Direct detection of coke deposits on fixed bed catalysts by electrical sensors

Müller, Norbert; Jess, Andreas; Moos, Ralf

doi:10.1016/j.snb.2009.03.008

Cited by 13 publications

(8 citation statements)

References 10 publications

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“…In previous studies with electrically contacted single catalyst particles as sensors, it has been shown that there is a clear relation between the amount of coke load, L coke , and electrical conductivity [28]. Deposits on the catalyst like ashes or contaminating oxides is highly unlikely and even if small deposits occurred, the huge increase in conductivity due to coke loading would prevail all other minor effects.…”

Section: Methodsmentioning

confidence: 99%

“…Deposits on the catalyst like ashes or contaminating oxides is highly unlikely and even if small deposits occurred, the huge increase in conductivity due to coke loading would prevail all other minor effects. In [28] it has additionally been shown that even for Cr 2 O 3 -coated catalyst pellets, the semiconductor gas sensor effect amounts only to a factor of 2-2.5 in the resistance for both H 2 or toluene, both dosed in the %-range. Hence, compared to the effect of coke loading with resistance changes of several decades, the gas sensor effect can be neglected.…”

Section: Methodsmentioning

confidence: 99%

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In situ detection of coke deposits on fixed-bed catalysts by a radio frequency-based method

Rauch

Fremerey

Jess

et al. 2013

Sensors and Actuators B: Chemical

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

In situ detection of coke deposits on fixed-bed catalysts by a radio frequency-based method

Rauch

Fremerey

Jess

et al. 2013

Sensors and Actuators B: Chemical

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“…The wires passed a ceramic tube which served as a feedthrough and were connected to the impedance analyzer (HP 4284A). Impedance spectra were taken from 100 Hz to 1 MHz with an amplitude of 1 V. More experimental details can be found in [17]. Fig.…”

Section: Methodsmentioning

confidence: 99%

“…The fresh catalyst (Al 2 O 3 ) behaves like a capacitor. With increasing coke load, highly conductive coke seeds are formed, which are responsible for the change of the signal [17]. Thus, the whole particle can be regarded as a parallel connection of different capacitors and resistors.…”

Section: In Situ Monitoring Of Cokementioning

confidence: 99%

In situ Monitoring of Coke Deposits during Coking and Regeneration of Solid Catalysts by Electrical Impedance‐based Sensors

2009

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The activity of solid catalysts is often substantially reduced by the formation of coke. The in situ monitoring of the coke load of catalyst particles could therefore be a controlling instrument of high value. Such sensors could be useful to measure the axial coke profile in a fixed bed reactor, both during coke formation and regeneration by coke burn-off. As a contribution to the development of such sensors, single particles of an alumina oxide catalyst were used as a model system. The particles were electrically contacted and characterized by electrical impedance spectroscopy. The coke formation/burn-off and the impedance were simultaneously measured in a magnetic suspension balance. A clear relationship between the coke loading and the respective electrical impedance signal could be observed, both during coke formation and during the regeneration by coke burn-off. Kinetic studies were conducted to verify the influence of mass transfer limitations on the impedance signal.

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“…al. [9,10] used electronic impedance spectroscopy (EIS) to measure the changes in electrical impedance of a catalyst pellet as coke deposited on the surface of the pellet. EIS characterizes materials by sending electrical signals of various frequencies into the sample and analyzing the signal that passes through the sample.…”

Section: Prior Workmentioning

confidence: 99%

Development of an impedance-based sensor for detection of catalyst coking in fuel reforming systems

Wheeler

2013

Sensors and Actuators B: Chemical

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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 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, indicating coke formation.Sensors were 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.

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Direct detection of coke deposits on fixed bed catalysts by electrical sensors

Cited by 13 publications

References 10 publications

In situ detection of coke deposits on fixed-bed catalysts by a radio frequency-based method

In situ detection of coke deposits on fixed-bed catalysts by a radio frequency-based method

In situ Monitoring of Coke Deposits during Coking and Regeneration of Solid Catalysts by Electrical Impedance‐based Sensors

Development of an impedance-based sensor for detection of catalyst coking in fuel reforming systems

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