Optically accessible channel reactor for the kinetic investigation of hydrocarbon reforming reactions

Abstract

A new experimental reactor concept for studying heterogeneously catalyzed gas phase reactions was developed, which allows true surface temperature measurements along the reactor through a quartz window without affecting the flow in the reactor using IR thermography. The catalyst is coated as a thin layer onto a metal plate. The laminar flow field is similar to the one in a monolith channel. A small stream of gas can be withdrawn with a moveable capillary to measure the concentration profile in the reactor. The spatial resolution of the gas sampling is ≤0.1 mm. Two- and three-dimensional fluid dynamic modeling of the channel reactor was performed to check the velocity field in the channel for different operating conditions. Buoyancy forces were insignificant at the conditions studied; the parabolic inlet flow profile was maintained along the reactor channel. The heat loss by radiation from the quartz glass top surface was found to be three times larger than the heat loss by free convection. The methanation of carbon monoxide and carbon dioxide was studied at 550 and 500 °C, respectively. For these reactions nearly isothermal conditions were observed. The partial oxidation of methane, performed without diluting the feed, was also studied at 500 and 550 °C. The measured hot spots correlated well with the concentration profile measurements. Film diffusional limitations were found only significant for the oxidation reaction.