A fast response, local gas-sampling system for studies of catalytic reactions at 1–103 Torr; application to the H2D2 exchange and H2 oxidation reactions on Pt

Abstract An experimental system designed for studies of catalytic reactions at pressures of 1–10 3 Torr is described. Special features of the system are the local sampling of gas close to the catalyst and the small response time (~50 msec). The gas is sampled locally in space at a distance of ~0.1 mm from the catalyst by a specially prepared quartz tube orifice leak. Gas analysis is made by mass spectrometry. The design reduces several of the problems connected with studies of mass-transfer-limited reactions and rapidly varying reaction rates such as, for example, ignition phenomena and chemical oscillations. Results for the H 2 D 2 exchange and H 2 oxidation reactions on polycrystalline Pt at 990 Torr are used to illustrate the performance of the experimental system.