Hysteresis phenomena in the NO-H{sub 2} reaction over Ru(0001)
The NO-H{sub 2} reaction was studied at NO pressures between 7.7 x 10{sup {minus}8} and 7.7 x 10{sup {minus}7} mbar and for H{sub 2}/NO ratios varying from 6 to 127. Hysteresis phenomena were observed during a heat and cool cycle dependent on the H{sub 2}/NO ratio, with the heating branch exhibiting less activity than the cooling branch. Apart from the H{sub 2}/NO ratio, the shape of the hysteresis also depends on the heating rate and the NO pressure. An almost 100% selectivity toward N{sub 2} is observed with only small amounts of NH{sub 3} formation at higher H{sub 2}/NO ratios. From the AES and TDS experiments it was concluded that an O layer that is inactive to reaction with hydrogen is responsible for the low reaction rate on the heating branch. Once the O layer is removed, the total reaction rate is determined by the removal of N{sub ads}. The lateral interaction between O{sub ads} and N{sub ads} turns out to be repulsive.
- Research Organization:
- Leiden Univ. (NL)
- OSTI ID:
- 20034442
- Journal Information:
- Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical, Vol. 104, Issue 14; Other Information: PBD: 13 Apr 2000; ISSN 1089-5647
- Country of Publication:
- United States
- Language:
- English
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