the atomic structure of each surface is given above each bar.

Additional research, which supports the contention that highly coordinated surface sites are most active for ammonia synthesis, has been carried out on rhenium. In this study the rate of ammonia synthesis over the (0001), (lOlO), (1120), and (1121) faces were determined (Fig. 4.4). Here, as in the case of iron the face with the highest activity, the (1121) plane, is the surface which exposes the most highly coordinated sites. It is also shown in Fig. 4.4 that the (1121) face... 

---