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

Abstract The aim of this work is to study whether a contactless radio frequency-based method is suitable to monitor both coking and regeneration (coke burn-off) of industrial fixed-bed catalysts directly and in operando . The tubular steel reactor serves as an electromagnetic cavity and two waveguide feeds (coaxial antennas) are used to impress and receive electromagnetic waves between 1 and 20 GHz. Shifts of the resonance frequencies mirror the coke loading in the lowly loaded state and strongly decreasing power transmission over the entire frequency range goes along with increasing coke load at higher coke loadings. Both the locally homogeneously distributed coking process and the coke burn-off process that starts in the reactor front and moves through the reactor can be observed by the radio frequency-based method.

[1]  Ralf Moos,et al.  Direct Catalyst Monitoring by Electrical Means: An Overview on Promising Novel Principles , 2009 .

[2]  Ralf Moos,et al.  Sensing the soot load in automotive diesel particulate filters by microwave methods , 2010 .

[3]  R. C. Weast.  CRC Handbook of Chemistry and Physics , 1973 .

[4]  J. Santamaría,et al.  Effect of thermal aging upon the regeneration kinetics of a coked Cr2O3Al2O3 catalyst , 1996 .

[5]  A. Jess,et al.  Verkokung und Koksabbrand in heterogenen Katalysatoren , 2006 .

[6]  Jacob A. Moulijn,et al.  Chemical Process Technology , 2001 .

[7]  James E. Parks,et al.  Loading and Regeneration Analysis of a Diesel Particulate Filter with a Radio Frequency-Based Sensor , 2010 .

[8]  Adrian Porch,et al.  Rubidium doped zeolite rho: structure and microwave conductivity of a metallic zeolite. , 2004, Dalton transactions.

[9]  Ralf Moos,et al.  Catalysts as Sensors—A Promising Novel Approach in Automotive Exhaust Gas Aftertreatment , 2010, Sensors.

[10]  Victor Ingeström,et al.  A Method for Estimating Soot Load in a DPF using an RF-based Sensor , 2012 .

[11]  Ralf Moos,et al.  Direct detection of coke deposits on fixed bed catalysts by electrical sensors , 2010 .

[12]  D. Pozar.  Microwave Engineering , 1990 .

[13]  Christoph Kern,et al.  Direct detection of coking and regeneration of single particles and fixed bed reactors by electrical sensors , 2010 .

[14]  Philip L. Walker,et al.  Gas Reactions of Carbon , 1975 .

[15]  Gunter Hagen,et al.  Monitoring the Ammonia Loading of Zeolite‐Based Ammonia SCR Catalysts by a Microwave Method , 2011 .

[16]  Christoph Kern,et al.  Regeneration of coked catalysts—modelling and verification of coke burn-off in single particles and fixed bed reactors , 2005 .

[17]  Ralf Moos,et al.  Determination of the NOx Loading of an Automotive Lean NOx Trap by Directly Monitoring the Electrical Properties of the Catalyst Material Itself , 2011, Sensors.

[18]  C. H. Bartholomew.  Mechanisms of catalyst deactivation , 2001 .

[19]  P. Magnoux,et al.  Organic chemistry of coke formation , 2001 .

[20]  D. Trimm.  The regeneration or disposal of deactivated heterogeneous catalysts , 2001 .

[21]  Ralf Moos,et al.  Catalyst State Observation via the Perturbation of a Microwave Cavity Resonator , 2008 .

[22]  Freek Kapteijn,et al.  Catalyst deactivation: is it predictable?: What to do? , 2001 .

[23]  A. Jess,et al.  Initial tests to detect quantitatively the coke loading of reforming catalysts by a contactless microwave method , 2011 .

[24]  M. Dressel,et al.  Analysis of broadband microwave conductivity and permittivity measurements of semiconducting materials , 2007, 0712.0741.

[25]  M. Larsson,et al.  Estimation of reversible and irreversible coke by transient experiments , 1997 .

[26]  E. Wolf,et al.  Catalysts deactivation by coking , 1982 .

[27]  S. Ordóñez,et al.  Thermogravimetric determination of coke deposits on alumina-supported noble metal catalysts used as hydrodechlorination catalysts , 2001 .

[28]  D. Trimm.  Control of coking , 1984 .

[29]  Ralf Moos,et al.  In situ Monitoring of Coke Deposits during Coking and Regeneration of Solid Catalysts by Electrical Impedance‐based Sensors , 2010 .