A Chopped Fast Flow Technique For Transient Surface Reaction Rate Measurements Carbon Deposition and Oxidation on Hot Pt

Journal Article

Halpern,B.,, . 1986

• رابط المنشور على الويب: Chemical Eng. Science
• رقم العدد: 4
• رقم الإصدار السنوي: 41
• الصفحات: 899-904

مستخلص المنشور

A novel "chopped fast flow" technique for surface reaction studies is described. It extends the molecular beam chopping approach to fast flow systems, exploits higher reactant and product fluxes, and permits transient rate measurements of fast surface reactions at much higher pressure. It employs an oscillating needle gas source to generate reactant square wave flows.
The method was used to measure rates of carbon deposition following impact of hydrocarbon molecules on a hot Pt surface (T >1000 oR). Square wave flows of hydrocarbon and oxygen, out of phase, produced period changes in carbon coverage, surface work function, and the-ionic electron emission current. Carbon deposition rates were inferred from the variation of emission current with time. Deposition probabilities were low and very sensitive to hydrocarbon chain length. The results suggest that energy transfer during the short physisorption lifetime of the hydrocarbon molecule limits the deposition probability.