Impedance-Based Sensor for Detection of Catalyst Coking in
Fuel Reforming Systems
Jeffery L. Wheeler, Jason M. Porter, and Neal P. Sullivan
Summary: A novel sensor for detecting the early stages of catalyst coking in fuel reforming
Description: A novel sensor for detecting the early stages of catalyst coking in fuel reforming
systems has been developed. The sensor was manufactured by inkjet printing a colloidal
suspension of ceramic powders to create thin (20 μm) catalytic and conductive elements of the
sensor. The catalytic elements of the sensor are composed of a Ni-YSZ cermet. The Ni-YSZ
cermet was prepared with a concentration below the percolation limit (20 vol%) of nickel,
ensuring a low electrical conductivity. As coke forms on the catalyst material, the nickel nodules
in the Ni-YSZ are connected by electrically conductive carbon and the conductivity of the
catalyst material increases. The sensor was tested in a 1% ethylene environment to induce
coking. The sensor showed a strong response to coking by producing a signal on the order of
hundreds of millivolts. The mass of the coke load was determined to be below the detection
limit of available thermogravimetric analyzers (TGA) (<10 μg). The coke load was further
examined with a field effect scanning electron microscope (FESEM) and was found to be
primarily filamentous carbon. Carbon lament 10-50 nm in diameter connected nickel nodules in
the sensors catalyst material resulting in a change in resistance in the catalyst material.
Main Advantages of this Invention:
 Low manufacturing cost using readily available
 Monitors coking in real time
Potential Areas of Application:
 Solid oxide fuel cell systems using hydrocarbon fuels
 Steam methane reforming to produce hydrogen
ID number: # 13012
Intel ectual Property Status: US utility application pending (#14/245,341).
Opportunity: We are seeking an exclusive or non-exclusive licensee for marketing,
manufacturing, and sale of this technology.
For more information contact:
William Vaughan, Director of Technology Transfer
Colorado School of Mines, 1500 Illinois Street, Guggenheim Hall Suite 314, Golden, CO 80401
Phone: 303-384-2555; e-mail: