Oscillating microbalance reactor

Characterization of Catalysts under Working Conditions with an Oscillating Microbalance Reactor... 

Fig. 1. The tapered element oscillating microbalance reactor manufactured by Patashnick and Rupprecht (TEOM Series 1500 PMA Reaction Kinetics Analyzer). The term Cat. refers to the catalyst sample.

It is impossible to comprehensively discuss all non-vibrational in situ techniques with a potential application to oxidation catalysts within this chapter. Therefore, we have selected only those methods for a more detailed presentation which have seen a widespread application so far and/or offer unique opportunities for understanding the functioning of real catalysts. For more specific in situ methods, such as the microscopy techniques mentioned above, Mossbauer spectroscopy which is restricted to the viewing of elements only, or thermo-analytical studies using an oscillating microbalance reactor,the reader is referred to the respective reviews. 

Chen, D., Bjorgum, E., Christensen, K., etal. (2007). Characterization of Catalysts underworking Conditions with an Oscillating Microbalance Reactor, Adv. Catal., 51, pp. 351-382. 

Volume 50 of Advances in Catalysis, published in 2006, was the hrst of a set of three focused on physical characterization of solid catalysts in the functioning state. This volume is the second in the set. The hrst four chapters are devoted to vibrational spectroscopies, including Fourier transform infrared (Lamberti et al.), ultraviolet Raman (Stair), inelastic neutron scattering (Albers and Parker), and infrared-visible sum frequency generation and polarization-modulation infrared rehection absorption (Rupprechter). Additional chapters deal with electron paramagnetic resonance (EPR) (Bruckner) and Mossbauer spectroscopies (Millet) and oscillating microbalance catalytic reactors (Chen et al.). 

The Tapered Element Oscillating Microbalance (TEOM) reactor has recently been applied to study deactivation of zeolite catalysts [7,8]. The main advantage of the TEOM reactor is that all gases in the reaction mixture are forced to flow through the catalyst bed as in a conventional fixed-bed reactor. Coupled with on-line gas chromatography, the catalyst activity, selectivity and coking rate can be measured simultaneously as a fimction of the amount of coke on the catalyst. Hence, the TEOM represents a unique way of studying the effect of coke deposition in detail. 

Kinetics and diffusion Steady-state isotopic transient kinetic analysis (SSITKA) Temporal analysis of products (TAP) Tapered element oscillating microbalance (TEOM) Temperature scanning reactor (TSR) Zero length chromatography (ZLC) Pulsed field gradient NMR... 

The experiments were performed in the Tapered Element Oscillating Microbalance (TEOM) reactor (7,8), in which carbon formation and deactivation could be measured simultaneously by coupling with on-line GC analysis. The dry reforming of methane was studied on an industrial Ni (11 wt%)/(Ca0)a-Al203 catalyst at temperatures of 500 °C and 650 °C, total pressures of 0.1 MPa and 0.5 MPa and a CO2/CH4 ratio of 1. The BET surface area of the catalyst was 5.5 m /g, and the Ni surface area 0.33 m /g. The detailed experimental procedures were similar to that reported previously (7). 

Rebo HP, Chen D, Blekkan EA, et al Application of the oscillating microbalance catalytic reactor kinetics and coke formation over Pt-Sn/A1203 in propane dehydrogenation. In Parmaliana A, Sanfilippo D, Frusteri F, Vaccari A, Arena Feditors Natural gas conversion V, vol. 119, Amsterdam, 1998, Elsevier, pp 617-622. 

In the inertial microbalance, the mass located at the tip of an oscillating tapered quartz element is detected as a change in its vibrational frequency. The design of this equipment provides a packed bed of catalyst through which all the gas is forced to flow, and the classical methods of testing for differential operation in an ideal plug-flow fixed-bed reactor can therefore be applied. 

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