Oscillations in methylamine decomposition on Pt, Rh, and Ir: Experiments and models

Oscillations with large amplitudes (>500 K), high frequencies (>8 Hz), and good reproducibility are observed in methylamine decomposition on electrically heated Pt, Rh, and Ir wires at pressures of 0.25–8.0 Torr and temperatures between 900 and 1500 K. The major reaction involves formation of HCN which is endothermic by 37 kcal/mol, so that the reaction strongly cools the wire, which counteracts resistive heating. A photodiode array was used to monitor spatial and temporal oscillations with resolutions of 1 mm and 30 Hz, respectively. On Pt, the frequency increased with increasing pressure and with decreasing wire diameter, while amplitude was a weak function of these parameters. On Ir, oscillations were more complex with regions of the wire often oscillating independently and more variability between experiments. However, the overall behavior resembles that on Pt. On Rh, frequencies were much lower (<0.03 Hz), oscillations occurred over a smaller temperature range and halves of the wire frequently oscill...

[1]  Dan Luss,et al.  Standing temperature waves on electrically heated catalytic ribbons , 1989 .

[2]  L. Schmidt,et al.  CH3NH2 decomposition and oxidation on polycrystalline platinum: Steady-state kinetics and oscillations , 1988 .

[3]  M. Sheintuch,et al.  Dynamic behavior of inhomogeneous solutions in catalysts with self-inhibited reactions , 1988 .

[4]  G. Ertl,et al.  Kinetic oscillations in the catalytic CO oxidation on Pt(100): Periodic perturbations , 1987 .

[5]  D. Luss,et al.  Identification of observed dynamic bifurcations and development of qualitative models , 1987 .

[6]  J. Sinfelt,et al.  Metal-catalyzed reactions of methylamine in the presence of hydrogen , 1986 .

[7]  Luis F. Razon,et al.  Intrinsically Unstable Behavior during the Oxidation of Carbon Monoxide on Platinum , 1986 .

[8]  Klavs F. Jensen,et al.  Bifurcation phenomena in CSTR dynamics: A system with extraneous thermal capacitance , 1986 .

[9]  A. Varma,et al.  Complex dynamic behaviour during ethylene oxidation on a supported silver catalyst , 1986 .

[10]  L. Doraiswamy.  Recent advances in the engineering analysis of chemically reacting systems , 1984 .

[11]  L. Schmidt,et al.  Reaction between nitric oxide and ammonia on polycrystalline platinum. 1. Steady-state kinetics , 1983 .

[12]  C. Vayenas,et al.  Kinetics, limit cycles, and mechanism of the ethylene oxidation on platinum , 1980 .

[13]  M. Flytzani-Stephanopoulos,et al.  Steady state and transient oscillations in NH3 oxidation on Pt , 1980 .

[14]  E. Wicke,et al.  Unstable and Oscillatory Behaviour in Heterogeneous Catalysis , 1980 .

[15]  H. Suhl,et al.  Theory of oscillatory oxidation of carbon monoxide over platinum , 1979 .

[16]  G. Eigenberger.  Kinetic instabilities in heterogeneously catalyzed reactions. Pt. 2, Oscillatory instabilities with Langmuir type reactions , 1978 .

[17]  N. J. Clark,et al.  Reactions of aliphatic amines over evaporated metal films , 1966 .

[18]  R. Moss,et al.  The catalytic fission of the carbon-nitrogen bond I. The reactions of methylamine and hydrogen on evaporated metal films , 1956, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.