A laboratory test setup for in situ measurements of the dielectric properties of catalyst powder samples under reaction conditions by microwave cavity perturbation: set up and initial tests

Dietrich, Markus, Rauch, Dieter, Porch, Adrian ORCID: https://orcid.org/0000-0001-5293-8883 and Moos, Ralf 2014. A laboratory test setup for in situ measurements of the dielectric properties of catalyst powder samples under reaction conditions by microwave cavity perturbation: set up and initial tests. Sensors 14 (9) , pp. 16856-16868. 10.3390/s140916856

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Abstract

The catalytic behavior of zeolite catalysts for the ammonia-based selective catalytic reduction (SCR) of nitrogen oxides (NOX) depends strongly on the type of zeolite material. An essential precondition for SCR is a previous ammonia gas adsorption that occurs on acidic sites of the zeolite. In order to understand and develop SCR active materials, it is crucial to know the amount of sorbed ammonia under reaction conditions. To support classical temperature-programmed desorption (TPD) experiments, a correlation of the dielectric properties with the catalytic properties and the ammonia sorption under reaction conditions appears promising. In this work, a laboratory test setup, which enables direct measurements of the dielectric properties of catalytic powder samples under a defined gas atmosphere and temperature by microwave cavity perturbation, has been developed. Based on previous investigations and computational simulations, a resonator cavity and a heating system were designed, installed and characterized. The resonator cavity is designed to operate in its TM010 mode at 1.2 GHz. The first measurement of the ammonia loading of an H-ZSM-5 zeolite confirmed the operating performance of the test setup at constant temperatures of up to 300 °C. It showed how both real and imaginary parts of the relative complex permittivity are strongly correlated with the mass of stored ammonia.

Item Type:	Article
Date Type:	Published Online
Status:	Published
Schools:	Engineering
Subjects:	T Technology > TA Engineering (General). Civil engineering (General)
Uncontrolled Keywords:	ammonia SCR; ammonia storage; H-ZSM-5; cavity perturbation; complex permittivity; in operando; radio frequency
Publisher:	MDPI Publishing
ISSN:	1424-8220
Date of First Compliant Deposit:	18 April 2017
Date of Acceptance:	2 September 2014
Last Modified:	05 May 2023 23:15
URI:	https://orca.cardiff.ac.uk/id/eprint/67138

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