Optical frequency domain reflectometry measurements of spatio-temporal temperature inside catalytic reactors: Applied to study wrong-way behavior

•New method of measuring internal catalytic reactor temperature.•Method achieves ±3 mm precision and sampling frequency of 0.9 Hz.•Method applied to transient exothermic catalytic reaction in a monolith channel.•Method demonstrates wrong-way temperature rise for Pt-catalyzed NH3 oxidation.•Temperature rise due to feed temperature decrease exceeds that due to flow increase.

An Optical Backscatter Reflectometer (OBR) with optical frequency domain reflectometry (OFDR) enables measurement of the spatial temporal temperature inside catalytic reactors with unparalleled combined spatial and temporal resolution. It was used to measure the transient temperature inside a single channel of a washcoated monolith reactor in which the Pt-catalyzed oxidation of ammonia was carried out. Measurements of the monolith temperature response to either a rapid step decrease in the feed temperature or an increase of the flow rate were used to test the capability of the OFDR technique and to determine their impact on the transient temperature rise of the monolithic catalyst. The rapid step increase in the flow rate can generate a transient peak temperature of the solid phase higher than that at the steady state. This transient temperature rise was smaller than that caused by a sudden decrease of the feed temperature.

Graphical abstractThe use of optical fiber to measure the spatio-temporal temperature inside a monolith reactor: applied to study wrong-way behavior. Hoang Nguyen, Dan Luss, Michael P. Harold.Figure optionsDownload full-size imageDownload as PowerPoint slide